Recognise more exceptions (#129)

CLAUDE.md

@@ -67,13 +67,12 @@ dotnet run --project WoofWare.PawPrint.App/WoofWare.PawPrint.App.fsproj -- CShar
 - `Corelib.fs`: Core library type definitions (String, Array, etc.)
 
 **WoofWare.PawPrint.Test**
-- Uses Expecto as the test framework
+- Uses NUnit as the test framework
 - Test cases are defined in `TestPureCases.fs` and `TestImpureCases.fs`
-- C# source files in `sources{Pure,Impure}/` are compiled and executed by the runtime as test cases
+- C# source files in `sources{Pure,Impure}/` are compiled and executed by the runtime as test cases; files in `sourcesPure` are automatically turned into test cases with no further action (see TestPureCases.fs for the mechanism)
 - `TestHarness.fs` provides infrastructure for running test assemblies through the interpreter
 - Run all tests with `dotnet run --project WoofWare.PawPrint.Test/WoofWare.PawPrint.Test.fsproj -- --no-spinner` (note the additional `--`)
 - Run a specific test with `dotnet run --project WoofWare.PawPrint.Test/WoofWare.PawPrint.Test.fsproj -- --filter-test-case StringWithinTestName --no-spinner`
-- Pending test definitions must be moved into the non-pending test case list before they can be run.
 
 **WoofWare.PawPrint.App**
 - Entry point application for running the interpreter

WoofWare.PawPrint.Domain/Assembly.fs

@@ -423,8 +423,8 @@ module Assembly =
     let rec resolveTypeRef
         (assemblies : ImmutableDictionary<string, DumpedAssembly>)
         (referencedInAssembly : DumpedAssembly)
-        (target : TypeRef)
         (genericArgs : ImmutableArray<TypeDefn>)
+        (target : TypeRef)
         : TypeResolutionResult
         =
         match target.ResolutionScope with
@@ -495,7 +495,7 @@ module Assembly =
         | None ->
 
         match assy.TypeRef ns name with
-        | Some typeRef -> resolveTypeRef assemblies assy typeRef genericArgs
+        | Some typeRef -> resolveTypeRef assemblies assy genericArgs typeRef
         | None ->
 
         match assy.ExportedType (Some ns) name with
@@ -532,7 +532,7 @@ module DumpedAssembly =
             | Some (BaseTypeInfo.TypeRef r) ->
                 let assy = loadedAssemblies.[source.FullName]
                 // TODO: generics
-                match Assembly.resolveTypeRef loadedAssemblies assy assy.TypeRefs.[r] ImmutableArray.Empty with
+                match Assembly.resolveTypeRef loadedAssemblies assy ImmutableArray.Empty assy.TypeRefs.[r] with
                 | TypeResolutionResult.FirstLoadAssy _ ->
                     failwith
                         "seems pretty unlikely that we could have constructed this object without loading its base type"
@@ -560,3 +560,36 @@ module DumpedAssembly =
             | None -> ResolvedBaseType.Object
 
         go source baseTypeInfo
+
+    let typeInfoToTypeDefn
+        (bct : BaseClassTypes<DumpedAssembly>)
+        (assemblies : ImmutableDictionary<string, DumpedAssembly>)
+        (ti : TypeInfo<TypeDefn, TypeDefn>)
+        : TypeDefn
+        =
+        ti
+        |> TypeInfo.toTypeDefn
+            bct
+            (fun n -> assemblies.[n.FullName])
+            _.Name
+            (fun x y -> x.TypeDefs.[y])
+            (fun x y ->
+                let r = x.TypeRefs.[y] |> Assembly.resolveTypeRef assemblies x ImmutableArray.Empty
+
+                match r with
+                | TypeResolutionResult.FirstLoadAssy assemblyReference -> failwith "todo"
+                | TypeResolutionResult.Resolved (dumpedAssembly, typeInfo) ->
+                    let result =
+                        typeInfo |> TypeInfo.mapGeneric (fun typeDef -> failwith "TODO: generics")
+
+                    dumpedAssembly, result
+            )
+
+    let typeInfoToTypeDefn'
+        (bct : BaseClassTypes<DumpedAssembly>)
+        (assemblies : ImmutableDictionary<string, DumpedAssembly>)
+        (ti : TypeInfo<GenericParamFromMetadata, TypeDefn>)
+        =
+        ti
+        |> TypeInfo.mapGeneric (fun (par, _) -> TypeDefn.GenericTypeParameter par.SequenceNumber)
+        |> typeInfoToTypeDefn bct assemblies

WoofWare.PawPrint.Domain/ConcreteType.fs

@@ -33,6 +33,20 @@ type ConcreteType<'typeGeneric> =
             _Generics : ImmutableArray<'typeGeneric>
         }
 
+    override this.ToString () : string =
+        let basic = $"%s{this.Assembly.Name}.%s{this.Namespace}.%s{this.Name}"
+
+        let generics =
+            if this.Generics.IsEmpty then
+                ""
+            else
+                this.Generics
+                |> Seq.map string
+                |> String.concat ", "
+                |> fun x -> "<" + x + ">"
+
+        basic + generics
+
     member this.Assembly : AssemblyName = this._AssemblyName
     member this.Definition : ComparableTypeDefinitionHandle = this._Definition
     member this.Generics : ImmutableArray<'typeGeneric> = this._Generics

WoofWare.PawPrint.Domain/Constants.fs

@@ -0,0 +1,16 @@
+namespace WoofWare.PawPrint
+
+[<AutoOpen>]
+module Constants =
+
+    [<Literal>]
+    let SIZEOF_INT = 4
+
+    [<Literal>]
+    let SIZEOF_OBJ = 8
+
+    [<Literal>]
+    let DEFAULT_STRUCT_ALIGNMENT = 8
+
+    [<Literal>]
+    let NATIVE_INT_SIZE = 8

WoofWare.PawPrint.Domain/FieldInfo.fs

@@ -32,9 +32,14 @@ type FieldInfo<'typeGeneric, 'fieldGeneric> =
         /// literal, and other characteristics.
         /// </summary>
         Attributes : FieldAttributes
+
+        /// Static fields don't have an offset at all; also, instance fields which don't have an explicit offset (but
+        /// which of course do have one implicitly, which is most fields) are None here.
+        Offset : int option
     }
 
     member this.HasFieldRVA = this.Attributes.HasFlag FieldAttributes.HasFieldRVA
+    member this.IsStatic = this.Attributes.HasFlag FieldAttributes.Static
 
     override this.ToString () : string =
         $"%s{this.DeclaringType.Assembly.Name}.{this.DeclaringType.Name}.%s{this.Name}"
@@ -52,23 +57,28 @@ module FieldInfo =
         let fieldSig = def.DecodeSignature (TypeDefn.typeProvider assembly, ())
         let declaringType = def.GetDeclaringType ()
 
-        let typeGenerics =
-            mr.GetTypeDefinition(declaringType).GetGenericParameters ()
-            |> GenericParameter.readAll mr
-
         let decType = mr.GetTypeDefinition declaringType
+
+        let typeGenerics = decType.GetGenericParameters () |> GenericParameter.readAll mr
+
         let declaringTypeNamespace = mr.GetString decType.Namespace
         let declaringTypeName = mr.GetString decType.Name
 
         let declaringType =
             ConcreteType.make assembly declaringType declaringTypeNamespace declaringTypeName typeGenerics
 
+        let offset =
+            match def.GetOffset () with
+            | -1 -> None
+            | s -> Some s
+
         {
             Name = name
             Signature = fieldSig
             DeclaringType = declaringType
             Handle = handle
             Attributes = def.Attributes
+            Offset = offset
         }
 
     let mapTypeGenerics<'a, 'b, 'field> (f : int -> 'a -> 'b) (input : FieldInfo<'a, 'field>) : FieldInfo<'b, 'field> =
@@ -80,5 +90,5 @@ module FieldInfo =
             DeclaringType = declaringType
             Signature = input.Signature
             Attributes = input.Attributes
-
+            Offset = input.Offset
         }

WoofWare.PawPrint.Domain/TypeConcretisation.fs

@@ -138,6 +138,23 @@ module ConcreteActivePatterns =
             | None -> None
         | _ -> None
 
+    let (|ConcreteChar|_|) (concreteTypes : AllConcreteTypes) (handle : ConcreteTypeHandle) : unit option =
+        match handle with
+        | ConcreteTypeHandle.Concrete id ->
+            match concreteTypes.Mapping |> Map.tryFind id with
+            | Some ct ->
+                if
+                    ct.Assembly.Name = "System.Private.CoreLib"
+                    && ct.Namespace = "System"
+                    && ct.Name = "Char"
+                    && ct.Generics.IsEmpty
+                then
+                    Some ()
+                else
+                    None
+            | None -> None
+        | _ -> None
+
     let (|ConcreteRuntimeFieldHandle|_|) (concreteTypes : AllConcreteTypes) (handle : ConcreteTypeHandle) =
         match handle with
         | ConcreteTypeHandle.Concrete id ->
@@ -166,6 +183,24 @@ module ConcreteActivePatterns =
             | _ -> None
         | _ -> None
 
+    let (|ConcreteGenericArray|_|)
+        (concreteTypes : AllConcreteTypes)
+        (eltType : ConcreteTypeHandle)
+        (handle : ConcreteTypeHandle)
+        =
+        match handle with
+        | ConcreteTypeHandle.Concrete id ->
+            match concreteTypes.Mapping |> Map.tryFind id with
+            | Some ct when
+                ct.Assembly.Name = "System.Private.CoreLib"
+                && ct.Namespace = "System"
+                && ct.Name = "Array"
+                && Seq.tryExactlyOne ct.Generics = Some eltType
+                ->
+                Some ()
+            | _ -> None
+        | _ -> None
+
     let (|ConcreteObj|_|) (concreteTypes : AllConcreteTypes) (handle : ConcreteTypeHandle) : unit option =
         match handle with
         | ConcreteTypeHandle.Concrete id ->
@@ -285,6 +320,40 @@ module ConcreteActivePatterns =
             | None -> None
         | _ -> None
 
+    let (|ConcreteUInt32|_|) (concreteTypes : AllConcreteTypes) (handle : ConcreteTypeHandle) : unit option =
+        match handle with
+        | ConcreteTypeHandle.Concrete id ->
+            match concreteTypes.Mapping |> Map.tryFind id with
+            | Some ct ->
+                if
+                    ct.Assembly.Name = "System.Private.CoreLib"
+                    && ct.Namespace = "System"
+                    && ct.Name = "UInt32"
+                    && ct.Generics.IsEmpty
+                then
+                    Some ()
+                else
+                    None
+            | None -> None
+        | _ -> None
+
+    let (|ConcreteUInt64|_|) (concreteTypes : AllConcreteTypes) (handle : ConcreteTypeHandle) : unit option =
+        match handle with
+        | ConcreteTypeHandle.Concrete id ->
+            match concreteTypes.Mapping |> Map.tryFind id with
+            | Some ct ->
+                if
+                    ct.Assembly.Name = "System.Private.CoreLib"
+                    && ct.Namespace = "System"
+                    && ct.Name = "UInt64"
+                    && ct.Generics.IsEmpty
+                then
+                    Some ()
+                else
+                    None
+            | None -> None
+        | _ -> None
+
     let (|ConcreteSingle|_|) (concreteTypes : AllConcreteTypes) (handle : ConcreteTypeHandle) : unit option =
         match handle with
         | ConcreteTypeHandle.Concrete id ->
@@ -314,6 +383,13 @@ module ConcreteActivePatterns =
         | ConcreteTypeHandle.Pointer inner -> Some inner
         | _ -> None
 
+type IAssemblyLoad =
+    abstract LoadAssembly :
+        loadedAssemblies : ImmutableDictionary<string, DumpedAssembly> ->
+        referencedIn : AssemblyName ->
+        handle : AssemblyReferenceHandle ->
+            ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly
+
 [<RequireQualifiedAccess>]
 module TypeConcretization =
 
@@ -389,8 +465,7 @@ module TypeConcretization =
 
     // Helper function for assembly loading with retry pattern
     let private loadAssemblyAndResolveTypeRef
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (loadAssembly : IAssemblyLoad)
         (ctx : ConcretizationContext<'corelib>)
         (currentAssembly : AssemblyName)
         (typeRef : TypeRef)
@@ -403,7 +478,7 @@ module TypeConcretization =
 
         // First try to resolve without loading new assemblies
         let resolutionResult =
-            Assembly.resolveTypeRef ctx.LoadedAssemblies currentAssy typeRef ImmutableArray.Empty
+            Assembly.resolveTypeRef ctx.LoadedAssemblies currentAssy ImmutableArray.Empty typeRef
 
         match resolutionResult with
         | TypeResolutionResult.Resolved (targetAssy, typeInfo) -> (targetAssy, typeInfo), ctx
@@ -411,7 +486,8 @@ module TypeConcretization =
             // Need to load the assembly
             match typeRef.ResolutionScope with
             | TypeRefResolutionScope.Assembly assyRef ->
-                let newAssemblies, _ = loadAssembly currentAssembly assyRef
+                let newAssemblies, _ =
+                    loadAssembly.LoadAssembly ctx.LoadedAssemblies currentAssembly assyRef
 
                 let newCtx =
                     { ctx with
@@ -420,7 +496,7 @@ module TypeConcretization =
 
                 // Now try to resolve again with the loaded assembly
                 let resolutionResult2 =
-                    Assembly.resolveTypeRef newCtx.LoadedAssemblies currentAssy typeRef ImmutableArray.Empty
+                    Assembly.resolveTypeRef newCtx.LoadedAssemblies currentAssy ImmutableArray.Empty typeRef
 
                 match resolutionResult2 with
                 | TypeResolutionResult.Resolved (targetAssy, typeInfo) -> (targetAssy, typeInfo), newCtx
@@ -567,8 +643,7 @@ module TypeConcretization =
                 ImmutableArray.Empty // No generic parameters
 
     let private concretizeTypeReference
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (loadAssembly : IAssemblyLoad)
         (ctx : ConcretizationContext<'corelib>)
         (currentAssembly : AssemblyName)
         (typeRef : TypeRef)
@@ -591,14 +666,13 @@ module TypeConcretization =
 
     /// Concretize a type in a specific generic context
     let rec concretizeType
-        (ctx : ConcretizationContext<'corelib>)
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (ctx : ConcretizationContext<DumpedAssembly>)
+        (loadAssembly : IAssemblyLoad)
         (assembly : AssemblyName)
         (typeGenerics : ImmutableArray<ConcreteTypeHandle>)
         (methodGenerics : ImmutableArray<ConcreteTypeHandle>)
         (typeDefn : TypeDefn)
-        : ConcreteTypeHandle * ConcretizationContext<'corelib>
+        : ConcreteTypeHandle * ConcretizationContext<DumpedAssembly>
         =
 
         let key = (assembly, typeDefn)
@@ -688,15 +762,14 @@ module TypeConcretization =
         | _ -> failwithf "TODO: Concretization of %A not implemented" typeDefn
 
     and private concretizeGenericInstantiation
-        (ctx : ConcretizationContext<'corelib>)
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (ctx : ConcretizationContext<DumpedAssembly>)
+        (loadAssembly : IAssemblyLoad)
         (assembly : AssemblyName)
         (typeGenerics : ImmutableArray<ConcreteTypeHandle>)
         (methodGenerics : ImmutableArray<ConcreteTypeHandle>)
         (genericDef : TypeDefn)
         (args : ImmutableArray<TypeDefn>)
-        : ConcreteTypeHandle * ConcretizationContext<'corelib>
+        : ConcreteTypeHandle * ConcretizationContext<DumpedAssembly>
         =
         // First, concretize all type arguments
         let argHandles, ctxAfterArgs =
@@ -769,7 +842,8 @@ module TypeConcretization =
 
                     | false, _ ->
                         // Need to load the assembly
-                        let newAssemblies, loadedAssy = loadAssembly assembly assyRef
+                        let newAssemblies, loadedAssy =
+                            loadAssembly.LoadAssembly ctx.LoadedAssemblies assembly assyRef
 
                         let ctxWithNewAssy =
                             { ctxAfterArgs with
@@ -847,14 +921,13 @@ module Concretization =
 
     /// Helper to concretize an array of types
     let private concretizeTypeArray
-        (ctx : TypeConcretization.ConcretizationContext<'corelib>)
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (ctx : TypeConcretization.ConcretizationContext<DumpedAssembly>)
+        (loadAssembly : IAssemblyLoad)
         (assembly : AssemblyName)
         (typeArgs : ImmutableArray<ConcreteTypeHandle>)
         (methodArgs : ImmutableArray<ConcreteTypeHandle>)
         (types : ImmutableArray<TypeDefn>)
-        : ImmutableArray<ConcreteTypeHandle> * TypeConcretization.ConcretizationContext<'corelib>
+        : ImmutableArray<ConcreteTypeHandle> * TypeConcretization.ConcretizationContext<DumpedAssembly>
         =
 
         let handles = ImmutableArray.CreateBuilder types.Length
@@ -871,14 +944,13 @@ module Concretization =
 
     /// Helper to concretize a method signature
     let private concretizeMethodSignature
-        (ctx : TypeConcretization.ConcretizationContext<'corelib>)
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (ctx : TypeConcretization.ConcretizationContext<DumpedAssembly>)
+        (loadAssembly : IAssemblyLoad)
         (assembly : AssemblyName)
         (typeArgs : ImmutableArray<ConcreteTypeHandle>)
         (methodArgs : ImmutableArray<ConcreteTypeHandle>)
         (signature : TypeMethodSignature<TypeDefn>)
-        : TypeMethodSignature<ConcreteTypeHandle> * TypeConcretization.ConcretizationContext<'corelib>
+        : TypeMethodSignature<ConcreteTypeHandle> * TypeConcretization.ConcretizationContext<DumpedAssembly>
         =
 
         // Concretize return type
@@ -909,8 +981,7 @@ module Concretization =
 
     /// Helper to ensure base type assembly is loaded
     let rec private ensureBaseTypeAssembliesLoaded
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (loadAssembly : IAssemblyLoad)
         (assemblies : ImmutableDictionary<string, DumpedAssembly>)
         (assyName : AssemblyName)
         (baseTypeInfo : BaseTypeInfo option)
@@ -930,7 +1001,7 @@ module Concretization =
                 | true, _ -> assemblies
                 | false, _ ->
                     // Need to load the assembly - pass the assembly that contains the reference
-                    let newAssemblies, _ = loadAssembly assy.Name assyRef
+                    let newAssemblies, _ = loadAssembly.LoadAssembly assemblies assy.Name assyRef
                     newAssemblies
             | _ -> assemblies
         | Some (BaseTypeInfo.TypeDef _)
@@ -940,8 +1011,7 @@ module Concretization =
     /// Concretize a method's signature and body
     let concretizeMethod
         (ctx : AllConcreteTypes)
-        (loadAssembly :
-            AssemblyName -> AssemblyReferenceHandle -> ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly)
+        (loadAssembly : IAssemblyLoad)
         (assemblies : ImmutableDictionary<string, DumpedAssembly>)
         (baseTypes : BaseClassTypes<DumpedAssembly>)
         (method : WoofWare.PawPrint.MethodInfo<'ty, GenericParamFromMetadata, TypeDefn>)
@@ -1140,8 +1210,7 @@ module Concretization =
                 // Recursively convert generic arguments
                 let genericArgs =
                     concreteType.Generics
-                    |> Seq.map (fun h -> concreteHandleToTypeDefn baseClassTypes h concreteTypes assemblies)
-                    |> ImmutableArray.CreateRange
+                    |> ImmutableArray.map (fun h -> concreteHandleToTypeDefn baseClassTypes h concreteTypes assemblies)
 
                 let baseDef =
                     TypeDefn.FromDefinition (concreteType.Definition, concreteType.Assembly.FullName, signatureTypeKind)

WoofWare.PawPrint.Domain/TypeDefn.fs

@@ -6,6 +6,8 @@ open System.Reflection.Metadata
 open System.Reflection.Metadata.Ecma335
 open Microsoft.FSharp.Core
 
+[<RequireQualifiedAccess>]
+[<NoComparison>]
 type ResolvedBaseType =
     | Enum
     | ValueType
@@ -167,8 +169,8 @@ module PrimitiveType =
         | PrimitiveType.Double -> 8
         | PrimitiveType.String -> 8
         | PrimitiveType.TypedReference -> failwith "todo"
-        | PrimitiveType.IntPtr -> 8
-        | PrimitiveType.UIntPtr -> 8
+        | PrimitiveType.IntPtr -> NATIVE_INT_SIZE
+        | PrimitiveType.UIntPtr -> NATIVE_INT_SIZE
         | PrimitiveType.Object -> 8
 
 type TypeDefn =

WoofWare.PawPrint.Domain/TypeInfo.fs

@@ -29,6 +29,10 @@ type InterfaceImplementation =
         RelativeToAssembly : AssemblyName
     }
 
+type Layout =
+    | Default
+    | Custom of size : int * packingSize : int
+
 /// <summary>
 /// Represents detailed information about a type definition in a .NET assembly.
 /// This is a strongly-typed representation of TypeDefinition from System.Reflection.Metadata.
@@ -93,6 +97,8 @@ type TypeInfo<'generic, 'fieldGeneric> =
         Events : EventDefn ImmutableArray
 
         ImplementedInterfaces : InterfaceImplementation ImmutableArray
+
+        Layout : Layout
     }
 
     member this.IsInterface = this.TypeAttributes.HasFlag TypeAttributes.Interface
@@ -184,6 +190,18 @@ type BaseClassTypes<'corelib> =
         TypedReference : TypeInfo<GenericParamFromMetadata, TypeDefn>
         IntPtr : TypeInfo<GenericParamFromMetadata, TypeDefn>
         UIntPtr : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        Exception : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        ArithmeticException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        DivideByZeroException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        OverflowException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        StackOverflowException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        TypeLoadException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        IndexOutOfRangeException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        InvalidCastException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        MissingFieldException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        MissingMethodException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        NullReferenceException : TypeInfo<GenericParamFromMetadata, TypeDefn>
+        OutOfMemoryException : TypeInfo<GenericParamFromMetadata, TypeDefn>
     }
 
 [<RequireQualifiedAccess>]
@@ -213,6 +231,7 @@ module TypeInfo =
             Generics = gen
             Events = t.Events
             ImplementedInterfaces = t.ImplementedInterfaces
+            Layout = t.Layout
         }
 
     let mapGeneric<'a, 'b, 'field> (f : 'a -> 'b) (t : TypeInfo<'a, 'field>) : TypeInfo<'b, 'field> =
@@ -308,6 +327,14 @@ module TypeInfo =
 
             result.ToImmutable ()
 
+        let layout =
+            let l = typeDef.GetLayout ()
+
+            if l.IsDefault then
+                Layout.Default
+            else
+                Layout.Custom (size = l.Size, packingSize = l.PackingSize)
+
         {
             Namespace = ns
             Name = name
@@ -323,6 +350,7 @@ module TypeInfo =
             Events = events
             ImplementedInterfaces = interfaces
             DeclaringType = declaringType
+            Layout = layout
         }
 
     let isBaseType<'corelib>
@@ -348,10 +376,10 @@ module TypeInfo =
 
     let rec resolveBaseType<'corelib, 'generic, 'field>
         (baseClassTypes : BaseClassTypes<'corelib>)
+        (sourceAssy : 'corelib)
         (getName : 'corelib -> AssemblyName)
         (getTypeDef : 'corelib -> TypeDefinitionHandle -> TypeInfo<'generic, 'field>)
-        (getTypeRef : 'corelib -> TypeReferenceHandle -> TypeInfo<'generic, 'field>)
-        (sourceAssembly : AssemblyName)
+        (getTypeRef : 'corelib -> TypeReferenceHandle -> 'corelib * TypeInfo<'generic, 'field>)
         (value : BaseTypeInfo option)
         : ResolvedBaseType
         =
@@ -361,40 +389,48 @@ module TypeInfo =
 
         match value with
         | BaseTypeInfo.TypeDef typeDefinitionHandle ->
-            match isBaseType baseClassTypes getName sourceAssembly typeDefinitionHandle with
+            match isBaseType baseClassTypes getName (getName sourceAssy) typeDefinitionHandle with
             | Some x -> x
             | None ->
                 let baseType = getTypeDef baseClassTypes.Corelib typeDefinitionHandle
-                resolveBaseType baseClassTypes getName getTypeDef getTypeRef sourceAssembly baseType.BaseType
+                resolveBaseType baseClassTypes sourceAssy getName getTypeDef getTypeRef baseType.BaseType
         | BaseTypeInfo.TypeRef typeReferenceHandle ->
-            let typeRef = getTypeRef baseClassTypes.Corelib typeReferenceHandle
-            failwith $"{typeRef}"
+            let targetAssy, typeRef = getTypeRef sourceAssy typeReferenceHandle
+
+            match isBaseType baseClassTypes getName (getName targetAssy) typeRef.TypeDefHandle with
+            | Some x -> x
+            | None ->
+                let baseType = getTypeDef baseClassTypes.Corelib typeRef.TypeDefHandle
+                resolveBaseType baseClassTypes sourceAssy getName getTypeDef getTypeRef baseType.BaseType
         | BaseTypeInfo.TypeSpec typeSpecificationHandle -> failwith "todo"
         | BaseTypeInfo.ForeignAssemblyType (assemblyName, typeDefinitionHandle) ->
             resolveBaseType
                 baseClassTypes
+                sourceAssy
                 getName
                 getTypeDef
                 getTypeRef
-                assemblyName
                 (Some (BaseTypeInfo.TypeDef typeDefinitionHandle))
 
     let toTypeDefn
         (baseClassTypes : BaseClassTypes<'corelib>)
+        (assemblies : AssemblyName -> 'corelib)
         (getName : 'corelib -> AssemblyName)
         (getTypeDef : 'corelib -> TypeDefinitionHandle -> TypeInfo<'generic, 'field>)
-        (getTypeRef : 'corelib -> TypeReferenceHandle -> TypeInfo<'generic, 'field>)
+        (getTypeRef : 'corelib -> TypeReferenceHandle -> 'corelib * TypeInfo<'generic, 'field>)
         (ty : TypeInfo<TypeDefn, TypeDefn>)
         : TypeDefn
         =
         let stk =
-            match resolveBaseType baseClassTypes getName getTypeDef getTypeRef ty.Assembly ty.BaseType with
+            match resolveBaseType baseClassTypes (assemblies ty.Assembly) getName getTypeDef getTypeRef ty.BaseType with
             | ResolvedBaseType.Enum
             | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
             | ResolvedBaseType.Object
             | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
 
         let defn =
+            // The only allowed construction of FromDefinition!
+            // All other constructions should use DumpedAssembly.typeInfoToTypeDefn.
             TypeDefn.FromDefinition (ComparableTypeDefinitionHandle.Make ty.TypeDefHandle, ty.Assembly.FullName, stk)
 
         if ty.Generics.IsEmpty then

WoofWare.PawPrint.Domain/WoofWare.PawPrint.Domain.fsproj

@@ -7,6 +7,7 @@
 
     <ItemGroup>
         <Compile Include="StringToken.fs" />
+        <Compile Include="Constants.fs" />
         <Compile Include="ImmutableArray.fs" />
         <Compile Include="Tokens.fs" />
         <Compile Include="TypeRef.fs" />

WoofWare.PawPrint.Test/LoggerFactory.fs

@@ -23,7 +23,7 @@ module LoggerFactory =
     let makeTest () : (unit -> LogLine list) * ILoggerFactory =
         // Shared sink for all loggers created by the factory.
         let sink = ResizeArray ()
-        let isEnabled (logLevel : LogLevel) : bool = logLevel >= LogLevel.Debug
+        let isEnabled (logLevel : LogLevel) : bool = logLevel >= LogLevel.Information
 
         let createLogger (category : string) : ILogger =
             { new ILogger with

WoofWare.PawPrint.Test/TestImpureCases.fs

@@ -1,5 +1,6 @@
 namespace WoofWare.Pawprint.Test
 
+open System
 open System.Collections.Immutable
 open System.IO
 open FsUnitTyped

WoofWare.PawPrint.Test/TestPureCases.fs

@@ -1,5 +1,6 @@
 namespace WoofWare.Pawprint.Test
 
+open System
 open System.Collections.Immutable
 open System.IO
 open FsUnitTyped
@@ -16,141 +17,65 @@ module TestPureCases =
 
     let unimplemented =
         [
-            {
-                FileName = "CrossAssemblyTypes.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "InitializeArray.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "GenericEdgeCases.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "Threads.cs"
-                ExpectedReturnCode = 3
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "ComplexTryCatch.cs"
-                ExpectedReturnCode = 14
-                NativeImpls = NativeImpls.PassThru ()
-            }
-            {
-                FileName = "ResizeArray.cs"
-                ExpectedReturnCode = 109
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "Sizeof.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "LdtokenField.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
+            "CrossAssemblyTypes.cs"
+            "OverlappingStructs.cs"
+            "AdvancedStructLayout.cs"
+            "InitializeArray.cs"
+            "Threads.cs"
+            "ComplexTryCatch.cs"
+            "ResizeArray.cs"
+            "LdtokenField.cs"
+            "GenericEdgeCases.cs"
+            "UnsafeAs.cs"
         ]
+        |> Set.ofList
+
+    let requiresMocks =
+        let empty = MockEnv.make ()
 
-    let cases : EndToEndTestCase list =
         [
-            {
-                FileName = "NoOp.cs"
-                ExpectedReturnCode = 1
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "TestShl.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "TestShr.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "StaticVariables.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "Ldind.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "CustomDelegate.cs"
-                ExpectedReturnCode = 8
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "ArgumentOrdering.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "BasicLock.cs"
-                ExpectedReturnCode = 1
-                NativeImpls =
-                    let mock = MockEnv.make ()
-
-                    { mock with
-                        System_Threading_Monitor = System_Threading_Monitor.passThru
-                    }
-            }
-            {
-                FileName = "TriangleNumber.cs"
-                ExpectedReturnCode = 10
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "ExceptionWithNoOpFinally.cs"
-                ExpectedReturnCode = 3
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "ExceptionWithNoOpCatch.cs"
-                ExpectedReturnCode = 10
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "Floats.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "TryCatchWithThrowInBody.cs"
-                ExpectedReturnCode = 4
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "Ldelema.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "TypeConcretization.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "TestOr.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
-            {
-                FileName = "InterfaceDispatch.cs"
-                ExpectedReturnCode = 0
-                NativeImpls = MockEnv.make ()
-            }
+            "BasicLock.cs",
+            (1,
+             { empty with
+                 System_Threading_Monitor = System_Threading_Monitor.passThru
+             })
         ]
+        |> Map.ofList
+
+    let customExitCodes =
+        [
+            "NoOp.cs", 1
+            "CustomDelegate.cs", 8
+            "ExceptionWithNoOpFinally.cs", 3
+            "ExceptionWithNoOpCatch.cs", 10
+            "TryCatchWithThrowInBody.cs", 4
+            "ResizeArray.cs", 114
+            "Threads.cs", 3
+            "TriangleNumber.cs", 10
+        ]
+        |> Map.ofList
+
+    let allPure =
+        assy.GetManifestResourceNames ()
+        |> Seq.choose (fun res ->
+            let s = "WoofWare.PawPrint.Test.sourcesPure."
+
+            if res.StartsWith (s, StringComparison.OrdinalIgnoreCase) then
+                res.Substring s.Length |> Some
+            else
+                None
+        )
+        |> Set.ofSeq
+
+    let simpleCases : string list =
+        allPure
+        |> Seq.filter (fun s ->
+            (customExitCodes.ContainsKey s
+             || requiresMocks.ContainsKey s
+             || unimplemented.Contains s)
+            |> not
+        )
+        |> Seq.toList
 
     let runTest (case : EndToEndTestCase) : unit =
         let source = Assembly.getEmbeddedResourceAsString case.FileName assy
@@ -163,11 +88,12 @@ module TestPureCases =
         use peImage = new MemoryStream (image)
 
         try
+            let realResult = RealRuntime.executeWithRealRuntime [||] image
+            realResult.ExitCode |> shouldEqual case.ExpectedReturnCode
+
             let terminalState, terminatingThread =
                 Program.run loggerFactory (Some case.FileName) peImage dotnetRuntimes case.NativeImpls []
 
-            let realResult = RealRuntime.executeWithRealRuntime [||] image
-
             let exitCode =
                 match terminalState.ThreadState.[terminatingThread].MethodState.EvaluationStack.Values with
                 | [] -> failwith "expected program to return a value, but it returned void"
@@ -178,16 +104,49 @@ module TestPureCases =
 
             exitCode |> shouldEqual realResult.ExitCode
 
-            exitCode |> shouldEqual case.ExpectedReturnCode
         with _ ->
             for message in messages () do
                 System.Console.Error.WriteLine $"{message}"
 
             reraise ()
 
+    [<TestCaseSource(nameof simpleCases)>]
+    let ``Standard tests`` (fileName : string) =
+        {
+            FileName = fileName
+            ExpectedReturnCode = 0
+            NativeImpls = MockEnv.make ()
+        }
+        |> runTest
+
+    [<TestCaseSource(nameof customExitCodes)>]
+    let ``Custom exit code tests`` (KeyValue (fileName : string, exitCode : int)) =
+        if unimplemented.Contains fileName then
+            Assert.Inconclusive ()
+
+        {
+            FileName = fileName
+            ExpectedReturnCode = exitCode
+            NativeImpls = MockEnv.make ()
+        }
+        |> runTest
+
+    [<TestCaseSource(nameof requiresMocks)>]
+    let ``Tests which require mocks`` (KeyValue (fileName : string, (exitCode : int, mock : NativeImpls))) =
+        {
+            FileName = fileName
+            ExpectedReturnCode = exitCode
+            NativeImpls = mock
+        }
+        |> runTest
+
+
     [<TestCaseSource(nameof unimplemented)>]
     [<Explicit>]
-    let ``Can evaluate C# files, unimplemented`` (case : EndToEndTestCase) = runTest case
-
-    [<TestCaseSource(nameof cases)>]
-    let ``Can evaluate C# files`` (case : EndToEndTestCase) = runTest case
+    let ``Can evaluate C# files, unimplemented`` (fileName : string) =
+        {
+            FileName = fileName
+            ExpectedReturnCode = 0
+            NativeImpls = MockEnv.make ()
+        }
+        |> runTest

WoofWare.PawPrint.Test/sourcesPure/AdvancedStructLayout.cs

@@ -0,0 +1,480 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
+
+public class StructLayoutTestsAdvanced
+{
+    // Test structs
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct PointerTestStruct
+    {
+        public int A;
+        public byte B;
+        public short C;
+        public int D;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    unsafe struct FixedBufferStruct
+    {
+        public int Header;
+        public fixed byte Buffer[64];
+        public int Footer;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    unsafe struct NestedFixedStruct
+    {
+        public fixed int IntArray[4];
+        public fixed double DoubleArray[2];
+    }
+
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
+    struct MarshalStringStruct
+    {
+        public int Id;
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
+        public string Name;
+        public double Value;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct MarshalArrayStruct
+    {
+        public int Count;
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
+        public int[] Values;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct BlittableStruct
+    {
+        public int X;
+        public double Y;
+        public long Z;
+    }
+
+    ref struct RefStruct
+    {
+        public int Value;
+        public Span<int> Span;
+
+        public RefStruct(int value)
+        {
+            Value = value;
+            Span = new Span<int>(new int[] { value, value * 2, value * 3 });
+        }
+    }
+
+    readonly struct ReadOnlyStruct
+    {
+        public readonly int X;
+        public readonly int Y;
+
+        public ReadOnlyStruct(int x, int y)
+        {
+            X = x;
+            Y = y;
+        }
+
+        public int Sum => X + Y;
+    }
+
+    readonly ref struct ReadOnlyRefStruct
+    {
+        public readonly int Value;
+        public readonly ReadOnlySpan<byte> Data;
+
+        public ReadOnlyRefStruct(int value, ReadOnlySpan<byte> data)
+        {
+            Value = value;
+            Data = data;
+        }
+    }
+
+    struct Generic<T> where T : struct
+    {
+        public T Value;
+        public int Index;
+
+        public Generic(T value, int index)
+        {
+            Value = value;
+            Index = index;
+        }
+    }
+
+    struct DoubleGeneric<T, U>
+    {
+        public T First;
+        public U Second;
+    }
+
+    interface IIndexable
+    {
+        int GetIndex();
+        void SetIndex(int value);
+    }
+
+    struct StructWithInterface : IIndexable
+    {
+        public int Index;
+        public string Data;
+
+        public int GetIndex() => Index;
+        public void SetIndex(int value) => Index = value;
+    }
+
+    interface IMutable
+    {
+        void Mutate();
+    }
+
+    struct MutableStruct : IMutable
+    {
+        public int Counter;
+
+        public void Mutate()
+        {
+            Counter++;
+        }
+    }
+
+    struct RefReturnStruct
+    {
+        public int A;
+        public int B;
+        public int C;
+
+        public static ref int GetRef(ref RefReturnStruct s, int index)
+        {
+            if (index == 0) return ref s.A;
+            if (index == 1) return ref s.B;
+            return ref s.C;
+        }
+    }
+
+    static unsafe int TestUnsafePointers()
+    {
+        var s = new PointerTestStruct { A = 0x12345678, B = 0xAB, C = 0x1234, D = unchecked((int)0xDEADBEEF) };
+
+        // Test sizeof
+        int size = sizeof(PointerTestStruct);
+        if (size == 0) return 1;
+
+        // Test pointer access
+        PointerTestStruct* ptr = &s;
+        if (ptr->A != 0x12345678) return 2;
+        if (ptr->B != 0xAB) return 3;
+        if (ptr->C != 0x1234) return 4;
+        if (ptr->D != unchecked((int)0xDEADBEEF)) return 5;
+
+        // Test pointer arithmetic and casting
+        byte* bytePtr = (byte*)ptr;
+        int* intPtr = (int*)bytePtr;
+        if (*intPtr != 0x12345678) return 6; // First int field
+
+        // Verify field offsets
+        int* dPtr = &(ptr->D);
+        int* aPtr = &(ptr->A);
+        long ptrDiff = (byte*)dPtr - (byte*)aPtr;
+        if (ptrDiff < 8) return 7; // D should be at least 8 bytes from A
+
+        // Test modification through pointer
+        ptr->A = 999;
+        if (s.A != 999) return 8;
+
+        return 0;
+    }
+
+    static unsafe int TestFixedBuffers()
+    {
+        var f = new FixedBufferStruct();
+        f.Header = 0xFEED;
+        f.Footer = 0xBEEF;
+
+        // Test fixed buffer access
+        for (int i = 0; i < 64; i++)
+        {
+            f.Buffer[i] = (byte)(i % 256);
+        }
+
+        if (f.Header != 0xFEED) return 10;
+        if (f.Footer != 0xBEEF) return 11;
+
+        // Verify buffer contents
+        for (int i = 0; i < 64; i++)
+        {
+            if (f.Buffer[i] != (byte)(i % 256)) return 12;
+        }
+
+        // Test pointer to fixed buffer
+        byte* bufPtr = f.Buffer;
+        bufPtr[0] = 255;
+        if (f.Buffer[0] != 255) return 13;
+
+        // Test nested fixed arrays
+        var n = new NestedFixedStruct();
+        n.IntArray[0] = 100;
+        n.IntArray[3] = 400;
+        n.DoubleArray[0] = 1.5;
+        n.DoubleArray[1] = 2.5;
+
+        if (n.IntArray[0] != 100) return 14;
+        if (n.IntArray[3] != 400) return 15;
+        if (Math.Abs(n.DoubleArray[0] - 1.5) > 0.0001) return 16;
+        if (Math.Abs(n.DoubleArray[1] - 2.5) > 0.0001) return 17;
+
+        return 0;
+    }
+
+    static unsafe int TestMarshaling()
+    {
+        // Test string marshaling
+        var ms = new MarshalStringStruct
+        {
+            Id = 42,
+            Name = "TestString",
+            Value = 3.14159
+        };
+
+        if (ms.Id != 42) return 20;
+        if (ms.Name != "TestString") return 21;
+        if (Math.Abs(ms.Value - 3.14159) > 0.00001) return 22;
+
+        // Test Marshal.SizeOf
+        int marshalSize = Marshal.SizeOf(typeof(MarshalStringStruct));
+        if (marshalSize == 0) return 23;
+
+        // Test array marshaling
+        var ma = new MarshalArrayStruct
+        {
+            Count = 5,
+            Values = new int[] { 1, 2, 3, 4, 5, 6, 7, 8 }
+        };
+
+        if (ma.Count != 5) return 24;
+        if (ma.Values.Length != 8) return 25;
+        if (ma.Values[7] != 8) return 26;
+
+        // Test StructureToPtr and PtrToStructure
+        var blittable = new BlittableStruct { X = 100, Y = 200.5, Z = 300 };
+        IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(BlittableStruct)));
+        try
+        {
+            Marshal.StructureToPtr(blittable, ptr, false);
+            var recovered = (BlittableStruct)Marshal.PtrToStructure(ptr, typeof(BlittableStruct));
+
+            if (recovered.X != 100) return 27;
+            if (Math.Abs(recovered.Y - 200.5) > 0.00001) return 28;
+            if (recovered.Z != 300) return 29;
+        }
+        finally
+        {
+            Marshal.FreeHGlobal(ptr);
+        }
+
+        return 0;
+    }
+
+    static int TestRefStructs()
+    {
+        // Test ref struct
+        var rs = new RefStruct(10);
+        if (rs.Value != 10) return 30;
+        if (rs.Span.Length != 3) return 31;
+        if (rs.Span[0] != 10) return 32;
+        if (rs.Span[1] != 20) return 33;
+        if (rs.Span[2] != 30) return 34;
+
+        // Modify through span
+        rs.Span[0] = 100;
+        if (rs.Span[0] != 100) return 35;
+
+        // Test readonly struct
+        var ros = new ReadOnlyStruct(5, 7);
+        if (ros.X != 5) return 36;
+        if (ros.Y != 7) return 37;
+        if (ros.Sum != 12) return 38;
+
+        // Verify immutability - create new instance
+        var ros2 = new ReadOnlyStruct(10, 20);
+        if (ros.X != 5) return 39; // Original should be unchanged
+
+        // Test readonly ref struct
+        byte[] data = { 1, 2, 3, 4 };
+        var rors = new ReadOnlyRefStruct(42, new ReadOnlySpan<byte>(data));
+        if (rors.Value != 42) return 40;
+        if (rors.Data.Length != 4) return 41;
+        if (rors.Data[3] != 4) return 42;
+
+        return 0;
+    }
+
+    static int TestGenerics()
+    {
+        // Test single generic parameter
+        var g1 = new Generic<int>(42, 1);
+        if (g1.Value != 42) return 50;
+        if (g1.Index != 1) return 51;
+
+        var g2 = new Generic<double>(3.14, 2);
+        if (Math.Abs(g2.Value - 3.14) > 0.00001) return 52;
+        if (g2.Index != 2) return 53;
+
+        // Test with custom struct
+        var inner = new ReadOnlyStruct(10, 20);
+        var g3 = new Generic<ReadOnlyStruct>(inner, 3);
+        if (g3.Value.X != 10) return 54;
+        if (g3.Value.Y != 20) return 55;
+        if (g3.Index != 3) return 56;
+
+        // Test double generic
+        var dg = new DoubleGeneric<int, string> { First = 100, Second = "test" };
+        if (dg.First != 100) return 57;
+        if (dg.Second != "test") return 58;
+
+        // Test with different type combinations
+        var dg2 = new DoubleGeneric<double, long> { First = 2.718, Second = long.MaxValue };
+        if (Math.Abs(dg2.First - 2.718) > 0.00001) return 59;
+        if (dg2.Second != long.MaxValue) return 60;
+
+        return 0;
+    }
+
+    static int TestByRefReturns()
+    {
+        var r = new RefReturnStruct { A = 10, B = 20, C = 30 };
+
+        // Test ref return
+        ref int refA = ref RefReturnStruct.GetRef(ref r, 0);
+        if (refA != 10) return 70;
+
+        // Modify through ref
+        refA = 100;
+        if (r.A != 100) return 71;
+
+        ref int refB = ref RefReturnStruct.GetRef(ref r, 1);
+        refB = 200;
+        if (r.B != 200) return 72;
+
+        ref int refC = ref RefReturnStruct.GetRef(ref r, 2);
+        refC = 300;
+        if (r.C != 300) return 73;
+
+        // Test ref local
+        ref int localRef = ref r.A;
+        localRef = 1000;
+        if (r.A != 1000) return 74;
+
+        // Test that ref points to actual field
+        localRef = 2000;
+        if (refA != 2000) return 75; // Both should see the change
+
+        return 0;
+    }
+
+    static int TestStructInterfaces()
+    {
+        // Test struct implementing interface
+        var s = new StructWithInterface { Index = 42, Data = "test" };
+        if (s.GetIndex() != 42) return 80;
+
+        s.SetIndex(100);
+        if (s.Index != 100) return 81;
+
+        // Test boxing to interface
+        IIndexable boxed = s; // Boxing occurs here
+        if (boxed.GetIndex() != 100) return 82;
+
+        // Modify through interface (modifies boxed copy)
+        boxed.SetIndex(200);
+        if (boxed.GetIndex() != 200) return 83;
+        if (s.Index != 100) return 84; // Original should be unchanged
+
+        // Test mutable interface
+        var m = new MutableStruct { Counter = 0 };
+        m.Mutate();
+        if (m.Counter != 1) return 85;
+
+        // Box to interface and mutate
+        IMutable boxedMutable = m; // Boxing
+        boxedMutable.Mutate();
+        if (m.Counter != 1) return 86; // Original unchanged
+
+        // Cast back to see boxed mutation
+        var unboxed = (MutableStruct)boxedMutable;
+        if (unboxed.Counter != 2) return 87;
+
+        // Direct interface call on boxed struct maintains state
+        boxedMutable.Mutate();
+        boxedMutable.Mutate();
+        var unboxed2 = (MutableStruct)boxedMutable;
+        if (unboxed2.Counter != 4) return 88;
+
+        return 0;
+    }
+
+    static unsafe int TestCombinedScenarios()
+    {
+        // Test generic with fixed buffer struct
+        var f = new FixedBufferStruct();
+        f.Header = 999;
+        f.Buffer[0] = 123;
+        f.Footer = 111;
+
+        var generic = new Generic<FixedBufferStruct>(f, 42);
+        if (generic.Value.Header != 999) return 90;
+        if (generic.Value.Buffer[0] != 123) return 91;
+        if (generic.Value.Footer != 111) return 92;
+        if (generic.Index != 42) return 93;
+
+        // Test marshaling with generic
+        var marshalable = new BlittableStruct { X = 10, Y = 20.0, Z = 30 };
+        var genericMarshal = new Generic<BlittableStruct>(marshalable, 5);
+
+        if (genericMarshal.Value.X != 10) return 94;
+        if (Math.Abs(genericMarshal.Value.Y - 20.0) > 0.00001) return 95;
+        if (genericMarshal.Value.Z != 30) return 96;
+
+        return 0;
+    }
+
+    public static int Main(string[] argv)
+    {
+        int result = 0;
+
+        unsafe
+        {
+            result = TestUnsafePointers();
+            if (result != 0) return result;
+
+            result = TestFixedBuffers();
+            if (result != 0) return result;
+        }
+
+        result = TestMarshaling();
+        if (result != 0) return result;
+
+        result = TestRefStructs();
+        if (result != 0) return result;
+
+        result = TestGenerics();
+        if (result != 0) return result;
+
+        result = TestByRefReturns();
+        if (result != 0) return result;
+
+        result = TestStructInterfaces();
+        if (result != 0) return result;
+
+        unsafe
+        {
+            result = TestCombinedScenarios();
+            if (result != 0) return result;
+        }
+
+        return 0; // All tests passed
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/ComparisonOperations.cs

@@ -0,0 +1,255 @@
+public class TestComparisonOperations
+{
+    // Test Ceq: Compare equal
+    public static int TestCompareEqual()
+    {
+        // Integer equality
+        if ((5 == 5) != true) return 1;
+        if ((5 == 6) != false) return 2;
+        if ((int.MaxValue == int.MaxValue) != true) return 3;
+        if ((int.MinValue == int.MaxValue) != false) return 4;
+        
+        // Negative numbers
+        if ((-1 == -1) != true) return 5;
+        if ((-5 == 5) != false) return 6;
+        
+        // Long equality
+        if ((100L == 100L) != true) return 7;
+        if ((100L == 101L) != false) return 8;
+        
+        // Mixed sizes (after promotion)
+        int i = 42;
+        long l = 42L;
+        if ((l == (long)i) != true) return 9;
+        
+        // Zero comparisons
+        if ((0 == 0) != true) return 10;
+        if ((0 == 1) != false) return 11;
+        
+        return 0;
+    }
+    
+    // Test Cgt: Compare greater than (signed)
+    public static int TestCompareGreaterThan()
+    {
+        // Positive integers
+        if ((10 > 5) != true) return 20;
+        if ((5 > 10) != false) return 21;
+        if ((5 > 5) != false) return 22;
+        
+        // Negative integers
+        if ((-5 > -10) != true) return 23;
+        if ((-10 > -5) != false) return 24;
+        if ((5 > -5) != true) return 25;
+        if ((-5 > 5) != false) return 26;
+        
+        // Boundary values
+        if ((int.MaxValue > int.MinValue) != true) return 27;
+        if ((int.MinValue > int.MaxValue) != false) return 28;
+        if ((int.MaxValue > (int.MaxValue - 1)) != true) return 29;
+        
+        // Zero comparisons
+        if ((1 > 0) != true) return 30;
+        if ((0 > 1) != false) return 31;
+        if ((-1 > 0) != false) return 32;
+        if ((0 > -1) != true) return 33;
+        
+        return 0;
+    }
+    
+    // Test Cgt_un: Compare greater than (unsigned)
+    public static int TestCompareGreaterThanUnsigned()
+    {
+        uint a = 10;
+        uint b = 5;
+        
+        // Basic unsigned comparison
+        if ((a > b) != true) return 40;
+        if ((b > a) != false) return 41;
+        if ((a > a) != false) return 42;
+        
+        // High bit set (would be negative if signed)
+        uint high = 0x80000000;
+        uint low = 0x7FFFFFFF;
+        if ((high > low) != true) return 43;  // Unsigned: high > low
+        
+        // Maximum values
+        uint max = uint.MaxValue;
+        uint min = uint.MinValue;
+        if ((max > min) != true) return 44;
+        if ((min > max) != false) return 45;
+        
+        // Interpret negative as unsigned
+        uint negAsUint = unchecked((uint)-1);
+        uint one = 1;
+        if ((negAsUint > one) != true) return 46;  // 0xFFFFFFFF > 1
+        
+        return 0;
+    }
+    
+    // Test Clt: Compare less than (signed)
+    public static int TestCompareLessThan()
+    {
+        // Positive integers
+        if ((5 < 10) != true) return 50;
+        if ((10 < 5) != false) return 51;
+        if ((5 < 5) != false) return 52;
+        
+        // Negative integers
+        if ((-10 < -5) != true) return 53;
+        if ((-5 < -10) != false) return 54;
+        if ((-5 < 5) != true) return 55;
+        if ((5 < -5) != false) return 56;
+        
+        // Boundary values
+        if ((int.MinValue < int.MaxValue) != true) return 57;
+        if ((int.MaxValue < int.MinValue) != false) return 58;
+        
+        // Zero comparisons
+        if ((0 < 1) != true) return 59;
+        if ((1 < 0) != false) return 60;
+        if ((0 < -1) != false) return 61;
+        if ((-1 < 0) != true) return 62;
+        
+        return 0;
+    }
+    
+    // Test Clt_un: Compare less than (unsigned)
+    public static int TestCompareLessThanUnsigned()
+    {
+        uint a = 5;
+        uint b = 10;
+        
+        // Basic unsigned comparison
+        if ((a < b) != true) return 70;
+        if ((b < a) != false) return 71;
+        if ((a < a) != false) return 72;
+        
+        // High bit set
+        uint high = 0x80000000;
+        uint low = 0x7FFFFFFF;
+        if ((low < high) != true) return 73;  // Unsigned: low < high
+        
+        // Boundary values
+        uint max = uint.MaxValue;
+        uint min = uint.MinValue;
+        if ((min < max) != true) return 74;
+        if ((max < min) != false) return 75;
+        
+        // Negative as unsigned
+        uint one = 1;
+        uint negAsUint = unchecked((uint)-1);
+        if ((one < negAsUint) != true) return 76;  // 1 < 0xFFFFFFFF
+        
+        return 0;
+    }
+    
+    // Test comparison combinations
+    public static int TestComparisonCombinations()
+    {
+        int x = 10;
+        int y = 20;
+        int z = 10;
+        
+        // Equality chains
+        if ((x == z) != true) return 80;
+        if ((x == y) != false) return 81;
+        
+        // Inequality combinations
+        if ((x < y && y > x) != true) return 82;
+        if ((x < y && x == y) != false) return 83;
+        
+        // Transitive comparisons
+        if (x < y && y < 30)
+        {
+            if ((x < 30) != true) return 84;
+        }
+        else
+        {
+            return 85;
+        }
+        
+        return 0;
+    }
+    
+    // Test comparisons with different types
+    public static int TestMixedTypeComparisons()
+    {
+        // byte comparisons (unsigned by default)
+        byte b1 = 200;
+        byte b2 = 100;
+        if ((b1 > b2) != true) return 90;
+        
+        // sbyte comparisons (signed)
+        sbyte sb1 = -50;
+        sbyte sb2 = 50;
+        if ((sb1 < sb2) != true) return 91;
+        
+        // short comparisons
+        short s1 = -1000;
+        short s2 = 1000;
+        if ((s1 < s2) != true) return 92;
+        if ((s1 == s2) != false) return 93;
+        
+        // long comparisons
+        long l1 = long.MaxValue;
+        long l2 = long.MinValue;
+        if ((l1 > l2) != true) return 94;
+        
+        return 0;
+    }
+    
+    // Test null comparisons
+    public static int TestNullComparisons()
+    {
+        object obj1 = null;
+        object obj2 = null;
+        object obj3 = new object();
+        
+        // Null equality
+        if ((obj1 == obj2) != true) return 100;
+        if ((obj1 == obj3) != false) return 101;
+        if ((obj3 == obj1) != false) return 102;
+        
+        // String null comparisons
+        string s1 = null;
+        string s2 = null;
+        string s3 = "";
+        
+        if ((s1 == s2) != true) return 103;
+        if ((s1 == s3) != false) return 104;
+        
+        return 0;
+    }
+    
+    public static int Main(string[] argv)
+    {
+        int result;
+        
+        result = TestCompareEqual();
+        if (result != 0) return 100 + result;
+        
+        result = TestCompareGreaterThan();
+        if (result != 0) return 200 + result;
+        
+        result = TestCompareGreaterThanUnsigned();
+        if (result != 0) return 300 + result;
+        
+        result = TestCompareLessThan();
+        if (result != 0) return 400 + result;
+        
+        result = TestCompareLessThanUnsigned();
+        if (result != 0) return 500 + result;
+        
+        result = TestComparisonCombinations();
+        if (result != 0) return 600 + result;
+        
+        result = TestMixedTypeComparisons();
+        if (result != 0) return 700 + result;
+        
+        result = TestNullComparisons();
+        if (result != 0) return 800 + result;
+        
+        return 0;
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/InitializeArray.cs

@@ -8,7 +8,7 @@ namespace HelloWorldApp
         {
             int[] array = new[] { 1, 2, 3 };
 
-            if (array.Sum() != 60)
+            if (array.Sum() != 6)
             {
                 return 1;
             }

WoofWare.PawPrint.Test/sourcesPure/Initobj.cs

@@ -0,0 +1,503 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+public class TestInitobj
+{
+    // Simple struct with various primitive types
+    private struct SimpleStruct
+    {
+        public int IntField;
+        public bool BoolField;
+        public char CharField;
+        public double DoubleField;
+        public byte ByteField;
+    }
+
+    // Nested struct
+    private struct NestedStruct
+    {
+        public SimpleStruct Inner;
+        public int OuterField;
+    }
+
+    // Struct with arrays and references
+    private struct ComplexStruct
+    {
+        public object ObjectRef;
+        public string StringRef;
+        public int[] ArrayRef;
+        public int ValueField;
+    }
+
+    // Generic struct
+    private struct GenericStruct<T>
+    {
+        public T Value;
+        public int Count;
+    }
+
+    // Struct for field tests
+    private struct StructWithStructField
+    {
+        public SimpleStruct NestedField;
+        public int OtherField;
+    }
+
+    // Class with struct field for heap test
+    private class ClassWithStructField
+    {
+        public SimpleStruct StructField;
+        public int IntField;
+    }
+
+    // Test 1: Initialize simple struct with local variable
+    public static int Test1()
+    {
+        SimpleStruct s = new SimpleStruct
+        {
+            IntField = 42,
+            BoolField = true,
+            CharField = 'X',
+            DoubleField = 3.14,
+            ByteField = 255
+        };
+
+        // Verify initial values
+        if (s.IntField != 42) return 1;
+        if (s.BoolField != true) return 2;
+        if (s.CharField != 'X') return 3;
+        if (s.DoubleField != 3.14) return 4;
+        if (s.ByteField != 255) return 5;
+
+        // Use default to reset the struct (generates initobj)
+        s = default(SimpleStruct);
+
+        // Verify all fields are zeroed
+        if (s.IntField != 0) return 6;
+        if (s.BoolField != false) return 7;
+        if (s.CharField != '\0') return 8;
+        if (s.DoubleField != 0.0) return 9;
+        if (s.ByteField != 0) return 10;
+
+        return 0;
+    }
+
+    // Test 2: Initialize nested struct
+    public static int Test2()
+    {
+        NestedStruct n = new NestedStruct
+        {
+            Inner = new SimpleStruct
+            {
+                IntField = 100,
+                BoolField = true,
+                CharField = 'A',
+                DoubleField = 1.23,
+                ByteField = 128
+            },
+            OuterField = 999
+        };
+
+        // Verify initial values
+        if (n.Inner.IntField != 100) return 20;
+        if (n.OuterField != 999) return 21;
+
+        // Reset using default keyword (which should generate initobj)
+        n = default(NestedStruct);
+
+        // Verify all fields are zeroed
+        if (n.Inner.IntField != 0) return 22;
+        if (n.Inner.BoolField != false) return 23;
+        if (n.Inner.CharField != '\0') return 24;
+        if (n.Inner.DoubleField != 0.0) return 25;
+        if (n.Inner.ByteField != 0) return 26;
+        if (n.OuterField != 0) return 27;
+
+        return 0;
+    }
+
+    // Test 3: Initialize struct with reference types
+    public static int Test3()
+    {
+        ComplexStruct c = new ComplexStruct
+        {
+            ObjectRef = new object(),
+            StringRef = "Hello",
+            ArrayRef = new int[3],
+            ValueField = 42
+        };
+        c.ArrayRef[0] = 1;
+        c.ArrayRef[1] = 2;
+        c.ArrayRef[2] = 3;
+
+        // Verify initial values
+        if (c.ObjectRef == null) return 30;
+        if (c.StringRef != "Hello") return 31;
+        if (c.ArrayRef == null || c.ArrayRef.Length != 3) return 32;
+        if (c.ValueField != 42) return 33;
+
+        // Reset using default
+        c = default(ComplexStruct);
+
+        // Verify references are null and value is zero
+        if (c.ObjectRef != null) return 34;
+        if (c.StringRef != null) return 35;
+        if (c.ArrayRef != null) return 36;
+        if (c.ValueField != 0) return 37;
+
+        return 0;
+    }
+
+    // Test 4: Initialize generic struct
+    public static int Test4()
+    {
+        GenericStruct<int> gi = new GenericStruct<int>
+        {
+            Value = 123,
+            Count = 456
+        };
+
+        if (gi.Value != 123) return 40;
+        if (gi.Count != 456) return 41;
+
+        gi = default(GenericStruct<int>);
+
+        if (gi.Value != 0) return 42;
+        if (gi.Count != 0) return 43;
+
+        // Test with reference type
+        GenericStruct<string> gs = new GenericStruct<string>
+        {
+            Value = "Test",
+            Count = 789
+        };
+
+        if (gs.Value != "Test") return 44;
+        if (gs.Count != 789) return 45;
+
+        gs = default(GenericStruct<string>);
+
+        if (gs.Value != null) return 46;
+        if (gs.Count != 0) return 47;
+
+        return 0;
+    }
+
+    // Test 5: Initialize struct in array element using ref
+    public static int Test5()
+    {
+        SimpleStruct[] array = new SimpleStruct[3];
+
+        // Set values in first element
+        array[0].IntField = 111;
+        array[0].BoolField = true;
+        array[0].CharField = 'Z';
+
+        if (array[0].IntField != 111) return 50;
+        if (array[0].BoolField != true) return 51;
+        if (array[0].CharField != 'Z') return 52;
+
+        // Reset first element using default assignment
+        array[0] = default(SimpleStruct);
+
+        if (array[0].IntField != 0) return 53;
+        if (array[0].BoolField != false) return 54;
+        if (array[0].CharField != '\0') return 55;
+
+        // Also test with ref local
+        array[1].IntField = 222;
+        ref SimpleStruct secondElement = ref array[1];
+        secondElement = default(SimpleStruct);
+
+        if (array[1].IntField != 0) return 56;
+
+        return 0;
+    }
+
+    // Test 6: Initialize struct through method parameter
+    public static int Test6()
+    {
+        SimpleStruct s = new SimpleStruct
+        {
+            IntField = 200,
+            BoolField = true,
+            CharField = 'M',
+            DoubleField = 2.71,
+            ByteField = 64
+        };
+
+        ResetStruct(ref s);
+
+        if (s.IntField != 0) return 60;
+        if (s.BoolField != false) return 61;
+        if (s.CharField != '\0') return 62;
+        if (s.DoubleField != 0.0) return 63;
+        if (s.ByteField != 0) return 64;
+
+        return 0;
+    }
+
+    private static void ResetStruct(ref SimpleStruct s)
+    {
+        s = default(SimpleStruct);
+    }
+
+    // Test 7: Initialize multiple structs
+    public static int Test7()
+    {
+        SimpleStruct s1 = new SimpleStruct { IntField = 1 };
+        SimpleStruct s2 = new SimpleStruct { IntField = 2 };
+        SimpleStruct s3 = new SimpleStruct { IntField = 3 };
+
+        if (s1.IntField != 1) return 70;
+        if (s2.IntField != 2) return 71;
+        if (s3.IntField != 3) return 72;
+
+        s1 = default(SimpleStruct);
+        s2 = default(SimpleStruct);
+        s3 = default(SimpleStruct);
+
+        if (s1.IntField != 0) return 73;
+        if (s2.IntField != 0) return 74;
+        if (s3.IntField != 0) return 75;
+
+        return 0;
+    }
+
+    // Test 8: Initialize struct passed as argument (tests Argument case)
+    public static int Test8()
+    {
+        SimpleStruct s = new SimpleStruct
+        {
+            IntField = 333,
+            BoolField = true,
+            CharField = 'Q',
+            DoubleField = 4.56,
+            ByteField = 77
+        };
+
+        int result = InitializeArgumentStruct(ref s);
+        if (result != 0) return result;
+
+        // Verify struct was reset
+        if (s.IntField != 0) return 80;
+        if (s.BoolField != false) return 81;
+        if (s.CharField != '\0') return 82;
+        if (s.DoubleField != 0.0) return 83;
+        if (s.ByteField != 0) return 84;
+
+        return 0;
+    }
+
+    private static int InitializeArgumentStruct(ref SimpleStruct arg)
+    {
+        // Verify initial values
+        if (arg.IntField != 333) return 85;
+        if (arg.BoolField != true) return 86;
+
+        // Reset using default - this should use initobj on the argument
+        arg = default(SimpleStruct);
+
+        return 0;
+    }
+
+    // Test 9: Initialize struct field (tests Field case)
+    public static int Test9()
+    {
+        StructWithStructField container = new StructWithStructField
+        {
+            NestedField = new SimpleStruct
+            {
+                IntField = 444,
+                BoolField = true,
+                CharField = 'F',
+                DoubleField = 7.89,
+                ByteField = 88
+            },
+            OtherField = 555
+        };
+
+        // Verify initial values
+        if (container.NestedField.IntField != 444) return 90;
+        if (container.OtherField != 555) return 91;
+
+        // Reset the nested field using ref
+        ref SimpleStruct fieldRef = ref container.NestedField;
+        fieldRef = default(SimpleStruct);
+
+        // Verify nested field was reset but other field unchanged
+        if (container.NestedField.IntField != 0) return 92;
+        if (container.NestedField.BoolField != false) return 93;
+        if (container.NestedField.CharField != '\0') return 94;
+        if (container.NestedField.DoubleField != 0.0) return 95;
+        if (container.NestedField.ByteField != 0) return 96;
+        if (container.OtherField != 555) return 97;
+
+        return 0;
+    }
+
+    // Test 10: Initialize struct in heap-allocated object (tests Heap case)
+    public static int Test10()
+    {
+        ClassWithStructField obj = new ClassWithStructField
+        {
+            StructField = new SimpleStruct
+            {
+                IntField = 666,
+                BoolField = true,
+                CharField = 'H',
+                DoubleField = 9.99,
+                ByteField = 99
+            },
+            IntField = 777
+        };
+
+        // Verify initial values
+        if (obj.StructField.IntField != 666) return 100;
+        if (obj.IntField != 777) return 101;
+
+        // Reset the struct field
+        obj.StructField = default(SimpleStruct);
+
+        // Verify struct field was reset but other field unchanged
+        if (obj.StructField.IntField != 0) return 102;
+        if (obj.StructField.BoolField != false) return 103;
+        if (obj.StructField.CharField != '\0') return 104;
+        if (obj.StructField.DoubleField != 0.0) return 105;
+        if (obj.StructField.ByteField != 0) return 106;
+        if (obj.IntField != 777) return 107;
+
+        return 0;
+    }
+
+    // Test 11: Initialize struct through unsafe pointer manipulation
+    public static unsafe int Test11()
+    {
+        SimpleStruct s = new SimpleStruct
+        {
+            IntField = 888,
+            BoolField = true,
+            CharField = 'P',
+            DoubleField = 11.11,
+            ByteField = 111
+        };
+
+        // Get a pointer to the struct
+        SimpleStruct* ptr = &s;
+
+        // Initialize through pointer
+        *ptr = default(SimpleStruct);
+
+        // Verify all fields are zeroed
+        if (s.IntField != 0) return 110;
+        if (s.BoolField != false) return 111;
+        if (s.CharField != '\0') return 112;
+        if (s.DoubleField != 0.0) return 113;
+        if (s.ByteField != 0) return 114;
+
+        return 0;
+    }
+
+    // Test 12: Initialize struct through Unsafe.AsRef
+    public static int Test12()
+    {
+        SimpleStruct s = new SimpleStruct
+        {
+            IntField = 999,
+            BoolField = true,
+            CharField = 'U',
+            DoubleField = 12.34,
+            ByteField = 200
+        };
+
+        // Use Unsafe to get a ref and initialize it
+        ref SimpleStruct sRef = ref s;
+        sRef = default(SimpleStruct);
+
+        // Verify all fields are zeroed
+        if (s.IntField != 0) return 120;
+        if (s.BoolField != false) return 121;
+        if (s.CharField != '\0') return 122;
+        if (s.DoubleField != 0.0) return 123;
+        if (s.ByteField != 0) return 124;
+
+        return 0;
+    }
+
+    // Test 13: Initialize readonly struct
+    public static int Test13()
+    {
+        ReadonlyStruct ros = new ReadonlyStruct(100, true);
+
+        // Verify initial values through properties
+        if (ros.IntValue != 100) return 130;
+        if (ros.BoolValue != true) return 131;
+
+        // Reset using default
+        ros = default(ReadonlyStruct);
+
+        // Verify zeroed
+        if (ros.IntValue != 0) return 132;
+        if (ros.BoolValue != false) return 133;
+
+        return 0;
+    }
+
+    private readonly struct ReadonlyStruct
+    {
+        public readonly int IntValue;
+        public readonly bool BoolValue;
+
+        public ReadonlyStruct(int i, bool b)
+        {
+            IntValue = i;
+            BoolValue = b;
+        }
+    }
+
+    public static int Main(string[] argv)
+    {
+        var result = Test1();
+        if (result != 0) return result;
+
+        result = Test2();
+        if (result != 0) return result;
+
+        result = Test3();
+        if (result != 0) return result;
+
+        result = Test4();
+        if (result != 0) return result;
+
+        result = Test5();
+        if (result != 0) return result;
+
+        result = Test6();
+        if (result != 0) return result;
+
+        result = Test7();
+        if (result != 0) return result;
+
+        result = Test8();
+        if (result != 0) return result;
+
+        result = Test9();
+        if (result != 0) return result;
+
+        result = Test10();
+        if (result != 0) return result;
+
+        result = Test11();
+        if (result != 0) return result;
+
+        result = Test12();
+        if (result != 0) return result;
+
+        result = Test13();
+        if (result != 0) return result;
+
+        // All tests passed
+        return 0;
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/OverlappingStructs.cs

@@ -0,0 +1,364 @@
+using System;
+using System.Runtime.InteropServices;
+
+public class StructLayoutTests
+{
+    // Test structs with various layouts
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct SequentialStruct
+    {
+        public int A;
+        public byte B;
+        public long C;
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    struct ExplicitUnion
+    {
+        [FieldOffset(0)] public int AsInt;
+        [FieldOffset(0)] public float AsFloat;
+        [FieldOffset(0)] public byte Byte0;
+        [FieldOffset(1)] public byte Byte1;
+        [FieldOffset(2)] public byte Byte2;
+        [FieldOffset(3)] public byte Byte3;
+    }
+
+    [StructLayout(LayoutKind.Explicit, Size = 16)]
+    struct FixedSizeStruct
+    {
+        [FieldOffset(0)] public long First;
+        [FieldOffset(8)] public int Second;
+        [FieldOffset(12)] public short Third;
+    }
+
+    [StructLayout(LayoutKind.Sequential, Pack = 1)]
+    struct PackedStruct
+    {
+        public byte A;
+        public int B;
+        public byte C;
+    }
+
+    [StructLayout(LayoutKind.Auto)]
+    struct AutoLayoutStruct
+    {
+        public int X;
+        public string Y;
+        public double Z;
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    struct NestedUnion
+    {
+        [FieldOffset(0)] public ExplicitUnion Inner;
+        [FieldOffset(0)] public long AsLong;
+        [FieldOffset(4)] public int UpperInt;
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    struct LargeUnion
+    {
+        [FieldOffset(0)] public long Long1;
+        [FieldOffset(8)] public long Long2;
+        [FieldOffset(0)] public double Double1;
+        [FieldOffset(8)] public double Double2;
+        [FieldOffset(0)] public decimal AsDecimal;
+    }
+
+    // Static fields for testing
+    static SequentialStruct staticSequential;
+    static ExplicitUnion staticUnion;
+    static FixedSizeStruct staticFixed;
+
+    // Instance fields for testing
+    class FieldContainer
+    {
+        public SequentialStruct instanceSequential;
+        public ExplicitUnion instanceUnion;
+        public PackedStruct instancePacked;
+        public NestedUnion instanceNested;
+    }
+
+    static int TestSequentialLayout()
+    {
+        var s = new SequentialStruct { A = 42, B = 255, C = long.MaxValue };
+
+        // Test field access
+        if (s.A != 42) return 1;
+        if (s.B != 255) return 2;
+        if (s.C != long.MaxValue) return 3;
+
+        // Test copy semantics
+        var s2 = s;
+        s2.A = 100;
+        if (s.A != 42) return 4; // Should be unchanged (value type)
+        if (s2.A != 100) return 5;
+
+        // Test static field storage
+        staticSequential = s;
+        if (staticSequential.A != 42) return 6;
+        if (staticSequential.C != long.MaxValue) return 7;
+
+        return 0;
+    }
+
+    static int TestExplicitUnion()
+    {
+        var u = new ExplicitUnion();
+
+        // Test overlapping int/float
+        u.AsInt = 0x3F800000; // IEEE 754 representation of 1.0f
+        if (Math.Abs(u.AsFloat - 1.0f) > 0.0001f) return 10;
+
+        // Test byte-level access
+        u.AsInt = 0x12345678;
+        bool isLittleEndian = BitConverter.IsLittleEndian;
+        if (isLittleEndian)
+        {
+            if (u.Byte0 != 0x78) return 11;
+            if (u.Byte1 != 0x56) return 12;
+            if (u.Byte2 != 0x34) return 13;
+            if (u.Byte3 != 0x12) return 14;
+        }
+        else
+        {
+            if (u.Byte0 != 0x12) return 11;
+            if (u.Byte1 != 0x34) return 12;
+            if (u.Byte2 != 0x56) return 13;
+            if (u.Byte3 != 0x78) return 14;
+        }
+
+        // Test static field
+        staticUnion = u;
+        if (staticUnion.AsInt != 0x12345678) return 15;
+
+        return 0;
+    }
+
+    static int TestFixedSizeStruct()
+    {
+        var f = new FixedSizeStruct { First = -1, Second = 42, Third = 1000 };
+
+        if (f.First != -1) return 20;
+        if (f.Second != 42) return 21;
+        if (f.Third != 1000) return 22;
+
+        // Test size is respected
+        int size = Marshal.SizeOf(typeof(FixedSizeStruct));
+        if (size != 16) return 23;
+
+        staticFixed = f;
+        if (staticFixed.Second != 42) return 24;
+
+        return 0;
+    }
+
+    static int TestPackedStruct()
+    {
+        var p = new PackedStruct { A = 1, B = 0x12345678, C = 2 };
+
+        if (p.A != 1) return 30;
+        if (p.B != 0x12345678) return 31;
+        if (p.C != 2) return 32;
+
+        // Packed struct should be 6 bytes (1 + 4 + 1)
+        int size = Marshal.SizeOf(typeof(PackedStruct));
+        if (size != 6) return 33;
+
+        return 0;
+    }
+
+    static int TestInstanceFields()
+    {
+        var container = new FieldContainer();
+
+        container.instanceSequential = new SequentialStruct { A = 111, B = 222, C = 333 };
+        if (container.instanceSequential.A != 111) return 40;
+
+        container.instanceUnion = new ExplicitUnion { AsInt = unchecked((int)0xDEADBEEF) };
+        if (container.instanceUnion.AsInt != unchecked((int)0xDEADBEEF)) return 41;
+
+        container.instancePacked = new PackedStruct { A = 10, B = 20, C = 30 };
+        if (container.instancePacked.B != 20) return 42;
+
+        container.instanceNested = new NestedUnion();
+        container.instanceNested.Inner.AsInt = 100;
+        if (container.instanceNested.Inner.AsInt != 100) return 43;
+
+        return 0;
+    }
+
+    static int TestStructPassing()
+    {
+        var s = new SequentialStruct { A = 500, B = 50, C = 5005 };
+        int result = ProcessSequential(s);
+        if (result != 555) return 50; // 500 + 50 + 5 (C % 1000)
+
+        var u = new ExplicitUnion { AsInt = 1000 };
+        u = TransformUnion(u);
+        if (u.AsInt != 2000) return 51;
+
+        return 0;
+    }
+
+    static int ProcessSequential(SequentialStruct s)
+    {
+        return s.A + s.B + (int)(s.C % 1000);
+    }
+
+    static ExplicitUnion TransformUnion(ExplicitUnion u)
+    {
+        u.AsInt *= 2;
+        return u;
+    }
+
+    static int TestNestedUnion()
+    {
+        var n = new NestedUnion();
+        n.Inner.AsInt = 0x12345678;
+
+        // Lower 32 bits should match Inner.AsInt
+        if ((n.AsLong & 0xFFFFFFFF) != 0x12345678) return 60;
+
+        // Modify upper int
+        n.UpperInt = unchecked((int)0xABCDEF00);
+
+        // Check both parts
+        if (n.Inner.AsInt != 0x12345678) return 61;
+        if (n.UpperInt != unchecked((int)0xABCDEF00)) return 62;
+
+        return 0;
+    }
+
+    static int TestLargeUnion()
+    {
+        var l = new LargeUnion();
+
+        // Test double/long overlap
+        l.Double1 = 1.0;
+        l.Double2 = 2.0;
+
+        // IEEE 754: 1.0 = 0x3FF0000000000000
+        if (l.Long1 != 0x3FF0000000000000) return 70;
+        // IEEE 754: 2.0 = 0x4000000000000000
+        if (l.Long2 != 0x4000000000000000) return 71;
+
+        // Test decimal overlap (decimal is 128 bits)
+        l.AsDecimal = 42m;
+        // Just verify it doesn't crash and maintains some structure
+        if (l.AsDecimal != 42m) return 72;
+
+        return 0;
+    }
+
+    static int TestAutoLayout()
+    {
+        // Auto layout structs can't use FieldOffset, but we can still test basic functionality
+        var a = new AutoLayoutStruct { X = 100, Y = "test", Z = 3.14159 };
+
+        if (a.X != 100) return 80;
+        if (a.Y != "test") return 81;
+        if (Math.Abs(a.Z - 3.14159) > 0.00001) return 82;
+
+        // Test copy
+        var a2 = a;
+        a2.X = 200;
+        if (a.X != 100) return 83; // Original should be unchanged
+        if (a2.X != 200) return 84;
+
+        return 0;
+    }
+
+    static int TestStructArray()
+    {
+        var arr = new ExplicitUnion[3];
+        arr[0].AsInt = 10;
+        arr[1].AsInt = 20;
+        arr[2].AsInt = 30;
+
+        if (arr[0].AsInt != 10) return 90;
+        if (arr[1].AsInt != 20) return 91;
+        if (arr[2].AsInt != 30) return 92;
+
+        // Modify through float view
+        arr[1].AsFloat = 2.5f;
+        if (Math.Abs(arr[1].AsFloat - 2.5f) > 0.0001f) return 93;
+
+        return 0;
+    }
+
+    static int TestBoxingUnboxing()
+    {
+        ExplicitUnion u = new ExplicitUnion { AsInt = 999 };
+        object boxed = u; // Box
+        ExplicitUnion unboxed = (ExplicitUnion)boxed; // Unbox
+
+        if (unboxed.AsInt != 999) return 100;
+
+        // Modify original, boxed should remain unchanged
+        u.AsInt = 111;
+        ExplicitUnion fromBoxed = (ExplicitUnion)boxed;
+        if (fromBoxed.AsInt != 999) return 101; // Should still be 999
+
+        return 0;
+    }
+
+    static int TestDefaultValues()
+    {
+        // Test that default struct initialization zeroes memory
+        var s = new SequentialStruct();
+        if (s.A != 0) return 110;
+        if (s.B != 0) return 111;
+        if (s.C != 0) return 112;
+
+        var u = new ExplicitUnion();
+        if (u.AsInt != 0) return 113;
+        if (u.AsFloat != 0.0f) return 114;
+
+        return 0;
+    }
+
+    public static int Main(string[] argv)
+    {
+        int result = 0;
+
+        result = TestExplicitUnion();
+        if (result != 0) return result;
+
+        result = TestSequentialLayout();
+        if (result != 0) return result;
+
+        result = TestFixedSizeStruct();
+        if (result != 0) return result;
+
+        result = TestPackedStruct();
+        if (result != 0) return result;
+
+        result = TestInstanceFields();
+        if (result != 0) return result;
+
+        result = TestStructPassing();
+        if (result != 0) return result;
+
+        result = TestNestedUnion();
+        if (result != 0) return result;
+
+        result = TestLargeUnion();
+        if (result != 0) return result;
+
+        result = TestAutoLayout();
+        if (result != 0) return result;
+
+        result = TestStructArray();
+        if (result != 0) return result;
+
+        result = TestBoxingUnboxing();
+        if (result != 0) return result;
+
+        result = TestDefaultValues();
+        if (result != 0) return result;
+
+        return 0; // All tests passed
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/Sizeof.cs

@@ -10,16 +10,16 @@ unsafe public class Program
 
     public struct MediumStruct
     {
-        public int Value1;
-        public int Value2;
+        public int MediumValue1;
+        public int MediumValue2;
     }
 
     public struct LargeStruct
     {
-        public long Value1;
-        public long Value2;
-        public long Value3;
-        public long Value4;
+        public long LongValue1;
+        public long LongValue2;
+        public long LongValue3;
+        public long LongValue4;
     }
 
     public struct NestedStruct

WoofWare.PawPrint.Test/sourcesPure/Sizeof2.cs

@@ -0,0 +1,235 @@
+using System;
+using System.Runtime.InteropServices;
+
+unsafe public class Program
+{
+    // Test for empty struct (should be 1 byte, not 0)
+    public struct EmptyStruct
+    {
+    }
+
+    // Test for char alignment (should align to 2, not 1)
+    public struct CharStruct
+    {
+        public byte B;
+        public char C;  // Should be at offset 2, not 1
+    }
+
+    // Test for end padding
+    public struct NeedsEndPadding
+    {
+        public int X;
+        public byte Y;
+        // Should pad to 8 bytes total (multiple of 4)
+    }
+
+    // Test Pack=1 (no padding)
+    [StructLayout(LayoutKind.Sequential, Pack = 1)]
+    public struct PackedStruct
+    {
+        public byte B;
+        public int I;   // At offset 1, not 4
+        public byte B2;
+        // Total 6 bytes, no padding
+    }
+
+    // Test Pack=2
+    [StructLayout(LayoutKind.Sequential, Pack = 2)]
+    public struct Pack2Struct
+    {
+        public byte B;
+        public int I;   // At offset 2 (2-byte aligned, not 4)
+        public byte B2;
+        // Should pad to 8 bytes (multiple of 2)
+    }
+
+    // Test custom size smaller than natural size
+    [StructLayout(LayoutKind.Sequential, Size = 12)]
+    public struct CustomSizeSmaller
+    {
+        public long L1;
+        public long L2;
+        // Natural size is 16, but Size=12 is ignored (12 < 16)
+    }
+
+    // Test custom size larger than natural size
+    [StructLayout(LayoutKind.Sequential, Size = 20)]
+    public struct CustomSizeLarger
+    {
+        public long L;
+        // Natural size is 8, custom size 20 should win
+    }
+
+    // Test custom size not multiple of alignment
+    [StructLayout(LayoutKind.Sequential, Size = 15)]
+    public struct CustomSizeOdd
+    {
+        public long L;
+        // Size=15 should be honored even though not multiple of 8
+    }
+
+    // Test Pack=0 (means default, not 0)
+    [StructLayout(LayoutKind.Sequential, Pack = 0)]
+    public struct Pack0Struct
+    {
+        public byte B;
+        public int I;  // Should be at offset 4 (default packing)
+    }
+
+    // Test both Pack and Size
+    [StructLayout(LayoutKind.Sequential, Pack = 1, Size = 10)]
+    public struct PackAndSize
+    {
+        public byte B;
+        public int I;
+        // Natural packed size is 5, custom size 10 should win
+    }
+
+    // Test explicit with custom Size
+    [StructLayout(LayoutKind.Explicit, Size = 10)]
+    public struct ExplicitWithSize
+    {
+        [FieldOffset(0)]
+        public int I;
+        [FieldOffset(2)]
+        public short S;
+        // Max offset+size is 4, but Size=10 should win
+    }
+
+    public struct SmallStruct
+    {
+        public byte Value;
+    }
+
+    public struct MediumStruct
+    {
+        public int MediumValue1;
+        public int MediumValue2;
+    }
+
+    public struct LargeStruct
+    {
+        public long LongValue1;
+        public long LongValue2;
+        public long LongValue3;
+        public long LongValue4;
+    }
+
+    public struct NestedStruct
+    {
+        public SmallStruct Small;
+        public MediumStruct Medium;
+        public int Extra;
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    public struct UnionStruct
+    {
+        [FieldOffset(0)]
+        public int AsInt;
+        [FieldOffset(0)]
+        public float AsFloat;
+    }
+
+    public static int Main(string[] args)
+    {
+        // Test 1: Basic primitive types
+        if (sizeof(byte) != 1) return 1;
+        if (sizeof(sbyte) != 1) return 2;
+        if (sizeof(short) != 2) return 3;
+        if (sizeof(ushort) != 2) return 4;
+        if (sizeof(int) != 4) return 5;
+        if (sizeof(uint) != 4) return 6;
+        if (sizeof(long) != 8) return 7;
+        if (sizeof(ulong) != 8) return 8;
+        if (sizeof(float) != 4) return 9;
+        if (sizeof(double) != 8) return 10;
+        if (sizeof(char) != 2) return 11;
+        if (sizeof(bool) != 1) return 12;
+
+        // Test 2: Struct sizes
+        if (sizeof(SmallStruct) != 1) return 13;
+        if (sizeof(MediumStruct) != 8) return 14;
+        if (sizeof(LargeStruct) != 32) return 15;
+
+        // Test 3: Nested struct size
+        // SmallStruct (1) + padding (3) + MediumStruct (8) + int (4) = 16
+        if (sizeof(NestedStruct) != 16) return 16;
+
+        // Test 4: Union struct size
+        if (sizeof(UnionStruct) != 4) return 17;
+
+        // Test 5: Enum size (underlying type is int)
+        if (sizeof(DayOfWeek) != 4) return 18;
+
+        // Test 6: Empty struct (should be 1, not 0)
+        if (sizeof(EmptyStruct) != 1) return 19;
+
+        // Test 7: Char alignment
+        // byte (1) + padding (1) + char (2) = 4
+        if (sizeof(CharStruct) != 4) return 20;
+
+        // Test 8: End padding
+        // int (4) + byte (1) + padding (3) = 8
+        if (sizeof(NeedsEndPadding) != 8) return 21;
+
+        // Test 9: Pack=1 removes all padding
+        // byte (1) + int (4) + byte (1) = 6
+        if (sizeof(PackedStruct) != 6) return 22;
+
+        // Test 10: Pack=2
+        // byte (1) + padding (1) + int (4) + byte (1) + padding (1) = 8
+        if (sizeof(Pack2Struct) != 8) return 23;
+
+        // Test 11: Custom size smaller than natural (ignored)
+        if (sizeof(CustomSizeSmaller) != 16) return 24;
+
+        // Test 12: Custom size larger than natural (honored)
+        if (sizeof(CustomSizeLarger) != 20) return 25;
+
+        // Test 13: Custom size not multiple of alignment (honored)
+        if (sizeof(CustomSizeOdd) != 15) return 26;
+
+        // Test 14: Pack=0 means default packing
+        // byte (1) + padding (3) + int (4) = 8
+        if (sizeof(Pack0Struct) != 8) return 27;
+
+        // Test 15: Pack and Size together
+        // Natural packed: byte (1) + int (4) = 5, but Size=10
+        if (sizeof(PackAndSize) != 10) return 28;
+
+        // Test 16: Explicit with Size
+        // Max used is 4, but Size=10
+        if (sizeof(ExplicitWithSize) != 10) return 29;
+
+        // Test 17: Pointer types
+        unsafe
+        {
+            if (sizeof(IntPtr) != sizeof(void*)) return 30;
+            if (sizeof(UIntPtr) != sizeof(void*)) return 31;
+        }
+
+        // Test 18: Using sizeof in expressions
+        int totalSize = sizeof(int) + sizeof(long) + sizeof(byte);
+        if (totalSize != 13) return 32;
+
+        // Test 19: Array element size calculation
+        int arrayElementSize = sizeof(MediumStruct);
+        int arraySize = arrayElementSize * 3;
+        if (arraySize != 24) return 33;
+
+        // Test 20: Complex nested struct with Pack
+        // byte (1) + CharStruct (4) + byte (1) = 6
+        if (sizeof(PackedNested) != 6) return 34;
+
+        return 0;
+    }
+
+    [StructLayout(LayoutKind.Sequential, Pack = 1)]
+    struct PackedNested
+    {
+        public byte B;
+        public CharStruct C;
+        public byte B2;
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/StackOperations.cs

@@ -0,0 +1,184 @@
+public class TestStackOperations
+{
+    // Test LdArg0-3: Load method arguments
+    public static int TestLoadArguments(int arg0, int arg1, int arg2, int arg3)
+    {
+        // LdArg0 loads 'this' for instance methods or first arg for static
+        if (arg0 != 10) return 1;
+
+        // LdArg1 loads second argument
+        if (arg1 != 20) return 2;
+
+        // LdArg2 loads third argument
+        if (arg2 != 30) return 3;
+
+        // LdArg3 loads fourth argument
+        if (arg3 != 40) return 4;
+
+        return 0;
+    }
+
+    // Test Ldloc_0-3 and Stloc_0-3: Load/store local variables
+    public static int TestLocalVariables()
+    {
+        int local0 = 100;
+        int local1 = 200;
+        int local2 = 300;
+        int local3 = 400;
+
+        // Test loading locals
+        if (local0 != 100) return 10;
+        if (local1 != 200) return 11;
+        if (local2 != 300) return 12;
+        if (local3 != 400) return 13;
+
+        // Test storing to locals
+        local0 = local1 + local2;  // Stloc_0
+        if (local0 != 500) return 14;
+
+        local1 = local2 * 2;  // Stloc_1
+        if (local1 != 600) return 15;
+
+        local2 = local3 - 100;  // Stloc_2
+        if (local2 != 300) return 16;
+
+        local3 = local0 / 5;  // Stloc_3
+        if (local3 != 100) return 17;
+
+        return 0;
+    }
+
+    // Test Pop: Remove top stack value
+    public static int TestPop()
+    {
+        int value = 42;
+
+        // Push value on stack then pop it
+        PushAndPop(value);
+
+        // If we get here, pop worked
+        return 0;
+    }
+
+    private static void PushAndPop(int value)
+    {
+        // The compiler will generate pop instructions
+        // for unused return values
+        GetValue();
+        GetValue();
+    }
+
+    private static int GetValue()
+    {
+        return 123;
+    }
+
+    // Test Dup: Duplicate top stack value
+    public static int TestDup()
+    {
+        int value = 50;
+
+        // Dup is used when same value is needed twice
+        int result1 = value * value;  // Compiler may use dup here
+        if (result1 != 2500) return 20;
+
+        // More complex dup scenario
+        int x = 10;
+        int result2 = AddTwice(x);
+        if (result2 != 20) return 21;
+
+        return 0;
+    }
+
+    private static int AddTwice(int val)
+    {
+        // Compiler may generate dup to use val twice
+        return val + val;
+    }
+
+    // Test Ret: Return from method
+    public static int TestReturn()
+    {
+        // Test void return
+        VoidReturn();
+
+        // Test value return
+        int result = ValueReturn(5);
+        if (result != 5) return 30;
+
+        // Test early return
+        result = EarlyReturn(true);
+        if (result != 1) return 31;
+
+        result = EarlyReturn(false);
+        if (result != 2) return 32;
+
+        return 0;
+    }
+
+    private static void VoidReturn()
+    {
+        // Ret with no value
+        return;
+    }
+
+    private static int ValueReturn(int x)
+    {
+        // Ret with value
+        return x;
+    }
+
+    private static int EarlyReturn(bool condition)
+    {
+        if (condition)
+            return 1;  // Early ret
+
+        return 2;  // Normal ret
+    }
+
+    // Test combinations of stack operations
+    public static int TestStackCombinations()
+    {
+        int a = 10, b = 20, c = 30;
+
+        // Complex expression using multiple locals
+        int result = (a + b) * c - (b - a);
+        if (result != 890) return 40;
+
+        // Nested method calls
+        result = Compute(a, Compute(b, c));
+        if (result != 60) return 41;
+
+        return 0;
+    }
+
+    private static int Compute(int x, int y)
+    {
+        return x + y;
+    }
+
+    public static int Main(string[] argv)
+    {
+        int result;
+
+        result = TestLoadArguments(10, 20, 30, 40);
+        if (result != 0) return 100 + result;
+
+        result = TestLocalVariables();
+        if (result != 0) return 200 + result;
+
+        result = TestPop();
+        if (result != 0) return 300 + result;
+
+        result = TestDup();
+        if (result != 0) return 400 + result;
+
+        result = TestReturn();
+        if (result != 0) return 500 + result;
+
+        result = TestStackCombinations();
+        if (result != 0) return 600 + result;
+
+        return 0;
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/UnsafeAs.cs

@@ -0,0 +1,276 @@
+using System;
+using System.Runtime.CompilerServices;
+
+public class TestUnsafeAs
+{
+    private struct Int32Wrapper
+    {
+        public int Value;
+    }
+
+    private struct UInt32Wrapper
+    {
+        public uint Value;
+    }
+
+    private struct TwoInt16s
+    {
+        public short First;
+        public short Second;
+    }
+
+    private struct FourBytes
+    {
+        public byte B0;
+        public byte B1;
+        public byte B2;
+        public byte B3;
+    }
+
+    private enum TestEnum : int
+    {
+        Value1 = 0x12345678,
+        Value2 = -1
+    }
+
+    // Test 1: Int32 -> UInt32 reinterpretation
+    public static int Test1()
+    {
+        int original = -1;
+        ref uint reinterpreted = ref Unsafe.As<int, uint>(ref original);
+
+        if (reinterpreted != 0xFFFFFFFF)
+            return 1;
+
+        reinterpreted = 0x12345678;
+        if (original != 0x12345678)
+            return 2;
+
+        original = int.MinValue;
+        if (reinterpreted != 0x80000000)
+            return 3;
+
+        return 0;
+    }
+
+    // Test 2: Struct -> Struct reinterpretation
+    public static int Test2()
+    {
+        Int32Wrapper wrapper = new Int32Wrapper { Value = 0x01020304 };
+        ref FourBytes bytes = ref Unsafe.As<Int32Wrapper, FourBytes>(ref wrapper);
+
+        if (BitConverter.IsLittleEndian)
+        {
+            if (bytes.B0 != 0x04) return 10;
+            if (bytes.B1 != 0x03) return 11;
+            if (bytes.B2 != 0x02) return 12;
+            if (bytes.B3 != 0x01) return 13;
+        }
+        else
+        {
+            if (bytes.B0 != 0x01) return 14;
+            if (bytes.B1 != 0x02) return 15;
+            if (bytes.B2 != 0x03) return 16;
+            if (bytes.B3 != 0x04) return 17;
+        }
+
+        bytes.B0 = 0xFF;
+        int expectedValue = BitConverter.IsLittleEndian ? 0x010203FF : unchecked((int)0xFF020304);
+        if (wrapper.Value != expectedValue)
+            return 18;
+
+        return 0;
+    }
+
+    // Test 3: Int32 -> Two Int16s
+    public static int Test3()
+    {
+        int value = 0x12345678;
+        ref TwoInt16s halves = ref Unsafe.As<int, TwoInt16s>(ref value);
+
+        if (BitConverter.IsLittleEndian)
+        {
+            if (halves.First != unchecked((short)0x5678)) return 20;
+            if (halves.Second != 0x1234) return 21;
+        }
+        else
+        {
+            if (halves.First != 0x1234) return 22;
+            if (halves.Second != unchecked((short)0x5678)) return 23;
+        }
+
+        halves.First = -1;
+        int expectedValue = BitConverter.IsLittleEndian ? 0x1234FFFF : unchecked((int)0xFFFF5678);
+        if (value != expectedValue)
+            return 24;
+
+        return 0;
+    }
+
+    // Test 4: Array element reinterpretation
+    public static int Test4()
+    {
+        int[] intArray = new int[] { 0x01020304, 0x05060708 };
+        ref uint uintRef = ref Unsafe.As<int, uint>(ref intArray[0]);
+
+        if (uintRef != 0x01020304u)
+            return 30;
+
+        uintRef = 0xAABBCCDD;
+        if (intArray[0] != unchecked((int)0xAABBCCDD))
+            return 31;
+        if (intArray[1] != 0x05060708)
+            return 32;
+
+        return 0;
+    }
+
+    // Test 5: Bool -> Byte
+    public static int Test5()
+    {
+        bool trueValue = true;
+        bool falseValue = false;
+
+        ref byte trueByte = ref Unsafe.As<bool, byte>(ref trueValue);
+        ref byte falseByte = ref Unsafe.As<bool, byte>(ref falseValue);
+
+        if (trueByte != 1)
+            return 40;
+        if (falseByte != 0)
+            return 41;
+
+        // Modify through byte reference
+        trueByte = 0;
+        if (trueValue != false)
+            return 42;
+
+        falseByte = 1;
+        if (falseValue != true)
+            return 43;
+
+        return 0;
+    }
+
+    // Test 6: Char -> UInt16
+    public static int Test6()
+    {
+        char ch = 'A';
+        ref ushort asUInt16 = ref Unsafe.As<char, ushort>(ref ch);
+
+        if (asUInt16 != 65)
+            return 50;
+
+        asUInt16 = 0x03B1; // Greek lowercase alpha
+        if (ch != 'α')
+            return 51;
+
+        return 0;
+    }
+
+    // Test 7: Float -> Int32
+    public static int Test7()
+    {
+        float floatValue = 1.0f;
+        ref int intBits = ref Unsafe.As<float, int>(ref floatValue);
+
+        // IEEE 754: 1.0f = 0x3F800000
+        if (intBits != 0x3F800000)
+            return 60;
+
+        intBits = 0x40000000; // 2.0f in IEEE 754
+        if (floatValue != 2.0f)
+            return 61;
+
+        floatValue = -0.0f;
+        if (intBits != unchecked((int)0x80000000))
+            return 62;
+
+        return 0;
+    }
+
+    // Test 8: Double -> Int64
+    public static int Test8()
+    {
+        double doubleValue = 1.0;
+        ref long longBits = ref Unsafe.As<double, long>(ref doubleValue);
+
+        // IEEE 754: 1.0 = 0x3FF0000000000000
+        if (longBits != 0x3FF0000000000000L)
+            return 70;
+
+        longBits = 0x4000000000000000L; // 2.0 in IEEE 754
+        if (doubleValue != 2.0)
+            return 71;
+
+        return 0;
+    }
+
+    // Test 9: Enum -> Underlying type
+    public static int Test9()
+    {
+        TestEnum enumValue = TestEnum.Value1;
+        ref int underlying = ref Unsafe.As<TestEnum, int>(ref enumValue);
+
+        if (underlying != 0x12345678)
+            return 80;
+
+        underlying = -1;
+        if (enumValue != TestEnum.Value2)
+            return 81;
+
+        return 0;
+    }
+
+    // Test 10: Local variable reinterpretation
+    public static int Test10()
+    {
+        int local = unchecked((int)0xDEADBEEF);
+        ref uint localAsUint = ref Unsafe.As<int, uint>(ref local);
+
+        if (localAsUint != 0xDEADBEEF)
+            return 90;
+
+        localAsUint = 0xCAFEBABE;
+        if (local != unchecked((int)0xCAFEBABE))
+            return 91;
+
+        return 0;
+    }
+
+    public static int Main(string[] argv)
+    {
+        var result = Test1();
+        if (result != 0) return result;
+
+        result = Test2();
+        if (result != 0) return result;
+
+        result = Test3();
+        if (result != 0) return result;
+
+        result = Test4();
+        if (result != 0) return result;
+
+        result = Test5();
+        if (result != 0) return result;
+
+        result = Test6();
+        if (result != 0) return result;
+
+        result = Test7();
+        if (result != 0) return result;
+
+        result = Test8();
+        if (result != 0) return result;
+
+        result = Test9();
+        if (result != 0) return result;
+
+        result = Test10();
+        if (result != 0) return result;
+
+        // All tests passed
+        return 0;
+    }
+}
+

WoofWare.PawPrint/AbstractMachine.fs

@@ -1,6 +1,5 @@
 namespace WoofWare.PawPrint
 
-open System.Collections.Immutable
 open Microsoft.Extensions.Logging
 open Microsoft.FSharp.Core
 open WoofWare.PawPrint.ExternImplementations
@@ -43,7 +42,7 @@ module AbstractMachine =
                 | Some {
                            WasConstructingObj = Some _
                        } ->
-                    IlMachineState.executeDelegateConstructor instruction state
+                    IlMachineState.executeDelegateConstructor baseClassTypes instruction state
                     // can't advance the program counter here - there's no IL instructions executing!
                     |> IlMachineState.returnStackFrame loggerFactory baseClassTypes thread
                     |> Option.get
@@ -55,18 +54,19 @@ module AbstractMachine =
                     // We've been instructed to run a delegate.
                     let delegateToRunAddr =
                         match instruction.Arguments.[0] with
+                        | CliType.RuntimePointer (CliRuntimePointer.Managed (ManagedPointerSource.Heap addr))
                         | CliType.ObjectRef (Some addr) -> addr
                         | _ -> failwith "expected a managed object ref to delegate"
 
                     let delegateToRun = state.ManagedHeap.NonArrayObjects.[delegateToRunAddr]
 
                     let target =
-                        match delegateToRun.Fields.["_target"] with
+                        match delegateToRun |> AllocatedNonArrayObject.DereferenceField "_target" with
                         | CliType.ObjectRef addr -> addr
                         | x -> failwith $"TODO: delegate target wasn't an object ref: %O{x}"
 
                     let methodPtr =
-                        match delegateToRun.Fields.["_methodPtr"] with
+                        match delegateToRun |> AllocatedNonArrayObject.DereferenceField "_methodPtr" with
                         | CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.FunctionPointer mi)) -> mi
                         | d -> failwith $"unexpectedly not a method pointer in delegate invocation: {d}"
 
@@ -222,5 +222,5 @@ module AbstractMachine =
             |> ExecutionResult.Stepped
         | IlOp.Switch immutableArray -> failwith "TODO: Switch unimplemented"
         | IlOp.UnaryStringToken (unaryStringTokenIlOp, stringHandle) ->
-            UnaryStringTokenIlOp.execute baseClassTypes unaryStringTokenIlOp stringHandle state thread
+            UnaryStringTokenIlOp.execute loggerFactory baseClassTypes unaryStringTokenIlOp stringHandle state thread
             |> ExecutionResult.Stepped

WoofWare.PawPrint/BasicCliType.fs

@@ -1,8 +1,9 @@
 namespace WoofWare.PawPrint
 
+open System
 open System.Collections.Immutable
 open System.Reflection
-open System.Reflection.Metadata
+open Checked
 
 /// Source:
 /// Table I.6: Data Types Directly Supported by the CLI
@@ -41,7 +42,9 @@ type ManagedPointerSource =
     | Argument of sourceThread : ThreadId * methodFrame : int * whichVar : uint16
     | Heap of ManagedHeapAddress
     | ArrayIndex of arr : ManagedHeapAddress * index : int
+    | Field of ManagedPointerSource * fieldName : string
     | Null
+    | InterpretedAsType of ManagedPointerSource * ConcreteType<ConcreteTypeHandle>
 
     override this.ToString () =
         match this with
@@ -52,6 +55,8 @@ type ManagedPointerSource =
         | ManagedPointerSource.Argument (source, method, var) ->
             $"<argument %i{var} in method frame %i{method} of thread %O{source}>"
         | ManagedPointerSource.ArrayIndex (arr, index) -> $"<index %i{index} of array %O{arr}>"
+        | ManagedPointerSource.Field (source, name) -> $"<field %s{name} of %O{source}>"
+        | ManagedPointerSource.InterpretedAsType (src, ty) -> $"<%O{src} as %s{ty.Namespace}.%s{ty.Name}>"
 
 [<RequireQualifiedAccess>]
 type UnsignedNativeIntSource =
@@ -64,6 +69,7 @@ type NativeIntSource =
     | ManagedPointer of ManagedPointerSource
     | FunctionPointer of MethodInfo<ConcreteTypeHandle, ConcreteTypeHandle, ConcreteTypeHandle>
     | TypeHandlePtr of ConcreteTypeHandle
+    | FieldHandlePtr of int64
 
     override this.ToString () : string =
         match this with
@@ -72,12 +78,14 @@ type NativeIntSource =
         | NativeIntSource.FunctionPointer methodDefinition ->
             $"<pointer to {methodDefinition.Name} in {methodDefinition.DeclaringType.Assembly.Name}>"
         | NativeIntSource.TypeHandlePtr ptr -> $"<type ID %O{ptr}>"
+        | NativeIntSource.FieldHandlePtr ptr -> $"<field ID %O{ptr}>"
 
 [<RequireQualifiedAccess>]
 module NativeIntSource =
     let isZero (n : NativeIntSource) : bool =
         match n with
         | NativeIntSource.Verbatim i -> i = 0L
+        | NativeIntSource.FieldHandlePtr _
         | NativeIntSource.TypeHandlePtr _ -> false
         | NativeIntSource.FunctionPointer _ -> failwith "TODO"
         | NativeIntSource.ManagedPointer src ->
@@ -89,6 +97,7 @@ module NativeIntSource =
         match n with
         | NativeIntSource.Verbatim i -> i >= 0L
         | NativeIntSource.FunctionPointer _ -> failwith "TODO"
+        | NativeIntSource.FieldHandlePtr _
         | NativeIntSource.TypeHandlePtr _ -> true
         | NativeIntSource.ManagedPointer _ -> true
 
@@ -113,17 +122,51 @@ type CliNumericType =
     | Float32 of float32
     | Float64 of float
 
-[<RequireQualifiedAccess>]
-type CliRuntimePointerSource =
-    | LocalVariable of sourceThread : ThreadId * methodFrame : int * whichVar : uint16
-    | Argument of sourceThread : ThreadId * methodFrame : int * whichVar : uint16
-    | Heap of ManagedHeapAddress
-    | ArrayIndex of arr : ManagedHeapAddress * index : int
-    | Null
+    static member SizeOf (t : CliNumericType) : int =
+        match t with
+        | CliNumericType.Int32 _ -> 4
+        | CliNumericType.Int64 _ -> 8
+        | CliNumericType.NativeInt _ -> 8
+        | CliNumericType.NativeFloat _ -> 8
+        | CliNumericType.Int8 _ -> 1
+        | CliNumericType.Int16 _ -> 2
+        | CliNumericType.UInt8 _ -> 1
+        | CliNumericType.UInt16 _ -> 2
+        | CliNumericType.Float32 _ -> 4
+        | CliNumericType.Float64 _ -> 8
+
+    static member ToBytes (t : CliNumericType) : byte[] =
+        match t with
+        | CliNumericType.Int32 i -> BitConverter.GetBytes i
+        | CliNumericType.Int64 i -> BitConverter.GetBytes i
+        | CliNumericType.NativeInt src ->
+            match src with
+            | NativeIntSource.Verbatim i -> BitConverter.GetBytes i
+            | NativeIntSource.ManagedPointer src ->
+                match src with
+                | ManagedPointerSource.Null -> BitConverter.GetBytes 0L
+                | _ -> failwith "refusing to express pointer as bytes"
+            | NativeIntSource.FieldHandlePtr _ -> failwith "refusing to express FieldHandlePtr as bytes"
+            | NativeIntSource.FunctionPointer _ -> failwith "refusing to express FunctionPointer as bytes"
+            | NativeIntSource.TypeHandlePtr _ -> failwith "refusing to express TypeHandlePtr as bytes"
+        | CliNumericType.NativeFloat f -> BitConverter.GetBytes f
+        | CliNumericType.Int8 i -> BitConverter.GetBytes i
+        | CliNumericType.Int16 i -> BitConverter.GetBytes i
+        | CliNumericType.UInt8 i -> BitConverter.GetBytes i
+        | CliNumericType.UInt16 i -> BitConverter.GetBytes i
+        | CliNumericType.Float32 i -> BitConverter.GetBytes i
+        | CliNumericType.Float64 i -> BitConverter.GetBytes i
 
 type CliRuntimePointer =
-    | Unmanaged of int64
-    | Managed of CliRuntimePointerSource
+    | Verbatim of int64
+    | FieldRegistryHandle of int64
+    | Managed of ManagedPointerSource
+
+type SizeofResult =
+    {
+        Alignment : int
+        Size : int
+    }
 
 /// This is the kind of type that can be stored in arguments, local variables, statics, array elements, fields.
 type CliType =
@@ -141,11 +184,350 @@ type CliType =
     /// as a concatenated list of its fields.
     | ValueType of CliValueType
 
-and CliValueType =
+    static member SizeOf (t : CliType) : SizeofResult =
+        match t with
+        | CliType.Numeric ty ->
+            let size = CliNumericType.SizeOf ty
+
+            {
+                Size = size
+                Alignment = size
+            }
+        | CliType.Bool _ ->
+            {
+                Size = 1
+                Alignment = 1
+            }
+        | CliType.Char _ ->
+            {
+                Size = 2
+                Alignment = 2
+            }
+        | CliType.ObjectRef _ ->
+            {
+                Size = 8
+                Alignment = 8
+            }
+        | CliType.RuntimePointer _ ->
+            {
+                Size = 8
+                Alignment = 8
+            }
+        | CliType.ValueType vt -> CliValueType.SizeOf vt
+
+    static member ToBytes (t : CliType) : byte[] =
+        match t with
+        | CliType.Numeric n -> CliNumericType.ToBytes n
+        | CliType.Bool b -> [| b |]
+        | CliType.Char (high, low) -> [| low ; high |]
+        | CliType.ObjectRef None -> Array.zeroCreate NATIVE_INT_SIZE
+        | CliType.ObjectRef (Some i) -> failwith "todo"
+        | CliType.RuntimePointer cliRuntimePointer -> failwith "todo"
+        | CliType.ValueType cvt -> CliValueType.ToBytes cvt
+
+    static member OfBytesAsType (targetType : ConcreteTypeHandle) (bytes : byte[]) : CliType = failwith "TODO"
+
+and CliField =
     {
-        Fields : (string * CliType) list
+        Name : string
+        Contents : CliType
+        /// "None" for "no explicit offset specified"; we expect most offsets to be None.
+        Offset : int option
+        Type : ConcreteTypeHandle
     }
 
+and CliConcreteField =
+    private
+        {
+            Name : string
+            Contents : CliType
+            Offset : int
+            Size : int
+            Alignment : int
+            ConfiguredOffset : int option
+            EditedAtTime : uint64
+            Type : ConcreteTypeHandle
+        }
+
+    static member ToCliField (this : CliConcreteField) : CliField =
+        {
+            Offset = this.ConfiguredOffset
+            Contents = this.Contents
+            Name = this.Name
+            Type = this.Type
+        }
+
+and CliValueType =
+    private
+        {
+            _Fields : CliConcreteField list
+            Layout : Layout
+            /// We track dependency orderings between updates to overlapping fields with a monotonically increasing
+            /// timestamp.
+            NextTimestamp : uint64
+        }
+
+    static member private ComputeConcreteFields (layout : Layout) (fields : CliField list) : CliConcreteField list =
+        // Minimum size only matters for `sizeof` computation
+        let _minimumSize, packingSize =
+            match layout with
+            | Layout.Custom (size = size ; packingSize = packing) ->
+                size, if packing = 0 then DEFAULT_STRUCT_ALIGNMENT else packing
+            | Layout.Default -> 0, DEFAULT_STRUCT_ALIGNMENT
+
+        let seqFields, nonSeqFields =
+            fields |> List.partition (fun field -> field.Offset.IsNone)
+
+        match seqFields, nonSeqFields with
+        | [], [] -> []
+        | _ :: _, [] ->
+            // Sequential layout: compute offsets respecting alignment
+            let _, concreteFields =
+                ((0, []), seqFields)
+                ||> List.fold (fun (currentOffset, acc) field ->
+                    let size = CliType.SizeOf field.Contents
+                    let alignmentCap = min size.Alignment packingSize
+                    let error = currentOffset % alignmentCap
+
+                    let alignedOffset =
+                        if error > 0 then
+                            currentOffset + (alignmentCap - error)
+                        else
+                            currentOffset
+
+                    let concreteField =
+                        {
+                            Name = field.Name
+                            Contents = field.Contents
+                            Offset = alignedOffset
+                            Size = size.Size
+                            Alignment = size.Alignment
+                            ConfiguredOffset = field.Offset
+                            EditedAtTime = 0UL
+                            Type = field.Type
+                        }
+
+                    alignedOffset + size.Size, concreteField :: acc
+                )
+
+            List.rev concreteFields
+
+        | [], _ :: _ ->
+            // Explicit layout: use provided offsets
+            nonSeqFields
+            |> List.map (fun field ->
+                let size = CliType.SizeOf field.Contents
+
+                {
+                    Name = field.Name
+                    Contents = field.Contents
+                    Offset = field.Offset.Value
+                    Size = size.Size
+                    Alignment = size.Alignment
+                    ConfiguredOffset = field.Offset
+                    EditedAtTime = 0UL
+                    Type = field.Type
+                }
+            )
+
+        | _ :: _, _ :: _ -> failwith "unexpectedly mixed explicit and automatic layout of fields"
+
+    static member ToBytes (cvt : CliValueType) : byte[] =
+        let bytes = Array.zeroCreate<byte> (CliValueType.SizeOf(cvt).Size)
+
+        cvt._Fields
+        |> List.sortBy _.EditedAtTime
+        |> List.iter (fun candidateField ->
+            let fieldBytes : byte[] = CliType.ToBytes candidateField.Contents
+
+            for i = 0 to candidateField.Size - 1 do
+                bytes.[candidateField.Offset + i] <- fieldBytes.[i]
+        )
+
+        bytes
+
+    static member OfFields (layout : Layout) (f : CliField list) : CliValueType =
+        let fields = CliValueType.ComputeConcreteFields layout f
+
+        {
+            _Fields = fields
+            Layout = layout
+            NextTimestamp = 1UL
+        }
+
+    static member AddField (f : CliField) (vt : CliValueType) : CliValueType =
+        // Recompute all fields with the new one added
+        // TODO: the existence of this function at all is rather dubious, but it's there
+        // at the moment to support delegate types.
+        // The whole function is just a bodge and it will hopefully go away soon; I just don't know how.
+        let prevFields = vt._Fields |> List.map (fun f -> f.Name, f) |> Map.ofList
+
+        let allFields =
+            f
+            :: (vt._Fields
+                |> List.map (fun cf ->
+                    {
+                        Name = cf.Name
+                        Contents = cf.Contents
+                        Offset =
+                            match vt.Layout with
+                            | Layout.Default -> None
+                            | Layout.Custom _ -> Some cf.Offset
+                        Type = cf.Type
+                    }
+                ))
+
+        let newFields =
+            CliValueType.ComputeConcreteFields vt.Layout allFields
+            |> List.map (fun field ->
+                match Map.tryFind field.Name prevFields with
+                | Some prev ->
+                    { field with
+                        EditedAtTime = prev.EditedAtTime
+                    }
+                | None ->
+                    { field with
+                        EditedAtTime = vt.NextTimestamp
+                    }
+            )
+
+        {
+            _Fields = newFields
+            Layout = vt.Layout
+            NextTimestamp = vt.NextTimestamp + 1UL
+        }
+
+    /// Returns the offset and size.
+    static member GetFieldLayout (field : string) (cvt : CliValueType) : int * int =
+        let targetField =
+            cvt._Fields
+            |> List.tryFind (fun f -> f.Name = field)
+            |> Option.defaultWith (fun () -> failwithf $"Field '%s{field}' not found")
+
+        targetField.Offset, targetField.Size
+
+    // TODO: use DereferenceFieldAt for the implementation.
+    // We should eventually be able to dereference an arbitrary field of a struct
+    // as though it were any other field of any other type, to accommodate Unsafe.As.
+    static member DereferenceField (field : string) (cvt : CliValueType) : CliType =
+        let targetField =
+            cvt._Fields
+            |> List.tryFind (fun f -> f.Name = field)
+            |> Option.defaultWith (fun () -> failwithf $"Field '%s{field}' not found")
+
+        // Identify all fields that overlap with the target field's memory range
+        let targetStart = targetField.Offset
+        let targetEnd = targetField.Offset + targetField.Size
+
+        let affectedFields =
+            cvt._Fields
+            |> List.filter (fun f ->
+                let fieldStart = f.Offset
+                let fieldEnd = f.Offset + f.Size
+                // Fields overlap if their ranges intersect
+                fieldStart < targetEnd && targetStart < fieldEnd
+            )
+
+        match affectedFields with
+        | [] -> failwith "unexpectedly didn't dereference a field"
+        | [ f ] -> f.Contents
+        | fields ->
+            let bytes = CliValueType.ToBytes cvt
+
+            let fieldBytes =
+                bytes.[targetField.Offset .. targetField.Offset + targetField.Size - 1]
+
+            CliType.OfBytesAsType targetField.Type fieldBytes
+
+    static member FieldsAt (offset : int) (cvt : CliValueType) : CliConcreteField list =
+        cvt._Fields |> List.filter (fun f -> f.Offset = offset)
+
+    static member DereferenceFieldAt (offset : int) (size : int) (cvt : CliValueType) : CliType =
+        let targetField =
+            CliValueType.FieldsAt offset cvt |> List.tryFind (fun f -> f.Size = size)
+
+        match targetField with
+        | None -> failwith "TODO: couldn't find the field"
+        | Some f -> f.Contents
+
+    static member SizeOf (vt : CliValueType) : SizeofResult =
+        let minimumSize, packingSize =
+            match vt.Layout with
+            | Layout.Custom (size = size ; packingSize = packing) ->
+                size, if packing = 0 then DEFAULT_STRUCT_ALIGNMENT else packing
+            | Layout.Default -> 0, DEFAULT_STRUCT_ALIGNMENT
+
+        if vt._Fields.IsEmpty then
+            {
+                Size = minimumSize
+                Alignment = 1
+            }
+        else
+            // Now we can just use the precomputed offsets and sizes
+            let finalOffset, alignment =
+                vt._Fields
+                |> List.fold
+                    (fun (maxEnd, maxAlign) field ->
+                        let fieldEnd = field.Offset + field.Size
+                        let alignmentCap = min field.Alignment packingSize
+                        max maxEnd fieldEnd, max maxAlign alignmentCap
+                    )
+                    (0, 0)
+
+            let error = finalOffset % alignment
+
+            let size =
+                if error = 0 then
+                    finalOffset
+                else
+                    finalOffset + (alignment - error)
+
+            {
+                Size = max size minimumSize
+                Alignment = alignment
+            }
+
+    /// Sets the value of the specified field, *without* touching any overlapping fields.
+    /// `DereferenceField` handles resolving conflicts between overlapping fields.
+    static member WithFieldSet (field : string) (value : CliType) (cvt : CliValueType) : CliValueType =
+        {
+            Layout = cvt.Layout
+            _Fields =
+                cvt._Fields
+                |> List.replaceWhere (fun f ->
+                    if f.Name = field then
+                        { f with
+                            Contents = value
+                            EditedAtTime = cvt.NextTimestamp
+                        }
+                        |> Some
+                    else
+                        None
+                )
+            NextTimestamp = cvt.NextTimestamp + 1UL
+        }
+
+    /// To facilitate bodges. This function absolutely should not exist.
+    static member TryExactlyOneField (cvt : CliValueType) : CliField option =
+        match cvt._Fields with
+        | [] -> None
+        | [ x ] ->
+            if x.Offset = 0 then
+                Some (CliConcreteField.ToCliField x)
+            else
+                None
+        | _ -> None
+
+    /// To facilitate bodges. This function absolutely should not exist.
+    static member TrySequentialFields (cvt : CliValueType) : CliField list option =
+        let isNone, isSome =
+            cvt._Fields |> List.partition (fun field -> field.ConfiguredOffset.IsNone)
+
+        match isSome with
+        | [] -> Some (isNone |> List.map CliConcreteField.ToCliField)
+        | [ field ] when field.ConfiguredOffset = Some 0 -> Some [ CliConcreteField.ToCliField field ]
+        | _ -> None
+
 type CliTypeResolutionResult =
     | Resolved of CliType
     | FirstLoad of WoofWare.PawPrint.AssemblyReference
@@ -160,31 +542,14 @@ module CliType =
 
     let ofManagedObject (ptr : ManagedHeapAddress) : CliType = CliType.ObjectRef (Some ptr)
 
-    let rec sizeOf (ty : CliType) : int =
-        match ty with
-        | CliType.Numeric ty ->
-            match ty with
-            | CliNumericType.Int32 _ -> 4
-            | CliNumericType.Int64 _ -> 8
-            | CliNumericType.NativeInt _ -> 8
-            | CliNumericType.NativeFloat _ -> 8
-            | CliNumericType.Int8 _ -> 1
-            | CliNumericType.Int16 _ -> 2
-            | CliNumericType.UInt8 _ -> 1
-            | CliNumericType.UInt16 _ -> 2
-            | CliNumericType.Float32 _ -> 4
-            | CliNumericType.Float64 _ -> 8
-        | CliType.Bool _ -> 1
-        | CliType.Char _ -> 2
-        | CliType.ObjectRef _ -> 8
-        | CliType.RuntimePointer _ -> 8
-        | CliType.ValueType vt ->
-            match vt.Fields with
-            | [] -> failwith "is it even possible to instantiate a value type with no fields"
-            | [ _, f ] -> sizeOf f
-            | _ -> failwith $"TODO: %O{vt.Fields} (need to consider struct layout)"
+    let sizeOf (ty : CliType) : int = CliType.SizeOf(ty).Size
 
-    let zeroOfPrimitive (primitiveType : PrimitiveType) : CliType =
+    let zeroOfPrimitive
+        (concreteTypes : AllConcreteTypes)
+        (corelib : BaseClassTypes<DumpedAssembly>)
+        (primitiveType : PrimitiveType)
+        : CliType
+        =
         match primitiveType with
         | PrimitiveType.Boolean -> CliType.Bool 0uy
         | PrimitiveType.Char -> CliType.Char (0uy, 0uy)
@@ -204,8 +569,40 @@ module CliType =
         | PrimitiveType.Double -> CliType.Numeric (CliNumericType.Float64 0.0)
         | PrimitiveType.String -> CliType.ObjectRef None
         | PrimitiveType.TypedReference -> failwith "todo"
-        | PrimitiveType.IntPtr -> CliType.RuntimePointer (CliRuntimePointer.Managed CliRuntimePointerSource.Null)
-        | PrimitiveType.UIntPtr -> CliType.RuntimePointer (CliRuntimePointer.Managed CliRuntimePointerSource.Null)
+        | PrimitiveType.IntPtr ->
+            {
+                Name = "_value"
+                Contents =
+                    CliType.Numeric (
+                        CliNumericType.NativeInt (NativeIntSource.ManagedPointer ManagedPointerSource.Null)
+                    )
+                Offset = None
+                Type =
+                    AllConcreteTypes.findExistingConcreteType
+                        concreteTypes
+                        (corelib.IntPtr.Assembly, corelib.IntPtr.Namespace, corelib.IntPtr.Name, ImmutableArray.Empty)
+                    |> Option.get
+            }
+            |> List.singleton
+            |> CliValueType.OfFields Layout.Default
+            |> CliType.ValueType
+        | PrimitiveType.UIntPtr ->
+            {
+                Name = "_value"
+                Contents =
+                    CliType.Numeric (
+                        CliNumericType.NativeInt (NativeIntSource.ManagedPointer ManagedPointerSource.Null)
+                    )
+                Offset = None
+                Type =
+                    AllConcreteTypes.findExistingConcreteType
+                        concreteTypes
+                        (corelib.UIntPtr.Assembly, corelib.UIntPtr.Namespace, corelib.UIntPtr.Name, ImmutableArray.Empty)
+                    |> Option.get
+            }
+            |> List.singleton
+            |> CliValueType.OfFields Layout.Default
+            |> CliType.ValueType
         | PrimitiveType.Object -> CliType.ObjectRef None
 
     let rec zeroOf
@@ -230,11 +627,11 @@ module CliType =
         match handle with
         | ConcreteTypeHandle.Byref _ ->
             // Byref types are managed references - the zero value is a null reference
-            CliType.RuntimePointer (CliRuntimePointer.Managed CliRuntimePointerSource.Null), concreteTypes
+            CliType.RuntimePointer (CliRuntimePointer.Managed ManagedPointerSource.Null), concreteTypes
 
         | ConcreteTypeHandle.Pointer _ ->
             // Pointer types are unmanaged pointers - the zero value is a null pointer
-            CliType.RuntimePointer (CliRuntimePointer.Unmanaged 0L), concreteTypes
+            CliType.RuntimePointer (CliRuntimePointer.Managed ManagedPointerSource.Null), concreteTypes
 
         | ConcreteTypeHandle.Concrete _ ->
             // This is a concrete type - look it up in the mapping
@@ -248,72 +645,82 @@ module CliType =
             let typeDef = assembly.TypeDefs.[concreteType.Definition.Get]
 
             // Check if it's a primitive type by comparing with corelib types FIRST
-            if concreteType.Assembly = corelib.Corelib.Name && concreteType.Generics.IsEmpty then
+            if
+                concreteType.Assembly.FullName = corelib.Corelib.Name.FullName
+                && concreteType.Generics.IsEmpty
+            then
                 // Check against known primitive types
                 if TypeInfo.NominallyEqual typeDef corelib.Boolean then
-                    zeroOfPrimitive PrimitiveType.Boolean, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Boolean, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Char then
-                    zeroOfPrimitive PrimitiveType.Char, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Char, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.SByte then
-                    zeroOfPrimitive PrimitiveType.SByte, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.SByte, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Byte then
-                    zeroOfPrimitive PrimitiveType.Byte, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Byte, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Int16 then
-                    zeroOfPrimitive PrimitiveType.Int16, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Int16, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.UInt16 then
-                    zeroOfPrimitive PrimitiveType.UInt16, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.UInt16, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Int32 then
-                    zeroOfPrimitive PrimitiveType.Int32, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Int32, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.UInt32 then
-                    zeroOfPrimitive PrimitiveType.UInt32, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.UInt32, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Int64 then
-                    zeroOfPrimitive PrimitiveType.Int64, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Int64, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.UInt64 then
-                    zeroOfPrimitive PrimitiveType.UInt64, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.UInt64, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Single then
-                    zeroOfPrimitive PrimitiveType.Single, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Single, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Double then
-                    zeroOfPrimitive PrimitiveType.Double, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Double, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.String then
-                    zeroOfPrimitive PrimitiveType.String, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.String, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.Object then
-                    zeroOfPrimitive PrimitiveType.Object, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.Object, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.IntPtr then
-                    zeroOfPrimitive PrimitiveType.IntPtr, concreteTypes
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.IntPtr, concreteTypes
                 elif TypeInfo.NominallyEqual typeDef corelib.UIntPtr then
-                    zeroOfPrimitive PrimitiveType.UIntPtr, concreteTypes
-                else if
-                    // Check if it's an array type
-                    typeDef = corelib.Array
-                then
-                    CliType.ObjectRef None, concreteTypes // Arrays are reference types
+                    zeroOfPrimitive concreteTypes corelib PrimitiveType.UIntPtr, concreteTypes
+                elif TypeInfo.NominallyEqual typeDef corelib.Array then
+                    // Arrays are reference types
+                    CliType.ObjectRef None, concreteTypes
                 else if
+
                     // Not a known primitive, now check for cycles
                     Set.contains handle visited
                 then
                     // We're in a cycle - return a default zero value for the type
-                    // For value types in cycles, we'll return a null reference as a safe fallback
-                    // This should only happen with self-referential types
+                    // Value types can't be self-referential unless they are specifically known to the
+                    // runtime - for example, System.Byte is a value type with a single field,
+                    // of type System.Byte.
+                    // Since we check for (nominal) equality against all such types in the first branch,
+                    // this code path is only hit with reference types.
                     CliType.ObjectRef None, concreteTypes
                 else
                     let visited = Set.add handle visited
                     // Not a known primitive, check if it's a value type or reference type
                     determineZeroForCustomType concreteTypes assemblies corelib handle concreteType typeDef visited
             else if
+
                 // Not from corelib or has generics
                 concreteType.Assembly = corelib.Corelib.Name
                 && typeDef = corelib.Array
                 && concreteType.Generics.Length = 1
             then
-                // This is an array type
+                // This is an array type, so null is appropriate
                 CliType.ObjectRef None, concreteTypes
             else if
+
                 // Custom type - now check for cycles
                 Set.contains handle visited
             then
-                // We're in a cycle - return a default zero value for the type
-                // For value types in cycles, we'll return a null reference as a safe fallback
-                // This should only happen with self-referential types
+                // We're in a cycle - return a default zero value for the type.
+                // Value types can't be self-referential unless they are specifically known to the
+                // runtime - for example, System.Byte is a value type with a single field,
+                // of type System.Byte.
+                // Since we check for (nominal) equality against all such types in the first branch,
+                // this code path is only hit with reference types.
                 CliType.ObjectRef None, concreteTypes
             else
                 let visited = Set.add handle visited
@@ -343,7 +750,7 @@ module CliType =
             // It's a value type - need to create zero values for all non-static fields
             let mutable currentConcreteTypes = concreteTypes
 
-            let fieldZeros =
+            let vt =
                 typeDef.Fields
                 |> List.filter (fun field -> not (field.Attributes.HasFlag FieldAttributes.Static))
                 |> List.map (fun field ->
@@ -359,13 +766,15 @@ module CliType =
                         zeroOfWithVisited currentConcreteTypes assemblies corelib fieldHandle visited
 
                     currentConcreteTypes <- updatedConcreteTypes2
-                    (field.Name, fieldZero)
-                )
 
-            let vt =
-                {
-                    Fields = fieldZeros
-                }
+                    {
+                        Name = field.Name
+                        Contents = fieldZero
+                        Offset = field.Offset
+                        Type = fieldHandle
+                    }
+                )
+                |> CliValueType.OfFields typeDef.Layout
 
             CliType.ValueType vt, currentConcreteTypes
         else
@@ -393,20 +802,22 @@ module CliType =
         // The field type might reference generic parameters of the declaring type
         let methodGenerics = ImmutableArray.Empty // Fields don't have method generics
 
-        let loadAssembly
-            (assyName : AssemblyName)
-            (ref : AssemblyReferenceHandle)
-            : ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly
-            =
-            match assemblies.TryGetValue assyName.FullName with
-            | true, currentAssy ->
-                let targetAssyRef = currentAssy.AssemblyReferences.[ref]
+        let loadAssembly =
+            { new IAssemblyLoad with
+                member _.LoadAssembly loaded assyName ref =
+                    match loaded.TryGetValue assyName.FullName with
+                    | true, currentAssy ->
+                        let targetAssyRef = currentAssy.AssemblyReferences.[ref]
 
-                match assemblies.TryGetValue targetAssyRef.Name.FullName with
-                | true, targetAssy -> assemblies, targetAssy
-                | false, _ ->
-                    failwithf "Assembly %s not loaded when trying to resolve reference" targetAssyRef.Name.FullName
-            | false, _ -> failwithf "Current assembly %s not loaded when trying to resolve reference" assyName.FullName
+                        match loaded.TryGetValue targetAssyRef.Name.FullName with
+                        | true, targetAssy -> loaded, targetAssy
+                        | false, _ ->
+                            failwithf
+                                "Assembly %s not loaded when trying to resolve reference"
+                                targetAssyRef.Name.FullName
+                    | false, _ ->
+                        failwithf "Current assembly %s not loaded when trying to resolve reference" assyName.FullName
+            }
 
         let handle, newCtx =
             TypeConcretization.concretizeType
@@ -418,3 +829,41 @@ module CliType =
                 fieldType
 
         handle, newCtx.ConcreteTypes
+
+    let withFieldSet (field : string) (value : CliType) (c : CliType) : CliType =
+        match c with
+        | CliType.Numeric cliNumericType -> failwith "todo"
+        | CliType.Bool b -> failwith "todo"
+        | CliType.Char (high, low) -> failwith "todo"
+        | CliType.ObjectRef managedHeapAddressOption -> failwith "todo"
+        | CliType.RuntimePointer cliRuntimePointer -> failwith "todo"
+        | CliType.ValueType cvt -> CliValueType.WithFieldSet field value cvt |> CliType.ValueType
+
+    let getField (field : string) (value : CliType) : CliType =
+        match value with
+        | CliType.Numeric cliNumericType -> failwith "todo"
+        | CliType.Bool b -> failwith "todo"
+        | CliType.Char (high, low) -> failwith "todo"
+        | CliType.ObjectRef managedHeapAddressOption -> failwith "todo"
+        | CliType.RuntimePointer cliRuntimePointer -> failwith "todo"
+        | CliType.ValueType cvt -> CliValueType.DereferenceField field cvt
+
+    /// Returns the offset and size.
+    let getFieldLayout (field : string) (value : CliType) : int * int =
+        match value with
+        | CliType.Numeric cliNumericType -> failwith "todo"
+        | CliType.Bool b -> failwith "todo"
+        | CliType.Char (high, low) -> failwith "todo"
+        | CliType.ObjectRef managedHeapAddressOption -> failwith "todo"
+        | CliType.RuntimePointer cliRuntimePointer -> failwith "todo"
+        | CliType.ValueType cvt -> CliValueType.GetFieldLayout field cvt
+
+    /// Returns None if there isn't *exactly* one field that starts there. This rules out some valid programs.
+    let getFieldAt (offset : int) (value : CliType) : CliConcreteField option =
+        match value with
+        | CliType.Numeric cliNumericType -> failwith "todo"
+        | CliType.Bool b -> failwith "todo"
+        | CliType.Char (high, low) -> failwith "todo"
+        | CliType.ObjectRef managedHeapAddressOption -> failwith "todo"
+        | CliType.RuntimePointer cliRuntimePointer -> failwith "todo"
+        | CliType.ValueType cvt -> CliValueType.FieldsAt offset cvt |> List.tryExactlyOne

WoofWare.PawPrint/BinaryArithmetic.fs

@@ -4,25 +4,133 @@ namespace WoofWare.PawPrint
 
 type IArithmeticOperation =
     abstract Int32Int32 : int32 -> int32 -> int32
+    abstract Int32NativeInt : int32 -> nativeint -> nativeint
+    abstract NativeIntInt32 : nativeint -> int32 -> nativeint
     abstract Int64Int64 : int64 -> int64 -> int64
     abstract FloatFloat : float -> float -> float
+    abstract NativeIntNativeInt : nativeint -> nativeint -> nativeint
+    abstract Int32ManagedPtr : IlMachineState -> int32 -> ManagedPointerSource -> Choice<ManagedPointerSource, int>
+    abstract ManagedPtrInt32 : IlMachineState -> ManagedPointerSource -> int32 -> Choice<ManagedPointerSource, int>
+
+    abstract ManagedPtrManagedPtr :
+        IlMachineState -> ManagedPointerSource -> ManagedPointerSource -> Choice<ManagedPointerSource, nativeint>
+
     abstract Name : string
 
 [<RequireQualifiedAccess>]
 module ArithmeticOperation =
+    let private addInt32ManagedPtr state v ptr =
+        match ptr with
+        | LocalVariable (sourceThread, methodFrame, whichVar) -> failwith "refusing to add to a local variable address"
+        | Argument (sourceThread, methodFrame, whichVar) -> failwith "refusing to add to an argument address"
+        | Heap managedHeapAddress -> failwith "refusing to add to a heap address"
+        | ArrayIndex (arr, index) -> failwith "TODO: arrays"
+        | Field (src, fieldName) ->
+            let obj = IlMachineState.dereferencePointer state src
+            let offset, _ = CliType.getFieldLayout fieldName obj
+
+            match CliType.getFieldAt (offset + v) obj with
+            | None -> failwith "TODO: couldn't identify field at offset"
+            | Some field ->
+                ManagedPointerSource.Field (src, CliConcreteField.ToCliField(field).Name)
+                |> Choice1Of2
+        | Null -> Choice2Of2 v
+        | InterpretedAsType (managedPointerSource, concreteType) -> failwith "todo"
+
+    let private mulInt32ManagedPtr (state : IlMachineState) v ptr =
+        if v = 0 then
+            Choice2Of2 0
+        elif v = 1 then
+            Choice1Of2 ptr
+        else
+
+        match ptr with
+        | ManagedPointerSource.Null -> Choice2Of2 0
+        | _ -> failwith "refusing to multiply pointers"
+
     let add =
         { new IArithmeticOperation with
             member _.Int32Int32 a b = (# "add" a b : int32 #)
             member _.Int64Int64 a b = (# "add" a b : int64 #)
             member _.FloatFloat a b = (# "add" a b : float #)
+            member _.NativeIntNativeInt a b = (# "add" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "add" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "add" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr _ ptr1 ptr2 =
+                match ptr1, ptr2 with
+                | ManagedPointerSource.Null, _ -> Choice1Of2 ptr2
+                | _, ManagedPointerSource.Null -> Choice1Of2 ptr1
+                | _, _ -> failwith "refusing to add two managed pointers"
+
+            member _.Int32ManagedPtr state val1 ptr2 = addInt32ManagedPtr state val1 ptr2
+            member _.ManagedPtrInt32 state ptr1 val2 = addInt32ManagedPtr state val2 ptr1
+
             member _.Name = "add"
         }
 
+    let addOvf =
+        { new IArithmeticOperation with
+            member _.Int32Int32 a b = (# "add.ovf" a b : int32 #)
+            member _.Int64Int64 a b = (# "add.ovf" a b : int64 #)
+            member _.FloatFloat a b = (# "add.ovf" a b : float #)
+            member _.NativeIntNativeInt a b = (# "add.ovf" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "add.ovf" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "add.ovf" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr _ ptr1 ptr2 =
+                match ptr1, ptr2 with
+                | ManagedPointerSource.Null, _ -> Choice1Of2 ptr2
+                | _, ManagedPointerSource.Null -> Choice1Of2 ptr1
+                | _, _ -> failwith "refusing to add two managed pointers"
+
+            member _.Int32ManagedPtr state val1 ptr2 = addInt32ManagedPtr state val1 ptr2
+            member _.ManagedPtrInt32 state ptr1 val2 = addInt32ManagedPtr state val2 ptr1
+
+            member _.Name = "add.ovf"
+        }
+
     let sub =
         { new IArithmeticOperation with
             member _.Int32Int32 a b = (# "sub" a b : int32 #)
             member _.Int64Int64 a b = (# "sub" a b : int64 #)
             member _.FloatFloat a b = (# "sub" a b : float #)
+            member _.NativeIntNativeInt a b = (# "sub" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "sub" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "sub" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr state ptr1 ptr2 =
+                match ptr1, ptr2 with
+                | ptr1, ManagedPointerSource.Null -> Choice1Of2 ptr1
+                | ManagedPointerSource.Null, _ -> failwith "refusing to create negative pointer"
+                | ManagedPointerSource.ArrayIndex (arr1, index1), ManagedPointerSource.ArrayIndex (arr2, index2) ->
+                    if arr1 <> arr2 then
+                        failwith "refusing to operate on pointers to different arrays"
+
+                    (index1 - index2) |> nativeint |> Choice2Of2
+                | ManagedPointerSource.ArrayIndex _, _ -> failwith $"refusing to operate on array index ptr vs %O{ptr2}"
+                | ManagedPointerSource.Argument _, _
+                | _, ManagedPointerSource.Argument _ ->
+                    failwith $"refusing to operate on pointers to arguments: %O{ptr1} and %O{ptr2}"
+                | ManagedPointerSource.Field (obj1, fieldName1), ManagedPointerSource.Field (obj2, fieldName2) ->
+                    if obj1 <> obj2 then
+                        failwith "refusing to operate on field pointers in different objects"
+
+                    let obj = IlMachineState.dereferencePointer state obj1
+
+                    let offset1, _ = CliType.getFieldLayout fieldName1 obj
+                    let offset2, _ = CliType.getFieldLayout fieldName2 obj
+
+                    (offset1 - offset2) |> nativeint |> Choice2Of2
+                | _, _ -> failwith "TODO"
+
+            member _.Int32ManagedPtr state val1 ptr2 =
+                match ptr2 with
+                | ManagedPointerSource.Null -> Choice2Of2 val1
+                | _ -> failwith "refusing to subtract a pointer"
+
+            member _.ManagedPtrInt32 state ptr1 val2 = failwith "TODO: subtract from pointer"
+
             member _.Name = "sub"
         }
 
@@ -31,21 +139,143 @@ module ArithmeticOperation =
             member _.Int32Int32 a b = (# "mul" a b : int32 #)
             member _.Int64Int64 a b = (# "mul" a b : int64 #)
             member _.FloatFloat a b = (# "mul" a b : float #)
+            member _.NativeIntNativeInt a b = (# "mul" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "mul" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "mul" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr _ ptr1 ptr2 =
+                match ptr1, ptr2 with
+                | ManagedPointerSource.Null, _ -> Choice2Of2 (nativeint 0)
+                | _, ManagedPointerSource.Null -> Choice2Of2 (nativeint 0)
+                | _, _ -> failwith "refusing to multiply two managed pointers"
+
+            member _.Int32ManagedPtr state a ptr = mulInt32ManagedPtr state a ptr
+            member _.ManagedPtrInt32 state ptr a = mulInt32ManagedPtr state a ptr
+
             member _.Name = "mul"
         }
 
+    let rem =
+        { new IArithmeticOperation with
+            member _.Int32Int32 a b = (# "rem" a b : int32 #)
+            member _.Int64Int64 a b = (# "rem" a b : int64 #)
+            member _.FloatFloat a b = (# "rem" a b : float #)
+            member _.NativeIntNativeInt a b = (# "rem" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "rem" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "rem" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr _ ptr1 ptr2 = failwith "refusing to rem pointers"
+
+            member _.Int32ManagedPtr _ a ptr = failwith "refusing to rem pointer"
+
+            member _.ManagedPtrInt32 _ ptr a = failwith "refusing to rem pointer"
+
+            member _.Name = "mul"
+        }
+
+    let mulOvf =
+        { new IArithmeticOperation with
+            member _.Int32Int32 a b = (# "mul.ovf" a b : int32 #)
+            member _.Int64Int64 a b = (# "mul.ovf" a b : int64 #)
+            member _.FloatFloat a b = (# "mul.ovf" a b : float #)
+            member _.NativeIntNativeInt a b = (# "mul.ovf" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "mul.ovf" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "mul.ovf" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr _ ptr1 ptr2 =
+                match ptr1, ptr2 with
+                | ManagedPointerSource.Null, _ -> Choice2Of2 (nativeint 0)
+                | _, ManagedPointerSource.Null -> Choice2Of2 (nativeint 0)
+                | _, _ -> failwith "refusing to multiply two managed pointers"
+
+            member _.Int32ManagedPtr state a ptr = mulInt32ManagedPtr state a ptr
+            member _.ManagedPtrInt32 state a ptr = mulInt32ManagedPtr state ptr a
+
+            member _.Name = "mul_ovf"
+        }
+
+    let div =
+        { new IArithmeticOperation with
+            member _.Int32Int32 a b = (# "div" a b : int32 #)
+            member _.Int64Int64 a b = (# "div" a b : int64 #)
+            member _.FloatFloat a b = (# "div" a b : float #)
+            member _.NativeIntNativeInt a b = (# "div" a b : nativeint #)
+            member _.Int32NativeInt a b = (# "div" a b : nativeint #)
+            member _.NativeIntInt32 a b = (# "div" a b : nativeint #)
+
+            member _.ManagedPtrManagedPtr _ ptr1 ptr2 =
+                match ptr1, ptr2 with
+                | ManagedPointerSource.Null, _ -> Choice2Of2 (nativeint 0)
+                | _, _ -> failwith "refusing to divide two managed pointers"
+
+            member _.Int32ManagedPtr _ a ptr =
+                if a = 0 then
+                    Choice2Of2 0
+                else
+                    failwith "refusing to divide pointers"
+
+            member _.ManagedPtrInt32 _ ptr a =
+                if a = 1 then
+                    Choice1Of2 ptr
+                else
+                    failwith "refusing to divide a pointer"
+
+            member _.Name = "div"
+        }
+
 [<RequireQualifiedAccess>]
 module BinaryArithmetic =
-    let execute (op : IArithmeticOperation) (val1 : EvalStackValue) (val2 : EvalStackValue) : EvalStackValue =
+    let execute
+        (op : IArithmeticOperation)
+        (state : IlMachineState)
+        (val1 : EvalStackValue)
+        (val2 : EvalStackValue)
+        : EvalStackValue
+        =
         // see table at https://learn.microsoft.com/en-us/dotnet/api/system.reflection.emit.opcodes.add?view=net-9.0
         match val1, val2 with
         | EvalStackValue.Int32 val1, EvalStackValue.Int32 val2 -> op.Int32Int32 val1 val2 |> EvalStackValue.Int32
-        | EvalStackValue.Int32 val1, EvalStackValue.NativeInt val2 -> failwith "" |> EvalStackValue.NativeInt
-        | EvalStackValue.Int32 val1, EvalStackValue.ManagedPointer val2 -> failwith "" |> EvalStackValue.ManagedPointer
+        | EvalStackValue.Int32 val1, EvalStackValue.NativeInt val2 ->
+            let val2 =
+                match val2 with
+                | NativeIntSource.Verbatim n -> nativeint<int64> n
+                | v -> failwith $"refusing to operate on non-verbatim native int %O{v}"
+
+            op.Int32NativeInt val1 val2
+            |> int64<nativeint>
+            |> NativeIntSource.Verbatim
+            |> EvalStackValue.NativeInt
+        | EvalStackValue.Int32 val1, EvalStackValue.ManagedPointer val2 ->
+            match op.Int32ManagedPtr state val1 val2 with
+            | Choice1Of2 v -> EvalStackValue.ManagedPointer v
+            | Choice2Of2 i -> EvalStackValue.Int32 i
         | EvalStackValue.Int32 val1, EvalStackValue.ObjectRef val2 -> failwith "" |> EvalStackValue.ObjectRef
         | EvalStackValue.Int64 val1, EvalStackValue.Int64 val2 -> op.Int64Int64 val1 val2 |> EvalStackValue.Int64
-        | EvalStackValue.NativeInt val1, EvalStackValue.Int32 val2 -> failwith "" |> EvalStackValue.NativeInt
-        | EvalStackValue.NativeInt val1, EvalStackValue.NativeInt val2 -> failwith "" |> EvalStackValue.NativeInt
+        | EvalStackValue.NativeInt val1, EvalStackValue.Int32 val2 ->
+            let val1 =
+                match val1 with
+                | NativeIntSource.Verbatim n -> nativeint<int64> n
+                | v -> failwith $"refusing to operate on non-verbatim native int %O{v}"
+
+            op.NativeIntInt32 val1 val2
+            |> int64<nativeint>
+            |> NativeIntSource.Verbatim
+            |> EvalStackValue.NativeInt
+        | EvalStackValue.NativeInt val1, EvalStackValue.NativeInt val2 ->
+            let val1 =
+                match val1 with
+                | NativeIntSource.Verbatim n -> nativeint<int64> n
+                | v -> failwith $"refusing to operate on non-verbatim native int %O{v}"
+
+            let val2 =
+                match val2 with
+                | NativeIntSource.Verbatim n -> nativeint<int64> n
+                | v -> failwith $"refusing to operate on non-verbatim native int %O{v}"
+
+            op.NativeIntNativeInt val1 val2
+            |> int64<nativeint>
+            |> NativeIntSource.Verbatim
+            |> EvalStackValue.NativeInt
         | EvalStackValue.NativeInt val1, EvalStackValue.ManagedPointer val2 ->
             failwith "" |> EvalStackValue.ManagedPointer
         | EvalStackValue.NativeInt val1, EvalStackValue.ObjectRef val2 -> failwith "" |> EvalStackValue.ObjectRef
@@ -53,6 +283,13 @@ module BinaryArithmetic =
         | EvalStackValue.ManagedPointer val1, EvalStackValue.NativeInt val2 ->
             failwith "" |> EvalStackValue.ManagedPointer
         | EvalStackValue.ObjectRef val1, EvalStackValue.NativeInt val2 -> failwith "" |> EvalStackValue.ObjectRef
-        | EvalStackValue.ManagedPointer val1, EvalStackValue.Int32 val2 -> failwith "" |> EvalStackValue.ManagedPointer
+        | EvalStackValue.ManagedPointer val1, EvalStackValue.Int32 val2 ->
+            match op.ManagedPtrInt32 state val1 val2 with
+            | Choice1Of2 result -> EvalStackValue.ManagedPointer result
+            | Choice2Of2 result -> EvalStackValue.NativeInt (NativeIntSource.Verbatim (int64<int32> result))
         | EvalStackValue.ObjectRef val1, EvalStackValue.Int32 val2 -> failwith "" |> EvalStackValue.ObjectRef
+        | EvalStackValue.ManagedPointer val1, EvalStackValue.ManagedPointer val2 ->
+            match op.ManagedPtrManagedPtr state val1 val2 with
+            | Choice1Of2 result -> EvalStackValue.ManagedPointer result
+            | Choice2Of2 result -> EvalStackValue.NativeInt (NativeIntSource.Verbatim (int64<nativeint> result))
         | val1, val2 -> failwith $"invalid %s{op.Name} operation: {val1} and {val2}"

WoofWare.PawPrint/Corelib.fs

@@ -1,5 +1,8 @@
 namespace WoofWare.PawPrint
 
+open System.Collections.Immutable
+open System.Reflection.Metadata
+
 [<RequireQualifiedAccess>]
 module Corelib =
 
@@ -149,6 +152,66 @@ module Corelib =
             )
             |> Seq.exactlyOne
 
+        let exceptionType =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "Exception" then Some v else None)
+            |> Seq.exactlyOne
+
+        let arithmeticException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "ArithmeticException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let divideByZeroException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "DivideByZeroException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let overflowException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "OverflowException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let stackOverflowException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "StackOverflowException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let typeLoadException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "TypeLoadException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let indexOutOfRangeException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "IndexOutOfRangeException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let invalidCastException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "InvalidCastException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let missingFieldException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "MissingFieldException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let missingMethodException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "MissingMethodException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let nullReferenceException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "NullReferenceException" then Some v else None)
+            |> Seq.exactlyOne
+
+        let outOfMemoryException =
+            corelib.TypeDefs
+            |> Seq.choose (fun (KeyValue (_, v)) -> if v.Name = "OutOfMemoryException" then Some v else None)
+            |> Seq.exactlyOne
+
         {
             Corelib = corelib
             String = stringType
@@ -179,4 +242,94 @@ module Corelib =
             TypedReference = typedReferenceType
             IntPtr = intPtrType
             UIntPtr = uintPtrType
+            Exception = exceptionType
+            ArithmeticException = arithmeticException
+            DivideByZeroException = divideByZeroException
+            OverflowException = overflowException
+            StackOverflowException = stackOverflowException
+            TypeLoadException = typeLoadException
+            IndexOutOfRangeException = indexOutOfRangeException
+            InvalidCastException = invalidCastException
+            MissingFieldException = missingFieldException
+            MissingMethodException = missingMethodException
+            NullReferenceException = nullReferenceException
+            OutOfMemoryException = outOfMemoryException
         }
+
+    let concretizeAll
+        (loaded : ImmutableDictionary<string, DumpedAssembly>)
+        (bct : BaseClassTypes<DumpedAssembly>)
+        (t : AllConcreteTypes)
+        : AllConcreteTypes
+        =
+        let ctx =
+            {
+                TypeConcretization.ConcretizationContext.InProgress = ImmutableDictionary.Empty
+                TypeConcretization.ConcretizationContext.ConcreteTypes = t
+                TypeConcretization.ConcretizationContext.LoadedAssemblies = loaded
+                TypeConcretization.ConcretizationContext.BaseTypes = bct
+            }
+
+        let loader =
+            { new IAssemblyLoad with
+                member _.LoadAssembly _ _ _ =
+                    failwith "should have already loaded this assembly"
+            }
+
+        let tys =
+            [
+                bct.String
+                bct.Boolean
+                bct.Char
+                bct.SByte
+                bct.Byte
+                bct.Int16
+                bct.UInt16
+                bct.Int32
+                bct.UInt32
+                bct.Int64
+                bct.UInt64
+                bct.Single
+                bct.Double
+                bct.Array
+                bct.Enum
+                bct.ValueType
+                bct.DelegateType
+                bct.Object
+                bct.RuntimeTypeHandle
+                bct.RuntimeMethodHandle
+                bct.RuntimeFieldHandle
+                bct.RuntimeFieldInfoStub
+                bct.RuntimeFieldHandleInternal
+                bct.RuntimeType
+                bct.Void
+                bct.TypedReference
+                bct.IntPtr
+                bct.UIntPtr
+            ]
+
+        (ctx, tys)
+        ||> List.fold (fun ctx ty ->
+            let stk =
+                match DumpedAssembly.resolveBaseType ctx.BaseTypes ctx.LoadedAssemblies ty.Assembly ty.BaseType with
+                | ResolvedBaseType.Enum
+                | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
+                | ResolvedBaseType.Object
+                | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
+
+            let _handle, ctx =
+                TypeConcretization.concretizeType
+                    ctx
+                    loader
+                    ty.Assembly
+                    ImmutableArray.Empty
+                    ImmutableArray.Empty
+                    (TypeDefn.FromDefinition (
+                        ComparableTypeDefinitionHandle.Make ty.TypeDefHandle,
+                        ty.Assembly.FullName,
+                        stk
+                    ))
+
+            ctx
+        )
+        |> _.ConcreteTypes

WoofWare.PawPrint/EvalStack.fs

@@ -1,5 +1,7 @@
 namespace WoofWare.PawPrint
 
+#nowarn "42"
+
 /// See I.12.3.2.1 for definition
 type EvalStackValue =
     | Int32 of int32
@@ -8,10 +10,8 @@ type EvalStackValue =
     | Float of float
     | ManagedPointer of ManagedPointerSource
     | ObjectRef of ManagedHeapAddress
-    // Fraser thinks this isn't really a thing in CoreCLR
-    // | TransientPointer of TransientPointerSource
-    /// Mapping of field name to value
-    | UserDefinedValueType of (string * EvalStackValue) list
+    /// This doesn't match what the CLR does in reality, but we can work out whatever we need from it.
+    | UserDefinedValueType of CliValueType
 
     override this.ToString () =
         match this with
@@ -21,13 +21,7 @@ type EvalStackValue =
         | EvalStackValue.Float f -> $"Float(%f{f})"
         | EvalStackValue.ManagedPointer managedPointerSource -> $"Pointer(%O{managedPointerSource})"
         | EvalStackValue.ObjectRef managedHeapAddress -> $"ObjectRef(%O{managedHeapAddress})"
-        | EvalStackValue.UserDefinedValueType evalStackValues ->
-            let desc =
-                evalStackValues
-                |> List.map (snd >> string<EvalStackValue>)
-                |> String.concat " | "
-
-            $"Struct(%s{desc})"
+        | EvalStackValue.UserDefinedValueType evalStackValues -> $"Struct(%O{evalStackValues})"
 
 [<RequireQualifiedAccess>]
 module EvalStackValue =
@@ -55,6 +49,7 @@ module EvalStackValue =
                     failwith "todo"
             | NativeIntSource.ManagedPointer _ -> failwith "TODO"
             | NativeIntSource.FunctionPointer _ -> failwith "TODO"
+            | NativeIntSource.FieldHandlePtr _ -> failwith "TODO"
             | NativeIntSource.TypeHandlePtr _ -> failwith "TODO"
         | EvalStackValue.Float f -> failwith "todo"
         | EvalStackValue.ManagedPointer managedPointerSource ->
@@ -83,7 +78,14 @@ module EvalStackValue =
         match value with
         | EvalStackValue.Int32 i -> Some (int64<int> i)
         | EvalStackValue.Int64 i -> Some i
-        | EvalStackValue.NativeInt nativeIntSource -> failwith "todo"
+        | EvalStackValue.NativeInt src ->
+            match src with
+            | NativeIntSource.Verbatim int64 -> Some int64
+            | NativeIntSource.ManagedPointer ManagedPointerSource.Null -> Some 0L
+            | NativeIntSource.ManagedPointer _
+            | NativeIntSource.FunctionPointer _
+            | NativeIntSource.TypeHandlePtr _
+            | NativeIntSource.FieldHandlePtr _ -> failwith "refusing to convert pointer to int64"
         | EvalStackValue.Float f -> failwith "todo"
         | EvalStackValue.ManagedPointer managedPointerSource -> failwith "todo"
         | EvalStackValue.ObjectRef managedHeapAddress -> failwith "todo"
@@ -100,6 +102,52 @@ module EvalStackValue =
         | EvalStackValue.ObjectRef managedHeapAddress -> failwith "todo"
         | EvalStackValue.UserDefinedValueType evalStackValues -> failwith "todo"
 
+    /// Then truncates to int32.
+    let convToUInt8 (value : EvalStackValue) : int32 option =
+        match value with
+        | EvalStackValue.Int32 (i : int32) ->
+            let v = (# "conv.u1" i : uint8 #)
+            Some (int32<uint8> v)
+        | EvalStackValue.Int64 int64 ->
+            let v = (# "conv.u1" int64 : uint8 #)
+            Some (int32<uint8> v)
+        | EvalStackValue.NativeInt nativeIntSource -> failwith "todo"
+        | EvalStackValue.Float f -> failwith "todo"
+        | EvalStackValue.ManagedPointer managedPointerSource -> failwith "todo"
+        | EvalStackValue.ObjectRef managedHeapAddress -> failwith "todo"
+        | EvalStackValue.UserDefinedValueType evalStackValues -> failwith "todo"
+
+    let rec ofCliType (v : CliType) : EvalStackValue =
+        match v with
+        | CliType.Numeric numeric ->
+            match numeric with
+            | CliNumericType.Int32 i -> EvalStackValue.Int32 i
+            | CliNumericType.Int64 i -> EvalStackValue.Int64 i
+            | CliNumericType.NativeInt i -> EvalStackValue.NativeInt i
+            // Sign-extend types int8 and int16
+            // Zero-extend unsigned int8/unsigned int16
+            | CliNumericType.Int8 b -> int32<int8> b |> EvalStackValue.Int32
+            | CliNumericType.UInt8 b -> int32<uint8> b |> EvalStackValue.Int32
+            | CliNumericType.Int16 s -> int32<int16> s |> EvalStackValue.Int32
+            | CliNumericType.UInt16 s -> int32<uint16> s |> EvalStackValue.Int32
+            | CliNumericType.Float32 f -> EvalStackValue.Float (float<float32> f)
+            | CliNumericType.Float64 f -> EvalStackValue.Float f
+            | CliNumericType.NativeFloat f -> EvalStackValue.Float f
+        | CliType.ObjectRef i ->
+            match i with
+            | None -> EvalStackValue.ManagedPointer ManagedPointerSource.Null
+            | Some i -> EvalStackValue.ManagedPointer (ManagedPointerSource.Heap i)
+        // Zero-extend bool/char
+        | CliType.Bool b -> int32 b |> EvalStackValue.Int32
+        | CliType.Char (high, low) -> int32 high * 256 + int32 low |> EvalStackValue.Int32
+        | CliType.RuntimePointer ptr ->
+            match ptr with
+            | CliRuntimePointer.Verbatim ptrInt -> NativeIntSource.Verbatim ptrInt |> EvalStackValue.NativeInt
+            | CliRuntimePointer.FieldRegistryHandle ptrInt ->
+                NativeIntSource.FieldHandlePtr ptrInt |> EvalStackValue.NativeInt
+            | CliRuntimePointer.Managed ptr -> ptr |> EvalStackValue.ManagedPointer
+        | CliType.ValueType fields -> EvalStackValue.UserDefinedValueType fields
+
     let rec toCliTypeCoerced (target : CliType) (popped : EvalStackValue) : CliType =
         match target with
         | CliType.Numeric numeric ->
@@ -107,7 +155,13 @@ module EvalStackValue =
             | CliNumericType.Int32 _ ->
                 match popped with
                 | EvalStackValue.Int32 i -> CliType.Numeric (CliNumericType.Int32 i)
-                | EvalStackValue.UserDefinedValueType [ popped ] -> toCliTypeCoerced target (snd popped)
+                | EvalStackValue.UserDefinedValueType popped ->
+                    let popped = CliValueType.DereferenceFieldAt 0 4 popped
+                    // TODO: when we have a general mechanism to coerce CliTypes to each other,
+                    // do that
+                    match popped with
+                    | CliType.Numeric (CliNumericType.Int32 i) -> CliType.Numeric (CliNumericType.Int32 i)
+                    | _ -> failwith "TODO"
                 | i -> failwith $"TODO: %O{i}"
             | CliNumericType.Int64 _ ->
                 match popped with
@@ -117,17 +171,34 @@ module EvalStackValue =
                     | NativeIntSource.Verbatim i -> CliType.Numeric (CliNumericType.Int64 i)
                     | NativeIntSource.ManagedPointer ptr -> failwith "TODO"
                     | NativeIntSource.FunctionPointer f -> failwith $"TODO: {f}"
-                    // CliType.Numeric (CliNumericType.ProvenanceTrackedNativeInt64 f)
+                    | NativeIntSource.FieldHandlePtr f -> failwith $"TODO: {f}"
                     | NativeIntSource.TypeHandlePtr f -> failwith $"TODO: {f}"
                 // CliType.Numeric (CliNumericType.TypeHandlePtr f)
                 | i -> failwith $"TODO: %O{i}"
             | CliNumericType.NativeInt _ ->
                 match popped with
-                | EvalStackValue.NativeInt s -> CliNumericType.NativeInt s
+                | EvalStackValue.NativeInt s -> CliNumericType.NativeInt s |> CliType.Numeric
                 | EvalStackValue.ManagedPointer ptrSrc ->
                     CliNumericType.NativeInt (NativeIntSource.ManagedPointer ptrSrc)
+                    |> CliType.Numeric
+                | EvalStackValue.UserDefinedValueType vt ->
+                    let popped = CliValueType.DereferenceFieldAt 0 NATIVE_INT_SIZE vt
+                    // TODO: when we have a general mechanism to coerce CliTypes to each other,
+                    // do that
+                    match popped with
+                    | CliType.Numeric (CliNumericType.NativeInt i) -> CliType.Numeric (CliNumericType.NativeInt i)
+                    | CliType.Numeric (CliNumericType.Int64 i) ->
+                        CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.Verbatim i))
+                    | CliType.RuntimePointer ptr ->
+                        match ptr with
+                        | CliRuntimePointer.Verbatim i ->
+                            CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.Verbatim i))
+                        | CliRuntimePointer.FieldRegistryHandle ptr ->
+                            CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.FieldHandlePtr ptr))
+                        | CliRuntimePointer.Managed src ->
+                            CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.ManagedPointer src))
+                    | _ -> failwith $"TODO: {popped}"
                 | _ -> failwith $"TODO: {popped}"
-                |> CliType.Numeric
             | CliNumericType.NativeFloat f -> failwith "todo"
             | CliNumericType.Int8 _ ->
                 match popped with
@@ -156,34 +227,29 @@ module EvalStackValue =
         | CliType.ObjectRef _ ->
             match popped with
             | EvalStackValue.ManagedPointer ptrSource ->
-                match ptrSource with
-                | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-                    CliRuntimePointerSource.LocalVariable (sourceThread, methodFrame, whichVar)
-                    |> CliRuntimePointer.Managed
-                    |> CliType.RuntimePointer
-                | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
-                    CliRuntimePointerSource.Argument (sourceThread, methodFrame, whichVar)
-                    |> CliRuntimePointer.Managed
-                    |> CliType.RuntimePointer
-                | ManagedPointerSource.Heap managedHeapAddress -> CliType.ObjectRef (Some managedHeapAddress)
-                | ManagedPointerSource.Null -> CliType.ObjectRef None
-                | ManagedPointerSource.ArrayIndex (arr, ind) ->
-                    CliType.RuntimePointer (CliRuntimePointer.Managed (CliRuntimePointerSource.ArrayIndex (arr, ind)))
+                ptrSource |> CliRuntimePointer.Managed |> CliType.RuntimePointer
+            | EvalStackValue.ObjectRef ptr ->
+                ManagedPointerSource.Heap ptr
+                |> CliRuntimePointer.Managed
+                |> CliType.RuntimePointer
             | EvalStackValue.NativeInt nativeIntSource ->
                 match nativeIntSource with
                 | NativeIntSource.Verbatim 0L -> CliType.ObjectRef None
                 | NativeIntSource.Verbatim i -> failwith $"refusing to interpret verbatim native int {i} as a pointer"
                 | NativeIntSource.FunctionPointer _ -> failwith "TODO"
                 | NativeIntSource.TypeHandlePtr _ -> failwith "refusing to interpret type handle ID as an object ref"
+                | NativeIntSource.FieldHandlePtr _ -> failwith "refusing to interpret field handle ID as an object ref"
                 | NativeIntSource.ManagedPointer ptr ->
                     match ptr with
                     | ManagedPointerSource.Null -> CliType.ObjectRef None
                     | ManagedPointerSource.Heap s -> CliType.ObjectRef (Some s)
                     | _ -> failwith "TODO"
-            | EvalStackValue.UserDefinedValueType fields ->
-                match fields with
-                | [ esv ] -> toCliTypeCoerced target (snd esv)
-                | fields -> failwith $"TODO: don't know how to coerce struct of {fields} to a pointer"
+            | EvalStackValue.UserDefinedValueType obj ->
+                let popped = CliValueType.DereferenceFieldAt 0 NATIVE_INT_SIZE obj
+
+                match popped with
+                | CliType.ObjectRef r -> CliType.ObjectRef r
+                | _ -> failwith "TODO"
             | _ -> failwith $"TODO: {popped}"
         | CliType.Bool _ ->
             match popped with
@@ -195,41 +261,19 @@ module EvalStackValue =
             | i -> failwith $"TODO: %O{i}"
         | CliType.RuntimePointer _ ->
             match popped with
-            | EvalStackValue.ManagedPointer src ->
-                match src with
-                | ManagedPointerSource.Heap addr -> CliType.ofManagedObject addr
-                | ManagedPointerSource.Null -> CliType.ObjectRef None
-                | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, var) ->
-                    CliRuntimePointerSource.LocalVariable (sourceThread, methodFrame, var)
-                    |> CliRuntimePointer.Managed
-                    |> CliType.RuntimePointer
-                | ManagedPointerSource.Argument (sourceThread, methodFrame, var) ->
-                    CliRuntimePointerSource.Argument (sourceThread, methodFrame, var)
-                    |> CliRuntimePointer.Managed
-                    |> CliType.RuntimePointer
-                | ManagedPointerSource.ArrayIndex (arr, index) ->
-                    CliRuntimePointerSource.ArrayIndex (arr, index)
-                    |> CliRuntimePointer.Managed
-                    |> CliType.RuntimePointer
+            | EvalStackValue.ManagedPointer src -> src |> CliRuntimePointer.Managed |> CliType.RuntimePointer
             | EvalStackValue.NativeInt intSrc ->
                 match intSrc with
-                | NativeIntSource.Verbatim i -> CliType.RuntimePointer (CliRuntimePointer.Unmanaged i)
-                | NativeIntSource.ManagedPointer src ->
-                    match src with
-                    | ManagedPointerSource.Heap src ->
-                        CliType.RuntimePointer (CliRuntimePointer.Managed (CliRuntimePointerSource.Heap src))
-                    | ManagedPointerSource.Null ->
-                        CliType.RuntimePointer (CliRuntimePointer.Managed CliRuntimePointerSource.Null)
-                    | ManagedPointerSource.LocalVariable (a, b, c) ->
-                        CliType.RuntimePointer (
-                            CliRuntimePointer.Managed (CliRuntimePointerSource.LocalVariable (a, b, c))
-                        )
-                    | ManagedPointerSource.Argument (a, b, c) ->
-                        CliType.RuntimePointer (CliRuntimePointer.Managed (CliRuntimePointerSource.Argument (a, b, c)))
-                    | ManagedPointerSource.ArrayIndex _ -> failwith "TODO"
+                | NativeIntSource.Verbatim i -> CliType.RuntimePointer (CliRuntimePointer.Verbatim i)
+                | NativeIntSource.ManagedPointer src -> src |> CliRuntimePointer.Managed |> CliType.RuntimePointer
                 | NativeIntSource.FunctionPointer methodInfo ->
                     CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.FunctionPointer methodInfo))
                 | NativeIntSource.TypeHandlePtr int64 -> failwith "todo"
+                | NativeIntSource.FieldHandlePtr int64 -> failwith "todo"
+            | EvalStackValue.ObjectRef addr ->
+                ManagedPointerSource.Heap addr
+                |> CliRuntimePointer.Managed
+                |> CliType.RuntimePointer
             | _ -> failwith $"TODO: %O{popped}"
         | CliType.Char _ ->
             match popped with
@@ -240,74 +284,38 @@ module EvalStackValue =
             | popped -> failwith $"Unexpectedly wanted a char from {popped}"
         | CliType.ValueType vt ->
             match popped with
-            | EvalStackValue.UserDefinedValueType popped ->
-                if vt.Fields.Length <> popped.Length then
-                    failwith
-                        $"mismatch: popped value type {popped} (length %i{popped.Length}) into {vt} (length %i{vt.Fields.Length})"
+            | EvalStackValue.UserDefinedValueType popped' ->
+                match CliValueType.TrySequentialFields vt, CliValueType.TrySequentialFields popped' with
+                | Some vt, Some popped ->
+                    if vt.Length <> popped.Length then
+                        failwith
+                            $"mismatch: popped value type {popped} (length %i{popped.Length}) into {vt} (length %i{vt.Length})"
 
-                let fields =
-                    List.map2
-                        (fun (name1, v1) (name2, v2) ->
-                            if name1 <> name2 then
-                                failwith $"TODO: name mismatch, {name1} vs {name2}"
+                    (vt, popped)
+                    ||> List.map2 (fun field1 popped ->
+                        if field1.Name <> popped.Name then
+                            failwith $"TODO: name mismatch, {field1.Name} vs {popped.Name}"
 
-                            name1, toCliTypeCoerced v1 v2
-                        )
-                        vt.Fields
-                        popped
+                        if field1.Offset <> popped.Offset then
+                            failwith $"TODO: offset mismatch for {field1.Name}, {field1.Offset} vs {popped.Offset}"
 
-                {
-                    Fields = fields
-                }
-                |> CliType.ValueType
+                        let contents = toCliTypeCoerced field1.Contents (ofCliType popped.Contents)
+
+                        {
+                            CliField.Name = field1.Name
+                            Contents = contents
+                            Offset = field1.Offset
+                            Type = field1.Type
+                        }
+                    )
+                    |> CliValueType.OfFields popped'.Layout
+                    |> CliType.ValueType
+                | _, _ -> failwith "TODO: overlapping fields going onto eval stack"
             | popped ->
-                match vt.Fields with
-                | [ _, target ] -> toCliTypeCoerced target popped
+                match CliValueType.TryExactlyOneField vt with
+                | Some field -> toCliTypeCoerced field.Contents popped
                 | _ -> failwith $"TODO: {popped} into value type {target}"
 
-    let rec ofCliType (v : CliType) : EvalStackValue =
-        match v with
-        | CliType.Numeric numeric ->
-            match numeric with
-            | CliNumericType.Int32 i -> EvalStackValue.Int32 i
-            | CliNumericType.Int64 i -> EvalStackValue.Int64 i
-            | CliNumericType.NativeInt i -> EvalStackValue.NativeInt i
-            // Sign-extend types int8 and int16
-            // Zero-extend unsigned int8/unsigned int16
-            | CliNumericType.Int8 b -> int32<int8> b |> EvalStackValue.Int32
-            | CliNumericType.UInt8 b -> int32<uint8> b |> EvalStackValue.Int32
-            | CliNumericType.Int16 s -> int32<int16> s |> EvalStackValue.Int32
-            | CliNumericType.UInt16 s -> int32<uint16> s |> EvalStackValue.Int32
-            | CliNumericType.Float32 f -> EvalStackValue.Float (float<float32> f)
-            | CliNumericType.Float64 f -> EvalStackValue.Float f
-            | CliNumericType.NativeFloat f -> EvalStackValue.Float f
-        | CliType.ObjectRef i ->
-            match i with
-            | None -> EvalStackValue.ManagedPointer ManagedPointerSource.Null
-            | Some i -> EvalStackValue.ManagedPointer (ManagedPointerSource.Heap i)
-        // Zero-extend bool/char
-        | CliType.Bool b -> int32 b |> EvalStackValue.Int32
-        | CliType.Char (high, low) -> int32 high * 256 + int32 low |> EvalStackValue.Int32
-        | CliType.RuntimePointer ptr ->
-            match ptr with
-            | CliRuntimePointer.Unmanaged ptrInt -> NativeIntSource.Verbatim ptrInt |> EvalStackValue.NativeInt
-            | CliRuntimePointer.Managed ptr ->
-                match ptr with
-                | CliRuntimePointerSource.LocalVariable (sourceThread, methodFrame, var) ->
-                    ManagedPointerSource.LocalVariable (sourceThread, methodFrame, var)
-                    |> EvalStackValue.ManagedPointer
-                | CliRuntimePointerSource.ArrayIndex (arr, ind) ->
-                    ManagedPointerSource.ArrayIndex (arr, ind) |> EvalStackValue.ManagedPointer
-                | CliRuntimePointerSource.Argument (sourceThread, methodFrame, var) ->
-                    ManagedPointerSource.Argument (sourceThread, methodFrame, var)
-                    |> EvalStackValue.ManagedPointer
-                | CliRuntimePointerSource.Heap addr -> EvalStackValue.ObjectRef addr
-                | CliRuntimePointerSource.Null -> EvalStackValue.ManagedPointer ManagedPointerSource.Null
-        | CliType.ValueType fields ->
-            fields.Fields
-            |> List.map (fun (name, f) -> name, ofCliType f)
-            |> EvalStackValue.UserDefinedValueType
-
 type EvalStack =
     {
         Values : EvalStackValue list

WoofWare.PawPrint/EvalStackValueComparisons.fs

@@ -123,11 +123,14 @@ module EvalStackValueComparisons =
     let rec ceq (var1 : EvalStackValue) (var2 : EvalStackValue) : bool =
         // Table III.4
         match var1, var2 with
-        | EvalStackValue.UserDefinedValueType [ _, u ], v -> ceq u v
-        | u, EvalStackValue.UserDefinedValueType [ _, v ] -> ceq u v
-        | EvalStackValue.UserDefinedValueType [], EvalStackValue.UserDefinedValueType [] -> true
-        | EvalStackValue.UserDefinedValueType _, _
-        | _, EvalStackValue.UserDefinedValueType _ -> failwith $"bad ceq: {var1} vs {var2}"
+        | EvalStackValue.UserDefinedValueType var1, v ->
+            match CliValueType.TryExactlyOneField var1 with
+            | None -> failwith "TODO"
+            | Some var1 -> ceq (EvalStackValue.ofCliType var1.Contents) v
+        | u, EvalStackValue.UserDefinedValueType var2 ->
+            match CliValueType.TryExactlyOneField var2 with
+            | None -> failwith "TODO"
+            | Some var2 -> ceq u (EvalStackValue.ofCliType var2.Contents)
         | EvalStackValue.Int32 var1, EvalStackValue.Int32 var2 -> var1 = var2
         | EvalStackValue.Int32 var1, EvalStackValue.NativeInt var2 -> failwith "TODO: int32 CEQ nativeint"
         | EvalStackValue.Int32 _, _ -> failwith $"bad ceq: Int32 vs {var2}"
@@ -151,6 +154,16 @@ module EvalStackValueComparisons =
             failwith $"TODO (CEQ): nativeint vs managed pointer"
         | EvalStackValue.NativeInt _, _ -> failwith $"bad ceq: NativeInt vs {var2}"
         | EvalStackValue.ObjectRef var1, EvalStackValue.ObjectRef var2 -> var1 = var2
+        | EvalStackValue.ManagedPointer src, EvalStackValue.ObjectRef var1
+        | EvalStackValue.ObjectRef var1, EvalStackValue.ManagedPointer src ->
+            match src with
+            | ManagedPointerSource.Heap src -> src = var1
+            | ManagedPointerSource.Null -> false
+            | ManagedPointerSource.Field _
+            | ManagedPointerSource.LocalVariable _
+            | ManagedPointerSource.Argument _ -> false
+            | ManagedPointerSource.ArrayIndex (arr, index) -> failwith "todo"
+            | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "todo"
         | EvalStackValue.ObjectRef _, _ -> failwith $"bad ceq: ObjectRef vs {var2}"
         | EvalStackValue.ManagedPointer var1, EvalStackValue.ManagedPointer var2 -> var1 = var2
         | EvalStackValue.ManagedPointer var1, EvalStackValue.NativeInt var2 ->

WoofWare.PawPrint/ExternImplementations/System.Threading.Monitor.fs

@@ -62,6 +62,7 @@ module System_Threading_Monitor =
                     match lockObj with
                     | EvalStackValue.ManagedPointer ManagedPointerSource.Null ->
                         failwith "TODO: throw ArgumentNullException"
+                    | EvalStackValue.ObjectRef addr
                     | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) ->
                         match IlMachineState.getSyncBlock addr state with
                         | SyncBlock.Free ->
@@ -87,6 +88,8 @@ module System_Threading_Monitor =
                         failwith "not really expecting to *edit* an argument..."
                     | ManagedPointerSource.Heap addr -> failwith "todo: managed heap"
                     | ManagedPointerSource.ArrayIndex _ -> failwith "todo: array index"
+                    | ManagedPointerSource.Field (managedPointerSource, fieldName) -> failwith "todo"
+                    | ManagedPointerSource.InterpretedAsType _ -> failwith "TODO"
 
                 (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
 
@@ -100,6 +103,7 @@ module System_Threading_Monitor =
                     match lockObj with
                     | EvalStackValue.ManagedPointer ManagedPointerSource.Null ->
                         failwith "TODO: throw ArgumentNullException"
+                    | EvalStackValue.ObjectRef addr
                     | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) ->
                         match IlMachineState.getSyncBlock addr state with
                         | SyncBlock.Free -> failwith "TODO: throw SynchronizationLockException"

WoofWare.PawPrint/FieldHandleRegistry.fs

@@ -1,5 +1,6 @@
 namespace WoofWare.PawPrint
 
+open System.Collections.Immutable
 open System.Reflection
 open System.Reflection.Metadata
 
@@ -33,8 +34,9 @@ module FieldHandleRegistry =
     /// Returns a (struct) System.RuntimeFieldHandle, with its contents (reference type) freshly allocated if necessary.
     let getOrAllocate
         (baseClassTypes : BaseClassTypes<'corelib>)
+        (allConcreteTypes : AllConcreteTypes)
         (allocState : 'allocState)
-        (allocate : (string * CliType) list -> 'allocState -> ManagedHeapAddress * 'allocState)
+        (allocate : CliValueType -> 'allocState -> ManagedHeapAddress * 'allocState)
         (declaringAssy : AssemblyName)
         (declaringType : ConcreteTypeHandle)
         (handle : FieldDefinitionHandle)
@@ -54,8 +56,20 @@ module FieldHandleRegistry =
                 failwith $"unexpected field name %s{field.Name} for BCL type RuntimeFieldHandle"
 
             {
-                Fields = [ "m_ptr", CliType.ofManagedObject runtimeFieldInfoStub ]
+                Name = "m_ptr"
+                Contents = CliType.ofManagedObject runtimeFieldInfoStub
+                Offset = None
+                Type =
+                    AllConcreteTypes.findExistingConcreteType
+                        allConcreteTypes
+                        (baseClassTypes.RuntimeFieldInfoStub.Assembly,
+                         baseClassTypes.RuntimeFieldInfoStub.Namespace,
+                         baseClassTypes.RuntimeFieldInfoStub.Name,
+                         ImmutableArray.Empty)
+                    |> Option.get
             }
+            |> List.singleton
+            |> CliValueType.OfFields Layout.Default
             |> CliType.ValueType
 
         let handle =
@@ -81,22 +95,93 @@ module FieldHandleRegistry =
             | TypeDefn.PrimitiveType PrimitiveType.IntPtr -> ()
             | s -> failwith $"bad sig: {s}"
 
+            // https://github.com/dotnet/runtime/blob/2b21c73fa2c32fa0195e4a411a435dda185efd08/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs#L1380
             {
-                Fields = [ "m_handle", CliType.RuntimePointer (CliRuntimePointer.Unmanaged newHandle) ]
+                Name = "m_handle"
+                Contents = CliType.RuntimePointer (CliRuntimePointer.FieldRegistryHandle newHandle)
+                Offset = None // no struct layout was specified
+                Type =
+                    AllConcreteTypes.findExistingConcreteType
+                        allConcreteTypes
+                        (baseClassTypes.IntPtr.Assembly,
+                         baseClassTypes.IntPtr.Namespace,
+                         baseClassTypes.IntPtr.Name,
+                         ImmutableArray.Empty)
+                    |> Option.get
             }
+            |> List.singleton
+            |> CliValueType.OfFields Layout.Default
             |> CliType.ValueType
 
+        // https://github.com/dotnet/runtime/blob/1d1bf92fcf43aa6981804dc53c5174445069c9e4/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs#L1074
         let runtimeFieldInfoStub =
+            let objType =
+                AllConcreteTypes.findExistingConcreteType
+                    allConcreteTypes
+                    (baseClassTypes.Object.Assembly,
+                     baseClassTypes.Object.Namespace,
+                     baseClassTypes.Object.Name,
+                     ImmutableArray.Empty)
+                |> Option.get
+
+            let intType =
+                AllConcreteTypes.findExistingConcreteType
+                    allConcreteTypes
+                    (baseClassTypes.Int32.Assembly,
+                     baseClassTypes.Int32.Namespace,
+                     baseClassTypes.Int32.Name,
+                     ImmutableArray.Empty)
+                |> Option.get
+
+            // LayoutKind.Sequential
             [
                 // If we ever implement a GC, something should change here
-                "m_keepalive", CliType.ObjectRef None
-                "m_c", CliType.ObjectRef None
-                "m_d", CliType.ObjectRef None
-                "m_b", CliType.Numeric (CliNumericType.Int32 0)
-                "m_e", CliType.ObjectRef None
+                {
+                    Name = "m_keepalive"
+                    Contents = CliType.ObjectRef None
+                    Offset = None
+                    Type = objType
+                }
+                {
+                    Name = "m_c"
+                    Contents = CliType.ObjectRef None
+                    Offset = None
+                    Type = objType
+                }
+                {
+                    Name = "m_d"
+                    Contents = CliType.ObjectRef None
+                    Offset = None
+                    Type = objType
+                }
+                {
+                    Name = "m_b"
+                    Contents = CliType.Numeric (CliNumericType.Int32 0)
+                    Offset = None
+                    Type = intType
+                }
+                {
+                    Name = "m_e"
+                    Contents = CliType.ObjectRef None
+                    Offset = None
+                    Type = objType
+                }
                 // RuntimeFieldHandleInternal: https://github.com/dotnet/runtime/blob/1d1bf92fcf43aa6981804dc53c5174445069c9e4/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs#L1048
-                "m_fieldHandle", runtimeFieldHandleInternal
+                {
+                    Name = "m_fieldHandle"
+                    Contents = runtimeFieldHandleInternal
+                    Offset = None
+                    Type =
+                        AllConcreteTypes.findExistingConcreteType
+                            allConcreteTypes
+                            (baseClassTypes.RuntimeFieldHandleInternal.Assembly,
+                             baseClassTypes.RuntimeFieldHandleInternal.Namespace,
+                             baseClassTypes.RuntimeFieldHandleInternal.Name,
+                             ImmutableArray.Empty)
+                        |> Option.get
+                }
             ]
+            |> CliValueType.OfFields Layout.Default // explicitly sequential but no custom packing size
 
         let alloc, state = allocate runtimeFieldInfoStub allocState
 

WoofWare.PawPrint/IlMachineState.fs

@@ -149,7 +149,73 @@ type StateLoadResult =
 module IlMachineState =
     type private Dummy = class end
 
+    let private loadAssembly'
+        (loggerFactory : ILoggerFactory)
+        (dotnetRuntimeDirs : string seq)
+        (referencedInAssembly : DumpedAssembly)
+        (r : AssemblyReferenceHandle)
+        (assemblies : ImmutableDictionary<string, DumpedAssembly>)
+        =
+        let assemblyRef = referencedInAssembly.AssemblyReferences.[r]
+        let assemblyName = assemblyRef.Name
+
+        match assemblies.TryGetValue assemblyName.FullName with
+        | true, v -> v, assemblyName
+        | false, _ ->
+            let logger = loggerFactory.CreateLogger typeof<Dummy>.DeclaringType
+
+            let assy =
+                dotnetRuntimeDirs
+                |> Seq.choose (fun dir ->
+                    let file = Path.Combine (dir, assemblyName.Name + ".dll")
+
+                    try
+                        use f = File.OpenRead file
+                        logger.LogInformation ("Loading assembly from file {AssemblyFileLoadPath}", file)
+                        Assembly.read loggerFactory (Some file) f |> Some
+                    with :? FileNotFoundException ->
+                        None
+                )
+                |> Seq.toList
+
+            match assy |> List.tryHead with
+            | None -> failwith $"Could not find a readable DLL in any runtime dir with name %s{assemblyName.Name}.dll"
+            | Some assy -> assy, assemblyName
+
+    /// <summary>
+    /// Create a new IlMachineState which has loaded the given assembly.
+    /// This involves reading assemblies from the disk and doing a complete parse of them, so it might be quite slow!
+    ///
+    /// This function doesn't do anything if the referenced assembly has already been loaded.
+    /// </summary>
+    /// <param name="loggerFactory">LoggerFactory into which to emit logs.</param>
+    /// <param name="referencedInAssembly">The assembly which contains an AssemblyReference which causes us to want to load a new assembly.</param>
+    /// <param name="r">The AssemblyReferenceHandle pointing at an assembly we want to load. *Important*: this is an AssemblyReferenceHandle from <c>referencedInAssembly</c>; in general, AssemblyReferenceHandles are only well-defined if you know what assembly they were defined in.</param>
+    /// <param name="state">The immutable state to augment with the new assembly.</param>
+    let loadAssembly
+        (loggerFactory : ILoggerFactory)
+        (referencedInAssembly : DumpedAssembly)
+        (r : AssemblyReferenceHandle)
+        (state : IlMachineState)
+        : IlMachineState * DumpedAssembly * AssemblyName
+        =
+        let dumped, assy =
+            loadAssembly' loggerFactory state.DotnetRuntimeDirs referencedInAssembly r state._LoadedAssemblies
+
+        state.WithLoadedAssembly assy dumped, dumped, assy
+
+    let private loader (loggerFactory : ILoggerFactory) (state : IlMachineState) : IAssemblyLoad =
+        { new IAssemblyLoad with
+            member _.LoadAssembly loaded assyName ref =
+                let targetAssy, name =
+                    loadAssembly' loggerFactory state.DotnetRuntimeDirs loaded.[assyName.FullName] ref loaded
+
+                let newAssys = loaded.SetItem (name.FullName, targetAssy)
+                newAssys, targetAssy
+        }
+
     let concretizeType
+        (loggerFactory : ILoggerFactory)
         (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (state : IlMachineState)
         (declaringAssembly : AssemblyName)
@@ -169,14 +235,7 @@ module IlMachineState =
         let handle, ctx =
             TypeConcretization.concretizeType
                 ctx
-                (fun assyName ref ->
-                    let currentAssy = state.LoadedAssembly assyName |> Option.get
-
-                    let targetAssy =
-                        currentAssy.AssemblyReferences.[ref].Name |> state.LoadedAssembly |> Option.get
-
-                    state._LoadedAssemblies, targetAssy
-                )
+                (loader loggerFactory state)
                 declaringAssembly
                 typeGenerics
                 methodGenerics
@@ -190,51 +249,6 @@ module IlMachineState =
 
         state, handle
 
-    /// <summary>
-    /// Create a new IlMachineState which has loaded the given assembly.
-    /// This involves reading assemblies from the disk and doing a complete parse of them, so it might be quite slow!
-    ///
-    /// This function doesn't do anything if the referenced assembly has already been loaded.
-    /// </summary>
-    /// <param name="loggerFactory">LoggerFactory into which to emit logs.</param>
-    /// <param name="referencedInAssembly">The assembly which contains an AssemblyReference which causes us to want to load a new assembly.</param>
-    /// <param name="r">The AssemblyReferenceHandle pointing at an assembly we want to load. *Important*: this is an AssemblyReferenceHandle from <c>referencedInAssembly</c>; in general, AssemblyReferenceHandles are only well-defined if you know what assembly they were defined in.</param>
-    /// <param name="state">The immutable state to augment with the new assembly.</param>
-    let loadAssembly
-        (loggerFactory : ILoggerFactory)
-        (referencedInAssembly : DumpedAssembly)
-        (r : AssemblyReferenceHandle)
-        (state : IlMachineState)
-        : IlMachineState * DumpedAssembly * AssemblyName
-        =
-        let assemblyRef = referencedInAssembly.AssemblyReferences.[r]
-        let assemblyName = assemblyRef.Name
-
-        match state.LoadedAssembly assemblyName with
-        | Some v -> state, v, assemblyName
-        | None ->
-            let logger = loggerFactory.CreateLogger typeof<Dummy>.DeclaringType
-
-            let assy =
-                state.DotnetRuntimeDirs
-                |> Seq.choose (fun dir ->
-                    let file = Path.Combine (dir, assemblyName.Name + ".dll")
-
-                    try
-                        use f = File.OpenRead file
-                        logger.LogInformation ("Loading assembly from file {AssemblyFileLoadPath}", file)
-                        Assembly.read loggerFactory (Some file) f |> Some
-                    with :? FileNotFoundException ->
-                        None
-                )
-                |> Seq.toList
-
-            match assy |> List.tryHead with
-            | None -> failwith $"Could not find a readable DLL in any runtime dir with name %s{assemblyName.Name}.dll"
-            | Some assy ->
-
-            state.WithLoadedAssembly assemblyName assy, assy, assemblyName
-
     let rec internal resolveTypeFromName
         (loggerFactory : ILoggerFactory)
         (ns : string option)
@@ -284,7 +298,7 @@ module IlMachineState =
         (state : IlMachineState)
         : IlMachineState * DumpedAssembly * WoofWare.PawPrint.TypeInfo<TypeDefn, TypeDefn>
         =
-        match Assembly.resolveTypeRef state._LoadedAssemblies referencedInAssembly target typeGenericArgs with
+        match Assembly.resolveTypeRef state._LoadedAssemblies referencedInAssembly typeGenericArgs target with
         | TypeResolutionResult.Resolved (assy, typeDef) -> state, assy, typeDef
         | TypeResolutionResult.FirstLoadAssy loadFirst ->
             let state, _, _ =
@@ -335,36 +349,8 @@ module IlMachineState =
                             assy
                             state
 
-                    // If the resolved argument has generics, create a GenericInstantiation
-                    // Otherwise, create a FromDefinition
                     let preservedArg =
-                        let baseType =
-                            resolvedArg.BaseType
-                            |> DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies assy.Name
-
-                        let signatureTypeKind =
-                            match baseType with
-                            | ResolvedBaseType.Enum
-                            | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-                            | ResolvedBaseType.Object -> SignatureTypeKind.Class
-                            | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-                        if resolvedArg.Generics.IsEmpty then
-                            TypeDefn.FromDefinition (
-                                ComparableTypeDefinitionHandle.Make resolvedArg.TypeDefHandle,
-                                assy.Name.FullName,
-                                signatureTypeKind
-                            )
-                        else
-                            // Preserve the generic instantiation
-                            let genericDef =
-                                TypeDefn.FromDefinition (
-                                    ComparableTypeDefinitionHandle.Make resolvedArg.TypeDefHandle,
-                                    assy.Name.FullName,
-                                    signatureTypeKind
-                                )
-
-                            TypeDefn.GenericInstantiation (genericDef, resolvedArg.Generics)
+                        DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies resolvedArg
 
                     args'.Add preservedArg
 
@@ -446,6 +432,42 @@ module IlMachineState =
         let sign = assy.TypeSpecs.[ty].Signature
 
         // Convert ConcreteTypeHandle to TypeDefn
+        let typeGenericArgsAsDefn =
+            typeGenericArgs
+            |> ImmutableArray.map (fun handle ->
+                Concretization.concreteHandleToTypeDefn
+                    baseClassTypes
+                    handle
+                    state.ConcreteTypes
+                    state._LoadedAssemblies
+            )
+
+        let methodGenericArgsAsDefn =
+            methodGenericArgs
+            |> ImmutableArray.map (fun handle ->
+                Concretization.concreteHandleToTypeDefn
+                    baseClassTypes
+                    handle
+                    state.ConcreteTypes
+                    state._LoadedAssemblies
+            )
+
+        resolveTypeFromDefn loggerFactory baseClassTypes sign typeGenericArgsAsDefn methodGenericArgsAsDefn assy state
+
+    /// Resolve a TypeDefinition using concrete type handles from execution context
+    let resolveTypeFromDefnConcrete
+        (loggerFactory : ILoggerFactory)
+        (baseClassTypes : BaseClassTypes<DumpedAssembly>)
+        (ty : TypeDefinitionHandle)
+        (assy : DumpedAssembly)
+        (typeGenericArgs : ConcreteTypeHandle ImmutableArray)
+        (methodGenericArgs : ConcreteTypeHandle ImmutableArray)
+        (state : IlMachineState)
+        : IlMachineState * DumpedAssembly * WoofWare.PawPrint.TypeInfo<TypeDefn, TypeDefn>
+        =
+        let typeDef = assy.TypeDefs.[ty]
+
+        // Convert ConcreteTypeHandle to TypeDefn for the generics
         let typeGenericArgsAsDefn =
             typeGenericArgs
             |> Seq.map (fun handle ->
@@ -468,7 +490,17 @@ module IlMachineState =
             )
             |> ImmutableArray.CreateRange
 
-        resolveTypeFromDefn loggerFactory baseClassTypes sign typeGenericArgsAsDefn methodGenericArgsAsDefn assy state
+        // Map the type definition's generics using the provided type generic arguments
+        let resolvedTypeDef =
+            typeDef
+            |> TypeInfo.mapGeneric (fun (param, _) ->
+                if param.SequenceNumber < typeGenericArgsAsDefn.Length then
+                    typeGenericArgsAsDefn.[param.SequenceNumber]
+                else
+                    failwithf "Generic type parameter %d out of range" param.SequenceNumber
+            )
+
+        state, assy, resolvedTypeDef
 
     /// Get zero value for a type that's already been concretized
     let cliTypeZeroOfHandle
@@ -498,13 +530,13 @@ module IlMachineState =
     /// Concretize a ConcreteType<TypeDefn> to get a ConcreteTypeHandle for static field access
     let concretizeFieldDeclaringType
         (loggerFactory : ILoggerFactory)
-        (baseClassTypes : BaseClassTypes<'corelib>)
+        (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (declaringType : ConcreteType<TypeDefn>)
         (state : IlMachineState)
         : ConcreteTypeHandle * IlMachineState
         =
         // Create a concretization context from the current state
-        let ctx : TypeConcretization.ConcretizationContext<'corelib> =
+        let ctx : TypeConcretization.ConcretizationContext<_> =
             {
                 InProgress = ImmutableDictionary.Empty
                 ConcreteTypes = state.ConcreteTypes
@@ -512,26 +544,6 @@ module IlMachineState =
                 BaseTypes = baseClassTypes
             }
 
-        // Helper function to get assembly from reference
-        let loadAssembly
-            (currentAssembly : AssemblyName)
-            (assyRef : AssemblyReferenceHandle)
-            : ImmutableDictionary<string, DumpedAssembly> * DumpedAssembly
-            =
-            let assyToLoad =
-                match state.LoadedAssembly currentAssembly with
-                | Some assy -> assy
-                | None -> failwithf "Assembly %s not loaded" currentAssembly.FullName
-
-            let referencedAssy = assyToLoad.AssemblyReferences.[assyRef]
-
-            match state.LoadedAssembly referencedAssy.Name with
-            | Some assy -> state._LoadedAssemblies, assy
-            | None ->
-                // Need to load the assembly
-                let newState, loadedAssy, _ = loadAssembly loggerFactory assyToLoad assyRef state
-                newState._LoadedAssemblies, loadedAssy
-
         // Concretize each generic argument first
         let mutable currentCtx = ctx
         let genericHandles = ImmutableArray.CreateBuilder declaringType.Generics.Length
@@ -540,7 +552,7 @@ module IlMachineState =
             let handle, newCtx =
                 TypeConcretization.concretizeType
                     currentCtx
-                    loadAssembly
+                    (loader loggerFactory state)
                     declaringType.Assembly
                     ImmutableArray.Empty // No type generics in this context
                     ImmutableArray.Empty // No method generics in this context
@@ -552,12 +564,13 @@ module IlMachineState =
         // Now we need to concretize the type definition itself
         // If it's a non-generic type, we can use concretizeTypeDefinition directly
         if declaringType.Generics.IsEmpty then
-            let handle, newCtx =
+            let handle, currentCtx =
                 TypeConcretization.concretizeTypeDefinition currentCtx declaringType.Assembly declaringType.Definition
 
             let newState =
                 { state with
-                    ConcreteTypes = newCtx.ConcreteTypes
+                    ConcreteTypes = currentCtx.ConcreteTypes
+                    _LoadedAssemblies = currentCtx.LoadedAssemblies
                 }
 
             handle, newState
@@ -601,7 +614,7 @@ module IlMachineState =
         (typeGenerics : ConcreteTypeHandle ImmutableArray)
         (methodGenerics : ConcreteTypeHandle ImmutableArray)
         (state : IlMachineState)
-        : IlMachineState * CliType
+        : IlMachineState * CliType * ConcreteTypeHandle
         =
 
         // First concretize the type
@@ -613,11 +626,11 @@ module IlMachineState =
                 state.WithLoadedAssembly assy.Name assy
 
         let state, handle =
-            concretizeType baseClassTypes state assy.Name typeGenerics methodGenerics ty
+            concretizeType loggerFactory baseClassTypes state assy.Name typeGenerics methodGenerics ty
 
         // Now get the zero value
         let zero, state = cliTypeZeroOfHandle state baseClassTypes handle
-        state, zero
+        state, zero, handle
 
     let pushToEvalStack' (o : EvalStackValue) (thread : ThreadId) (state : IlMachineState) =
         let activeThreadState = state.ThreadState.[thread]
@@ -674,14 +687,14 @@ module IlMachineState =
         (state : IlMachineState)
         : IlMachineState
         =
-        let heap = ManagedHeap.SetArrayValue arrayAllocation index v state.ManagedHeap
+        let heap = ManagedHeap.setArrayValue arrayAllocation index v state.ManagedHeap
 
         { state with
             ManagedHeap = heap
         }
 
     let getArrayValue (arrayAllocation : ManagedHeapAddress) (index : int) (state : IlMachineState) : CliType =
-        ManagedHeap.GetArrayValue arrayAllocation index state.ManagedHeap
+        ManagedHeap.getArrayValue arrayAllocation index state.ManagedHeap
 
     /// There might be no stack frame to return to, so you might get None.
     let returnStackFrame
@@ -740,14 +753,9 @@ module IlMachineState =
             | ResolvedBaseType.Delegate
             | ResolvedBaseType.Object -> state |> pushToEvalStack (CliType.ofManagedObject constructing) currentThread
             | ResolvedBaseType.ValueType ->
-                let vt =
-                    {
-                        Fields = Map.toList constructed.Fields
-                    }
-
                 state
                 // TODO: ordering of fields probably important
-                |> pushToEvalStack (CliType.ValueType vt) currentThread
+                |> pushToEvalStack (CliType.ValueType constructed.Contents) currentThread
             | ResolvedBaseType.Enum -> failwith "TODO"
         | None ->
             match threadStateAtEndOfMethod.MethodState.EvaluationStack.Values with
@@ -789,22 +797,7 @@ module IlMachineState =
         let concretizedMethod, newConcreteTypes, newAssemblies =
             Concretization.concretizeMethod
                 state.ConcreteTypes
-                (fun assyName ref ->
-                    match state.LoadedAssembly assyName with
-                    | Some currentAssy ->
-                        let targetAssyRef = currentAssy.AssemblyReferences.[ref]
-
-                        match state.LoadedAssembly targetAssyRef.Name with
-                        | Some _ ->
-                            // Assembly already loaded, return existing state
-                            state._LoadedAssemblies, state._LoadedAssemblies.[targetAssyRef.Name.FullName]
-                        | None ->
-                            // Need to load the assembly
-                            let newState, loadedAssy, _ = loadAssembly loggerFactory currentAssy ref state
-                            newState._LoadedAssemblies, loadedAssy
-                    | None ->
-                        failwithf "Current assembly %s not loaded when trying to resolve reference" assyName.FullName
-                )
+                (loader loggerFactory state)
                 state._LoadedAssemblies
                 baseClassTypes
                 methodToCall
@@ -850,6 +843,7 @@ module IlMachineState =
                 for i = 0 to generics.Length - 1 do
                     let state2, handle =
                         concretizeType
+                            loggerFactory
                             baseClassTypes
                             state
                             callingAssembly
@@ -905,14 +899,7 @@ module IlMachineState =
                     let handle, newCtx =
                         TypeConcretization.concretizeType
                             ctx
-                            (fun assyName ref ->
-                                let currentAssy = state.LoadedAssembly assyName |> Option.get
-
-                                let targetAssy =
-                                    currentAssy.AssemblyReferences.[ref].Name |> state.LoadedAssembly |> Option.get
-
-                                state._LoadedAssemblies, targetAssy
-                            )
+                            (loader loggerFactory state)
                             (state.ActiveAssembly thread).Name
                             ImmutableArray.Empty // No type generics for the concretization context
                             ImmutableArray.Empty // No method generics for the concretization context
@@ -923,6 +910,7 @@ module IlMachineState =
                     state <-
                         { state with
                             ConcreteTypes = newCtx.ConcreteTypes
+                            _LoadedAssemblies = newCtx.LoadedAssemblies
                         }
 
                 handles.ToImmutable (), state
@@ -1027,14 +1015,7 @@ module IlMachineState =
         let declaringHandle, newCtx =
             TypeConcretization.concretizeType
                 ctx
-                (fun assyName ref ->
-                    let currentAssy = state.LoadedAssembly assyName |> Option.get
-
-                    let targetAssy =
-                        currentAssy.AssemblyReferences.[ref].Name |> state.LoadedAssembly |> Option.get
-
-                    state._LoadedAssemblies, targetAssy
-                )
+                (loader loggerFactory state)
                 field.DeclaringType.Assembly
                 contextTypeGenerics
                 contextMethodGenerics
@@ -1069,7 +1050,7 @@ module IlMachineState =
                 Logger = logger
                 NextThreadId = 0
                 // CallStack = []
-                ManagedHeap = ManagedHeap.Empty
+                ManagedHeap = ManagedHeap.empty
                 ThreadState = Map.empty
                 InternedStrings = ImmutableDictionary.Empty
                 _LoadedAssemblies = ImmutableDictionary.Empty
@@ -1115,7 +1096,7 @@ module IlMachineState =
                 Elements = initialisation
             }
 
-        let alloc, heap = state.ManagedHeap |> ManagedHeap.AllocateArray o
+        let alloc, heap = state.ManagedHeap |> ManagedHeap.allocateArray o
 
         let state =
             { state with
@@ -1125,7 +1106,7 @@ module IlMachineState =
         alloc, state
 
     let allocateStringData (len : int) (state : IlMachineState) : int * IlMachineState =
-        let addr, heap = state.ManagedHeap |> ManagedHeap.AllocateString len
+        let addr, heap = state.ManagedHeap |> ManagedHeap.allocateString len
 
         let state =
             { state with
@@ -1135,7 +1116,7 @@ module IlMachineState =
         addr, state
 
     let setStringData (addr : int) (contents : string) (state : IlMachineState) : IlMachineState =
-        let heap = ManagedHeap.SetStringData addr contents state.ManagedHeap
+        let heap = ManagedHeap.setStringData addr contents state.ManagedHeap
 
         { state with
             ManagedHeap = heap
@@ -1143,18 +1124,18 @@ module IlMachineState =
 
     let allocateManagedObject
         (ty : ConcreteTypeHandle)
-        (fields : (string * CliType) list)
+        (fields : CliValueType)
         (state : IlMachineState)
         : ManagedHeapAddress * IlMachineState
         =
         let o =
             {
-                Fields = Map.ofList fields
+                Contents = fields
                 ConcreteType = ty
                 SyncBlock = SyncBlock.Free
             }
 
-        let alloc, heap = state.ManagedHeap |> ManagedHeap.AllocateNonArray o
+        let alloc, heap = state.ManagedHeap |> ManagedHeap.allocateNonArray o
 
         let state =
             { state with
@@ -1220,6 +1201,7 @@ module IlMachineState =
         (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (currentThread : ThreadId)
         (assy : DumpedAssembly)
+        (genericMethodTypeArgs : ImmutableArray<ConcreteTypeHandle>)
         (m : MemberReferenceHandle)
         (state : IlMachineState)
         : IlMachineState *
@@ -1283,6 +1265,7 @@ module IlMachineState =
                 // TODO: generics?
                 let state, t =
                     concretizeType
+                        loggerFactory
                         baseClassTypes
                         state
                         targetType.Assembly
@@ -1300,6 +1283,7 @@ module IlMachineState =
             // Concretize the field signature from the member reference
             let state, concreteFieldSig =
                 concretizeType
+                    loggerFactory
                     baseClassTypes
                     state
                     (state.ActiveAssembly(currentThread).Name)
@@ -1317,6 +1301,7 @@ module IlMachineState =
                         // Concretize the field's signature for comparison
                         let state, fieldSigConcrete =
                             concretizeType
+                                loggerFactory
                                 baseClassTypes
                                 state
                                 assy.Name
@@ -1354,11 +1339,12 @@ module IlMachineState =
                     state
                     (fun state ty ->
                         concretizeType
+                            loggerFactory
                             baseClassTypes
                             state
                             (state.ActiveAssembly(currentThread).Name)
                             concreteExtractedTypeArgs
-                            ImmutableArray.Empty
+                            genericMethodTypeArgs
                             ty
                     )
 
@@ -1371,11 +1357,12 @@ module IlMachineState =
                             state
                             (fun state ty ->
                                 concretizeType
+                                    loggerFactory
                                     baseClassTypes
                                     state
                                     assy.Name
                                     concreteExtractedTypeArgs
-                                    ImmutableArray.Empty
+                                    genericMethodTypeArgs
                                     ty
                             )
 
@@ -1429,13 +1416,62 @@ module IlMachineState =
         : IlMachineState
         =
         { state with
-            ManagedHeap = state.ManagedHeap |> ManagedHeap.SetSyncBlock addr syncBlockValue
+            ManagedHeap = state.ManagedHeap |> ManagedHeap.setSyncBlock addr syncBlockValue
         }
 
     let getSyncBlock (addr : ManagedHeapAddress) (state : IlMachineState) : SyncBlock =
-        state.ManagedHeap |> ManagedHeap.GetSyncBlock addr
+        state.ManagedHeap |> ManagedHeap.getSyncBlock addr
 
-    let executeDelegateConstructor (instruction : MethodState) (state : IlMachineState) : IlMachineState =
+    let getFieldValue (obj : ManagedPointerSource) (fieldName : string) (state : IlMachineState) : CliType =
+        match obj with
+        | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
+            getLocalVariable sourceThread methodFrame whichVar state
+            |> CliType.getField fieldName
+        | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) -> failwith "todo"
+        | ManagedPointerSource.Heap addr ->
+            ManagedHeap.get addr state.ManagedHeap
+            |> AllocatedNonArrayObject.DereferenceField fieldName
+        | ManagedPointerSource.ArrayIndex (arr, index) -> getArrayValue arr index state |> CliType.getField fieldName
+        | ManagedPointerSource.Field (src, fieldName) -> failwith "todo"
+        | ManagedPointerSource.Null -> failwith "TODO: throw NRE"
+        | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "TODO"
+
+    let setFieldValue
+        (obj : ManagedPointerSource)
+        (v : CliType)
+        (fieldName : string)
+        (state : IlMachineState)
+        : IlMachineState
+        =
+        match obj with
+        | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
+            let v =
+                getLocalVariable sourceThread methodFrame whichVar state
+                |> CliType.withFieldSet fieldName v
+
+            state |> setLocalVariable sourceThread methodFrame whichVar v
+        | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) -> failwith "todo"
+        | ManagedPointerSource.Heap addr ->
+            let newValue =
+                ManagedHeap.get addr state.ManagedHeap
+                |> AllocatedNonArrayObject.SetField fieldName v
+
+            { state with
+                ManagedHeap = ManagedHeap.set addr newValue state.ManagedHeap
+            }
+        | ManagedPointerSource.ArrayIndex (arr, index) ->
+            let v = getArrayValue arr index state |> CliType.withFieldSet fieldName v
+            state |> setArrayValue arr v index
+        | ManagedPointerSource.Field (managedPointerSource, fieldName) -> failwith "todo"
+        | ManagedPointerSource.Null -> failwith "TODO: throw NRE"
+        | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "TODO"
+
+    let executeDelegateConstructor
+        (baseClassTypes : BaseClassTypes<DumpedAssembly>)
+        (instruction : MethodState)
+        (state : IlMachineState)
+        : IlMachineState
+        =
         // We've been called with arguments already popped from the stack into local arguments.
         let constructing = instruction.Arguments.[0]
         let targetObj = instruction.Arguments.[1]
@@ -1443,12 +1479,17 @@ module IlMachineState =
 
         let targetObj =
             match targetObj with
-            | CliType.ObjectRef target -> target
+            | CliType.RuntimePointer (CliRuntimePointer.Managed (ManagedPointerSource.Heap target))
+            | CliType.ObjectRef (Some target) -> Some target
+            | CliType.ObjectRef None
+            | CliType.RuntimePointer (CliRuntimePointer.Managed ManagedPointerSource.Null) -> None
             | _ -> failwith $"Unexpected target type for delegate: {targetObj}"
 
         let constructing =
             match constructing with
+            | CliType.RuntimePointer (CliRuntimePointer.Managed ManagedPointerSource.Null)
             | CliType.ObjectRef None -> failwith "unexpectedly constructing the null delegate"
+            | CliType.RuntimePointer (CliRuntimePointer.Managed (ManagedPointerSource.Heap target))
             | CliType.ObjectRef (Some target) -> target
             | _ -> failwith $"Unexpectedly not constructing a managed object: {constructing}"
 
@@ -1459,14 +1500,42 @@ module IlMachineState =
 
         // Standard delegate fields in .NET are _target and _methodPtr
         // Update the fields with the target object and method pointer
-        let updatedFields =
-            heapObj.Fields
-            |> Map.add "_target" (CliType.ObjectRef targetObj)
-            |> Map.add "_methodPtr" methodPtr
+        let allConcreteTypes = state.ConcreteTypes
 
         let updatedObj =
+            let newContents =
+                heapObj.Contents
+                |> CliValueType.AddField
+                    {
+                        Name = "_target"
+                        Contents = CliType.ObjectRef targetObj
+                        Offset = None
+                        Type =
+                            AllConcreteTypes.findExistingConcreteType
+                                allConcreteTypes
+                                (baseClassTypes.Object.Assembly,
+                                 baseClassTypes.Object.Namespace,
+                                 baseClassTypes.Object.Name,
+                                 ImmutableArray.Empty)
+                            |> Option.get
+                    }
+                |> CliValueType.AddField
+                    {
+                        Name = "_methodPtr"
+                        Contents = methodPtr
+                        Offset = None
+                        Type =
+                            AllConcreteTypes.findExistingConcreteType
+                                allConcreteTypes
+                                (baseClassTypes.Object.Assembly,
+                                 baseClassTypes.Object.Namespace,
+                                 baseClassTypes.Object.Name,
+                                 ImmutableArray.Empty)
+                            |> Option.get
+                    }
+
             { heapObj with
-                Fields = updatedFields
+                Contents = newContents
             }
 
         let updatedHeap =
@@ -1480,6 +1549,7 @@ module IlMachineState =
 
     /// Returns the type handle and an allocated System.RuntimeType.
     let getOrAllocateType
+        (loggerFactory : ILoggerFactory)
         (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (defn : ConcreteTypeHandle)
         (state : IlMachineState)
@@ -1491,10 +1561,18 @@ module IlMachineState =
                 baseClassTypes.Corelib.Name.FullName,
                 SignatureTypeKind.Class
             )
-            |> concretizeType baseClassTypes state baseClassTypes.Corelib.Name ImmutableArray.Empty ImmutableArray.Empty
+            |> concretizeType
+                loggerFactory
+                baseClassTypes
+                state
+                baseClassTypes.Corelib.Name
+                ImmutableArray.Empty
+                ImmutableArray.Empty
 
         let result, reg, state =
             TypeHandleRegistry.getOrAllocate
+                state.ConcreteTypes
+                baseClassTypes
                 state
                 (fun fields state -> allocateManagedObject runtimeType fields state)
                 defn
@@ -1535,11 +1613,18 @@ module IlMachineState =
                 baseClassTypes.Corelib.Name.FullName,
                 SignatureTypeKind.Class
             )
-            |> concretizeType baseClassTypes state baseClassTypes.Corelib.Name ImmutableArray.Empty ImmutableArray.Empty
+            |> concretizeType
+                loggerFactory
+                baseClassTypes
+                state
+                baseClassTypes.Corelib.Name
+                ImmutableArray.Empty
+                ImmutableArray.Empty
 
         let result, reg, state =
             FieldHandleRegistry.getOrAllocate
                 baseClassTypes
+                state.ConcreteTypes
                 state
                 (fun fields state -> allocateManagedObject runtimeType fields state)
                 declaringAssy
@@ -1578,6 +1663,38 @@ module IlMachineState =
             | false, _ -> None
             | true, v -> Some v
 
+    let rec dereferencePointer (state : IlMachineState) (src : ManagedPointerSource) : CliType =
+        match src with
+        | ManagedPointerSource.Null -> failwith "TODO: throw NRE"
+        | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
+            state.ThreadState.[sourceThread].MethodStates.[methodFrame].LocalVariables.[int<uint16> whichVar]
+        | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
+            state.ThreadState.[sourceThread].MethodStates.[methodFrame].Arguments.[int<uint16> whichVar]
+        | ManagedPointerSource.Heap addr ->
+            let result = ManagedHeap.get addr state.ManagedHeap
+            // TODO: this is awfully dubious, this ain't no value type
+            CliType.ValueType result.Contents
+        | ManagedPointerSource.ArrayIndex (arr, index) -> getArrayValue arr index state
+        | ManagedPointerSource.Field (addr, name) ->
+            let obj = dereferencePointer state addr
+
+            match obj with
+            | CliType.ValueType vt -> vt |> CliValueType.DereferenceField name
+            | v -> failwith $"could not find field {name} on object {v}"
+        | ManagedPointerSource.InterpretedAsType (src, ty) ->
+            let src = dereferencePointer state src
+
+            let concrete =
+                match
+                    AllConcreteTypes.findExistingConcreteType
+                        state.ConcreteTypes
+                        (ty.Assembly, ty.Namespace, ty.Name, ty.Generics)
+                with
+                | Some ty -> ty
+                | None -> failwith "not concretised type"
+
+            failwith $"TODO: interpret as type %s{ty.Assembly.Name}.%s{ty.Namespace}.%s{ty.Name}, object %O{src}"
+
     let lookupTypeDefn
         (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (state : IlMachineState)
@@ -1586,42 +1703,7 @@ module IlMachineState =
         : IlMachineState * TypeDefn
         =
         let defn = activeAssy.TypeDefs.[typeDef]
-
-        let baseType =
-            defn.BaseType
-            |> DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies defn.Assembly
-
-        let signatureTypeKind =
-            match baseType with
-            | ResolvedBaseType.Enum
-            | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-            | ResolvedBaseType.Object -> SignatureTypeKind.Class
-            | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-        let result =
-            if defn.Generics.IsEmpty then
-                TypeDefn.FromDefinition (
-                    ComparableTypeDefinitionHandle.Make defn.TypeDefHandle,
-                    defn.Assembly.FullName,
-                    signatureTypeKind
-                )
-            else
-                // Preserve the generic instantiation by converting GenericParameters to TypeDefn.GenericTypeParameter
-                let genericDef =
-                    TypeDefn.FromDefinition (
-                        ComparableTypeDefinitionHandle.Make defn.TypeDefHandle,
-                        defn.Assembly.FullName,
-                        signatureTypeKind
-                    )
-
-                let genericArgs =
-                    defn.Generics
-                    |> Seq.mapi (fun i _ -> TypeDefn.GenericTypeParameter i)
-                    |> ImmutableArray.CreateRange
-
-                TypeDefn.GenericInstantiation (genericDef, genericArgs)
-
-        state, result
+        state, DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies defn
 
     let lookupTypeRef
         (loggerFactory : ILoggerFactory)
@@ -1649,25 +1731,4 @@ module IlMachineState =
         let state, assy, resolved =
             resolveTypeFromRef loggerFactory activeAssy ref typeGenerics state
 
-        let baseType =
-            resolved.BaseType
-            |> DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies assy.Name
-
-        let signatureTypeKind =
-            match baseType with
-            | ResolvedBaseType.Enum
-            | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-            | ResolvedBaseType.Object -> SignatureTypeKind.Class
-            | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-        let result =
-            TypeDefn.FromDefinition (
-                ComparableTypeDefinitionHandle.Make resolved.TypeDefHandle,
-                assy.Name.FullName,
-                signatureTypeKind
-            )
-
-        if resolved.Generics.IsEmpty then
-            state, result, assy
-        else
-            failwith "TODO: add generics"
+        state, DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies resolved, assy

WoofWare.PawPrint/IlMachineStateExecution.fs

@@ -10,6 +10,7 @@ open Microsoft.Extensions.Logging
 [<RequireQualifiedAccess>]
 module IlMachineStateExecution =
     let getTypeOfObj
+        (loggerFactory : ILoggerFactory)
         (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (state : IlMachineState)
         (esv : EvalStackValue)
@@ -17,24 +18,18 @@ module IlMachineStateExecution =
         =
         match esv with
         | EvalStackValue.Int32 _ ->
-            TypeDefn.FromDefinition (
-                ComparableTypeDefinitionHandle.Make baseClassTypes.Int32.TypeDefHandle,
-                baseClassTypes.Corelib.Name.FullName,
-                SignatureTypeKind.ValueType
-            )
+            DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies baseClassTypes.Int32
             |> IlMachineState.concretizeType
+                loggerFactory
                 baseClassTypes
                 state
                 baseClassTypes.Corelib.Name
                 ImmutableArray.Empty
                 ImmutableArray.Empty
         | EvalStackValue.Int64 _ ->
-            TypeDefn.FromDefinition (
-                ComparableTypeDefinitionHandle.Make baseClassTypes.Int64.TypeDefHandle,
-                baseClassTypes.Corelib.Name.FullName,
-                SignatureTypeKind.ValueType
-            )
+            DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies baseClassTypes.Int64
             |> IlMachineState.concretizeType
+                loggerFactory
                 baseClassTypes
                 state
                 baseClassTypes.Corelib.Name
@@ -42,12 +37,9 @@ module IlMachineStateExecution =
                 ImmutableArray.Empty
         | EvalStackValue.NativeInt nativeIntSource -> failwith "todo"
         | EvalStackValue.Float _ ->
-            TypeDefn.FromDefinition (
-                ComparableTypeDefinitionHandle.Make baseClassTypes.Double.TypeDefHandle,
-                baseClassTypes.Corelib.Name.FullName,
-                SignatureTypeKind.ValueType
-            )
+            DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies baseClassTypes.Double
             |> IlMachineState.concretizeType
+                loggerFactory
                 baseClassTypes
                 state
                 baseClassTypes.Corelib.Name
@@ -58,12 +50,14 @@ module IlMachineStateExecution =
             | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) -> failwith "todo"
             | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) -> failwith "todo"
             | ManagedPointerSource.Heap addr ->
-                let o = ManagedHeap.Get addr state.ManagedHeap
+                let o = ManagedHeap.get addr state.ManagedHeap
                 state, o.ConcreteType
             | ManagedPointerSource.ArrayIndex (arr, index) -> failwith "todo"
             | ManagedPointerSource.Null -> failwith "todo"
+            | ManagedPointerSource.Field (managedPointerSource, fieldName) -> failwith "todo"
+            | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "todo"
         | EvalStackValue.ObjectRef addr ->
-            let o = ManagedHeap.Get addr state.ManagedHeap
+            let o = ManagedHeap.get addr state.ManagedHeap
             state, o.ConcreteType
         | EvalStackValue.UserDefinedValueType tuples -> failwith "todo"
 
@@ -124,16 +118,13 @@ module IlMachineStateExecution =
 
         match
             if isIntrinsic then
-                Intrinsics.call baseClassTypes methodToCall thread state
+                Intrinsics.call loggerFactory baseClassTypes methodToCall thread state
             else
                 None
         with
         | Some result -> result
         | None ->
 
-        if methodToCall.Name = "GetValue" then
-            printfn ""
-
         // Get zero values for all parameters
         let state, argZeroObjects =
             ((state, []), methodToCall.Signature.ParameterTypes)
@@ -167,7 +158,8 @@ module IlMachineStateExecution =
                     | None -> failwith "unexpectedly no `this` on the eval stack of instance method"
                     | Some this -> this
 
-                let state, callingObjTyHandle = getTypeOfObj baseClassTypes state callingObj
+                let state, callingObjTyHandle =
+                    getTypeOfObj loggerFactory baseClassTypes state callingObj
 
                 let callingObjTy =
                     let ty =
@@ -211,6 +203,7 @@ module IlMachineStateExecution =
                         let state, retType =
                             meth.Signature.ReturnType
                             |> IlMachineState.concretizeType
+                                loggerFactory
                                 baseClassTypes
                                 state
                                 meth.DeclaringType.Assembly
@@ -222,6 +215,7 @@ module IlMachineStateExecution =
                             ||> Seq.mapFold (fun state ty ->
                                 ty
                                 |> IlMachineState.concretizeType
+                                    loggerFactory
                                     baseClassTypes
                                     state
                                     meth.DeclaringType.Assembly
@@ -418,7 +412,7 @@ module IlMachineStateExecution =
                     // where Newobj puts the object pointer on top
                     let thisArg, newState =
                         popAndCoerceArg
-                            (CliType.RuntimePointer (CliRuntimePointer.Managed CliRuntimePointerSource.Null))
+                            (CliType.RuntimePointer (CliRuntimePointer.Managed ManagedPointerSource.Null))
                             currentState
 
                     currentState <- newState
@@ -441,7 +435,7 @@ module IlMachineStateExecution =
 
                     let thisArg, newState =
                         popAndCoerceArg
-                            (CliType.RuntimePointer (CliRuntimePointer.Managed CliRuntimePointerSource.Null))
+                            (CliType.RuntimePointer (CliRuntimePointer.Managed ManagedPointerSource.Null))
                             currentState
 
                     args.Add thisArg
@@ -578,34 +572,13 @@ module IlMachineStateExecution =
                             typeDef.Name
                         )
 
-                        // TypeDef won't have any generics; it would be a TypeSpec if it did
-                        // Create a TypeDefn from the TypeDef handle
                         let baseTypeDefn =
-                            let baseTypeDef = sourceAssembly.TypeDefs.[typeDefinitionHandle]
-
-                            let baseType =
-                                baseTypeDef.BaseType
-                                |> DumpedAssembly.resolveBaseType
-                                    baseClassTypes
-                                    state._LoadedAssemblies
-                                    sourceAssembly.Name
-
-                            let signatureTypeKind =
-                                match baseType with
-                                | ResolvedBaseType.Enum
-                                | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-                                | ResolvedBaseType.Object
-                                | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-                            TypeDefn.FromDefinition (
-                                ComparableTypeDefinitionHandle.Make typeDefinitionHandle,
-                                sourceAssembly.Name.FullName,
-                                signatureTypeKind
-                            )
+                            DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies typeDef
 
                         // Concretize the base type
                         let state, baseTypeHandle =
                             IlMachineState.concretizeType
+                                loggerFactory
                                 baseClassTypes
                                 state
                                 sourceAssembly.Name
@@ -639,26 +612,13 @@ module IlMachineStateExecution =
 
                         // Create a TypeDefn from the resolved TypeRef
                         let baseTypeDefn =
-                            let baseType =
-                                targetType.BaseType
-                                |> DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies assy.Name
-
-                            let signatureTypeKind =
-                                match baseType with
-                                | ResolvedBaseType.Enum
-                                | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-                                | ResolvedBaseType.Object
-                                | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-                            TypeDefn.FromDefinition (
-                                ComparableTypeDefinitionHandle.Make targetType.TypeDefHandle,
-                                assy.Name.FullName,
-                                signatureTypeKind
-                            )
+                            targetType
+                            |> DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies
 
                         // Concretize the base type
                         let state, baseTypeHandle =
                             IlMachineState.concretizeType
+                                loggerFactory
                                 baseClassTypes
                                 state
                                 sourceAssembly.Name
@@ -710,6 +670,7 @@ module IlMachineStateExecution =
                         state
                         (fun state typeDefn ->
                             IlMachineState.concretizeType
+                                loggerFactory
                                 baseClassTypes
                                 state
                                 concreteType.Assembly
@@ -734,6 +695,7 @@ module IlMachineStateExecution =
                                     ||> Seq.fold (fun (state, acc) typeDefn ->
                                         let state, handle =
                                             IlMachineState.concretizeType
+                                                loggerFactory
                                                 baseClassTypes
                                                 state
                                                 concreteType.Assembly

WoofWare.PawPrint/Intrinsics.fs

@@ -1,6 +1,8 @@
 namespace WoofWare.PawPrint
 
 open System
+open System.Collections.Immutable
+open Microsoft.Extensions.Logging
 
 [<RequireQualifiedAccess>]
 module Intrinsics =
@@ -14,10 +16,99 @@ module Intrinsics =
             "System.Private.CoreLib", "ArgumentNullException", "ThrowIfNull"
             // https://github.com/dotnet/runtime/blob/ec11903827fc28847d775ba17e0cd1ff56cfbc2e/src/coreclr/System.Private.CoreLib/src/System/Type.CoreCLR.cs#L82
             "System.Private.CoreLib", "Type", "GetTypeFromHandle"
+            // https://github.com/dotnet/runtime/blob/108fa7856efcfd39bc991c2d849eabbf7ba5989c/src/libraries/System.Private.CoreLib/src/System/ReadOnlySpan.cs#L161
+            "System.Private.CoreLib", "ReadOnlySpan`1", "get_Length"
+            // https://github.com/dotnet/runtime/blob/9e5e6aa7bc36aeb2a154709a9d1192030c30a2ef/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs#L153
+            "System.Private.CoreLib", "RuntimeHelpers", "CreateSpan"
+            // https://github.com/dotnet/runtime/blob/d258af50034c192bf7f0a18856bf83d2903d98ae/src/libraries/System.Private.CoreLib/src/System/Math.cs#L127
+            // https://github.com/dotnet/runtime/blob/d258af50034c192bf7f0a18856bf83d2903d98ae/src/libraries/System.Private.CoreLib/src/System/Math.cs#L137
+            "System.Private.CoreLib", "Math", "Abs"
+            // https://github.com/dotnet/runtime/blob/d258af50034c192bf7f0a18856bf83d2903d98ae/src/libraries/System.Private.CoreLib/src/System/Math.cs#L965C10-L1062C19
+            "System.Private.CoreLib", "Math", "Max"
+            // https://github.com/dotnet/runtime/blob/d258af50034c192bf7f0a18856bf83d2903d98ae/src/libraries/System.Private.CoreLib/src/System/Buffer.cs#L150
+            "System.Private.CoreLib", "Buffer", "Memmove"
+            // https://github.com/dotnet/runtime/blob/1c3221b63340d7f81dfd829f3bcd822e582324f6/src/libraries/System.Private.CoreLib/src/System/Threading/Thread.cs#L799
+            "System.Private.CoreLib", "Thread", "get_CurrentThread"
         ]
         |> Set.ofList
 
+    type private RefTypeProcessingStatus =
+        | InProgress
+        | Completed of bool
+
+    let rec private containsRefType
+        (loggerFactory : ILoggerFactory)
+        (baseClassTypes : BaseClassTypes<DumpedAssembly>)
+        (state : IlMachineState)
+        (seenSoFar : ImmutableDictionary<TypeInfo<TypeDefn, TypeDefn>, RefTypeProcessingStatus>)
+        (td : TypeInfo<TypeDefn, TypeDefn>)
+        : IlMachineState * ImmutableDictionary<_, RefTypeProcessingStatus> * bool
+        =
+        match seenSoFar.TryGetValue td with
+        | true, InProgress ->
+            // We've hit a cycle. Optimistically assume this path does not introduce a reference type.
+            // If another path finds a reference type, its 'true' will override this.
+            state, seenSoFar, false
+        | true, Completed v ->
+            // We've already calculated this; return the memoized result.
+            state, seenSoFar, v
+        | false, _ ->
+            // Check if this type itself is a reference type.
+            let baseType =
+                td.BaseType
+                |> DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies td.Assembly
+
+            match baseType with
+            | ResolvedBaseType.Delegate
+            | ResolvedBaseType.Object ->
+                // Short-circuit: if the type itself is a reference type, we're done.
+                let seenSoFar = seenSoFar.Add (td, Completed true)
+                state, seenSoFar, true
+            | ResolvedBaseType.Enum
+            | ResolvedBaseType.ValueType ->
+                // It's a value type, so we must check its fields.
+                // Mark as in progress before recursing.
+                let seenSoFarWithInProgress = seenSoFar.Add (td, InProgress)
+
+                let stateAfterFieldResolution, nonStaticFields =
+                    ((state, []), td.Fields)
+                    ||> List.fold (fun (currentState, acc) field ->
+                        if field.IsStatic then
+                            currentState, acc
+                        else
+                            // TODO: generics
+                            let newState, _, info =
+                                IlMachineState.resolveTypeFromDefn
+                                    loggerFactory
+                                    baseClassTypes
+                                    field.Signature
+                                    ImmutableArray.Empty
+                                    ImmutableArray.Empty
+                                    (currentState.LoadedAssembly (td.Assembly) |> Option.get)
+                                    currentState
+
+                            newState, info :: acc
+                    )
+
+                // Recurse through the fields, correctly propagating state.
+                let finalState, finalSeenSoFar, fieldsContainRefType =
+                    ((stateAfterFieldResolution, seenSoFarWithInProgress, false), nonStaticFields)
+                    ||> List.fold (fun (currentState, currentSeenSoFar, currentResult) field ->
+                        if currentResult then
+                            (currentState, currentSeenSoFar, true) // Short-circuit
+                        else
+                            let newState, newSeenSoFar, fieldResult =
+                                containsRefType loggerFactory baseClassTypes currentState currentSeenSoFar field
+
+                            (newState, newSeenSoFar, currentResult || fieldResult)
+                    )
+
+                // Mark as completed with the final result before returning.
+                let finalSeenSoFar = finalSeenSoFar.SetItem (td, Completed fieldsContainRefType)
+                finalState, finalSeenSoFar, fieldsContainRefType
+
     let call
+        (loggerFactory : ILoggerFactory)
         (baseClassTypes : BaseClassTypes<_>)
         (methodToCall : WoofWare.PawPrint.MethodInfo<ConcreteTypeHandle, ConcreteTypeHandle, ConcreteTypeHandle>)
         (currentThread : ThreadId)
@@ -42,6 +133,8 @@ module Intrinsics =
             None
         else
 
+        // In general, some implementations are in:
+        // https://github.com/dotnet/runtime/blob/108fa7856efcfd39bc991c2d849eabbf7ba5989c/src/coreclr/tools/Common/TypeSystem/IL/Stubs/UnsafeIntrinsics.cs#L192
         match methodToCall.DeclaringType.Assembly.Name, methodToCall.DeclaringType.Name, methodToCall.Name with
         | "System.Private.CoreLib", "Type", "get_TypeHandle" ->
             // TODO: check return type is RuntimeTypeHandle
@@ -50,7 +143,14 @@ module Intrinsics =
             | _ -> ()
 
             // https://github.com/dotnet/runtime/blob/ec11903827fc28847d775ba17e0cd1ff56cfbc2e/src/libraries/System.Private.CoreLib/src/System/Type.cs#L470
+
+            // TODO: check return type is RuntimeTypeHandle
+            match methodToCall.Signature.ParameterTypes with
+            | _ :: _ -> failwith "bad signature Type.get_TypeHandle"
+            | _ -> ()
+
             // no args, returns RuntimeTypeHandle, a struct with a single field (a RuntimeType class)
+            // https://github.com/dotnet/runtime/blob/1d1bf92fcf43aa6981804dc53c5174445069c9e4/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs#L18
 
             // The thing on top of the stack will be a RuntimeType.
             let arg, state = IlMachineState.popEvalStack currentThread state
@@ -58,8 +158,12 @@ module Intrinsics =
             let arg =
                 let rec go (arg : EvalStackValue) =
                     match arg with
-                    | EvalStackValue.UserDefinedValueType [ _, s ] -> go s
+                    | EvalStackValue.UserDefinedValueType vt ->
+                        match CliValueType.TryExactlyOneField vt with
+                        | None -> failwith "TODO"
+                        | Some field -> go (EvalStackValue.ofCliType field.Contents)
                     | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> failwith "TODO: throw NRE"
+                    | EvalStackValue.ObjectRef addr
                     | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) -> Some addr
                     | s -> failwith $"TODO: called with unrecognised arg %O{s}"
 
@@ -67,34 +171,72 @@ module Intrinsics =
 
             let state =
                 let vt =
+                    // https://github.com/dotnet/runtime/blob/2b21c73fa2c32fa0195e4a411a435dda185efd08/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs#L92
                     {
-                        Fields = [ "m_type", CliType.ObjectRef arg ]
+                        Name = "m_type"
+                        Contents = CliType.ObjectRef arg
+                        Offset = None
+                        Type =
+                            AllConcreteTypes.findExistingConcreteType
+                                state.ConcreteTypes
+                                (baseClassTypes.RuntimeType.Assembly,
+                                 baseClassTypes.RuntimeType.Namespace,
+                                 baseClassTypes.RuntimeType.Name,
+                                 ImmutableArray.Empty)
+                            |> Option.get
                     }
+                    |> List.singleton
+                    |> CliValueType.OfFields Layout.Default
 
                 IlMachineState.pushToEvalStack (CliType.ValueType vt) currentThread state
                 |> IlMachineState.advanceProgramCounter currentThread
 
             Some state
+        | "System.Private.CoreLib", "Type", "get_IsValueType" ->
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [], ConcreteBool state.ConcreteTypes -> ()
+            | _ -> failwith "bad signature Type.get_IsValueType"
+
+            let this, state = IlMachineState.popEvalStack currentThread state
+
+            let this =
+                match this with
+                | EvalStackValue.ObjectRef ptr ->
+                    IlMachineState.dereferencePointer state (ManagedPointerSource.Heap ptr)
+                | EvalStackValue.ManagedPointer ptr -> IlMachineState.dereferencePointer state ptr
+                | EvalStackValue.Float _
+                | EvalStackValue.Int32 _
+                | EvalStackValue.Int64 _ -> failwith "refusing to dereference literal"
+                | _ -> failwith "TODO"
+            // `this` should be of type Type
+            let ty =
+                match this with
+                | CliType.ValueType cvt ->
+                    match CliValueType.DereferenceField "m_handle" cvt with
+                    | CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.TypeHandlePtr cth)) -> cth
+                    | _ -> failwith ""
+                | _ -> failwith "expected a Type"
+
+            let ty = AllConcreteTypes.lookup ty state.ConcreteTypes |> Option.get
+            let ty = state.LoadedAssembly(ty.Assembly).Value.TypeDefs.[ty.Definition.Get]
+
+            let isValueType =
+                match DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies ty.Assembly ty.BaseType with
+                | ResolvedBaseType.Enum
+                | ResolvedBaseType.ValueType -> true
+                | ResolvedBaseType.Object
+                | ResolvedBaseType.Delegate -> false
+
+            IlMachineState.pushToEvalStack (CliType.ofBool isValueType) currentThread state
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
         | "System.Private.CoreLib", "Unsafe", "AsPointer" ->
             // Method signature: 1 generic parameter, we take a Byref of that parameter, and return a TypeDefn.Pointer(Void)
             let arg, state = IlMachineState.popEvalStack currentThread state
 
             let toPush =
                 match arg with
-                | EvalStackValue.ManagedPointer ptr ->
-                    match ptr with
-                    | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-                        CliRuntimePointer.Managed (
-                            CliRuntimePointerSource.LocalVariable (sourceThread, methodFrame, whichVar)
-                        )
-                    | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
-                        CliRuntimePointer.Managed (
-                            CliRuntimePointerSource.Argument (sourceThread, methodFrame, whichVar)
-                        )
-                    | ManagedPointerSource.Heap managedHeapAddress ->
-                        CliRuntimePointer.Managed (CliRuntimePointerSource.Heap managedHeapAddress)
-                    | ManagedPointerSource.Null -> failwith "todo"
-                    | ManagedPointerSource.ArrayIndex _ -> failwith "TODO"
+                | EvalStackValue.ManagedPointer ptr -> CliRuntimePointer.Managed ptr
                 | x -> failwith $"TODO: Unsafe.AsPointer(%O{x})"
 
             IlMachineState.pushToEvalStack (CliType.RuntimePointer toPush) currentThread state
@@ -131,6 +273,47 @@ module Intrinsics =
             let result =
                 BitConverter.Int32BitsToSingle arg |> CliNumericType.Float32 |> CliType.Numeric
 
+            state
+            |> IlMachineState.pushToEvalStack result currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
+        | "System.Private.CoreLib", "BitConverter", "DoubleToUInt64Bits" ->
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [ ConcreteDouble state.ConcreteTypes ], ConcreteUInt64 state.ConcreteTypes -> ()
+            | _ -> failwith "bad signature BitConverter.DoubleToUInt64Bits"
+
+            let arg, state = IlMachineState.popEvalStack currentThread state
+
+            let arg =
+                match arg with
+                | EvalStackValue.Float i -> i
+                | _ -> failwith "$TODO: {arr}"
+
+            let result =
+                BitConverter.DoubleToUInt64Bits arg
+                |> int64<uint64>
+                |> CliNumericType.Int64
+                |> CliType.Numeric
+
+            state
+            |> IlMachineState.pushToEvalStack result currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
+        | "System.Private.CoreLib", "BitConverter", "UInt64BitsToDouble" ->
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [ ConcreteUInt64 state.ConcreteTypes ], ConcreteDouble state.ConcreteTypes -> ()
+            | _ -> failwith "bad signature BitConverter.DoubleToUInt64Bits"
+
+            let arg, state = IlMachineState.popEvalStack currentThread state
+
+            let arg =
+                match arg with
+                | EvalStackValue.Int64 i -> uint64 i
+                | _ -> failwith "$TODO: {arr}"
+
+            let result =
+                BitConverter.UInt64BitsToDouble arg |> CliNumericType.Float64 |> CliType.Numeric
+
             state
             |> IlMachineState.pushToEvalStack result currentThread
             |> IlMachineState.advanceProgramCounter currentThread
@@ -166,6 +349,44 @@ module Intrinsics =
                 | EvalStackValue.Float f -> BitConverter.DoubleToInt64Bits f |> EvalStackValue.Int64
                 | _ -> failwith "TODO"
 
+            state
+            |> IlMachineState.pushToEvalStack' result currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
+        | "System.Private.CoreLib", "BitConverter", "SingleToUInt32Bits" ->
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [ ConcreteSingle state.ConcreteTypes ], ConcreteUInt32 state.ConcreteTypes -> ()
+            | _ -> failwith "bad signature BitConverter.SingleToUInt32Bits"
+
+            let arg, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                match arg with
+                | EvalStackValue.Float f ->
+                    BitConverter.SingleToUInt32Bits (float32<float> f)
+                    |> int<uint32>
+                    |> EvalStackValue.Int32
+                | _ -> failwith "TODO"
+
+            state
+            |> IlMachineState.pushToEvalStack' result currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
+        | "System.Private.CoreLib", "BitConverter", "UInt32BitsToSingle" ->
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [ ConcreteUInt32 state.ConcreteTypes ], ConcreteSingle state.ConcreteTypes -> ()
+            | _ -> failwith "bad signature BitConverter.UInt32BitsToSingle"
+
+            let arg, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                match arg with
+                | EvalStackValue.Int32 f ->
+                    BitConverter.UInt32BitsToSingle (uint32<int> f)
+                    |> float<float32>
+                    |> EvalStackValue.Float
+                | _ -> failwith "TODO"
+
             state
             |> IlMachineState.pushToEvalStack' result currentThread
             |> IlMachineState.advanceProgramCounter currentThread
@@ -179,7 +400,8 @@ module Intrinsics =
                 let arg1 =
                     match arg1 with
                     | EvalStackValue.ObjectRef h
-                    | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap h) -> h
+                    | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap h) -> Some h
+                    | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> None
                     | EvalStackValue.Int32 _
                     | EvalStackValue.Int64 _
                     | EvalStackValue.Float _ -> failwith $"this isn't a string! {arg1}"
@@ -190,29 +412,38 @@ module Intrinsics =
                 let arg2 =
                     match arg2 with
                     | EvalStackValue.ObjectRef h
-                    | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap h) -> h
+                    | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap h) -> Some h
+                    | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> None
                     | EvalStackValue.Int32 _
                     | EvalStackValue.Int64 _
                     | EvalStackValue.Float _ -> failwith $"this isn't a string! {arg2}"
                     | _ -> failwith $"TODO: %O{arg2}"
 
-                if arg1 = arg2 then
-                    state
-                    |> IlMachineState.pushToEvalStack (CliType.ofBool true) currentThread
-                    |> IlMachineState.advanceProgramCounter currentThread
-                    |> Some
-                else
+                let areEqual =
+                    match arg1, arg2 with
+                    | None, None -> true
+                    | Some _, None
+                    | None, Some _ -> false
+                    | Some arg1, Some arg2 ->
+                        if arg1 = arg2 then
+                            true
+                        else
 
-                let arg1 = ManagedHeap.Get arg1 state.ManagedHeap
-                let arg2 = ManagedHeap.Get arg2 state.ManagedHeap
+                        let arg1 = ManagedHeap.get arg1 state.ManagedHeap
+                        let arg2 = ManagedHeap.get arg2 state.ManagedHeap
 
-                if arg1.Fields.["_firstChar"] <> arg2.Fields.["_firstChar"] then
-                    state
-                    |> IlMachineState.pushToEvalStack (CliType.ofBool false) currentThread
-                    |> IlMachineState.advanceProgramCounter currentThread
-                    |> Some
-                else
-                    failwith "TODO"
+                        if
+                            AllocatedNonArrayObject.DereferenceField "_firstChar" arg1
+                            <> AllocatedNonArrayObject.DereferenceField "_firstChar" arg2
+                        then
+                            false
+                        else
+                            failwith "TODO"
+
+                state
+                |> IlMachineState.pushToEvalStack (CliType.ofBool areEqual) currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+                |> Some
             | _ -> None
         | "System.Private.CoreLib", "Unsafe", "ReadUnaligned" ->
             let ptr, state = IlMachineState.popEvalStack currentThread state
@@ -220,19 +451,13 @@ module Intrinsics =
             let v : CliType =
                 let rec go ptr =
                     match ptr with
-                    | EvalStackValue.ManagedPointer src ->
-                        match src with
-                        | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) -> failwith "todo"
-                        | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) -> failwith "todo"
-                        | ManagedPointerSource.Heap managedHeapAddress -> failwith "todo"
-                        | ManagedPointerSource.ArrayIndex (arr, index) ->
-                            state |> IlMachineState.getArrayValue arr index
-                        | ManagedPointerSource.Null -> failwith "TODO: throw NRE"
+                    | EvalStackValue.ManagedPointer src -> IlMachineState.dereferencePointer state src
                     | EvalStackValue.NativeInt src -> failwith "TODO"
                     | EvalStackValue.ObjectRef ptr -> failwith "TODO"
-                    | EvalStackValue.UserDefinedValueType [ _, field ] -> go field
-                    | EvalStackValue.UserDefinedValueType []
-                    | EvalStackValue.UserDefinedValueType (_ :: _ :: _)
+                    | EvalStackValue.UserDefinedValueType vt ->
+                        match CliValueType.TryExactlyOneField vt with
+                        | None -> failwith "TODO"
+                        | Some field -> go (EvalStackValue.ofCliType field.Contents)
                     | EvalStackValue.Int32 _
                     | EvalStackValue.Int64 _
                     | EvalStackValue.Float _ -> failwith $"this isn't a pointer! {ptr}"
@@ -277,15 +502,46 @@ module Intrinsics =
             | [], ConcreteBool state.ConcreteTypes -> ()
             | _ -> failwith "bad signature for System.Private.CoreLib.RuntimeHelpers.IsReferenceOrContainsReference"
 
-            let generic =
-                AllConcreteTypes.lookup (Seq.exactlyOne methodToCall.Generics) state.ConcreteTypes
+            let arg = Seq.exactlyOne methodToCall.Generics
 
-            let generic =
-                match generic with
-                | None -> failwith "somehow have not already concretised type in IsReferenceOrContainsReferences"
-                | Some generic -> generic
+            let state, result =
+                // Some types appear circular, because they're hardcoded in the runtime. We have to special-case them.
+                match arg with
+                | ConcreteChar state.ConcreteTypes -> state, false
+                | _ ->
 
-            failwith $"TODO: do the thing on %O{generic}"
+                let generic = AllConcreteTypes.lookup arg state.ConcreteTypes
+
+                let generic =
+                    match generic with
+                    | None -> failwith "somehow have not already concretised type in IsReferenceOrContainsReferences"
+                    | Some generic -> generic
+
+                let td =
+                    state.LoadedAssembly generic.Assembly
+                    |> Option.get
+                    |> fun a -> a.TypeDefs.[generic.Definition.Get]
+
+                let baseType =
+                    td.BaseType
+                    |> DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies generic.Assembly
+
+                match baseType with
+                | ResolvedBaseType.Enum
+                | ResolvedBaseType.ValueType ->
+                    td
+                    |> TypeInfo.mapGeneric (fun (par, _) -> TypeDefn.GenericTypeParameter par.SequenceNumber)
+                    |> containsRefType loggerFactory baseClassTypes state ImmutableDictionary.Empty
+                    |> fun (state, _, result) -> state, result
+                | ResolvedBaseType.Object
+                | ResolvedBaseType.Delegate -> state, true
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack (CliType.ofBool result) currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            Some state
         | "System.Private.CoreLib", "RuntimeHelpers", "InitializeArray" ->
             // https://github.com/dotnet/runtime/blob/9e5e6aa7bc36aeb2a154709a9d1192030c30a2ef/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.CoreCLR.cs#L18
             match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
@@ -297,11 +553,110 @@ module Intrinsics =
             failwith "TODO: if arg1 contains null handle, throw ArgumentException"
 
             failwith "TODO: array initialization"
+        | "System.Private.CoreLib", "Unsafe", "As" ->
+            // https://github.com/dotnet/runtime/blob/721fdf6dcb032da1f883d30884e222e35e3d3c99/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/Unsafe.cs#L64
+            let inputType, retType =
+                match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+                | [ input ], ret -> input, ret
+                | _ -> failwith "bad signature Unsafe.As"
+
+            let from, to_ =
+                match Seq.toList methodToCall.Generics with
+                | [ from ; to_ ] -> from, to_
+                | _ -> failwith "bad generics"
+
+            if ConcreteTypeHandle.Byref to_ <> retType then
+                failwith "bad return type"
+
+            if ConcreteTypeHandle.Byref from <> inputType then
+                failwith "bad input type"
+
+            let from =
+                match AllConcreteTypes.lookup from state.ConcreteTypes with
+                | None -> failwith "somehow have not concretised input type"
+                | Some t -> t
+
+            let to_ =
+                match AllConcreteTypes.lookup to_ state.ConcreteTypes with
+                | None -> failwith "somehow have not concretised ret type"
+                | Some t -> t
+
+            let inputAddr, state = IlMachineState.popEvalStack currentThread state
+
+            let ptr =
+                match inputAddr with
+                | EvalStackValue.Int32 _
+                | EvalStackValue.Int64 _
+                | EvalStackValue.Float _ -> failwith "expected pointer type"
+                | EvalStackValue.NativeInt nativeIntSource -> failwith "todo"
+                | EvalStackValue.ManagedPointer src ->
+                    ManagedPointerSource.InterpretedAsType (src, to_)
+                    |> EvalStackValue.ManagedPointer
+                | EvalStackValue.ObjectRef addr ->
+                    ManagedPointerSource.InterpretedAsType (ManagedPointerSource.Heap addr, to_)
+                    |> EvalStackValue.ManagedPointer
+                | EvalStackValue.UserDefinedValueType evalStackValueUserType -> failwith "todo"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack' ptr currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            Some state
+        | "System.Private.CoreLib", "Unsafe", "SizeOf" ->
+            // https://github.com/dotnet/runtime/blob/721fdf6dcb032da1f883d30884e222e35e3d3c99/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/Unsafe.cs#L51
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [], ConcreteInt32 state.ConcreteTypes -> ()
+            | _ -> failwith "bad signature Unsafe.SizeOf"
+
+            let ty =
+                match Seq.toList methodToCall.Generics with
+                | [ ty ] -> ty
+                | _ -> failwith "bad generics"
+
+            let zero, state = IlMachineState.cliTypeZeroOfHandle state baseClassTypes ty
+
+            let size = CliType.sizeOf zero
+
+            state
+            |> IlMachineState.pushToEvalStack (CliType.Numeric (CliNumericType.Int32 size)) currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
         | "System.Private.CoreLib", "RuntimeHelpers", "CreateSpan" ->
             // https://github.com/dotnet/runtime/blob/9e5e6aa7bc36aeb2a154709a9d1192030c30a2ef/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs#L153
             None
         | "System.Private.CoreLib", "Type", "op_Equality" ->
             // https://github.com/dotnet/runtime/blob/ec11903827fc28847d775ba17e0cd1ff56cfbc2e/src/libraries/System.Private.CoreLib/src/System/Type.cs#L703
             None
+        | "System.Private.CoreLib", "MemoryMarshal", "GetArrayDataReference" ->
+            // https://github.com/dotnet/runtime/blob/d258af50034c192bf7f0a18856bf83d2903d98ae/src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/MemoryMarshal.CoreCLR.cs#L20
+            let generic = Seq.exactlyOne methodToCall.Generics
+
+            match methodToCall.Signature.ParameterTypes, methodToCall.Signature.ReturnType with
+            | [ ConcreteGenericArray state.ConcreteTypes generic ], ConcreteByref t when t = generic -> ()
+            | _ -> failwith "bad signature MemoryMarshal.GetArrayDataReference"
+
+            let arr, state = IlMachineState.popEvalStack currentThread state
+
+            let toPush =
+                match arr with
+                | EvalStackValue.Int32 _
+                | EvalStackValue.Int64 _
+                | EvalStackValue.Float _ -> failwith "expected reference"
+                | EvalStackValue.NativeInt nativeIntSource -> failwith "todo"
+                | EvalStackValue.ObjectRef addr
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) ->
+                    if not (state.ManagedHeap.Arrays.ContainsKey addr) then
+                        failwith "array not found"
+
+                    EvalStackValue.ManagedPointer (ManagedPointerSource.ArrayIndex (addr, 0))
+                | EvalStackValue.UserDefinedValueType evalStackValueUserType -> failwith "todo"
+                | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> failwith "TODO: raise NRE"
+                | EvalStackValue.ManagedPointer _ -> failwith "todo"
+
+            state
+            |> IlMachineState.pushToEvalStack' toPush currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Some
         | a, b, c -> failwith $"TODO: implement JIT intrinsic {a}.{b}.{c}"
         |> Option.map (fun s -> s.WithThreadSwitchedToAssembly callerAssy currentThread |> fst)

WoofWare.PawPrint/List.fs

@@ -0,0 +1,12 @@
+namespace WoofWare.PawPrint
+
+[<RequireQualifiedAccess>]
+module List =
+    let replaceWhere (f : 'a -> 'a option) (l : 'a list) : 'a list =
+        ([], l)
+        ||> List.fold (fun acc x ->
+            match f x with
+            | None -> x :: acc
+            | Some y -> y :: acc
+        )
+        |> List.rev

WoofWare.PawPrint/ManagedHeap.fs

@@ -8,11 +8,20 @@ type SyncBlock =
 
 type AllocatedNonArrayObject =
     {
-        Fields : Map<string, CliType>
+        // TODO: this is a slightly odd domain; the same type for value types as class types!
+        Contents : CliValueType
         ConcreteType : ConcreteTypeHandle
         SyncBlock : SyncBlock
     }
 
+    static member DereferenceField (name : string) (f : AllocatedNonArrayObject) : CliType =
+        CliValueType.DereferenceField name f.Contents
+
+    static member SetField (name : string) (v : CliType) (f : AllocatedNonArrayObject) : AllocatedNonArrayObject =
+        { f with
+            Contents = CliValueType.WithFieldSet name v f.Contents
+        }
+
 type AllocatedArray =
     {
         Length : int
@@ -29,7 +38,9 @@ type ManagedHeap =
         StringArrayData : ImmutableArray<char>
     }
 
-    static member Empty : ManagedHeap =
+[<RequireQualifiedAccess>]
+module ManagedHeap =
+    let empty : ManagedHeap =
         {
             NonArrayObjects = Map.empty
             FirstAvailableAddress = 1
@@ -37,12 +48,12 @@ type ManagedHeap =
             StringArrayData = ImmutableArray.Empty
         }
 
-    static member GetSyncBlock (addr : ManagedHeapAddress) (heap : ManagedHeap) : SyncBlock =
+    let getSyncBlock (addr : ManagedHeapAddress) (heap : ManagedHeap) : SyncBlock =
         match heap.NonArrayObjects.TryGetValue addr with
         | false, _ -> failwith "TODO: getting sync block of array"
         | true, v -> v.SyncBlock
 
-    static member SetSyncBlock (addr : ManagedHeapAddress) (syncValue : SyncBlock) (heap : ManagedHeap) : ManagedHeap =
+    let setSyncBlock (addr : ManagedHeapAddress) (syncValue : SyncBlock) (heap : ManagedHeap) : ManagedHeap =
         match heap.NonArrayObjects.TryGetValue addr with
         | false, _ -> failwith "TODO: locked on an array object"
         | true, v ->
@@ -55,7 +66,7 @@ type ManagedHeap =
                 NonArrayObjects = heap.NonArrayObjects |> Map.add addr newV
             }
 
-    static member AllocateArray (ty : AllocatedArray) (heap : ManagedHeap) : ManagedHeapAddress * ManagedHeap =
+    let allocateArray (ty : AllocatedArray) (heap : ManagedHeap) : ManagedHeapAddress * ManagedHeap =
         let addr = heap.FirstAvailableAddress
 
         let heap =
@@ -68,7 +79,7 @@ type ManagedHeap =
 
         ManagedHeapAddress addr, heap
 
-    static member AllocateString (len : int) (heap : ManagedHeap) : int * ManagedHeap =
+    let allocateString (len : int) (heap : ManagedHeap) : int * ManagedHeap =
         let addr = heap.StringArrayData.Length
 
         let heap =
@@ -80,7 +91,7 @@ type ManagedHeap =
 
         addr, heap
 
-    static member SetStringData (addr : int) (contents : string) (heap : ManagedHeap) : ManagedHeap =
+    let setStringData (addr : int) (contents : string) (heap : ManagedHeap) : ManagedHeap =
         let newArr =
             (heap.StringArrayData, seq { 0 .. contents.Length - 1 })
             ||> Seq.fold (fun data count -> data.SetItem (addr + count, contents.[count]))
@@ -92,11 +103,7 @@ type ManagedHeap =
 
         heap
 
-    static member AllocateNonArray
-        (ty : AllocatedNonArrayObject)
-        (heap : ManagedHeap)
-        : ManagedHeapAddress * ManagedHeap
-        =
+    let allocateNonArray (ty : AllocatedNonArrayObject) (heap : ManagedHeap) : ManagedHeapAddress * ManagedHeap =
         let addr = heap.FirstAvailableAddress
 
         let heap =
@@ -109,7 +116,7 @@ type ManagedHeap =
 
         ManagedHeapAddress addr, heap
 
-    static member GetArrayValue (alloc : ManagedHeapAddress) (offset : int) (heap : ManagedHeap) : CliType =
+    let getArrayValue (alloc : ManagedHeapAddress) (offset : int) (heap : ManagedHeap) : CliType =
         match heap.Arrays.TryGetValue alloc with
         | false, _ -> failwith "TODO: array not on heap"
         | true, arr ->
@@ -119,17 +126,17 @@ type ManagedHeap =
 
         arr.Elements.[offset]
 
-    static member Get (alloc : ManagedHeapAddress) (heap : ManagedHeap) : AllocatedNonArrayObject =
+    let get (alloc : ManagedHeapAddress) (heap : ManagedHeap) : AllocatedNonArrayObject =
         // TODO: arrays too
         heap.NonArrayObjects.[alloc]
 
-    static member SetArrayValue
-        (alloc : ManagedHeapAddress)
-        (offset : int)
-        (v : CliType)
-        (heap : ManagedHeap)
-        : ManagedHeap
-        =
+    let set (alloc : ManagedHeapAddress) (v : AllocatedNonArrayObject) (heap : ManagedHeap) : ManagedHeap =
+        // TODO: arrays too
+        { heap with
+            NonArrayObjects = heap.NonArrayObjects |> Map.add alloc v
+        }
+
+    let setArrayValue (alloc : ManagedHeapAddress) (offset : int) (v : CliType) (heap : ManagedHeap) : ManagedHeap =
         let newArrs =
             heap.Arrays
             |> Map.change

WoofWare.PawPrint/NullaryIlOp.fs

@@ -1,5 +1,6 @@
 namespace WoofWare.PawPrint
 
+open System
 open Microsoft.Extensions.Logging
 
 [<RequireQualifiedAccess>]
@@ -37,19 +38,6 @@ module NullaryIlOp =
         | LdindR4 -> CliType.Numeric (CliNumericType.Float32 0.0f)
         | LdindR8 -> CliType.Numeric (CliNumericType.Float64 0.0)
 
-    /// Retrieve a value from a pointer
-    let private loadFromPointerSource (state : IlMachineState) (src : ManagedPointerSource) : CliType =
-        match src with
-        | ManagedPointerSource.Null -> failwith "unexpected null pointer in Ldind operation"
-        | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
-            state.ThreadState.[sourceThread].MethodStates.[methodFrame].Arguments.[int<uint16> whichVar]
-        | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-            state.ThreadState.[sourceThread].MethodStates.[methodFrame].LocalVariables.[int<uint16> whichVar]
-        | ManagedPointerSource.Heap managedHeapAddress -> failwith "TODO: Heap pointer dereferencing not implemented"
-        | ManagedPointerSource.ArrayIndex (arr, index) ->
-            let arr = state.ManagedHeap.Arrays.[arr]
-            arr.Elements.[index]
-
     // Unified Ldind implementation
     let private executeLdind
         (targetType : LdindTargetType)
@@ -61,11 +49,11 @@ module NullaryIlOp =
 
         let loadedValue =
             match popped with
-            | EvalStackValue.ManagedPointer src -> loadFromPointerSource state src
+            | EvalStackValue.ManagedPointer src -> IlMachineState.dereferencePointer state src
             | EvalStackValue.NativeInt nativeIntSource ->
                 failwith $"TODO: Native int pointer dereferencing not implemented for {targetType}"
             | EvalStackValue.ObjectRef managedHeapAddress ->
-                failwith "TODO: Object reference dereferencing not implemented"
+                IlMachineState.dereferencePointer state (ManagedPointerSource.Heap managedHeapAddress)
             | other -> failwith $"Unexpected eval stack value for Ldind operation: {other}"
 
         let loadedValue = loadedValue |> EvalStackValue.ofCliType
@@ -94,52 +82,39 @@ module NullaryIlOp =
         | EvalStackValue.ManagedPointer src ->
             match src with
             | ManagedPointerSource.Null -> failwith "TODO: throw NullReferenceException"
+            | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "TODO"
             | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
                 failwith "unexpected - can we really write to an argument?"
             | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-                { state with
-                    ThreadState =
-                        state.ThreadState
-                        |> Map.change
-                            sourceThread
-                            (fun state ->
-                                match state with
-                                | None -> failwith "tried to store in local variables of nonexistent stack frame"
-                                | Some state ->
-                                    let frame = state.MethodStates.[methodFrame]
-
-                                    let frame =
-                                        { frame with
-                                            LocalVariables =
-                                                frame.LocalVariables.SetItem (
-                                                    int<uint16> whichVar,
-                                                    EvalStackValue.toCliTypeCoerced varType valueToStore
-                                                )
-                                        }
-
-                                    { state with
-                                        MethodStates = state.MethodStates.SetItem (methodFrame, frame)
-                                    }
-                                    |> Some
-                            )
-                }
+                state
+                |> IlMachineState.setLocalVariable
+                    sourceThread
+                    methodFrame
+                    whichVar
+                    (EvalStackValue.toCliTypeCoerced varType valueToStore)
             | ManagedPointerSource.Heap managedHeapAddress -> failwith "todo"
             | ManagedPointerSource.ArrayIndex _ -> failwith "todo"
+            | ManagedPointerSource.Field (managedPointerSource, fieldName) ->
+                state
+                |> IlMachineState.setFieldValue
+                    managedPointerSource
+                    (EvalStackValue.toCliTypeCoerced varType valueToStore)
+                    fieldName
         | EvalStackValue.ObjectRef managedHeapAddress -> failwith "todo"
 
-    let internal ldElem
-        (targetCliTypeZero : CliType)
+    let internal getArrayElt
         (index : EvalStackValue)
         (arr : EvalStackValue)
         (currentThread : ThreadId)
         (state : IlMachineState)
-        : ExecutionResult
+        : CliType
         =
         let index =
             match index with
             | EvalStackValue.NativeInt src ->
                 match src with
                 | NativeIntSource.FunctionPointer _
+                | NativeIntSource.FieldHandlePtr _
                 | NativeIntSource.TypeHandlePtr _
                 | NativeIntSource.ManagedPointer _ -> failwith "Refusing to treat a pointer as an array index"
                 | NativeIntSource.Verbatim i -> i |> int32
@@ -153,14 +128,7 @@ module NullaryIlOp =
             | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> failwith "TODO: throw NRE"
             | _ -> failwith $"Invalid array: %O{arr}"
 
-        let value = IlMachineState.getArrayValue arrAddr index state
-
-        let state =
-            state
-            |> IlMachineState.pushToEvalStack value currentThread
-            |> IlMachineState.advanceProgramCounter currentThread
-
-        ExecutionResult.Stepped (state, WhatWeDid.Executed)
+        IlMachineState.getArrayValue arrAddr index state
 
     let internal stElem
         (targetCliTypeZero : CliType)
@@ -176,6 +144,7 @@ module NullaryIlOp =
             | EvalStackValue.NativeInt src ->
                 match src with
                 | NativeIntSource.FunctionPointer _
+                | NativeIntSource.FieldHandlePtr _
                 | NativeIntSource.TypeHandlePtr _
                 | NativeIntSource.ManagedPointer _ -> failwith "Refusing to treat a pointer as an array index"
                 | NativeIntSource.Verbatim i -> i |> int32
@@ -442,7 +411,7 @@ module NullaryIlOp =
         | Sub ->
             let val2, state = IlMachineState.popEvalStack currentThread state
             let val1, state = IlMachineState.popEvalStack currentThread state
-            let result = BinaryArithmetic.execute ArithmeticOperation.sub val1 val2
+            let result = BinaryArithmetic.execute ArithmeticOperation.sub state val1 val2
 
             state
             |> IlMachineState.pushToEvalStack' result currentThread
@@ -452,30 +421,84 @@ module NullaryIlOp =
         | Sub_ovf -> failwith "TODO: Sub_ovf unimplemented"
         | Sub_ovf_un -> failwith "TODO: Sub_ovf_un unimplemented"
         | Add ->
-            let val1, state = IlMachineState.popEvalStack currentThread state
             let val2, state = IlMachineState.popEvalStack currentThread state
-            let result = BinaryArithmetic.execute ArithmeticOperation.add val1 val2
+            let val1, state = IlMachineState.popEvalStack currentThread state
+            let result = BinaryArithmetic.execute ArithmeticOperation.add state val1 val2
 
             state
             |> IlMachineState.pushToEvalStack' result currentThread
             |> IlMachineState.advanceProgramCounter currentThread
             |> Tuple.withRight WhatWeDid.Executed
             |> ExecutionResult.Stepped
-        | Add_ovf -> failwith "TODO: Add_ovf unimplemented"
+        | Add_ovf ->
+            let val2, state = IlMachineState.popEvalStack currentThread state
+            let val1, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                try
+                    BinaryArithmetic.execute ArithmeticOperation.addOvf state val1 val2 |> Ok
+                with :? OverflowException as e ->
+                    Error e
+
+            let state =
+                match result with
+                | Ok result -> state |> IlMachineState.pushToEvalStack' result currentThread
+                | Error excToThrow -> failwith "TODO: throw OverflowException"
+
+            state
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Tuple.withRight WhatWeDid.Executed
+            |> ExecutionResult.Stepped
         | Add_ovf_un -> failwith "TODO: Add_ovf_un unimplemented"
         | Mul ->
-            let val1, state = IlMachineState.popEvalStack currentThread state
             let val2, state = IlMachineState.popEvalStack currentThread state
-            let result = BinaryArithmetic.execute ArithmeticOperation.mul val1 val2
+            let val1, state = IlMachineState.popEvalStack currentThread state
+            let result = BinaryArithmetic.execute ArithmeticOperation.mul state val1 val2
 
             state
             |> IlMachineState.pushToEvalStack' result currentThread
             |> IlMachineState.advanceProgramCounter currentThread
             |> Tuple.withRight WhatWeDid.Executed
             |> ExecutionResult.Stepped
-        | Mul_ovf -> failwith "TODO: Mul_ovf unimplemented"
+        | Mul_ovf ->
+            let val2, state = IlMachineState.popEvalStack currentThread state
+            let val1, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                try
+                    BinaryArithmetic.execute ArithmeticOperation.mulOvf state val1 val2 |> Ok
+                with :? OverflowException as e ->
+                    Error e
+
+            let state =
+                match result with
+                | Ok result -> state |> IlMachineState.pushToEvalStack' result currentThread
+                | Error excToThrow -> failwith "TODO: throw OverflowException"
+
+            state
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Tuple.withRight WhatWeDid.Executed
+            |> ExecutionResult.Stepped
         | Mul_ovf_un -> failwith "TODO: Mul_ovf_un unimplemented"
-        | Div -> failwith "TODO: Div unimplemented"
+        | Div ->
+            let val2, state = IlMachineState.popEvalStack currentThread state
+            let val1, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                try
+                    BinaryArithmetic.execute ArithmeticOperation.div state val1 val2 |> Ok
+                with :? OverflowException as e ->
+                    Error e
+
+            let state =
+                match result with
+                | Ok result -> state |> IlMachineState.pushToEvalStack' result currentThread
+                | Error excToThrow -> failwith "TODO: throw OverflowException"
+
+            state
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Tuple.withRight WhatWeDid.Executed
+            |> ExecutionResult.Stepped
         | Div_un -> failwith "TODO: Div_un unimplemented"
         | Shr ->
             let shift, state = IlMachineState.popEvalStack currentThread state
@@ -502,7 +525,33 @@ module NullaryIlOp =
                 |> IlMachineState.advanceProgramCounter currentThread
 
             (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
-        | Shr_un -> failwith "TODO: Shr_un unimplemented"
+        | Shr_un ->
+            let shift, state = IlMachineState.popEvalStack currentThread state
+            let number, state = IlMachineState.popEvalStack currentThread state
+
+            let shift =
+                match shift with
+                | EvalStackValue.Int32 i -> i
+                | EvalStackValue.NativeInt (NativeIntSource.Verbatim i) -> int<int64> i
+                | _ -> failwith $"Not allowed shift of {shift}"
+
+            let result =
+                // See table III.6
+                match number with
+                | EvalStackValue.Int32 i -> uint32<int> i >>> shift |> int32<uint32> |> EvalStackValue.Int32
+                | EvalStackValue.Int64 i -> uint64<int64> i >>> shift |> int64<uint64> |> EvalStackValue.Int64
+                | EvalStackValue.NativeInt (NativeIntSource.Verbatim i) ->
+                    (uint64<int64> i >>> shift |> int64<uint64>)
+                    |> NativeIntSource.Verbatim
+                    |> EvalStackValue.NativeInt
+                | _ -> failwith $"Not allowed to shift {number}"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack' result currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
         | Shl ->
             let shift, state = IlMachineState.popEvalStack currentThread state
             let number, state = IlMachineState.popEvalStack currentThread state
@@ -590,7 +639,37 @@ module NullaryIlOp =
                 |> IlMachineState.advanceProgramCounter currentThread
 
             (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
-        | Xor -> failwith "TODO: Xor unimplemented"
+        | Xor ->
+            let v2, state = IlMachineState.popEvalStack currentThread state
+            let v1, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                match v1, v2 with
+                | EvalStackValue.Int32 v1, EvalStackValue.Int32 v2 -> v1 ^^^ v2 |> EvalStackValue.Int32
+                | EvalStackValue.Int32 v1, EvalStackValue.NativeInt (NativeIntSource.Verbatim v2) ->
+                    int64<int32> v1 ^^^ v2 |> NativeIntSource.Verbatim |> EvalStackValue.NativeInt
+                | EvalStackValue.Int32 _, EvalStackValue.NativeInt _ ->
+                    failwith $"can't do binary operation on non-verbatim native int {v2}"
+                | EvalStackValue.Int64 v1, EvalStackValue.Int64 v2 -> v1 ^^^ v2 |> EvalStackValue.Int64
+                | EvalStackValue.NativeInt (NativeIntSource.Verbatim v1), EvalStackValue.Int32 v2 ->
+                    v1 ^^^ int64<int32> v2 |> NativeIntSource.Verbatim |> EvalStackValue.NativeInt
+                | EvalStackValue.NativeInt _, EvalStackValue.Int32 _ ->
+                    failwith $"can't do binary operation on non-verbatim native int {v1}"
+                | EvalStackValue.NativeInt (NativeIntSource.Verbatim v1),
+                  EvalStackValue.NativeInt (NativeIntSource.Verbatim v2) ->
+                    v1 ^^^ v2 |> NativeIntSource.Verbatim |> EvalStackValue.NativeInt
+                | EvalStackValue.NativeInt (NativeIntSource.Verbatim _), EvalStackValue.NativeInt _ ->
+                    failwith $"can't do binary operation on non-verbatim native int {v2}"
+                | EvalStackValue.NativeInt _, EvalStackValue.NativeInt (NativeIntSource.Verbatim _) ->
+                    failwith $"can't do binary operation on non-verbatim native int {v1}"
+                | _, _ -> failwith $"refusing to do binary operation on {v1} and {v2}"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack' result currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
         | Conv_I ->
             let popped, state = IlMachineState.popEvalStack currentThread state
             let converted = EvalStackValue.toNativeInt popped
@@ -661,7 +740,20 @@ module NullaryIlOp =
             let state = state |> IlMachineState.advanceProgramCounter currentThread
 
             (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
-        | Conv_U1 -> failwith "TODO: Conv_U1 unimplemented"
+        | Conv_U1 ->
+            let popped, state = IlMachineState.popEvalStack currentThread state
+            let converted = EvalStackValue.convToUInt8 popped
+
+            let state =
+                match converted with
+                | None -> failwith "TODO: Conv_U8 conversion failure unimplemented"
+                | Some conv ->
+                    state
+                    |> IlMachineState.pushToEvalStack' (EvalStackValue.Int32 conv) currentThread
+
+            let state = state |> IlMachineState.advanceProgramCounter currentThread
+
+            (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
         | Conv_U2 -> failwith "TODO: Conv_U2 unimplemented"
         | Conv_U4 -> failwith "TODO: Conv_U4 unimplemented"
         | Conv_U8 ->
@@ -684,6 +776,7 @@ module NullaryIlOp =
             let popped =
                 match popped with
                 | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> failwith "TODO: throw NRE"
+                | EvalStackValue.ObjectRef addr
                 | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) -> addr
                 | _ -> failwith $"can't get len of {popped}"
 
@@ -868,7 +961,16 @@ module NullaryIlOp =
         | Ldind_u8 -> failwith "TODO: Ldind_u8 unimplemented"
         | Ldind_r4 -> executeLdind LdindTargetType.LdindR4 currentThread state
         | Ldind_r8 -> executeLdind LdindTargetType.LdindR8 currentThread state
-        | Rem -> failwith "TODO: Rem unimplemented"
+        | Rem ->
+            let val2, state = IlMachineState.popEvalStack currentThread state
+            let val1, state = IlMachineState.popEvalStack currentThread state
+            let result = BinaryArithmetic.execute ArithmeticOperation.rem state val1 val2
+
+            state
+            |> IlMachineState.pushToEvalStack' result currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Tuple.withRight WhatWeDid.Executed
+            |> ExecutionResult.Stepped
         | Rem_un -> failwith "TODO: Rem_un unimplemented"
         | Volatile -> failwith "TODO: Volatile unimplemented"
         | Tail -> failwith "TODO: Tail unimplemented"
@@ -885,26 +987,33 @@ module NullaryIlOp =
         | Conv_ovf_i -> failwith "TODO: Conv_ovf_i unimplemented"
         | Conv_ovf_u -> failwith "TODO: Conv_ovf_u unimplemented"
         | Neg -> failwith "TODO: Neg unimplemented"
-        | Not -> failwith "TODO: Not unimplemented"
+        | Not ->
+            let val1, state = IlMachineState.popEvalStack currentThread state
+
+            let result =
+                match val1 with
+                | EvalStackValue.Int32 i -> ~~~i |> EvalStackValue.Int32
+                | EvalStackValue.Int64 i -> ~~~i |> EvalStackValue.Int64
+                | EvalStackValue.ManagedPointer _
+                | EvalStackValue.ObjectRef _ -> failwith "refusing to negate a pointer"
+                | _ -> failwith "TODO"
+
+            state
+            |> IlMachineState.pushToEvalStack' result currentThread
+            |> IlMachineState.advanceProgramCounter currentThread
+            |> Tuple.withRight WhatWeDid.Executed
+            |> ExecutionResult.Stepped
         | Ldind_ref ->
             let addr, state = IlMachineState.popEvalStack currentThread state
 
             let referenced =
                 match addr with
-                | EvalStackValue.ManagedPointer src ->
-                    match src with
-                    | ManagedPointerSource.Null -> failwith "TODO: throw NRE"
-                    | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-                        state.ThreadState.[sourceThread].MethodStates.[methodFrame].LocalVariables
-                            .[int<uint16> whichVar]
-                    | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
-                        state.ThreadState.[sourceThread].MethodStates.[methodFrame].Arguments.[int<uint16> whichVar]
-                    | ManagedPointerSource.Heap managedHeapAddress -> failwith "todo"
-                    | ManagedPointerSource.ArrayIndex _ -> failwith "todo"
+                | EvalStackValue.ManagedPointer src -> IlMachineState.dereferencePointer state src
                 | a -> failwith $"TODO: {a}"
 
             let state =
                 match referenced with
+                | CliType.RuntimePointer (CliRuntimePointer.Managed _)
                 | CliType.ObjectRef _ -> IlMachineState.pushToEvalStack referenced currentThread state
                 | _ -> failwith $"Unexpected non-reference {referenced}"
                 |> IlMachineState.advanceProgramCounter currentThread
@@ -928,19 +1037,92 @@ module NullaryIlOp =
                             arr
                             (EvalStackValue.toCliTypeCoerced (CliType.ObjectRef None) value)
                             index
+                    | ManagedPointerSource.Field _ -> failwith "TODO"
+                    | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "TODO"
                 | addr -> failwith $"TODO: {addr}"
 
             let state = state |> IlMachineState.advanceProgramCounter currentThread
 
             (state, WhatWeDid.Executed) |> ExecutionResult.Stepped
-        | Ldelem_i -> failwith "TODO: Ldelem_i unimplemented"
-        | Ldelem_i1 -> failwith "TODO: Ldelem_i1 unimplemented"
+        | Ldelem_i ->
+            let index, state = IlMachineState.popEvalStack currentThread state
+            let arr, state = IlMachineState.popEvalStack currentThread state
+
+            let value = getArrayElt index arr currentThread state
+
+            match value with
+            | CliType.Numeric (CliNumericType.NativeInt _) -> ()
+            | _ -> failwith "expected native int in Ldelem.i"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack value currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            ExecutionResult.Stepped (state, WhatWeDid.Executed)
+        | Ldelem_i1 ->
+            let index, state = IlMachineState.popEvalStack currentThread state
+            let arr, state = IlMachineState.popEvalStack currentThread state
+
+            let value = getArrayElt index arr currentThread state
+
+            failwith "TODO: we got back an int8; turn it into int32"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack value currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            ExecutionResult.Stepped (state, WhatWeDid.Executed)
         | Ldelem_u1 -> failwith "TODO: Ldelem_u1 unimplemented"
-        | Ldelem_i2 -> failwith "TODO: Ldelem_i2 unimplemented"
+        | Ldelem_i2 ->
+            let index, state = IlMachineState.popEvalStack currentThread state
+            let arr, state = IlMachineState.popEvalStack currentThread state
+
+            let value = getArrayElt index arr currentThread state
+
+            failwith "TODO: we got back an int16; turn it into int32"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack value currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            ExecutionResult.Stepped (state, WhatWeDid.Executed)
         | Ldelem_u2 -> failwith "TODO: Ldelem_u2 unimplemented"
-        | Ldelem_i4 -> failwith "TODO: Ldelem_i4 unimplemented"
+        | Ldelem_i4 ->
+            let index, state = IlMachineState.popEvalStack currentThread state
+            let arr, state = IlMachineState.popEvalStack currentThread state
+
+            let value = getArrayElt index arr currentThread state
+
+            match value with
+            | CliType.Numeric (CliNumericType.Int32 _) -> ()
+            | _ -> failwith "expected int32 in Ldelem.i4"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack value currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            ExecutionResult.Stepped (state, WhatWeDid.Executed)
         | Ldelem_u4 -> failwith "TODO: Ldelem_u4 unimplemented"
-        | Ldelem_i8 -> failwith "TODO: Ldelem_i8 unimplemented"
+        | Ldelem_i8 ->
+            let index, state = IlMachineState.popEvalStack currentThread state
+            let arr, state = IlMachineState.popEvalStack currentThread state
+
+            let value = getArrayElt index arr currentThread state
+
+            match value with
+            | CliType.Numeric (CliNumericType.Int64 _) -> ()
+            | _ -> failwith "expected int64 in Ldelem.i8"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack value currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            ExecutionResult.Stepped (state, WhatWeDid.Executed)
         | Ldelem_u8 -> failwith "TODO: Ldelem_u8 unimplemented"
         | Ldelem_r4 -> failwith "TODO: Ldelem_r4 unimplemented"
         | Ldelem_r8 -> failwith "TODO: Ldelem_r8 unimplemented"
@@ -948,7 +1130,19 @@ module NullaryIlOp =
             let index, state = IlMachineState.popEvalStack currentThread state
             let arr, state = IlMachineState.popEvalStack currentThread state
 
-            ldElem (CliType.ObjectRef None) index arr currentThread state
+            let value = getArrayElt index arr currentThread state
+
+            match value with
+            | CliType.ObjectRef _
+            | CliType.RuntimePointer _ -> ()
+            | _ -> failwith "expected object reference in Ldelem.ref"
+
+            let state =
+                state
+                |> IlMachineState.pushToEvalStack value currentThread
+                |> IlMachineState.advanceProgramCounter currentThread
+
+            ExecutionResult.Stepped (state, WhatWeDid.Executed)
         | Stelem_i ->
             let value, state = IlMachineState.popEvalStack currentThread state
             let index, state = IlMachineState.popEvalStack currentThread state

WoofWare.PawPrint/Program.fs

@@ -10,18 +10,16 @@ open Microsoft.Extensions.Logging
 module Program =
     /// Returns the pointer to the resulting array on the heap.
     let allocateArgs
+        (loggerFactory : ILoggerFactory)
         (args : string list)
         (corelib : BaseClassTypes<DumpedAssembly>)
         (state : IlMachineState)
         : ManagedHeapAddress * IlMachineState
         =
         let state, stringType =
-            TypeDefn.FromDefinition (
-                ComparableTypeDefinitionHandle.Make corelib.String.TypeDefHandle,
-                corelib.Corelib.Name.FullName,
-                SignatureTypeKind.Class
-            )
+            DumpedAssembly.typeInfoToTypeDefn' corelib state._LoadedAssemblies corelib.String
             |> IlMachineState.concretizeType
+                loggerFactory
                 corelib
                 state
                 corelib.Corelib.Name
@@ -126,7 +124,7 @@ module Program =
                 let rec go state =
                     // Resolve the type reference to find which assembly it's in
                     match
-                        Assembly.resolveTypeRef state._LoadedAssemblies currentAssembly typeRef ImmutableArray.Empty
+                        Assembly.resolveTypeRef state._LoadedAssemblies currentAssembly ImmutableArray.Empty typeRef
                     with
                     | TypeResolutionResult.FirstLoadAssy assyRef ->
                         // Need to load this assembly first
@@ -289,7 +287,7 @@ module Program =
         let arrayAllocation, state =
             match mainMethodFromMetadata.Signature.ParameterTypes |> Seq.toList with
             | [ TypeDefn.OneDimensionalArrayLowerBoundZero (TypeDefn.PrimitiveType PrimitiveType.String) ] ->
-                allocateArgs argv baseClassTypes state
+                allocateArgs loggerFactory argv baseClassTypes state
             | _ -> failwith "Main method must take an array of strings; other signatures not yet implemented"
 
         match mainMethodFromMetadata.Signature.ReturnType with
@@ -304,6 +302,11 @@ module Program =
 
         logger.LogInformation "Main method class now initialised"
 
+        let state =
+            { state with
+                ConcreteTypes = Corelib.concretizeAll state._LoadedAssemblies baseClassTypes state.ConcreteTypes
+            }
+
         // Now that BCL initialisation has taken place and the user-code classes are constructed,
         // overwrite the main thread completely using the already-concretized method.
         let methodState =

WoofWare.PawPrint/TypeHandleRegistry.fs

@@ -1,5 +1,7 @@
 namespace WoofWare.PawPrint
 
+open System.Collections.Immutable
+
 type TypeHandleRegistry =
     private
         {
@@ -17,8 +19,10 @@ module TypeHandleRegistry =
 
     /// Returns an allocated System.RuntimeType as well.
     let getOrAllocate
+        (allConcreteTypes : AllConcreteTypes)
+        (corelib : BaseClassTypes<DumpedAssembly>)
         (allocState : 'allocState)
-        (allocate : (string * CliType) list -> 'allocState -> ManagedHeapAddress * 'allocState)
+        (allocate : CliValueType -> 'allocState -> ManagedHeapAddress * 'allocState)
         (def : ConcreteTypeHandle)
         (reg : TypeHandleRegistry)
         : ManagedHeapAddress * TypeHandleRegistry * 'allocState
@@ -29,17 +33,64 @@ module TypeHandleRegistry =
 
         // Here follows the class System.RuntimeType, which is an internal class type with a constructor
         // whose only purpose is to throw.
+        // https://github.com/dotnet/runtime/blob/2b21c73fa2c32fa0195e4a411a435dda185efd08/src/libraries/System.Private.CoreLib/src/System/RuntimeType.cs#L14
+        // and https://github.com/dotnet/runtime/blob/f0168ee80ba9aca18a7e7140b2bb436defda623c/src/coreclr/System.Private.CoreLib/src/System/RuntimeType.CoreCLR.cs#L44
         let fields =
             [
                 // for the GC, I think?
-                "m_keepalive", CliType.ObjectRef None
-                // TODO: this is actually a System.IntPtr https://github.com/dotnet/runtime/blob/ec11903827fc28847d775ba17e0cd1ff56cfbc2e/src/coreclr/nativeaot/Runtime.Base/src/System/Primitives.cs#L339
-                "m_cache", CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.Verbatim 0L))
-                "m_handle", CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.TypeHandlePtr def))
+                {
+                    Name = "m_keepalive"
+                    Contents = CliType.ObjectRef None
+                    Offset = None
+                    Type =
+                        AllConcreteTypes.findExistingConcreteType
+                            allConcreteTypes
+                            (corelib.Object.Assembly,
+                             corelib.Object.Namespace,
+                             corelib.Object.Name,
+                             ImmutableArray.Empty)
+                        |> Option.get
+                }
+                {
+                    Name = "m_cache"
+                    Contents = CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.Verbatim 0L))
+                    Offset = None
+                    Type =
+                        AllConcreteTypes.findExistingConcreteType
+                            allConcreteTypes
+                            (corelib.IntPtr.Assembly,
+                             corelib.IntPtr.Namespace,
+                             corelib.IntPtr.Name,
+                             ImmutableArray.Empty)
+                        |> Option.get
+                }
+                {
+                    Name = "m_handle"
+                    Contents = CliType.Numeric (CliNumericType.NativeInt (NativeIntSource.TypeHandlePtr def))
+                    Offset = None
+                    Type =
+                        AllConcreteTypes.findExistingConcreteType
+                            allConcreteTypes
+                            (corelib.IntPtr.Assembly,
+                             corelib.IntPtr.Namespace,
+                             corelib.IntPtr.Name,
+                             ImmutableArray.Empty)
+                        |> Option.get
+                }
                 // This is the const -1, apparently?!
                 // https://github.com/dotnet/runtime/blob/f0168ee80ba9aca18a7e7140b2bb436defda623c/src/coreclr/System.Private.CoreLib/src/System/RuntimeType.CoreCLR.cs#L2496
-                "GenericParameterCountAny", CliType.Numeric (CliNumericType.Int32 -1)
+                {
+                    Name = "GenericParameterCountAny"
+                    Contents = CliType.Numeric (CliNumericType.Int32 -1)
+                    Offset = None
+                    Type =
+                        AllConcreteTypes.findExistingConcreteType
+                            allConcreteTypes
+                            (corelib.Int32.Assembly, corelib.Int32.Namespace, corelib.Int32.Name, ImmutableArray.Empty)
+                        |> Option.get
+                }
             ]
+            |> CliValueType.OfFields Layout.Default
 
         let alloc, state = allocate fields allocState
 

WoofWare.PawPrint/UnaryConstIlOp.fs

@@ -107,8 +107,8 @@ module internal UnaryConstIlOp =
                 | EvalStackValue.NativeInt i -> not (NativeIntSource.isZero i)
                 | EvalStackValue.Float f -> failwith "TODO: Brfalse_s float semantics undocumented"
                 | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> false
+                | EvalStackValue.ObjectRef _
                 | EvalStackValue.ManagedPointer _ -> true
-                | EvalStackValue.ObjectRef _ -> failwith "TODO: Brfalse_s ObjectRef comparison unimplemented"
                 | EvalStackValue.UserDefinedValueType _ ->
                     failwith "TODO: Brfalse_s UserDefinedValueType comparison unimplemented"
 
@@ -129,8 +129,8 @@ module internal UnaryConstIlOp =
                 | EvalStackValue.NativeInt i -> not (NativeIntSource.isZero i)
                 | EvalStackValue.Float f -> failwith "TODO: Brtrue_s float semantics undocumented"
                 | EvalStackValue.ManagedPointer ManagedPointerSource.Null -> false
+                | EvalStackValue.ObjectRef _
                 | EvalStackValue.ManagedPointer _ -> true
-                | EvalStackValue.ObjectRef _ -> failwith "TODO: Brtrue_s ObjectRef comparison unimplemented"
                 | EvalStackValue.UserDefinedValueType _ ->
                     failwith "TODO: Brtrue_s UserDefinedValueType comparison unimplemented"
 
@@ -422,6 +422,7 @@ module internal UnaryConstIlOp =
                 | EvalStackValue.Float v1, _ -> failwith $"invalid comparison, {v1} with {value2}"
                 | EvalStackValue.NativeInt v1, EvalStackValue.NativeInt v2 -> v1 <> v2
                 | EvalStackValue.ManagedPointer ptr1, EvalStackValue.ManagedPointer ptr2 -> ptr1 <> ptr2
+                | EvalStackValue.ObjectRef ptr1, EvalStackValue.ObjectRef ptr2 -> ptr1 <> ptr2
                 | _, _ -> failwith $"TODO {value1} {value2} (see table III.4)"
 
             state

WoofWare.PawPrint/UnaryMetadataIlOp.fs

@@ -28,6 +28,24 @@ module internal UnaryMetadataIlOp =
                 | MetadataToken.MethodSpecification h ->
                     let spec = activeAssy.MethodSpecs.[h]
 
+                    let state, methodGenerics =
+                        ((state, []), spec.Signature)
+                        ||> Seq.fold (fun (state, acc) typeDefn ->
+                            let state, concreteType =
+                                IlMachineState.concretizeType
+                                    loggerFactory
+                                    baseClassTypes
+                                    state
+                                    (state.ActiveAssembly thread).Name
+                                    currentMethod.DeclaringType.Generics
+                                    currentMethod.Generics
+                                    typeDefn
+
+                            state, concreteType :: acc
+                        )
+
+                    let methodGenerics = List.rev methodGenerics |> ImmutableArray.CreateRange
+
                     match spec.Method with
                     | MetadataToken.MethodDef token ->
                         let method =
@@ -44,6 +62,7 @@ module internal UnaryMetadataIlOp =
                                 baseClassTypes
                                 thread
                                 (state.ActiveAssembly thread)
+                                methodGenerics
                                 ref
                                 state
 
@@ -58,6 +77,7 @@ module internal UnaryMetadataIlOp =
                             baseClassTypes
                             thread
                             (state.ActiveAssembly thread)
+                            currentMethod.DeclaringType.Generics
                             h
                             state
 
@@ -114,6 +134,24 @@ module internal UnaryMetadataIlOp =
                 | MetadataToken.MethodSpecification h ->
                     let spec = activeAssy.MethodSpecs.[h]
 
+                    let state, methodGenerics =
+                        ((state, []), spec.Signature)
+                        ||> Seq.fold (fun (state, acc) typeDefn ->
+                            let state, concreteType =
+                                IlMachineState.concretizeType
+                                    loggerFactory
+                                    baseClassTypes
+                                    state
+                                    (state.ActiveAssembly thread).Name
+                                    currentMethod.DeclaringType.Generics
+                                    ImmutableArray.Empty
+                                    typeDefn
+
+                            state, concreteType :: acc
+                        )
+
+                    let methodGenerics = List.rev methodGenerics |> ImmutableArray.CreateRange
+
                     match spec.Method with
                     | MetadataToken.MethodDef token ->
                         let method =
@@ -128,6 +166,7 @@ module internal UnaryMetadataIlOp =
                                 baseClassTypes
                                 thread
                                 (state.ActiveAssembly thread)
+                                methodGenerics
                                 ref
                                 state
 
@@ -142,6 +181,7 @@ module internal UnaryMetadataIlOp =
                             baseClassTypes
                             thread
                             (state.ActiveAssembly thread)
+                            ImmutableArray.Empty
                             h
                             state
 
@@ -203,6 +243,7 @@ module internal UnaryMetadataIlOp =
                             baseClassTypes
                             thread
                             (state.ActiveAssembly thread)
+                            ImmutableArray.Empty
                             mr
                             state
 
@@ -255,7 +296,7 @@ module internal UnaryMetadataIlOp =
                 ((state, []), instanceFields)
                 ||> List.fold (fun (state, zeros) field ->
                     // TODO: generics
-                    let state, zero =
+                    let state, zero, concreteType =
                         IlMachineState.cliTypeZeroOf
                             loggerFactory
                             baseClassTypes
@@ -265,10 +306,18 @@ module internal UnaryMetadataIlOp =
                             ImmutableArray.Empty
                             state
 
-                    state, (field.Name, zero) :: zeros
+                    let field =
+                        {
+                            Name = field.Name
+                            Contents = zero
+                            Offset = field.Offset
+                            Type = concreteType
+                        }
+
+                    state, field :: zeros
                 )
 
-            let fields = List.rev fieldZeros
+            let fields = List.rev fieldZeros |> CliValueType.OfFields ctorType.Layout
 
             // Note: this is a bit unorthodox for value types, which *aren't* heap-allocated.
             // We'll perform their construction on the heap, though, to keep the interface
@@ -347,7 +396,7 @@ module internal UnaryMetadataIlOp =
                         ref
                 | x -> failwith $"TODO: Newarr element type resolution unimplemented for {x}"
 
-            let state, zeroOfType =
+            let state, zeroOfType, concreteTypeHandle =
                 IlMachineState.cliTypeZeroOf
                     loggerFactory
                     baseClassTypes
@@ -367,7 +416,55 @@ module internal UnaryMetadataIlOp =
                 |> IlMachineState.advanceProgramCounter thread
 
             state, WhatWeDid.Executed
-        | Box -> failwith "TODO: Box unimplemented"
+        | Box ->
+            let state, ty, assy =
+                match metadataToken with
+                | MetadataToken.TypeDefinition h ->
+                    let state, ty = IlMachineState.lookupTypeDefn baseClassTypes state activeAssy h
+                    state, ty, activeAssy
+                | MetadataToken.TypeReference ref ->
+                    IlMachineState.lookupTypeRef
+                        loggerFactory
+                        baseClassTypes
+                        state
+                        activeAssy
+                        currentMethod.DeclaringType.Generics
+                        ref
+                | MetadataToken.TypeSpecification spec -> state, activeAssy.TypeSpecs.[spec].Signature, activeAssy
+                | _ -> failwith $"unexpected token {metadataToken} in Box"
+
+            let state, typeHandle =
+                IlMachineState.concretizeType
+                    loggerFactory
+                    baseClassTypes
+                    state
+                    assy.Name
+                    currentMethod.DeclaringType.Generics
+                    currentMethod.Generics
+                    ty
+
+            let toBox, state = state |> IlMachineState.popEvalStack thread
+
+            let targetType =
+                AllConcreteTypes.lookup typeHandle state.ConcreteTypes |> Option.get
+
+            let defn =
+                state._LoadedAssemblies.[targetType.Assembly.FullName].TypeDefs.[targetType.Definition.Get]
+
+            let baseType =
+                DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies targetType.Assembly defn.BaseType
+
+            let toPush =
+                match baseType with
+                | ResolvedBaseType.Enum
+                | ResolvedBaseType.ValueType -> failwith "TODO: implement Box"
+                | ResolvedBaseType.Object
+                | ResolvedBaseType.Delegate -> toBox
+
+            state
+            |> IlMachineState.pushToEvalStack' toPush thread
+            |> IlMachineState.advanceProgramCounter thread
+            |> Tuple.withRight WhatWeDid.Executed
         | Ldelema ->
             let index, state = IlMachineState.popEvalStack thread state
             let arr, state = IlMachineState.popEvalStack thread state
@@ -409,22 +506,10 @@ module internal UnaryMetadataIlOp =
                     let activeAssy = state.ActiveAssembly thread
                     let ty = activeAssy.TypeDefs.[td]
 
-                    let baseTy =
-                        DumpedAssembly.resolveBaseType
-                            baseClassTypes
-                            state._LoadedAssemblies
-                            activeAssy.Name
-                            ty.BaseType
+                    let result =
+                        DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies ty
 
-                    let sigType =
-                        match baseTy with
-                        | ResolvedBaseType.Enum
-                        | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-                        | ResolvedBaseType.Object -> SignatureTypeKind.Class
-                        | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-                    state,
-                    TypeDefn.FromDefinition (ComparableTypeDefinitionHandle.Make td, activeAssy.Name.FullName, sigType)
+                    state, result
                 | MetadataToken.TypeSpecification handle ->
                     state, state.ActiveAssembly(thread).TypeSpecs.[handle].Signature
                 | MetadataToken.TypeReference handle ->
@@ -436,26 +521,12 @@ module internal UnaryMetadataIlOp =
                             ImmutableArray.Empty
                             state
 
-                    let baseTy =
-                        DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies assy.Name resol.BaseType
-
-                    let sigType =
-                        match baseTy with
-                        | ResolvedBaseType.Enum
-                        | ResolvedBaseType.ValueType -> SignatureTypeKind.ValueType
-                        | ResolvedBaseType.Object -> SignatureTypeKind.Class
-                        | ResolvedBaseType.Delegate -> SignatureTypeKind.Class
-
-                    state,
-                    TypeDefn.FromDefinition (
-                        ComparableTypeDefinitionHandle.Make resol.TypeDefHandle,
-                        assy.Name.FullName,
-                        sigType
-                    )
+                    state, DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies resol
                 | m -> failwith $"unexpected metadata token {m} in IsInst"
 
             let state, targetConcreteType =
                 IlMachineState.concretizeType
+                    loggerFactory
                     baseClassTypes
                     state
                     activeAssy.Name
@@ -469,13 +540,15 @@ module internal UnaryMetadataIlOp =
                     // null IsInstance check always succeeds and results in a null reference
                     EvalStackValue.ManagedPointer ManagedPointerSource.Null
                 | EvalStackValue.ManagedPointer (ManagedPointerSource.LocalVariable _) -> failwith "TODO"
+                | EvalStackValue.ObjectRef addr
                 | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) ->
                     match state.ManagedHeap.NonArrayObjects.TryGetValue addr with
                     | true, v ->
                         if v.ConcreteType = targetConcreteType then
                             actualObj
                         else
-                            failwith $"TODO: is {v.ConcreteType} an instance of {targetType} ({targetConcreteType})"
+                            failwith
+                                $"TODO: is {AllConcreteTypes.lookup v.ConcreteType state.ConcreteTypes |> Option.get} an instance of {AllConcreteTypes.lookup targetConcreteType state.ConcreteTypes |> Option.get}"
                     | false, _ ->
 
                     match state.ManagedHeap.Arrays.TryGetValue addr with
@@ -500,7 +573,14 @@ module internal UnaryMetadataIlOp =
                     state, field
                 | MetadataToken.MemberReference mr ->
                     let state, _, field, _ =
-                        IlMachineState.resolveMember loggerFactory baseClassTypes thread activeAssy mr state
+                        IlMachineState.resolveMember
+                            loggerFactory
+                            baseClassTypes
+                            thread
+                            activeAssy
+                            ImmutableArray.Empty
+                            mr
+                            state
 
                     match field with
                     | Choice1Of2 _method -> failwith "member reference was unexpectedly a method"
@@ -511,17 +591,18 @@ module internal UnaryMetadataIlOp =
                 logger.LogInformation (
                     "Storing in object field {FieldAssembly}.{FieldDeclaringType}.{FieldName} (type {FieldType})",
                     field.DeclaringType.Assembly.Name,
-                    field.Name,
+                    field.DeclaringType.Name,
                     field.Name,
                     field.Signature
                 )
 
             let valueToStore, state = IlMachineState.popEvalStack thread state
+            let currentObj, state = IlMachineState.popEvalStack thread state
 
             let state, declaringTypeHandle, typeGenerics =
                 IlMachineState.concretizeFieldForExecution loggerFactory baseClassTypes thread field state
 
-            let state, zero =
+            let state, zero, concreteTypeHandle =
                 IlMachineState.cliTypeZeroOf
                     loggerFactory
                     baseClassTypes
@@ -533,8 +614,6 @@ module internal UnaryMetadataIlOp =
 
             let valueToStore = EvalStackValue.toCliTypeCoerced zero valueToStore
 
-            let currentObj, state = IlMachineState.popEvalStack thread state
-
             if field.Attributes.HasFlag FieldAttributes.Static then
                 let state =
                     IlMachineState.setStatic declaringTypeHandle field.Name valueToStore state
@@ -548,33 +627,41 @@ module internal UnaryMetadataIlOp =
                 | EvalStackValue.Int64 _ -> failwith "unexpectedly setting field on an int64"
                 | EvalStackValue.NativeInt _ -> failwith "unexpectedly setting field on a nativeint"
                 | EvalStackValue.Float _ -> failwith "unexpectedly setting field on a float"
-                | EvalStackValue.ManagedPointer source ->
-                    match source with
-                    | ManagedPointerSource.Null -> failwith "TODO: raise NullReferenceException"
-                    | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-                        state
-                        |> IlMachineState.setLocalVariable sourceThread methodFrame whichVar valueToStore
-                    | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) -> failwith "todo"
-                    | ManagedPointerSource.ArrayIndex (arr, index) ->
-                        state |> IlMachineState.setArrayValue arr valueToStore index
-                    | ManagedPointerSource.Heap addr ->
-                        match state.ManagedHeap.NonArrayObjects.TryGetValue addr with
-                        | false, _ -> failwith $"todo: array {addr}"
-                        | true, v ->
-                            let v =
-                                { v with
-                                    Fields = v.Fields |> Map.add field.Name valueToStore
-                                }
+                | EvalStackValue.ObjectRef addr
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr) ->
+                    match state.ManagedHeap.NonArrayObjects.TryGetValue addr with
+                    | false, _ -> failwith $"todo: array {addr}"
+                    | true, v ->
+                        let v = AllocatedNonArrayObject.SetField field.Name valueToStore v
 
-                            let heap =
-                                { state.ManagedHeap with
-                                    NonArrayObjects = state.ManagedHeap.NonArrayObjects |> Map.add addr v
-                                }
-
-                            { state with
-                                ManagedHeap = heap
+                        let heap =
+                            { state.ManagedHeap with
+                                NonArrayObjects = state.ManagedHeap.NonArrayObjects |> Map.add addr v
                             }
-                | EvalStackValue.ObjectRef managedHeapAddress -> failwith "todo"
+
+                        { state with
+                            ManagedHeap = heap
+                        }
+                | EvalStackValue.ManagedPointer ManagedPointerSource.Null ->
+                    failwith "TODO: raise NullReferenceException"
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar)) ->
+                    let newValue =
+                        IlMachineState.getLocalVariable sourceThread methodFrame whichVar state
+                        |> CliType.withFieldSet field.Name valueToStore
+
+                    state
+                    |> IlMachineState.setLocalVariable sourceThread methodFrame whichVar newValue
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar)) ->
+                    failwith "todo"
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.ArrayIndex (arr, index)) ->
+                    let newValue =
+                        IlMachineState.getArrayValue arr index state
+                        |> CliType.withFieldSet field.Name valueToStore
+
+                    state |> IlMachineState.setArrayValue arr newValue index
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Field (managedPointerSource, fieldName)) ->
+                    failwith "todo"
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.InterpretedAsType (src, ty)) -> failwith "todo"
                 | EvalStackValue.UserDefinedValueType _ -> failwith "todo"
 
             state
@@ -600,6 +687,7 @@ module internal UnaryMetadataIlOp =
                             baseClassTypes
                             thread
                             (state.ActiveAssembly thread)
+                            ImmutableArray.Empty
                             mr
                             state
 
@@ -630,7 +718,7 @@ module internal UnaryMetadataIlOp =
 
             let popped, state = IlMachineState.popEvalStack thread state
 
-            let state, zero =
+            let state, zero, concreteTypeHandle =
                 IlMachineState.cliTypeZeroOf
                     loggerFactory
                     baseClassTypes
@@ -659,7 +747,14 @@ module internal UnaryMetadataIlOp =
                     state, field
                 | MetadataToken.MemberReference mr ->
                     let state, assyName, field, _ =
-                        IlMachineState.resolveMember loggerFactory baseClassTypes thread activeAssy mr state
+                        IlMachineState.resolveMember
+                            loggerFactory
+                            baseClassTypes
+                            thread
+                            activeAssy
+                            ImmutableArray.Empty
+                            mr
+                            state
 
                     match field with
                     | Choice1Of2 _method -> failwith "member reference was unexpectedly a method"
@@ -690,7 +785,7 @@ module internal UnaryMetadataIlOp =
                     match IlMachineState.getStatic declaringTypeHandle field.Name state with
                     | Some v -> state, v
                     | None ->
-                        let state, zero =
+                        let state, zero, concreteTypeHandle =
                             IlMachineState.cliTypeZeroOf
                                 loggerFactory
                                 baseClassTypes
@@ -713,39 +808,96 @@ module internal UnaryMetadataIlOp =
                 | EvalStackValue.Int64 int64 -> failwith "todo: int64"
                 | EvalStackValue.NativeInt nativeIntSource -> failwith $"todo: nativeint {nativeIntSource}"
                 | EvalStackValue.Float f -> failwith "todo: float"
-                | EvalStackValue.ManagedPointer managedPointerSource ->
-                    match managedPointerSource with
-                    | ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar) ->
-                        let currentValue =
-                            state.ThreadState.[sourceThread].MethodStates.[methodFrame].LocalVariables
-                                .[int<uint16> whichVar]
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.LocalVariable (sourceThread, methodFrame, whichVar)) ->
+                    let currentValue =
+                        state.ThreadState.[sourceThread].MethodStates.[methodFrame].LocalVariables
+                            .[int<uint16> whichVar]
+                        |> CliType.getField field.Name
 
-                        IlMachineState.pushToEvalStack currentValue thread state
-                    | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) ->
-                        let currentValue =
-                            state.ThreadState.[sourceThread].MethodStates.[methodFrame].Arguments.[int<uint16> whichVar]
+                    IlMachineState.pushToEvalStack currentValue thread state
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar)) ->
+                    let currentValue =
+                        state.ThreadState.[sourceThread].MethodStates.[methodFrame].Arguments.[int<uint16> whichVar]
+                        |> CliType.getField field.Name
 
-                        IlMachineState.pushToEvalStack currentValue thread state
-                    | ManagedPointerSource.Heap managedHeapAddress ->
-                        match state.ManagedHeap.NonArrayObjects.TryGetValue managedHeapAddress with
-                        | false, _ -> failwith $"todo: array {managedHeapAddress}"
-                        | true, v -> IlMachineState.pushToEvalStack v.Fields.[field.Name] thread state
-                    | ManagedPointerSource.ArrayIndex (arr, index) ->
-                        let currentValue = state |> IlMachineState.getArrayValue arr index
-                        IlMachineState.pushToEvalStack currentValue thread state
-                    | ManagedPointerSource.Null -> failwith "TODO: raise NullReferenceException"
-                | EvalStackValue.ObjectRef managedHeapAddress -> failwith $"todo: {managedHeapAddress}"
-                | EvalStackValue.UserDefinedValueType fields ->
-                    let result =
-                        fields |> List.pick (fun (k, v) -> if k = field.Name then Some v else None)
+                    IlMachineState.pushToEvalStack currentValue thread state
+                | EvalStackValue.ObjectRef managedHeapAddress
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap managedHeapAddress) ->
+                    match state.ManagedHeap.NonArrayObjects.TryGetValue managedHeapAddress with
+                    | false, _ -> failwith $"todo: array {managedHeapAddress}"
+                    | true, v ->
+                        IlMachineState.pushToEvalStack
+                            (AllocatedNonArrayObject.DereferenceField field.Name v)
+                            thread
+                            state
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.ArrayIndex (arr, index)) ->
+                    let currentValue =
+                        state |> IlMachineState.getArrayValue arr index |> CliType.getField field.Name
 
-                    IlMachineState.pushToEvalStack' result thread state
+                    IlMachineState.pushToEvalStack currentValue thread state
+                | EvalStackValue.ManagedPointer ManagedPointerSource.Null ->
+                    failwith "TODO: raise NullReferenceException"
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Field (src, fieldName)) ->
+                    let currentValue =
+                        IlMachineState.getFieldValue src fieldName state |> CliType.getField field.Name
+
+                    IlMachineState.pushToEvalStack currentValue thread state
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.InterpretedAsType (src, ty)) -> failwith "TODO"
+                | EvalStackValue.UserDefinedValueType vt ->
+                    let result = vt |> CliValueType.DereferenceField field.Name
+
+                    IlMachineState.pushToEvalStack result thread state
 
             state
             |> IlMachineState.advanceProgramCounter thread
             |> Tuple.withRight WhatWeDid.Executed
 
-        | Ldflda -> failwith "TODO: Ldflda unimplemented"
+        | Ldflda ->
+            let ptr, state = IlMachineState.popEvalStack thread state
+
+            let ptr =
+                match ptr with
+                | Int32 _
+                | Int64 _
+                | Float _ -> failwith "expected pointer type"
+                | NativeInt nativeIntSource -> failwith "todo"
+                | ManagedPointer src -> src
+                | ObjectRef addr -> ManagedPointerSource.Heap addr
+                | UserDefinedValueType evalStackValueUserType -> failwith "todo"
+
+            let state, field =
+                match metadataToken with
+                | MetadataToken.FieldDefinition f ->
+                    let field =
+                        activeAssy.Fields.[f]
+                        |> FieldInfo.mapTypeGenerics (fun _ -> failwith "no generics allowed on FieldDefinition")
+
+                    state, field
+                | MetadataToken.MemberReference mr ->
+                    let state, assyName, field, _ =
+                        // TODO: generics
+                        IlMachineState.resolveMember
+                            loggerFactory
+                            baseClassTypes
+                            thread
+                            activeAssy
+                            ImmutableArray.Empty
+                            mr
+                            state
+
+                    match field with
+                    | Choice1Of2 _method -> failwith "member reference was unexpectedly a method"
+                    | Choice2Of2 field -> state, field
+                | t -> failwith $"Unexpectedly asked to load from a non-field: {t}"
+
+            let result =
+                ManagedPointerSource.Field (ptr, field.Name) |> EvalStackValue.ManagedPointer
+
+            state
+            |> IlMachineState.pushToEvalStack' result thread
+            |> IlMachineState.advanceProgramCounter thread
+            |> Tuple.withRight WhatWeDid.Executed
+
         | Ldsfld ->
             let state, field =
                 match metadataToken with
@@ -760,7 +912,14 @@ module internal UnaryMetadataIlOp =
                         state, field
                 | MetadataToken.MemberReference mr ->
                     let state, _, field, _ =
-                        IlMachineState.resolveMember loggerFactory baseClassTypes thread activeAssy mr state
+                        IlMachineState.resolveMember
+                            loggerFactory
+                            baseClassTypes
+                            thread
+                            activeAssy
+                            ImmutableArray.Empty
+                            mr
+                            state
 
                     match field with
                     | Choice1Of2 _method -> failwith "member reference was unexpectedly a method"
@@ -791,7 +950,7 @@ module internal UnaryMetadataIlOp =
             let fieldValue, state =
                 match IlMachineState.getStatic declaringTypeHandle field.Name state with
                 | None ->
-                    let state, newVal =
+                    let state, newVal, concreteTypeHandle =
                         IlMachineState.cliTypeZeroOf
                             loggerFactory
                             baseClassTypes
@@ -867,14 +1026,9 @@ module internal UnaryMetadataIlOp =
                 | _ -> failwith $"expected heap allocation for array, got {arr}"
 
             let elementType =
-                TypeInfo.toTypeDefn
-                    baseClassTypes
-                    _.Name
-                    (fun x y -> x.TypeDefs.[y])
-                    (fun x y -> x.TypeRefs.[y] |> failwithf "%+A")
-                    elementType
+                DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies elementType
 
-            let state, zeroOfType =
+            let state, zeroOfType, concreteTypeHandle =
                 IlMachineState.cliTypeZeroOf
                     loggerFactory
                     baseClassTypes
@@ -941,7 +1095,72 @@ module internal UnaryMetadataIlOp =
             IlMachineState.pushToEvalStack toPush thread state
             |> IlMachineState.advanceProgramCounter thread
             |> Tuple.withRight WhatWeDid.Executed
-        | Initobj -> failwith "TODO: Initobj unimplemented"
+
+        | Initobj ->
+            let popped, state = IlMachineState.popEvalStack thread state
+            let declaringTypeGenerics = currentMethod.DeclaringType.Generics
+
+            let state, assy, targetType =
+                match metadataToken with
+                | MetadataToken.TypeDefinition defn ->
+                    state,
+                    activeAssy,
+                    activeAssy.TypeDefs.[defn]
+                    |> TypeInfo.mapGeneric (fun (p, _) -> TypeDefn.GenericTypeParameter p.SequenceNumber)
+                | MetadataToken.TypeSpecification spec ->
+                    let state, assy, ty =
+                        IlMachineState.resolveTypeFromSpecConcrete
+                            loggerFactory
+                            baseClassTypes
+                            spec
+                            activeAssy
+                            declaringTypeGenerics
+                            currentMethod.Generics
+                            state
+
+                    state, assy, ty
+                | x -> failwith $"TODO: Ldelem element type resolution unimplemented for {x}"
+
+            let targetType =
+                targetType
+                |> DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies
+
+            let state, zeroOfType, concreteTypeHandle =
+                IlMachineState.cliTypeZeroOf
+                    loggerFactory
+                    baseClassTypes
+                    assy
+                    targetType
+                    declaringTypeGenerics
+                    ImmutableArray.Empty
+                    state
+
+            let state =
+                match popped with
+                | EvalStackValue.Int32 _
+                | EvalStackValue.Int64 _
+                | EvalStackValue.NativeInt _
+                | EvalStackValue.Float _ -> failwith "unexpectedly not an address"
+                | EvalStackValue.ManagedPointer (ManagedPointerSource.Heap addr)
+                | EvalStackValue.ObjectRef addr -> failwith "todo"
+                | EvalStackValue.ManagedPointer src ->
+                    match src with
+                    | ManagedPointerSource.LocalVariable (thread, frame, var) ->
+                        state |> IlMachineState.setLocalVariable thread frame var zeroOfType
+                    | ManagedPointerSource.Argument (sourceThread, methodFrame, whichVar) -> failwith "todo"
+                    | ManagedPointerSource.ArrayIndex (arr, index) ->
+                        state |> IlMachineState.setArrayValue arr zeroOfType index
+                    | ManagedPointerSource.Field (managedPointerSource, fieldName) ->
+                        state |> IlMachineState.setFieldValue managedPointerSource zeroOfType fieldName
+                    | ManagedPointerSource.Null -> failwith "runtime error: unexpectedly Initobj'ing null"
+                    | ManagedPointerSource.InterpretedAsType (src, ty) -> failwith "TODO"
+                    | ManagedPointerSource.Heap _ -> failwith "logic error"
+                | EvalStackValue.UserDefinedValueType evalStackValueUserType -> failwith "todo"
+
+            state
+            |> IlMachineState.advanceProgramCounter thread
+            |> Tuple.withRight WhatWeDid.Executed
+
         | Ldsflda ->
 
             // TODO: check whether we should throw FieldAccessException
@@ -963,30 +1182,31 @@ module internal UnaryMetadataIlOp =
             | FirstLoadThis state -> state, WhatWeDid.SuspendedForClassInit
             | NothingToDo state ->
 
-            if TypeDefn.isManaged field.Signature then
-                match IlMachineState.getStatic declaringTypeHandle field.Name state with
-                | Some v ->
-                    IlMachineState.pushToEvalStack v thread state
-                    |> IlMachineState.advanceProgramCounter thread
-                    |> Tuple.withRight WhatWeDid.Executed
-                | None ->
-                    // Field is not yet initialised
-                    let state, zero =
-                        IlMachineState.cliTypeZeroOf
-                            loggerFactory
-                            baseClassTypes
-                            activeAssy
-                            field.Signature
-                            typeGenerics
-                            ImmutableArray.Empty // field can't have its own generics
-                            state
+            // TODO: if field type is unmanaged, push an unmanaged pointer
+            // TODO: Note that field may be a static global with an assigned relative virtual address
+            // (the offset of the field from the base address at which its containing PE file is loaded into memory)
+            // where the memory is unmanaged.
+            match IlMachineState.getStatic declaringTypeHandle field.Name state with
+            | Some v ->
+                IlMachineState.pushToEvalStack v thread state
+                |> IlMachineState.advanceProgramCounter thread
+                |> Tuple.withRight WhatWeDid.Executed
+            | None ->
+                // Field is not yet initialised
+                let state, zero, concreteTypeHandle =
+                    IlMachineState.cliTypeZeroOf
+                        loggerFactory
+                        baseClassTypes
+                        activeAssy
+                        field.Signature
+                        typeGenerics
+                        ImmutableArray.Empty // field can't have its own generics
+                        state
 
-                    IlMachineState.setStatic declaringTypeHandle field.Name zero state
-                    |> IlMachineState.pushToEvalStack (CliType.ObjectRef None) thread
-                    |> IlMachineState.advanceProgramCounter thread
-                    |> Tuple.withRight WhatWeDid.Executed
-            else
-                failwith "TODO: Ldsflda - push unmanaged pointer"
+                IlMachineState.setStatic declaringTypeHandle field.Name zero state
+                |> IlMachineState.pushToEvalStack (CliType.ObjectRef None) thread
+                |> IlMachineState.advanceProgramCounter thread
+                |> Tuple.withRight WhatWeDid.Executed
 
         | Ldftn ->
             let method, methodGenerics =
@@ -1038,6 +1258,50 @@ module internal UnaryMetadataIlOp =
         | Stobj -> failwith "TODO: Stobj unimplemented"
         | Constrained -> failwith "TODO: Constrained unimplemented"
         | Ldtoken ->
+            // Helper function to handle type tokens and create RuntimeTypeHandle
+            let handleTypeToken (typeDefn : TypeDefn) (state : IlMachineState) : IlMachineState =
+                let ty = baseClassTypes.RuntimeTypeHandle
+                let field = ty.Fields |> List.exactlyOne
+
+                if field.Name <> "m_type" then
+                    failwith $"unexpected field name ${field.Name} for BCL type RuntimeTypeHandle"
+
+                let methodGenerics = currentMethod.Generics
+                let typeGenerics = currentMethod.DeclaringType.Generics
+
+                let state, handle =
+                    IlMachineState.concretizeType
+                        loggerFactory
+                        baseClassTypes
+                        state
+                        activeAssy.Name
+                        typeGenerics
+                        methodGenerics
+                        typeDefn
+
+                let alloc, state =
+                    IlMachineState.getOrAllocateType loggerFactory baseClassTypes handle state
+
+                let vt =
+                    // https://github.com/dotnet/runtime/blob/2b21c73fa2c32fa0195e4a411a435dda185efd08/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs#L92
+                    {
+                        Name = "m_type"
+                        Contents = CliType.ObjectRef (Some alloc)
+                        Offset = None
+                        Type =
+                            AllConcreteTypes.findExistingConcreteType
+                                state.ConcreteTypes
+                                (baseClassTypes.Object.Assembly,
+                                 baseClassTypes.Object.Namespace,
+                                 baseClassTypes.Object.Name,
+                                 ImmutableArray.Empty)
+                            |> Option.get
+                    }
+                    |> List.singleton
+                    |> CliValueType.OfFields Layout.Default
+
+                IlMachineState.pushToEvalStack (CliType.ValueType vt) thread state
+
             let state =
                 match metadataToken with
                 | MetadataToken.FieldDefinition h ->
@@ -1070,28 +1334,12 @@ module internal UnaryMetadataIlOp =
                             methodGenerics
                             state
 
-                    let stk =
-                        match
-                            DumpedAssembly.resolveBaseType
-                                baseClassTypes
-                                state._LoadedAssemblies
-                                assy.Name
-                                typeDefn.BaseType
-                        with
-                        | ResolvedBaseType.ValueType
-                        | ResolvedBaseType.Enum -> SignatureTypeKind.ValueType
-                        | ResolvedBaseType.Delegate
-                        | ResolvedBaseType.Object -> SignatureTypeKind.Class
-
                     let typeDefn =
-                        TypeDefn.FromDefinition (
-                            ComparableTypeDefinitionHandle.Make typeDefn.TypeDefHandle,
-                            assy.Name.FullName,
-                            stk
-                        )
+                        DumpedAssembly.typeInfoToTypeDefn baseClassTypes state._LoadedAssemblies typeDefn
 
                     let state, handle =
                         IlMachineState.concretizeType
+                            loggerFactory
                             baseClassTypes
                             state
                             assy.Name
@@ -1099,12 +1347,25 @@ module internal UnaryMetadataIlOp =
                             methodGenerics
                             typeDefn
 
-                    let alloc, state = IlMachineState.getOrAllocateType baseClassTypes handle state
+                    let alloc, state =
+                        IlMachineState.getOrAllocateType loggerFactory baseClassTypes handle state
 
                     let vt =
                         {
-                            Fields = [ "m_type", CliType.ObjectRef (Some alloc) ]
+                            Name = "m_type"
+                            Contents = CliType.ObjectRef (Some alloc)
+                            Offset = None
+                            Type =
+                                AllConcreteTypes.findExistingConcreteType
+                                    state.ConcreteTypes
+                                    (baseClassTypes.Object.Assembly,
+                                     baseClassTypes.Object.Namespace,
+                                     baseClassTypes.Object.Name,
+                                     ImmutableArray.Empty)
+                                |> Option.get
                         }
+                        |> List.singleton
+                        |> CliValueType.OfFields Layout.Default
 
                     IlMachineState.pushToEvalStack (CliType.ValueType vt) thread state
                 | MetadataToken.TypeReference h ->
@@ -1123,6 +1384,7 @@ module internal UnaryMetadataIlOp =
 
                     let state, handle =
                         IlMachineState.concretizeType
+                            loggerFactory
                             baseClassTypes
                             state
                             assy.Name
@@ -1130,52 +1392,102 @@ module internal UnaryMetadataIlOp =
                             methodGenerics
                             typeDefn
 
-                    let alloc, state = IlMachineState.getOrAllocateType baseClassTypes handle state
+                    let alloc, state =
+                        IlMachineState.getOrAllocateType loggerFactory baseClassTypes handle state
 
                     let vt =
                         {
-                            Fields = [ "m_type", CliType.ObjectRef (Some alloc) ]
+                            Name = "m_type"
+                            Contents = CliType.ObjectRef (Some alloc)
+                            Offset = None
+                            Type =
+                                AllConcreteTypes.findExistingConcreteType
+                                    state.ConcreteTypes
+                                    (baseClassTypes.Object.Assembly,
+                                     baseClassTypes.Object.Namespace,
+                                     baseClassTypes.Object.Name,
+                                     ImmutableArray.Empty)
+                                |> Option.get
                         }
+                        |> List.singleton
+                        |> CliValueType.OfFields Layout.Default
 
                     IlMachineState.pushToEvalStack (CliType.ValueType vt) thread state
                 | MetadataToken.TypeDefinition h ->
-                    let ty = baseClassTypes.RuntimeTypeHandle
-                    let field = ty.Fields |> List.exactlyOne
-
-                    if field.Name <> "m_type" then
-                        failwith $"unexpected field name ${field.Name} for BCL type RuntimeTypeHandle"
-
-                    let methodGenerics = currentMethod.Generics
-
-                    let typeGenerics = currentMethod.DeclaringType.Generics
-
                     let state, typeDefn =
                         IlMachineState.lookupTypeDefn baseClassTypes state activeAssy h
 
-                    let state, handle =
-                        IlMachineState.concretizeType
-                            baseClassTypes
-                            state
-                            activeAssy.Name
-                            typeGenerics
-                            methodGenerics
-                            typeDefn
-
-                    let alloc, state = IlMachineState.getOrAllocateType baseClassTypes handle state
-
-                    let vt =
-                        {
-                            Fields = [ "m_type", CliType.ObjectRef (Some alloc) ]
-                        }
-
-                    IlMachineState.pushToEvalStack (CliType.ValueType vt) thread state
+                    handleTypeToken typeDefn state
                 | _ -> failwith $"Unexpected metadata token %O{metadataToken} in LdToken"
 
             state
             |> IlMachineState.advanceProgramCounter thread
             |> Tuple.withRight WhatWeDid.Executed
         | Cpobj -> failwith "TODO: Cpobj unimplemented"
-        | Ldobj -> failwith "TODO: Ldobj unimplemented"
+        | Ldobj ->
+            let state, ty, assy =
+                match metadataToken with
+                | MetadataToken.TypeDefinition h ->
+                    let state, ty = IlMachineState.lookupTypeDefn baseClassTypes state activeAssy h
+                    state, ty, activeAssy
+                | MetadataToken.TypeReference ref ->
+                    IlMachineState.lookupTypeRef
+                        loggerFactory
+                        baseClassTypes
+                        state
+                        activeAssy
+                        currentMethod.DeclaringType.Generics
+                        ref
+                | MetadataToken.TypeSpecification spec -> state, activeAssy.TypeSpecs.[spec].Signature, activeAssy
+                | _ -> failwith $"unexpected token {metadataToken} in Ldobj"
+
+            let state, typeHandle =
+                IlMachineState.concretizeType
+                    loggerFactory
+                    baseClassTypes
+                    state
+                    assy.Name
+                    currentMethod.DeclaringType.Generics
+                    currentMethod.Generics
+                    ty
+
+            let addr, state = state |> IlMachineState.popEvalStack thread
+
+            let obj =
+                match addr with
+                | EvalStackValue.ObjectRef addr ->
+                    IlMachineState.dereferencePointer state (ManagedPointerSource.Heap addr)
+                | EvalStackValue.ManagedPointer ptr -> IlMachineState.dereferencePointer state ptr
+                | EvalStackValue.Float _
+                | EvalStackValue.Int64 _
+                | EvalStackValue.Int32 _ -> failwith "refusing to interpret constant as address"
+                | _ -> failwith "TODO"
+
+            let targetType =
+                AllConcreteTypes.lookup typeHandle state.ConcreteTypes |> Option.get
+
+            let defn =
+                state._LoadedAssemblies.[targetType.Assembly.FullName].TypeDefs.[targetType.Definition.Get]
+
+            let baseType =
+                DumpedAssembly.resolveBaseType baseClassTypes state._LoadedAssemblies targetType.Assembly defn.BaseType
+
+            let toPush =
+                match baseType with
+                | ResolvedBaseType.Enum
+                | ResolvedBaseType.ValueType ->
+                    failwith
+                        $"TODO: push %O{obj} as type %s{targetType.Assembly.Name}.%s{targetType.Namespace}.%s{targetType.Name}"
+                | ResolvedBaseType.Object
+                | ResolvedBaseType.Delegate ->
+                    // III.4.13: reference types are just copied as pointers.
+                    // We should have received a pointer, so let's just pass it back.
+                    obj
+
+            state
+            |> IlMachineState.pushToEvalStack toPush thread
+            |> IlMachineState.advanceProgramCounter thread
+            |> Tuple.withRight WhatWeDid.Executed
         | Sizeof ->
             let state, ty, assy =
                 match metadataToken with
@@ -1190,10 +1502,12 @@ module internal UnaryMetadataIlOp =
                         activeAssy
                         currentMethod.DeclaringType.Generics
                         ref
+                | MetadataToken.TypeSpecification spec -> state, activeAssy.TypeSpecs.[spec].Signature, activeAssy
                 | _ -> failwith $"unexpected token {metadataToken} in Sizeof"
 
             let state, typeHandle =
                 IlMachineState.concretizeType
+                    loggerFactory
                     baseClassTypes
                     state
                     assy.Name

WoofWare.PawPrint/UnaryStringTokenIlOp.fs

@@ -2,12 +2,13 @@ namespace WoofWare.PawPrint
 
 open System.Collections.Immutable
 open System.Reflection
-open System.Reflection.Metadata
+open Microsoft.Extensions.Logging
 
 [<RequireQualifiedAccess>]
 [<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
 module internal UnaryStringTokenIlOp =
     let execute
+        (loggerFactory : ILoggerFactory)
         (baseClassTypes : BaseClassTypes<DumpedAssembly>)
         (op : UnaryStringTokenIlOp)
         (sh : StringToken)
@@ -27,6 +28,8 @@ module internal UnaryStringTokenIlOp =
 
                     let state = state |> IlMachineState.setStringData dataAddr stringToAllocate
 
+                    // String type is:
+                    // https://github.com/dotnet/runtime/blob/f0168ee80ba9aca18a7e7140b2bb436defda623c/src/libraries/System.Private.CoreLib/src/System/String.cs#L26
                     let stringInstanceFields =
                         baseClassTypes.String.Fields
                         |> List.choose (fun field ->
@@ -49,17 +52,39 @@ module internal UnaryStringTokenIlOp =
 
                     let fields =
                         [
-                            "_firstChar", CliType.ofChar state.ManagedHeap.StringArrayData.[dataAddr]
-                            "_stringLength", CliType.Numeric (CliNumericType.Int32 stringToAllocate.Length)
+                            {
+                                Name = "_firstChar"
+                                Contents = CliType.ofChar state.ManagedHeap.StringArrayData.[dataAddr]
+                                Offset = None
+                                Type =
+                                    AllConcreteTypes.findExistingConcreteType
+                                        state.ConcreteTypes
+                                        (baseClassTypes.Char.Assembly,
+                                         baseClassTypes.Char.Namespace,
+                                         baseClassTypes.Char.Name,
+                                         ImmutableArray.Empty)
+                                    |> Option.get
+                            }
+                            {
+                                Name = "_stringLength"
+                                Contents = CliType.Numeric (CliNumericType.Int32 stringToAllocate.Length)
+                                Offset = None
+                                Type =
+                                    AllConcreteTypes.findExistingConcreteType
+                                        state.ConcreteTypes
+                                        (baseClassTypes.Int32.Assembly,
+                                         baseClassTypes.Int32.Namespace,
+                                         baseClassTypes.Int32.Name,
+                                         ImmutableArray.Empty)
+                                    |> Option.get
+                            }
                         ]
+                        |> CliValueType.OfFields Layout.Default
 
                     let state, stringType =
-                        TypeDefn.FromDefinition (
-                            ComparableTypeDefinitionHandle.Make baseClassTypes.String.TypeDefHandle,
-                            baseClassTypes.Corelib.Name.FullName,
-                            SignatureTypeKind.Class
-                        )
+                        DumpedAssembly.typeInfoToTypeDefn' baseClassTypes state._LoadedAssemblies baseClassTypes.String
                         |> IlMachineState.concretizeType
+                            loggerFactory
                             baseClassTypes
                             state
                             baseClassTypes.Corelib.Name

WoofWare.PawPrint/WoofWare.PawPrint.fsproj

@@ -7,6 +7,7 @@
 
   <ItemGroup>
     <Compile Include="Tuple.fs" />
+    <Compile Include="List.fs" />
     <Compile Include="ImmutableArray.fs" />
     <Compile Include="Result.fs" />
     <Compile Include="Corelib.fs" />
@@ -19,10 +20,10 @@
     <Compile Include="Exceptions.fs" />
     <Compile Include="EvalStack.fs" />
     <Compile Include="EvalStackValueComparisons.fs" />
-    <Compile Include="BinaryArithmetic.fs" />
     <Compile Include="MethodState.fs" />
     <Compile Include="ThreadState.fs" />
     <Compile Include="IlMachineState.fs" />
+    <Compile Include="BinaryArithmetic.fs" />
     <Compile Include="Intrinsics.fs" />
     <Compile Include="IlMachineStateExecution.fs" />
     <Compile Include="NullaryIlOp.fs" />

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1755736253,
-        "narHash": "sha256-jlIQRypNhB1PcB1BE+expE4xZeJxzoAGr1iUbHQta8s=",
+        "lastModified": 1756381814,
+        "narHash": "sha256-tzo7YvAsGlzo4WiIHT0ooR59VHu+aKRQdHk7sIyoia4=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "596312aae91421d6923f18cecce934a7d3bfd6b8",
+        "rev": "aca2499b79170038df0dbaec8bf2f689b506ad32",
         "type": "github"
       },
       "original": {