Redo method devirtualization for ldvirtftn

Washi1337 · Jun 7, 2024 · 4214f1a · 4214f1a
1 parent cb6db0e
commit 4214f1a
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Showing 2 changed files with 30 additions and 26 deletions.
diff --git a/src/Platforms/Echo.Platforms.AsmResolver/Emulation/Dispatch/ObjectModel/CallHandlerBase.cs b/src/Platforms/Echo.Platforms.AsmResolver/Emulation/Dispatch/ObjectModel/CallHandlerBase.cs
@@ -257,7 +257,7 @@ private static CilDispatchResult Invoke(CilExecutionContext context, IMethodDesc
             }
         }
 
-        protected static MethodDefinition? FindMethodImplementationInType(TypeDefinition? type, MethodDefinition? baseMethod)
+        internal static MethodDefinition? FindMethodImplementationInType(TypeDefinition? type, MethodDefinition? baseMethod)
         {
             if (type is null || baseMethod is null || !baseMethod.IsVirtual)
                 return baseMethod;

diff --git a/src/Platforms/Echo.Platforms.AsmResolver/Emulation/Dispatch/ObjectModel/LdvirtftnHandler.cs b/src/Platforms/Echo.Platforms.AsmResolver/Emulation/Dispatch/ObjectModel/LdvirtftnHandler.cs
@@ -27,30 +27,34 @@ protected override CilDispatchResult DispatchInternal(CilExecutionContext contex
         if (thisObjectType == null)
             throw new CilEmulatorException("Unable to resolve the type of object");
 
-        var virtualFunction = ((IMethodDescriptor)instruction.Operand!);
-        var virtualFunctionName = virtualFunction.Name;
-        var virtualFunctionSignature = virtualFunction.Signature;
-
-        do
-        {   
-            // try resolve function
-            var resolvedVirtualFunction = thisObjectType.Methods
-                .FirstOrDefault(method => method.Name == virtualFunctionName 
-                && SignatureComparer.Default.Equals(method.Signature, virtualFunctionSignature));
-
-            // if resolved then push function pointer
-            if (resolvedVirtualFunction != null)
-            {
-                var functionPointer = methods.GetAddress(resolvedVirtualFunction);
-                stack.Push(factory.CreateNativeInteger(functionPointer), type);
-                return CilDispatchResult.Success();
-            }
-
-            // else switch to BaseType and try resolve again
-            thisObjectType = thisObjectType.BaseType?.Resolve();
-        }   // or exit and throw CilEmulationException
-        while (thisObjectType != null);
-
-        throw new CilEmulatorException($"Unable to resolve a virtual function for type {thisObjectType!.FullName}");
+        var virtualFunction = (IMethodDescriptor)instruction.Operand!;
+
+        IMethodDescriptor? implementation = CallHandlerBase.FindMethodImplementationInType(thisObjectType, virtualFunction.Resolve());
+
+        if (implementation == null)
+        {
+            return CilDispatchResult.Exception(
+                context.Machine.Heap.AllocateObject(
+                        context.Machine.ValueFactory.MissingMethodExceptionType,
+                        true)
+                    .AsObjectHandle(context.Machine)
+            );
+        }
+
+        // Instantiate any generics.
+        var genericContext = GenericContext.FromMethod(virtualFunction);
+        if (!genericContext.IsEmpty)
+        {
+            var instantiated = thisObjectType
+            .CreateMemberReference(implementation.Name!, implementation.Signature!);
+
+            implementation = genericContext.Method != null
+                ? instantiated.MakeGenericInstanceMethod(genericContext.Method.TypeArguments.ToArray())
+                : instantiated;
+        }
+
+        var functionPointer = methods.GetAddress(implementation);
+        stack.Push(factory.CreateNativeInteger(functionPointer), type);
+        return CilDispatchResult.Success();
     }
 }