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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using Internal.TypeSystem;
using Debug = System.Diagnostics.Debug;
namespace Internal.IL.Stubs
{
/// <summary>
/// Thunk to dynamically invoke a method using reflection. The method accepts an parameters as byrefs
/// lays them out on the stack, and calls the target method. This thunk has heavy dependencies
/// on the general dynamic invocation infrastructure in System.InvokeUtils and gets called from there
/// at runtime. See comments in System.InvokeUtils for a more thorough explanation.
/// </summary>
public sealed partial class DynamicInvokeMethodThunk : ILStubMethod
{
private TypeDesc _owningType;
private MethodSignature _targetSignature;
private MethodSignature _signature;
public DynamicInvokeMethodThunk(TypeDesc owningType, MethodSignature targetSignature)
{
_owningType = owningType;
_targetSignature = targetSignature;
}
// MethodSignature does not track information about the type of the this pointer. We will steal
// one of the unused upper bits to track whether the this pointer is a byref or an object. This makes
// the information passed around seamlesly, including name mangling.
private static MethodSignatureFlags MethodSignatureFlags_ValueTypeInstanceMethod => (MethodSignatureFlags)0x8000;
public static MethodSignature NormalizeSignature(MethodSignature sig, bool valueTypeInstanceMethod)
{
MethodSignatureFlags flags = 0;
if (sig.IsStatic)
{
flags |= MethodSignatureFlags.Static;
}
// TODO: Reflection invoke assumes unboxing stubs. It means that the "this" pointer is always a regular boxed object reference and
// that the dynamic invoke thunks cannot be used to invoke instance methods on unboxed value types currently. This will need
// to be addressed for the eventual allocation-free reflection invoke.
// else if (valueTypeInstanceMethod)
// {
// flags |= MethodSignatureFlags_ValueTypeInstanceMethod;
// }
TypeDesc[] parameters = new TypeDesc[sig.Length];
for (int i = 0; i < sig.Length; i++)
parameters[i] = NormalizeType(sig[i]);
return new MethodSignature(flags, 0, NormalizeType(sig.ReturnType), parameters);
static TypeDesc NormalizeType(TypeDesc type)
{
Debug.Assert(!type.ContainsSignatureVariables(treatGenericParameterLikeSignatureVariable: true));
if (type.IsByRef)
return type.Context.GetWellKnownType(WellKnownType.Byte).MakeByRefType();
if (type.IsPointer || type.IsFunctionPointer)
return type.Context.GetWellKnownType(WellKnownType.Void).MakePointerType();
if (type.IsEnum)
return type.UnderlyingType;
if (type.IsValueType)
return type;
return type.Context.GetWellKnownType(WellKnownType.Object);
}
}
public override TypeSystemContext Context
{
get
{
return _owningType.Context;
}
}
public override TypeDesc OwningType
{
get
{
return _owningType;
}
}
public override MethodSignature Signature
{
get
{
if (_signature == null)
{
var ptr = Context.GetWellKnownType(WellKnownType.Void).MakePointerType();
var byref = Context.GetWellKnownType(WellKnownType.Byte).MakeByRefType();
_signature = new MethodSignature(
MethodSignatureFlags.Static,
0,
byref,
new TypeDesc[]
{
ptr, // fptr
byref, // thisptr
byref, // refbuf
ptr // arguments
});
}
return _signature;
}
}
public override string Name => "DynamicInvoke";
public override string DiagnosticName => "DynamicInvoke";
public MethodSignature TargetSignature => _targetSignature;
public override MethodIL EmitIL()
{
ILEmitter emitter = new ILEmitter();
ILCodeStream codeStream = emitter.NewCodeStream();
// Handle instance methods.
if (!_targetSignature.IsStatic)
{
codeStream.EmitLdArg(1);
if ((_targetSignature.Flags & MethodSignatureFlags_ValueTypeInstanceMethod) == 0)
codeStream.Emit(ILOpcode.ldind_ref);
}
// Push the arguments.
if (_targetSignature.Length != 0)
{
var fieldByReferenceValueToken = emitter.NewToken(
Context.SystemModule.GetKnownType("System", "ByReference").GetKnownField("Value"));
for (int i = 0; i < _targetSignature.Length; i++)
{
codeStream.EmitLdArg(3);
if (i != 0)
{
codeStream.EmitLdc(i * Context.Target.PointerSize);
codeStream.Emit(ILOpcode.add);
}
codeStream.Emit(ILOpcode.ldfld, fieldByReferenceValueToken);
var parameterType = _targetSignature[i];
if (!parameterType.IsByRef)
{
codeStream.EmitLdInd(parameterType);
}
}
}
codeStream.EmitLdArg(0);
codeStream.Emit(ILOpcode.calli, emitter.NewToken(_targetSignature));
// Store the return value unless it is a byref
var returnType = _targetSignature.ReturnType;
if (!returnType.IsByRef)
{
if (!returnType.IsVoid)
{
var retVal = emitter.NewLocal(returnType);
codeStream.EmitStLoc(retVal);
codeStream.EmitLdArg(2);
codeStream.EmitLdLoc(retVal);
codeStream.EmitStInd(returnType);
}
codeStream.EmitLdArg(2);
}
codeStream.Emit(ILOpcode.ret);
return emitter.Link(this);
}
}
}
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