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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 System.Collections.Generic;
using Internal.TypeSystem;
namespace Internal.IL.Stubs
{
/// <summary>
/// Synthetic method override of "int ValueType.__GetFieldHelper(Int32, out EETypePtr)". This method is injected
/// into all value types that cannot have their Equals(object) and GetHashCode() methods operate on individual
/// bytes. The purpose of the override is to provide access to the value types' fields and their types.
/// </summary>
public sealed partial class ValueTypeGetFieldHelperMethodOverride : ILStubMethod
{
private DefType _owningType;
private MethodSignature _signature;
internal ValueTypeGetFieldHelperMethodOverride(DefType owningType)
{
_owningType = owningType;
}
public override TypeSystemContext Context
{
get
{
return _owningType.Context;
}
}
public override TypeDesc OwningType
{
get
{
return _owningType;
}
}
public override MethodSignature Signature
{
get
{
if (_signature == null)
{
TypeSystemContext context = _owningType.Context;
TypeDesc int32Type = context.GetWellKnownType(WellKnownType.Int32);
TypeDesc eeTypePtrType = context.SystemModule.GetKnownType("System", "EETypePtr");
_signature = new MethodSignature(0, 0, int32Type, new[] {
int32Type,
eeTypePtrType.MakeByRefType()
});
}
return _signature;
}
}
public override MethodIL EmitIL()
{
TypeDesc owningType = _owningType.InstantiateAsOpen();
ILEmitter emitter = new ILEmitter();
TypeDesc eeTypePtrType = Context.SystemModule.GetKnownType("System", "EETypePtr");
MethodDesc eeTypePtrOfMethod = eeTypePtrType.GetKnownMethod("EETypePtrOf", null);
ILToken eeTypePtrToken = emitter.NewToken(eeTypePtrType);
var switchStream = emitter.NewCodeStream();
var getFieldStream = emitter.NewCodeStream();
ArrayBuilder<ILCodeLabel> fieldGetters = new ArrayBuilder<ILCodeLabel>();
foreach (FieldDesc field in owningType.GetFields())
{
if (field.IsStatic)
continue;
ILCodeLabel label = emitter.NewCodeLabel();
fieldGetters.Add(label);
getFieldStream.EmitLabel(label);
getFieldStream.EmitLdArg(2);
// We need something we can instantiate EETypePtrOf over. Also, the classlib
// code doesn't handle pointers.
TypeDesc boxableFieldType = field.FieldType;
if (boxableFieldType.IsPointer || boxableFieldType.IsFunctionPointer)
boxableFieldType = Context.GetWellKnownType(WellKnownType.IntPtr);
// The fact that the type is a reference type is sufficient for the callers.
// Don't unnecessarily create an MethodTable for the field type.
if (!boxableFieldType.IsSignatureVariable && !boxableFieldType.IsValueType)
boxableFieldType = Context.GetWellKnownType(WellKnownType.Object);
// If this is an enum, it's okay to Equals/GetHashCode the underlying type.
// Don't unnecessarily create an MethodTable for the enum.
boxableFieldType = boxableFieldType.UnderlyingType;
MethodDesc ptrOfField = eeTypePtrOfMethod.MakeInstantiatedMethod(boxableFieldType);
getFieldStream.Emit(ILOpcode.call, emitter.NewToken(ptrOfField));
getFieldStream.Emit(ILOpcode.stobj, eeTypePtrToken);
getFieldStream.EmitLdArg(0);
getFieldStream.Emit(ILOpcode.ldflda, emitter.NewToken(field));
getFieldStream.EmitLdArg(0);
getFieldStream.Emit(ILOpcode.sub);
getFieldStream.Emit(ILOpcode.ret);
}
if (fieldGetters.Count > 0)
{
switchStream.EmitLdArg(1);
switchStream.EmitSwitch(fieldGetters.ToArray());
}
switchStream.EmitLdc(fieldGetters.Count);
switchStream.Emit(ILOpcode.ret);
return emitter.Link(this);
}
public override Instantiation Instantiation
{
get
{
return Instantiation.Empty;
}
}
public override bool IsVirtual
{
get
{
return true;
}
}
internal const string MetadataName = "__GetFieldHelper";
public override string Name
{
get
{
return MetadataName;
}
}
public override string DiagnosticName
{
get
{
return MetadataName;
}
}
}
}
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