/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Microsoft Public License. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Microsoft Public License, please send an email to
* dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
* by the terms of the Microsoft Public License.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Dynamic.Utils;
using System.Reflection;
using System.Reflection.Emit;
#if SILVERLIGHT
using System.Core;
#endif
#if CLR2
namespace Microsoft.Scripting.Ast.Compiler{
#else
namespace System.Linq.Expressions.Compiler {
#endif
partial class LambdaCompiler {
private void EmitBinaryExpression(Expression expr) {
EmitBinaryExpression(expr, CompilationFlags.EmitAsNoTail);
}
private void EmitBinaryExpression(Expression expr, CompilationFlags flags) {
BinaryExpression b = (BinaryExpression)expr;
Debug.Assert(b.NodeType != ExpressionType.AndAlso && b.NodeType != ExpressionType.OrElse && b.NodeType != ExpressionType.Coalesce);
if (b.Method != null) {
EmitBinaryMethod(b, flags);
return;
}
// For EQ and NE, if there is a user-specified method, use it.
// Otherwise implement the C# semantics that allow equality
// comparisons on non-primitive nullable structs that don't
// overload "=="
if ((b.NodeType == ExpressionType.Equal || b.NodeType == ExpressionType.NotEqual) &&
(b.Type == typeof(bool) || b.Type == typeof(bool?))) {
// If we have x==null, x!=null, null==x or null!=x where x is
// nullable but not null, then generate a call to x.HasValue.
Debug.Assert(!b.IsLiftedToNull || b.Type == typeof(bool?));
if (ConstantCheck.IsNull(b.Left) && !ConstantCheck.IsNull(b.Right) && TypeUtils.IsNullableType(b.Right.Type)) {
EmitNullEquality(b.NodeType, b.Right, b.IsLiftedToNull);
return;
}
if (ConstantCheck.IsNull(b.Right) && !ConstantCheck.IsNull(b.Left) && TypeUtils.IsNullableType(b.Left.Type)) {
EmitNullEquality(b.NodeType, b.Left, b.IsLiftedToNull);
return;
}
// For EQ and NE, we can avoid some conversions if we're
// ultimately just comparing two managed pointers.
EmitExpression(GetEqualityOperand(b.Left));
EmitExpression(GetEqualityOperand(b.Right));
} else {
// Otherwise generate it normally
EmitExpression(b.Left);
EmitExpression(b.Right);
}
EmitBinaryOperator(b.NodeType, b.Left.Type, b.Right.Type, b.Type, b.IsLiftedToNull);
}
private void EmitNullEquality(ExpressionType op, Expression e, bool isLiftedToNull) {
Debug.Assert(TypeUtils.IsNullableType(e.Type));
Debug.Assert(op == ExpressionType.Equal || op == ExpressionType.NotEqual);
// If we are lifted to null then just evaluate the expression for its side effects, discard,
// and generate null. If we are not lifted to null then generate a call to HasValue.
if (isLiftedToNull) {
EmitExpressionAsVoid(e);
_ilg.EmitDefault(typeof(bool?));
} else {
EmitAddress(e, e.Type);
_ilg.EmitHasValue(e.Type);
if (op == ExpressionType.Equal) {
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
}
}
}
private void EmitBinaryMethod(BinaryExpression b, CompilationFlags flags) {
if (b.IsLifted) {
ParameterExpression p1 = Expression.Variable(TypeUtils.GetNonNullableType(b.Left.Type), null);
ParameterExpression p2 = Expression.Variable(TypeUtils.GetNonNullableType(b.Right.Type), null);
MethodCallExpression mc = Expression.Call(null, b.Method, p1, p2);
Type resultType = null;
if (b.IsLiftedToNull) {
resultType = TypeUtils.GetNullableType(mc.Type);
} else {
switch (b.NodeType) {
case ExpressionType.Equal:
case ExpressionType.NotEqual:
case ExpressionType.LessThan:
case ExpressionType.LessThanOrEqual:
case ExpressionType.GreaterThan:
case ExpressionType.GreaterThanOrEqual:
if (mc.Type != typeof(bool)) {
throw Error.ArgumentMustBeBoolean();
}
resultType = typeof(bool);
break;
default:
resultType = TypeUtils.GetNullableType(mc.Type);
break;
}
}
var variables = new ParameterExpression[] { p1, p2 };
var arguments = new Expression[] { b.Left, b.Right };
ValidateLift(variables, arguments);
EmitLift(b.NodeType, resultType, mc, variables, arguments);
} else {
EmitMethodCallExpression(Expression.Call(null, b.Method, b.Left, b.Right), flags);
}
}
private void EmitBinaryOperator(ExpressionType op, Type leftType, Type rightType, Type resultType, bool liftedToNull) {
bool leftIsNullable = TypeUtils.IsNullableType(leftType);
bool rightIsNullable = TypeUtils.IsNullableType(rightType);
switch (op) {
case ExpressionType.ArrayIndex:
if (rightType != typeof(int)) {
throw ContractUtils.Unreachable;
}
_ilg.EmitLoadElement(leftType.GetElementType());
return;
case ExpressionType.Coalesce:
throw Error.UnexpectedCoalesceOperator();
}
if (leftIsNullable || rightIsNullable) {
EmitLiftedBinaryOp(op, leftType, rightType, resultType, liftedToNull);
} else {
EmitUnliftedBinaryOp(op, leftType, rightType);
EmitConvertArithmeticResult(op, resultType);
}
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
private void EmitUnliftedBinaryOp(ExpressionType op, Type leftType, Type rightType) {
Debug.Assert(!TypeUtils.IsNullableType(leftType));
Debug.Assert(!TypeUtils.IsNullableType(rightType));
if (op == ExpressionType.Equal || op == ExpressionType.NotEqual) {
EmitUnliftedEquality(op, leftType);
return;
}
if (!leftType.IsPrimitive) {
throw Error.OperatorNotImplementedForType(op, leftType);
}
switch (op) {
case ExpressionType.Add:
_ilg.Emit(OpCodes.Add);
break;
case ExpressionType.AddChecked:
if (TypeUtils.IsFloatingPoint(leftType)) {
_ilg.Emit(OpCodes.Add);
} else if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Add_Ovf_Un);
} else {
_ilg.Emit(OpCodes.Add_Ovf);
}
break;
case ExpressionType.Subtract:
_ilg.Emit(OpCodes.Sub);
break;
case ExpressionType.SubtractChecked:
if (TypeUtils.IsFloatingPoint(leftType)) {
_ilg.Emit(OpCodes.Sub);
} else if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Sub_Ovf_Un);
} else {
_ilg.Emit(OpCodes.Sub_Ovf);
}
break;
case ExpressionType.Multiply:
_ilg.Emit(OpCodes.Mul);
break;
case ExpressionType.MultiplyChecked:
if (TypeUtils.IsFloatingPoint(leftType)) {
_ilg.Emit(OpCodes.Mul);
} else if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Mul_Ovf_Un);
} else {
_ilg.Emit(OpCodes.Mul_Ovf);
}
break;
case ExpressionType.Divide:
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Div_Un);
} else {
_ilg.Emit(OpCodes.Div);
}
break;
case ExpressionType.Modulo:
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Rem_Un);
} else {
_ilg.Emit(OpCodes.Rem);
}
break;
case ExpressionType.And:
case ExpressionType.AndAlso:
_ilg.Emit(OpCodes.And);
break;
case ExpressionType.Or:
case ExpressionType.OrElse:
_ilg.Emit(OpCodes.Or);
break;
case ExpressionType.LessThan:
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Clt_Un);
} else {
_ilg.Emit(OpCodes.Clt);
}
break;
case ExpressionType.LessThanOrEqual: {
Label labFalse = _ilg.DefineLabel();
Label labEnd = _ilg.DefineLabel();
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Ble_Un_S, labFalse);
} else {
_ilg.Emit(OpCodes.Ble_S, labFalse);
}
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Br_S, labEnd);
_ilg.MarkLabel(labFalse);
_ilg.Emit(OpCodes.Ldc_I4_1);
_ilg.MarkLabel(labEnd);
}
break;
case ExpressionType.GreaterThan:
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Cgt_Un);
} else {
_ilg.Emit(OpCodes.Cgt);
}
break;
case ExpressionType.GreaterThanOrEqual: {
Label labFalse = _ilg.DefineLabel();
Label labEnd = _ilg.DefineLabel();
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Bge_Un_S, labFalse);
} else {
_ilg.Emit(OpCodes.Bge_S, labFalse);
}
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Br_S, labEnd);
_ilg.MarkLabel(labFalse);
_ilg.Emit(OpCodes.Ldc_I4_1);
_ilg.MarkLabel(labEnd);
}
break;
case ExpressionType.ExclusiveOr:
_ilg.Emit(OpCodes.Xor);
break;
case ExpressionType.LeftShift:
if (rightType != typeof(int)) {
throw ContractUtils.Unreachable;
}
_ilg.Emit(OpCodes.Shl);
break;
case ExpressionType.RightShift:
if (rightType != typeof(int)) {
throw ContractUtils.Unreachable;
}
if (TypeUtils.IsUnsigned(leftType)) {
_ilg.Emit(OpCodes.Shr_Un);
} else {
_ilg.Emit(OpCodes.Shr);
}
break;
default:
throw Error.UnhandledBinary(op);
}
}
// Binary/unary operations on 8 and 16 bit operand types will leave a
// 32-bit value on the stack, because that's how IL works. For these
// cases, we need to cast it back to the resultType, possibly using a
// checked conversion if the original operator was convert
private void EmitConvertArithmeticResult(ExpressionType op, Type resultType) {
Debug.Assert(!resultType.IsNullableType());
switch (Type.GetTypeCode(resultType)) {
case TypeCode.Byte:
_ilg.Emit(IsChecked(op) ? OpCodes.Conv_Ovf_U1 : OpCodes.Conv_U1);
break;
case TypeCode.SByte:
_ilg.Emit(IsChecked(op) ? OpCodes.Conv_Ovf_I1 : OpCodes.Conv_I1);
break;
case TypeCode.UInt16:
_ilg.Emit(IsChecked(op) ? OpCodes.Conv_Ovf_U2 : OpCodes.Conv_U2);
break;
case TypeCode.Int16:
_ilg.Emit(IsChecked(op) ? OpCodes.Conv_Ovf_I2 : OpCodes.Conv_I2);
break;
}
}
private void EmitUnliftedEquality(ExpressionType op, Type type) {
Debug.Assert(op == ExpressionType.Equal || op == ExpressionType.NotEqual);
if (!type.IsPrimitive && type.IsValueType && !type.IsEnum) {
throw Error.OperatorNotImplementedForType(op, type);
}
_ilg.Emit(OpCodes.Ceq);
if (op == ExpressionType.NotEqual) {
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
}
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
private void EmitLiftedBinaryOp(ExpressionType op, Type leftType, Type rightType, Type resultType, bool liftedToNull) {
Debug.Assert(TypeUtils.IsNullableType(leftType) || TypeUtils.IsNullableType(rightType));
switch (op) {
case ExpressionType.And:
if (leftType == typeof(bool?)) {
EmitLiftedBooleanAnd();
} else {
EmitLiftedBinaryArithmetic(op, leftType, rightType, resultType);
}
break;
case ExpressionType.Or:
if (leftType == typeof(bool?)) {
EmitLiftedBooleanOr();
} else {
EmitLiftedBinaryArithmetic(op, leftType, rightType, resultType);
}
break;
case ExpressionType.ExclusiveOr:
case ExpressionType.Add:
case ExpressionType.AddChecked:
case ExpressionType.Subtract:
case ExpressionType.SubtractChecked:
case ExpressionType.Multiply:
case ExpressionType.MultiplyChecked:
case ExpressionType.Divide:
case ExpressionType.Modulo:
case ExpressionType.LeftShift:
case ExpressionType.RightShift:
EmitLiftedBinaryArithmetic(op, leftType, rightType, resultType);
break;
case ExpressionType.LessThan:
case ExpressionType.LessThanOrEqual:
case ExpressionType.GreaterThan:
case ExpressionType.GreaterThanOrEqual:
case ExpressionType.Equal:
case ExpressionType.NotEqual:
EmitLiftedRelational(op, leftType, rightType, resultType, liftedToNull);
break;
case ExpressionType.AndAlso:
case ExpressionType.OrElse:
default:
throw ContractUtils.Unreachable;
}
}
private void EmitLiftedRelational(ExpressionType op, Type leftType, Type rightType, Type resultType, bool liftedToNull) {
Debug.Assert(TypeUtils.IsNullableType(leftType));
Label shortCircuit = _ilg.DefineLabel();
LocalBuilder locLeft = GetLocal(leftType);
LocalBuilder locRight = GetLocal(rightType);
// store values (reverse order since they are already on the stack)
_ilg.Emit(OpCodes.Stloc, locRight);
_ilg.Emit(OpCodes.Stloc, locLeft);
if (op == ExpressionType.Equal) {
// test for both null -> true
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(leftType);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(rightType);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.And);
_ilg.Emit(OpCodes.Dup);
_ilg.Emit(OpCodes.Brtrue_S, shortCircuit);
_ilg.Emit(OpCodes.Pop);
// test for either is null -> false
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(leftType);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(rightType);
_ilg.Emit(OpCodes.And);
_ilg.Emit(OpCodes.Dup);
_ilg.Emit(OpCodes.Brfalse_S, shortCircuit);
_ilg.Emit(OpCodes.Pop);
} else if (op == ExpressionType.NotEqual) {
// test for both null -> false
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(leftType);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(rightType);
_ilg.Emit(OpCodes.Or);
_ilg.Emit(OpCodes.Dup);
_ilg.Emit(OpCodes.Brfalse_S, shortCircuit);
_ilg.Emit(OpCodes.Pop);
// test for either is null -> true
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(leftType);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(rightType);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Or);
_ilg.Emit(OpCodes.Dup);
_ilg.Emit(OpCodes.Brtrue_S, shortCircuit);
_ilg.Emit(OpCodes.Pop);
} else {
// test for either is null -> false
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(leftType);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(rightType);
_ilg.Emit(OpCodes.And);
_ilg.Emit(OpCodes.Dup);
_ilg.Emit(OpCodes.Brfalse_S, shortCircuit);
_ilg.Emit(OpCodes.Pop);
}
// do op on values
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitGetValueOrDefault(leftType);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitGetValueOrDefault(rightType);
//RELEASING locLeft locRight
FreeLocal(locLeft);
FreeLocal(locRight);
EmitBinaryOperator(
op,
TypeUtils.GetNonNullableType(leftType),
TypeUtils.GetNonNullableType(rightType),
TypeUtils.GetNonNullableType(resultType),
false
);
if (!liftedToNull) {
_ilg.MarkLabel(shortCircuit);
}
if (!TypeUtils.AreEquivalent(resultType, TypeUtils.GetNonNullableType(resultType))) {
_ilg.EmitConvertToType(TypeUtils.GetNonNullableType(resultType), resultType, true);
}
if (liftedToNull) {
Label labEnd = _ilg.DefineLabel();
_ilg.Emit(OpCodes.Br, labEnd);
_ilg.MarkLabel(shortCircuit);
_ilg.Emit(OpCodes.Pop);
_ilg.Emit(OpCodes.Ldnull);
_ilg.Emit(OpCodes.Unbox_Any, resultType);
_ilg.MarkLabel(labEnd);
}
}
private void EmitLiftedBinaryArithmetic(ExpressionType op, Type leftType, Type rightType, Type resultType) {
bool leftIsNullable = TypeUtils.IsNullableType(leftType);
bool rightIsNullable = TypeUtils.IsNullableType(rightType);
Debug.Assert(leftIsNullable || rightIsNullable);
Label labIfNull = _ilg.DefineLabel();
Label labEnd = _ilg.DefineLabel();
LocalBuilder locLeft = GetLocal(leftType);
LocalBuilder locRight = GetLocal(rightType);
LocalBuilder locResult = GetLocal(resultType);
// store values (reverse order since they are already on the stack)
_ilg.Emit(OpCodes.Stloc, locRight);
_ilg.Emit(OpCodes.Stloc, locLeft);
// test for null
// use short circuiting
if (leftIsNullable) {
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(leftType);
_ilg.Emit(OpCodes.Brfalse_S, labIfNull);
}
if (rightIsNullable) {
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(rightType);
_ilg.Emit(OpCodes.Brfalse_S, labIfNull);
}
// do op on values
if (leftIsNullable) {
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitGetValueOrDefault(leftType);
} else {
_ilg.Emit(OpCodes.Ldloc, locLeft);
}
if (rightIsNullable) {
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitGetValueOrDefault(rightType);
} else {
_ilg.Emit(OpCodes.Ldloc, locRight);
}
//RELEASING locLeft locRight
FreeLocal(locLeft);
FreeLocal(locRight);
EmitBinaryOperator(op, TypeUtils.GetNonNullableType(leftType), TypeUtils.GetNonNullableType(rightType), TypeUtils.GetNonNullableType(resultType), false);
// construct result type
ConstructorInfo ci = resultType.GetConstructor(new Type[] { TypeUtils.GetNonNullableType(resultType) });
_ilg.Emit(OpCodes.Newobj, ci);
_ilg.Emit(OpCodes.Stloc, locResult);
_ilg.Emit(OpCodes.Br_S, labEnd);
// if null then create a default one
_ilg.MarkLabel(labIfNull);
_ilg.Emit(OpCodes.Ldloca, locResult);
_ilg.Emit(OpCodes.Initobj, resultType);
_ilg.MarkLabel(labEnd);
_ilg.Emit(OpCodes.Ldloc, locResult);
//RELEASING locResult
FreeLocal(locResult);
}
private void EmitLiftedBooleanAnd() {
Type type = typeof(bool?);
Label labComputeRight = _ilg.DefineLabel();
Label labReturnFalse = _ilg.DefineLabel();
Label labReturnNull = _ilg.DefineLabel();
Label labReturnValue = _ilg.DefineLabel();
Label labExit = _ilg.DefineLabel();
// store values (reverse order since they are already on the stack)
LocalBuilder locLeft = GetLocal(type);
LocalBuilder locRight = GetLocal(type);
_ilg.Emit(OpCodes.Stloc, locRight);
_ilg.Emit(OpCodes.Stloc, locLeft);
// compute left
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(type);
_ilg.Emit(OpCodes.Brfalse, labComputeRight);
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitGetValueOrDefault(type);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Brtrue, labReturnFalse);
// compute right
_ilg.MarkLabel(labComputeRight);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(type);
_ilg.Emit(OpCodes.Brfalse_S, labReturnNull);
_ilg.Emit(OpCodes.Ldloca, locRight);
//RELEASING locRight
FreeLocal(locRight);
_ilg.EmitGetValueOrDefault(type);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Brtrue_S, labReturnFalse);
// check left for null again
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(type);
_ilg.Emit(OpCodes.Brfalse, labReturnNull);
// return true
_ilg.Emit(OpCodes.Ldc_I4_1);
_ilg.Emit(OpCodes.Br_S, labReturnValue);
// return false
_ilg.MarkLabel(labReturnFalse);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Br_S, labReturnValue);
_ilg.MarkLabel(labReturnValue);
ConstructorInfo ci = type.GetConstructor(new Type[] { typeof(bool) });
_ilg.Emit(OpCodes.Newobj, ci);
_ilg.Emit(OpCodes.Stloc, locLeft);
_ilg.Emit(OpCodes.Br, labExit);
// return null
_ilg.MarkLabel(labReturnNull);
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.Emit(OpCodes.Initobj, type);
_ilg.MarkLabel(labExit);
_ilg.Emit(OpCodes.Ldloc, locLeft);
//RELEASING locLeft
FreeLocal(locLeft);
}
private void EmitLiftedBooleanOr() {
Type type = typeof(bool?);
Label labComputeRight = _ilg.DefineLabel();
Label labReturnTrue = _ilg.DefineLabel();
Label labReturnNull = _ilg.DefineLabel();
Label labReturnValue = _ilg.DefineLabel();
Label labExit = _ilg.DefineLabel();
// store values (reverse order since they are already on the stack)
LocalBuilder locLeft = GetLocal(type);
LocalBuilder locRight = GetLocal(type);
_ilg.Emit(OpCodes.Stloc, locRight);
_ilg.Emit(OpCodes.Stloc, locLeft);
// compute left
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(type);
_ilg.Emit(OpCodes.Brfalse, labComputeRight);
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitGetValueOrDefault(type);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Brfalse, labReturnTrue);
// compute right
_ilg.MarkLabel(labComputeRight);
_ilg.Emit(OpCodes.Ldloca, locRight);
_ilg.EmitHasValue(type);
_ilg.Emit(OpCodes.Brfalse_S, labReturnNull);
_ilg.Emit(OpCodes.Ldloca, locRight);
//RELEASING locRight
FreeLocal(locRight);
_ilg.EmitGetValueOrDefault(type);
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Brfalse_S, labReturnTrue);
// check left for null again
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.EmitHasValue(type);
_ilg.Emit(OpCodes.Brfalse, labReturnNull);
// return false
_ilg.Emit(OpCodes.Ldc_I4_0);
_ilg.Emit(OpCodes.Br_S, labReturnValue);
// return true
_ilg.MarkLabel(labReturnTrue);
_ilg.Emit(OpCodes.Ldc_I4_1);
_ilg.Emit(OpCodes.Br_S, labReturnValue);
_ilg.MarkLabel(labReturnValue);
ConstructorInfo ci = type.GetConstructor(new Type[] { typeof(bool) });
_ilg.Emit(OpCodes.Newobj, ci);
_ilg.Emit(OpCodes.Stloc, locLeft);
_ilg.Emit(OpCodes.Br, labExit);
// return null
_ilg.MarkLabel(labReturnNull);
_ilg.Emit(OpCodes.Ldloca, locLeft);
_ilg.Emit(OpCodes.Initobj, type);
_ilg.MarkLabel(labExit);
_ilg.Emit(OpCodes.Ldloc, locLeft);
//RELEASING locLeft
FreeLocal(locLeft);
}
}
}
|