Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / Microsoft / Scripting / Compiler / LambdaCompiler.Binary.cs / 1305376 / LambdaCompiler.Binary.cs
/* **************************************************************************** * * 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.Collections.Generic; using System.Diagnostics; using System.Dynamic.Utils; using System.Reflection; using System.Reflection.Emit; #if SILVERLIGHT using System.Core; #endif namespace System.Linq.Expressions.Compiler { 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); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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