C# ILGenerator.BranchIfTrue方法代码示例

        /// <summary>
        /// Generates code to push the "this" value for a function call.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        public void GenerateThis(ILGenerator generator)
        {
            // Optimization: if there are no with scopes, simply emit undefined.
            bool scopeChainHasWithScope = false;
            var scope = this.Scope;
            do
            {
                if (scope is ObjectScope && ((ObjectScope)scope).ProvidesImplicitThisValue == true)
                {
                    scopeChainHasWithScope = true;
                    break;
                }
                scope = scope.ParentScope;
            } while (scope != null);

            if (scopeChainHasWithScope == false)
            {
                // No with scopes in the scope chain, use undefined as the "this" value.
                EmitHelpers.EmitUndefined(generator);
                return;
            }

            var end = generator.CreateLabel();

            scope = this.Scope;
            ILLocalVariable scopeVariable = generator.CreateTemporaryVariable(typeof(Scope));
            EmitHelpers.LoadScope(generator);
            generator.StoreVariable(scopeVariable);

            do
            {
                if (scope is DeclarativeScope)
                {
                    if (scope.HasDeclaredVariable(this.Name))
                    {
                        // The variable exists but declarative scopes always produce undefined for
                        // the "this" value.
                        EmitHelpers.EmitUndefined(generator);
                        break;
                    }
                }
                else
                {
                    var objectScope = (ObjectScope)scope;

                    // Check if the property exists by calling scope.ScopeObject.HasProperty(propertyName)
                    if (objectScope.ProvidesImplicitThisValue == false)
                        EmitHelpers.EmitUndefined(generator);
                    generator.LoadVariable(scopeVariable);
                    generator.CastClass(typeof(ObjectScope));
                    generator.Call(ReflectionHelpers.ObjectScope_ScopeObject);
                    if (objectScope.ProvidesImplicitThisValue == true)
                        generator.Duplicate();
                    generator.LoadString(this.Name);
                    generator.Call(ReflectionHelpers.ObjectInstance_HasProperty);
                    generator.BranchIfTrue(end);
                    generator.Pop();

                    // If the name is not defined, use undefined for the "this" value.
                    if (scope.ParentScope == null)
                    {
                        EmitHelpers.EmitUndefined(generator);
                    }
                }

                // Try the parent scope.
                if (scope.ParentScope != null && scope.ExistsAtRuntime == true)
                {
                    generator.LoadVariable(scopeVariable);
                    generator.Call(ReflectionHelpers.Scope_ParentScope);
                    generator.StoreVariable(scopeVariable);
                }
                scope = scope.ParentScope;

            } while (scope != null);

            // Release the temporary variable.
            generator.ReleaseTemporaryVariable(scopeVariable);

            // Define a label at the end.
            generator.DefineLabelPosition(end);
        }

//.........这里部分代码省略.........
                        // TODO: share these variables somehow.
                        var cacheKey = generator.DeclareVariable(typeof(object));
                        var cachedIndex = generator.DeclareVariable(typeof(int));

                        // Store the object into a temp variable.
                        var objectInstance = generator.DeclareVariable(PrimitiveType.Object);
                        generator.StoreVariable(objectInstance);

                        // if (__object_cacheKey != object.InlineCacheKey)
                        generator.LoadVariable(cacheKey);
                        generator.LoadVariable(objectInstance);
                        generator.Call(ReflectionHelpers.ObjectInstance_InlineCacheKey);
                        var elseClause = generator.CreateLabel();
                        generator.BranchIfEqual(elseClause);

                        // xxx = object.InlineSetPropertyValueIfExists("property", value, strictMode, out __object_property_cachedIndex, out __object_cacheKey)
                        generator.LoadVariable(objectInstance);
                        generator.LoadString(this.Name);
                        generator.LoadVariable(value);
                        generator.LoadBoolean(optimizationInfo.StrictMode);
                        generator.LoadAddressOfVariable(cachedIndex);
                        generator.LoadAddressOfVariable(cacheKey);
                        if (throwIfUnresolvable == false)
                        {
                            // Set the property value unconditionally.
                            generator.Call(ReflectionHelpers.ObjectInstance_InlineSetPropertyValue);
                        }
                        else
                        {
                            // Set the property value if the property exists.
                            generator.Call(ReflectionHelpers.ObjectInstance_InlineSetPropertyValueIfExists);

                            // The return value is true if the property was defined, and false if it wasn't.
                            generator.BranchIfTrue(endOfSet);
                        }

                        var endOfIf = generator.CreateLabel();
                        generator.Branch(endOfIf);

                        // else
                        generator.DefineLabelPosition(elseClause);

                        // object.InlinePropertyValues[__object_property_cachedIndex] = value;
                        generator.LoadVariable(objectInstance);
                        generator.Call(ReflectionHelpers.ObjectInstance_InlinePropertyValues);
                        generator.LoadVariable(cachedIndex);
                        generator.LoadVariable(value);
                        generator.StoreArrayElement(typeof(object));
                        generator.Branch(endOfSet);

                        // End of the if statement
                        generator.DefineLabelPosition(endOfIf);

                    }
                    else
                    {
                        // Slow route.

                        if (scopeVariable == null)
                            EmitHelpers.LoadScope(generator);
                        else
                            generator.LoadVariable(scopeVariable);
                        generator.CastClass(typeof(ObjectScope));
                        generator.Call(ReflectionHelpers.ObjectScope_ScopeObject);
                        generator.LoadString(this.Name);
                        generator.LoadVariable(value);

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals() { NonDefaultBreakStatementBehavior = true };
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // We need a label for each case clause and one for the default case.
            var jumpTargets = new ILLabel[this.CaseClauses.Count];
            int defaultIndex = -1;
            ILLabel endOfSwitch = generator.CreateLabel();

            // Generate code for the switch value.
            var startOfSwitch = generator.CreateLabel();
            this.Value.GenerateCode(generator, optimizationInfo);
            EmitConversion.ToAny(generator, this.Value.ResultType);

            // Save the switch value in a variable.
            var switchValue = generator.CreateTemporaryVariable(typeof(object));
            generator.StoreVariable(switchValue);

            for (int i = 0; i < this.CaseClauses.Count; i ++)
            {
                var caseClause = this.CaseClauses[i];

                // Create a label for each clause.
                jumpTargets[i] = generator.CreateLabel();

                if (caseClause.Value == null)
                {
                    // This is a default clause.
                    defaultIndex = i;
                    continue;
                }

                // TypeComparer.StrictEquals(switchValue, caseValue)
                generator.LoadVariable(switchValue);
                caseClause.Value.GenerateCode(generator, optimizationInfo);
                EmitConversion.ToAny(generator, caseClause.Value.ResultType);
                generator.Call(ReflectionHelpers.TypeComparer_StrictEquals);

                // if (TypeComparer.StrictEquals(switchValue, caseValue) == true)
                //     goto case i
                generator.BranchIfTrue(jumpTargets[i]);
            }
            
            // None of the cases matched, jump to the default clause or the end of the switch.
            if (defaultIndex >= 0)
                generator.Branch(jumpTargets[defaultIndex]);
            else
                generator.Branch(endOfSwitch);

            for (int i = 0; i < this.CaseClauses.Count; i++)
            {
                // Define a label at the start of the case clause.
                generator.DefineLabelPosition(jumpTargets[i]);

                // Set up the information needed by the break statement.
                optimizationInfo.PushBreakOrContinueInfo(this.Labels, endOfSwitch, null, labelledOnly: false);

                // Emit the case clause statements.
                foreach (var statement in this.CaseClauses[i].BodyStatements)
                    statement.GenerateCode(generator, optimizationInfo);

                // Revert the information needed by the break statement.
                optimizationInfo.PopBreakOrContinueInfo();
            }

            // Define a label for the end of the switch statement.
            generator.DefineLabelPosition(endOfSwitch);

            // Release the switch value variable for use elsewhere.
            generator.ReleaseTemporaryVariable(switchValue);

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

        /// <summary>
        /// Generates CIL for the logical operators.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        private void GenerateLogical(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Get the statically-determined types of the left and right operands.
            PrimitiveType leftType = this.Left.ResultType;
            PrimitiveType rightType = this.Right.ResultType;

            // Load the left-hand side operand.
            this.Left.GenerateCode(generator, optimizationInfo);

            // Make sure the output type is consistant.
            if (leftType != rightType)
            {
                if (PrimitiveTypeUtilities.IsNumeric(leftType) == true && PrimitiveTypeUtilities.IsNumeric(rightType) == true)
                {
                    EmitConversion.ToNumber(generator, leftType);
                    leftType = PrimitiveType.Number;
                }
                else
                {
                    EmitConversion.ToAny(generator, leftType);
                    leftType = PrimitiveType.Any;
                }
            }

            // Duplicate and convert to a Boolean.
            generator.Duplicate();
            EmitConversion.ToBool(generator, leftType);

            // Stack contains "left, (bool)left"
            var endOfIf = generator.CreateLabel();
            if (this.OperatorType == OperatorType.LogicalAnd)
                generator.BranchIfFalse(endOfIf);
            else
                generator.BranchIfTrue(endOfIf);

            // Stack contains "left".  Load the right-hand side operand.
            generator.Pop();
            this.Right.GenerateCode(generator, optimizationInfo);

            // Make sure the output type is consistant.
            if (leftType != rightType)
            {
                if (PrimitiveTypeUtilities.IsNumeric(leftType) == true && PrimitiveTypeUtilities.IsNumeric(rightType) == true)
                    EmitConversion.ToNumber(generator, rightType);
                else
                    EmitConversion.ToAny(generator, rightType);
            }

            // Define the label used above.
            generator.DefineLabelPosition(endOfIf);
        }

        /// <summary>
        /// Pops the value on the stack, converts it from one type to another, then pushes the
        /// result onto the stack.  Undefined is converted to the given default value.
        /// </summary>
        /// <param name="generator"> The IL generator. </param>
        /// <param name="fromType"> The type to convert from. </param>
        /// <param name="targetParameter"> The type to convert to and the default value, if there is one. </param>
        private static void EmitTypeConversion(ILGenerator generator, Type fromType, BinderArgument argument)
        {
            // Emit either the default value if there is one, otherwise emit "undefined".
            if (argument.HasDefaultValue)
            {
                // Check if the input value is undefined.
                var elseClause = generator.CreateLabel();
                generator.Duplicate();
                generator.BranchIfNull(elseClause);
                generator.Duplicate();
                generator.LoadField(ReflectionHelpers.Undefined_Value);
                generator.CompareEqual();
                generator.BranchIfTrue(elseClause);

                // Convert as per normal.
                EmitTypeConversion(generator, fromType, argument.Type);

                // Jump to the end.
                var endOfIf = generator.CreateLabel();
                generator.Branch(endOfIf);
                generator.DefineLabelPosition(elseClause);

                // Pop the existing value and emit the default value.
                generator.Pop();
                EmitUndefined(generator, argument);

                // Define the end of the block.
                generator.DefineLabelPosition(endOfIf);
            }
            else
            {
                // Convert as per normal.
                EmitTypeConversion(generator, fromType, argument.Type);
            }
        }

        /// <summary>
        /// Pops the value on the stack, converts it to an object, then pushes the result onto the
        /// stack.
        /// </summary>
        /// <param name="generator"> The IL generator. </param>
        /// <param name="fromType"> The type to convert from. </param>
        internal static void EmitConversionToObject(ILGenerator generator, Type fromType)
        {
            // If the from type is a reference type, check for null.
            ILLabel endOfNullCheck = null;
            if (fromType.IsValueType == false)
            {
                var startOfElse = generator.CreateLabel();
                endOfNullCheck = generator.CreateLabel();
                generator.Duplicate();
                generator.BranchIfNotNull(startOfElse);
                generator.Pop();
                EmitHelpers.EmitNull(generator);
                generator.Branch(endOfNullCheck);
                generator.DefineLabelPosition(startOfElse);
            }

            switch (Type.GetTypeCode(fromType))
            {
                case TypeCode.Boolean:
                    generator.Box(typeof(bool));
                    break;
                case TypeCode.Byte:
                    generator.Box(typeof(int));
                    break;
                case TypeCode.Char:
                    generator.LoadInt32(1);
                    generator.NewObject(ReflectionHelpers.String_Constructor_Char_Int);
                    break;
                
                case TypeCode.DBNull:
                    throw new NotSupportedException("DBNull is not a supported return type.");
                case TypeCode.Decimal:
                    generator.Call(ReflectionHelpers.Decimal_ToDouble);
                    generator.Box(typeof(double));
                    break;
                case TypeCode.Double:
                    generator.Box(typeof(double));
                    break;
                case TypeCode.Empty:
                    throw new NotSupportedException("Empty is not a supported return type.");
                case TypeCode.Int16:
                    generator.Box(typeof(int));
                    break;
                case TypeCode.Int32:
                    generator.Box(typeof(int));
                    break;
                case TypeCode.Int64:
                    generator.ConvertToDouble();
                    generator.Box(typeof(double));
                    break;

                case TypeCode.DateTime:
                case TypeCode.Object:
                    // Check if the type must be wrapped with a ClrInstanceWrapper.
                    // Note: if the type is a value type it cannot be a primitive or it would
                    // have been handled elsewhere in the switch.
                    ILLabel endOfWrapCheck = null;
                    if (fromType.IsValueType == false)
                    {
                        generator.Duplicate();
                        generator.Call(ReflectionHelpers.TypeUtilities_IsPrimitiveOrObject);
                        endOfWrapCheck = generator.CreateLabel();
                        generator.BranchIfTrue(endOfWrapCheck);
                    }

                    // The type must be wrapped.
                    var temp = generator.CreateTemporaryVariable(fromType);
                    generator.StoreVariable(temp);
                    generator.LoadArgument(0);
                    generator.LoadVariable(temp);
                    if (fromType.IsValueType == true)
                        generator.Box(fromType);
                    generator.ReleaseTemporaryVariable(temp);
                    generator.NewObject(ReflectionHelpers.ClrInstanceWrapper_Constructor);
                    
                    // End of wrap check.
                    if (fromType.IsValueType == false)
                        generator.DefineLabelPosition(endOfWrapCheck);
                    break;

                case TypeCode.SByte:
                    generator.Box(typeof(int));
                    break;
                case TypeCode.Single:
                    generator.Box(typeof(double));
                    break;
                case TypeCode.String:
                    break;
                case TypeCode.UInt16:
                    generator.Box(typeof(int));
                    break;
                case TypeCode.UInt32:
                    generator.Box(typeof(uint));
                    break;
//.........这里部分代码省略.........