public override BoundNode VisitLabeledStatement(BoundLabeledStatement node)
        {
            Debug.Assert(node != null);

            var rewrittenBody = (BoundStatement)Visit(node.Body);

            BoundStatement labelStatement = new BoundLabelStatement(node.Syntax, node.Label);

            if (this.GenerateDebugInfo)
            {
                var labeledSyntax = node.Syntax as LabeledStatementSyntax;
                if (labeledSyntax != null)
                {
                    var span = TextSpan.FromBounds(labeledSyntax.Identifier.SpanStart, labeledSyntax.ColonToken.Span.End);
                    labelStatement = factory.SequencePointWithSpan(labeledSyntax, span, labelStatement);
                }
            }

            if (rewrittenBody == null)
            {
                // Body may be null if the body has no associated IL
                // (declaration with no initializer for instance.)
                return(labelStatement);
            }

            return(BoundStatementList.Synthesized(node.Syntax, labelStatement, rewrittenBody));
        }
        public override BoundNode VisitLabeledStatement(BoundLabeledStatement node)
        {
            Debug.Assert(node != null);

            var rewrittenBody = (BoundStatement)Visit(node.Body);

            BoundStatement labelStatement = new BoundLabelStatement(node.Syntax, node.Label);

            if (this.GenerateDebugInfo)
            {
                var labeledSyntax = node.Syntax as LabeledStatementSyntax;
                if (labeledSyntax != null)
                {
                    var span = TextSpan.FromBounds(labeledSyntax.Identifier.SpanStart, labeledSyntax.ColonToken.Span.End);
                    labelStatement = _factory.SequencePointWithSpan(labeledSyntax, span, labelStatement);
                }
            }

            if (rewrittenBody == null)
            {
                // Body may be null if the body has no associated IL
                // (declaration with no initializer for instance.)
                return labelStatement;
            }

            return BoundStatementList.Synthesized(node.Syntax, labelStatement, rewrittenBody);
        }
        public override BoundNode VisitLabeledStatement(BoundLabeledStatement node)
        {
            Debug.Assert(node != null);

            var rewrittenBody = (BoundStatement)Visit(node.Body);

            BoundStatement labelStatement = new BoundLabelStatement(node.Syntax, node.Label);

            if (this.Instrument)
            {
                var labeledSyntax = node.Syntax as LabeledStatementSyntax;
                if (labeledSyntax != null)
                {
                    labelStatement = _instrumenter.InstrumentLabelStatement(node, labelStatement); 
                }
            }

            if (rewrittenBody == null)
            {
                // Body may be null if the body has no associated IL
                // (declaration with no initializer for instance.)
                return labelStatement;
            }

            return BoundStatementList.Synthesized(node.Syntax, labelStatement, rewrittenBody);
        }
        private BoundStatement MakeLabeledStatement(
            BoundLabeledStatement node,
            BoundStatement?rewrittenBody
            )
        {
            BoundStatement labelStatement = new BoundLabelStatement(node.Syntax, node.Label);

            if (this.Instrument)
            {
                var labeledSyntax = node.Syntax as LabeledStatementSyntax;
                if (labeledSyntax != null)
                {
                    labelStatement = _instrumenter.InstrumentLabelStatement(node, labelStatement);
                }
            }

            if (rewrittenBody == null)
            {
                // Body may be null if the body has no associated IL
                // (declaration with no initializer for instance.)
                return(labelStatement);
            }

            return(BoundStatementList.Synthesized(node.Syntax, labelStatement, rewrittenBody));
        }
        public override BoundNode VisitLabeledStatement(BoundLabeledStatement node)
        {
            Debug.Assert(node != null);

            var rewrittenBody = (BoundStatement)Visit(node.Body);

            BoundStatement labelStatement = new BoundLabelStatement(node.Syntax, node.Label);

            if (this.Instrument)
            {
                var labeledSyntax = node.Syntax as LabeledStatementSyntax;
                if (labeledSyntax != null)
                {
                    labelStatement = _instrumenter.InstrumentLabelStatement(node, labelStatement);
                }
            }

            if (rewrittenBody == null)
            {
                // Body may be null if the body has no associated IL
                // (declaration with no initializer for instance.)
                return(labelStatement);
            }

            return(BoundStatementList.Synthesized(node.Syntax, labelStatement, rewrittenBody));
        }
示例#6
0
 public override BoundNode VisitLabelStatement(BoundLabelStatement node)
 {
     if (IsInside)
     {
         _labelsInside.Add(node.Label);
     }
     return(base.VisitLabelStatement(node));
 }
示例#7
0
        private BoundStatement RewriteWhileStatement(
            BoundWhileStatement loop,
            ImmutableArray <LocalSymbol> locals,
            BoundExpression rewrittenCondition,
            BoundStatement rewrittenBody,
            GeneratedLabelSymbol breakLabel,
            GeneratedLabelSymbol continueLabel,
            bool hasErrors)
        {
            if (locals.IsEmpty)
            {
                return(RewriteWhileStatement(loop, rewrittenCondition, rewrittenBody, breakLabel, continueLabel, hasErrors));
            }

            // We need to enter scope-block from the top, that is where an instance of a display class will be created
            // if any local is captured within a lambda.

            // while (condition)
            //   body;
            //
            // becomes
            //
            // continue:
            // {
            //     GotoIfFalse condition break;
            //     body
            //     goto continue;
            // }
            // break:

            SyntaxNode     syntax = loop.Syntax;
            BoundStatement continueLabelStatement  = new BoundLabelStatement(syntax, continueLabel);
            BoundStatement ifNotConditionGotoBreak = new BoundConditionalGoto(rewrittenCondition.Syntax, rewrittenCondition, false, breakLabel);

            if (this.Instrument && !loop.WasCompilerGenerated)
            {
                ifNotConditionGotoBreak = _instrumenter.InstrumentWhileStatementConditionalGotoStartOrBreak(loop, ifNotConditionGotoBreak);
                continueLabelStatement  = new BoundSequencePoint(null, continueLabelStatement);
            }

            return(BoundStatementList.Synthesized(syntax, hasErrors,
                                                  continueLabelStatement,
                                                  new BoundBlock(syntax,
                                                                 locals,
                                                                 ImmutableArray.Create(
                                                                     ifNotConditionGotoBreak,
                                                                     rewrittenBody,
                                                                     new BoundGotoStatement(syntax, continueLabel))),
                                                  new BoundLabelStatement(syntax, breakLabel)));
        }
 public override BoundNode VisitLabelStatement(BoundLabelStatement node)
 {
     CollectLabel(node.Label);
     return base.VisitLabelStatement(node);
 }
示例#9
0
 public override BoundNode VisitLabelStatement(BoundLabelStatement node)
 {
     if (IsInside) _labelsInside.Add(node.Label);
     return base.VisitLabelStatement(node);
 }
示例#10
0
 public override BoundNode VisitLabelStatement(BoundLabelStatement node)
 {
     AddTarget(node.Label);
     return(base.VisitLabelStatement(node));
 }
 public override BoundNode VisitLabelStatement(BoundLabelStatement node)
 {
     CollectLabel(node.Label);
     return(base.VisitLabelStatement(node));
 }
        private BoundStatement RewriteForStatement(
            BoundForStatement node,
            BoundStatement rewrittenInitializer,
            BoundExpression rewrittenCondition,
            BoundStatement rewrittenIncrement,
            BoundStatement rewrittenBody)
        {
            if (node.InnerLocals.IsEmpty)
            {
                return RewriteForStatementWithoutInnerLocals(
                    node,
                    node.OuterLocals,
                    rewrittenInitializer,
                    rewrittenCondition,
                    rewrittenIncrement,
                    rewrittenBody,
                    node.BreakLabel,
                    node.ContinueLabel, node.HasErrors);
            }

            // We need to enter inner_scope-block from the top, that is where an instance of a display class will be created
            // if any local is captured within a lambda.

            // for (initializer; condition; increment)
            //   body;
            //
            // becomes the following (with block added for locals)
            //
            // {
            //   initializer;
            // start:
            //   {
            //     GotoIfFalse condition break;
            //     body;
            // continue:
            //     increment;
            //     goto start;
            //   }
            // break:
            // }

            Debug.Assert(rewrittenBody != null);

            SyntaxNode syntax = node.Syntax;
            var statementBuilder = ArrayBuilder<BoundStatement>.GetInstance();

            //  initializer;
            if (rewrittenInitializer != null)
            {
                statementBuilder.Add(rewrittenInitializer);
            }

            var startLabel = new GeneratedLabelSymbol("start");

            // start:
            BoundStatement startLabelStatement = new BoundLabelStatement(syntax, startLabel);

            if (Instrument)
            {
                startLabelStatement = new BoundSequencePoint(null, startLabelStatement);
            }

            statementBuilder.Add(startLabelStatement);

            var blockBuilder = ArrayBuilder<BoundStatement>.GetInstance();

            // GotoIfFalse condition break;
            if (rewrittenCondition != null)
            {
                BoundStatement ifNotConditionGotoBreak = new BoundConditionalGoto(rewrittenCondition.Syntax, rewrittenCondition, false, node.BreakLabel);

                if (this.Instrument)
                {
                    ifNotConditionGotoBreak = _instrumenter.InstrumentForStatementConditionalGotoStartOrBreak(node, ifNotConditionGotoBreak);
                }

                blockBuilder.Add(ifNotConditionGotoBreak);
            }

            // body;
            blockBuilder.Add(rewrittenBody);

            // continue:
            //   increment;
            blockBuilder.Add(new BoundLabelStatement(syntax, node.ContinueLabel));
            if (rewrittenIncrement != null)
            {
                blockBuilder.Add(rewrittenIncrement);
            }

            // goto start;
            blockBuilder.Add(new BoundGotoStatement(syntax, startLabel));

            statementBuilder.Add(new BoundBlock(syntax, node.InnerLocals, blockBuilder.ToImmutableAndFree()));

            // break:
            statementBuilder.Add(new BoundLabelStatement(syntax, node.BreakLabel));

            var statements = statementBuilder.ToImmutableAndFree();
            return new BoundBlock(syntax, node.OuterLocals, statements, node.HasErrors);
        }
示例#13
0
 public override BoundNode VisitLabelStatement(BoundLabelStatement node)
 {
     AddTarget(node.Label);
     return base.VisitLabelStatement(node);
 }
        private BoundStatement RewriteForStatement(
            BoundForStatement node,
            BoundStatement rewrittenInitializer,
            BoundExpression rewrittenCondition,
            BoundStatement rewrittenIncrement,
            BoundStatement rewrittenBody)
        {
            if (node.InnerLocals.IsEmpty)
            {
                return(RewriteForStatementWithoutInnerLocals(
                           node,
                           node.OuterLocals,
                           rewrittenInitializer,
                           rewrittenCondition,
                           rewrittenIncrement,
                           rewrittenBody,
                           node.BreakLabel,
                           node.ContinueLabel, node.HasErrors));
            }

            // We need to enter inner_scope-block from the top, that is where an instance of a display class will be created
            // if any local is captured within a lambda.

            // for (initializer; condition; increment)
            //   body;
            //
            // becomes the following (with block added for locals)
            //
            // {
            //   initializer;
            // start:
            //   {
            //     GotoIfFalse condition break;
            //     body;
            // continue:
            //     increment;
            //     goto start;
            //   }
            // break:
            // }

            Debug.Assert(rewrittenBody != null);

            SyntaxNode syntax           = node.Syntax;
            var        statementBuilder = ArrayBuilder <BoundStatement> .GetInstance();

            //  initializer;
            if (rewrittenInitializer != null)
            {
                statementBuilder.Add(rewrittenInitializer);
            }

            var startLabel = new GeneratedLabelSymbol("start");

            // start:
            BoundStatement startLabelStatement = new BoundLabelStatement(syntax, startLabel);

            if (Instrument)
            {
                startLabelStatement = new BoundSequencePoint(null, startLabelStatement);
            }

            statementBuilder.Add(startLabelStatement);

            var blockBuilder = ArrayBuilder <BoundStatement> .GetInstance();

            // GotoIfFalse condition break;
            if (rewrittenCondition != null)
            {
                BoundStatement ifNotConditionGotoBreak = new BoundConditionalGoto(rewrittenCondition.Syntax, rewrittenCondition, false, node.BreakLabel);

                if (this.Instrument)
                {
                    ifNotConditionGotoBreak = _instrumenter.InstrumentForStatementConditionalGotoStartOrBreak(node, ifNotConditionGotoBreak);
                }

                blockBuilder.Add(ifNotConditionGotoBreak);
            }

            // body;
            blockBuilder.Add(rewrittenBody);

            // continue:
            //   increment;
            blockBuilder.Add(new BoundLabelStatement(syntax, node.ContinueLabel));
            if (rewrittenIncrement != null)
            {
                blockBuilder.Add(rewrittenIncrement);
            }

            // goto start;
            blockBuilder.Add(new BoundGotoStatement(syntax, startLabel));

            statementBuilder.Add(new BoundBlock(syntax, node.InnerLocals, blockBuilder.ToImmutableAndFree()));

            // break:
            statementBuilder.Add(new BoundLabelStatement(syntax, node.BreakLabel));

            var statements = statementBuilder.ToImmutableAndFree();

            return(new BoundBlock(syntax, node.OuterLocals, statements, node.HasErrors));
        }
        /// <summary>
        /// Generate a thread-safe accessor for a regular field-like event.
        /// 
        /// DelegateType tmp0 = _event; //backing field
        /// DelegateType tmp1;
        /// DelegateType tmp2;
        /// do {
        ///     tmp1 = tmp0;
        ///     tmp2 = (DelegateType)Delegate.Combine(tmp1, value); //Remove for -=
        ///     tmp0 = Interlocked.CompareExchange&lt;DelegateType&gt;(ref _event, tmp2, tmp1);
        /// } while ((object)tmp0 != (object)tmp1);
        /// </summary>
        internal static BoundBlock ConstructFieldLikeEventAccessorBody_Regular(SourceEventSymbol eventSymbol, bool isAddMethod, CSharpCompilation compilation, DiagnosticBag diagnostics)
        {
            CSharpSyntaxNode syntax = eventSymbol.CSharpSyntaxNode;

            TypeSymbol delegateType = eventSymbol.Type;
            MethodSymbol accessor = isAddMethod ? eventSymbol.AddMethod : eventSymbol.RemoveMethod;
            ParameterSymbol thisParameter = accessor.ThisParameter;

            TypeSymbol boolType = compilation.GetSpecialType(SpecialType.System_Boolean);
            MethodSymbol updateMethod = (MethodSymbol)compilation.GetSpecialTypeMember(isAddMethod ? SpecialMember.System_Delegate__Combine : SpecialMember.System_Delegate__Remove);
            MethodSymbol compareExchangeMethod = GetConstructedCompareExchangeMethod(delegateType, compilation, accessor.Locations[0], diagnostics);

            if ((object)compareExchangeMethod == null)
            {
                return new BoundBlock(syntax,
                    locals: ImmutableArray<LocalSymbol>.Empty,
                    statements: ImmutableArray.Create<BoundStatement>(
                        new BoundReturnStatement(syntax,
                            expressionOpt: null)
                { WasCompilerGenerated = true }))
                { WasCompilerGenerated = true };
            }

            GeneratedLabelSymbol loopLabel = new GeneratedLabelSymbol("loop");

            const int numTemps = 3;

            LocalSymbol[] tmps = new LocalSymbol[numTemps];
            BoundLocal[] boundTmps = new BoundLocal[numTemps];

            for (int i = 0; i < numTemps; i++)
            {
                tmps[i] = new SynthesizedLocal(accessor, delegateType, SynthesizedLocalKind.LoweringTemp);
                boundTmps[i] = new BoundLocal(syntax, tmps[i], null, delegateType);
            }

            BoundThisReference fieldReceiver = eventSymbol.IsStatic ?
                null :
                new BoundThisReference(syntax, thisParameter.Type) { WasCompilerGenerated = true };

            BoundFieldAccess boundBackingField = new BoundFieldAccess(syntax,
                receiver: fieldReceiver,
                fieldSymbol: eventSymbol.AssociatedField,
                constantValueOpt: null)
            { WasCompilerGenerated = true };

            BoundParameter boundParameter = new BoundParameter(syntax,
                parameterSymbol: accessor.Parameters[0])
            { WasCompilerGenerated = true };

            // tmp0 = _event;
            BoundStatement tmp0Init = new BoundExpressionStatement(syntax,
                expression: new BoundAssignmentOperator(syntax,
                    left: boundTmps[0],
                    right: boundBackingField,
                    type: delegateType)
            { WasCompilerGenerated = true })
            { WasCompilerGenerated = true };

            // LOOP:
            BoundStatement loopStart = new BoundLabelStatement(syntax,
                label: loopLabel)
            { WasCompilerGenerated = true };

            // tmp1 = tmp0;
            BoundStatement tmp1Update = new BoundExpressionStatement(syntax,
                expression: new BoundAssignmentOperator(syntax,
                    left: boundTmps[1],
                    right: boundTmps[0],
                    type: delegateType)
            { WasCompilerGenerated = true })
            { WasCompilerGenerated = true };

            // (DelegateType)Delegate.Combine(tmp1, value)
            BoundExpression delegateUpdate = BoundConversion.SynthesizedNonUserDefined(syntax,
                operand: BoundCall.Synthesized(syntax,
                    receiverOpt: null,
                    method: updateMethod,
                    arguments: ImmutableArray.Create<BoundExpression>(boundTmps[1], boundParameter)),
                kind: ConversionKind.ExplicitReference,
                type: delegateType);

            // tmp2 = (DelegateType)Delegate.Combine(tmp1, value);
            BoundStatement tmp2Update = new BoundExpressionStatement(syntax,
                expression: new BoundAssignmentOperator(syntax,
                    left: boundTmps[2],
                    right: delegateUpdate,
                    type: delegateType)
            { WasCompilerGenerated = true })
            { WasCompilerGenerated = true };

            // Interlocked.CompareExchange<DelegateType>(ref _event, tmp2, tmp1)
            BoundExpression compareExchange = BoundCall.Synthesized(syntax,
                receiverOpt: null,
                method: compareExchangeMethod,
                arguments: ImmutableArray.Create<BoundExpression>(boundBackingField, boundTmps[2], boundTmps[1]));

            // tmp0 = Interlocked.CompareExchange<DelegateType>(ref _event, tmp2, tmp1);
            BoundStatement tmp0Update = new BoundExpressionStatement(syntax,
                expression: new BoundAssignmentOperator(syntax,
                    left: boundTmps[0],
                    right: compareExchange,
                    type: delegateType)
            { WasCompilerGenerated = true })
            { WasCompilerGenerated = true };

            // tmp0 == tmp1 // i.e. exit when they are equal, jump to start otherwise
            BoundExpression loopExitCondition = new BoundBinaryOperator(syntax,
                operatorKind: BinaryOperatorKind.ObjectEqual,
                left: boundTmps[0],
                right: boundTmps[1],
                constantValueOpt: null,
                methodOpt: null,
                resultKind: LookupResultKind.Viable,
                type: boolType)
            { WasCompilerGenerated = true };
            
            // branchfalse (tmp0 == tmp1) LOOP
            BoundStatement loopEnd = new BoundConditionalGoto(syntax,
                condition: loopExitCondition,
                jumpIfTrue: false,
                label: loopLabel)
            { WasCompilerGenerated = true };

            BoundStatement @return = new BoundReturnStatement(syntax,
                expressionOpt: null)
            { WasCompilerGenerated = true };

            return new BoundBlock(syntax,
                locals: tmps.AsImmutable(),
                statements: ImmutableArray.Create<BoundStatement>(
                    tmp0Init,
                    loopStart,
                    tmp1Update,
                    tmp2Update,
                    tmp0Update,
                    loopEnd,
                    @return))
            { WasCompilerGenerated = true };

        }
示例#16
0
        /// <summary>
        /// Generate a thread-safe accessor for a regular field-like event.
        ///
        /// DelegateType tmp0 = _event; //backing field
        /// DelegateType tmp1;
        /// DelegateType tmp2;
        /// do {
        ///     tmp1 = tmp0;
        ///     tmp2 = (DelegateType)Delegate.Combine(tmp1, value); //Remove for -=
        ///     tmp0 = Interlocked.CompareExchange&lt;DelegateType&gt;(ref _event, tmp2, tmp1);
        /// } while ((object)tmp0 != (object)tmp1);
        ///
        /// Note, if System.Threading.Interlocked.CompareExchange&lt;T&gt; is not available,
        /// we emit the following code and mark the method Synchronized (unless it is a struct).
        ///
        /// _event = (DelegateType)Delegate.Combine(_event, value); //Remove for -=
        ///
        /// </summary>
        internal static BoundBlock ConstructFieldLikeEventAccessorBody_Regular(SourceEventSymbol eventSymbol, bool isAddMethod, CSharpCompilation compilation, DiagnosticBag diagnostics)
        {
            CSharpSyntaxNode syntax = eventSymbol.CSharpSyntaxNode;

            TypeSymbol      delegateType  = eventSymbol.Type;
            MethodSymbol    accessor      = isAddMethod ? eventSymbol.AddMethod : eventSymbol.RemoveMethod;
            ParameterSymbol thisParameter = accessor.ThisParameter;

            TypeSymbol boolType = compilation.GetSpecialType(SpecialType.System_Boolean);

            SpecialMember updateMethodId = isAddMethod ? SpecialMember.System_Delegate__Combine : SpecialMember.System_Delegate__Remove;
            MethodSymbol  updateMethod   = (MethodSymbol)compilation.GetSpecialTypeMember(updateMethodId);

            BoundStatement @return = new BoundReturnStatement(syntax,
                                                              expressionOpt: null)
            {
                WasCompilerGenerated = true
            };

            if (updateMethod == null)
            {
                MemberDescriptor memberDescriptor = SpecialMembers.GetDescriptor(updateMethodId);
                diagnostics.Add(new CSDiagnostic(new CSDiagnosticInfo(ErrorCode.ERR_MissingPredefinedMember,
                                                                      memberDescriptor.DeclaringTypeMetadataName,
                                                                      memberDescriptor.Name),
                                                 syntax.Location));

                return(new BoundBlock(syntax,
                                      locals: ImmutableArray <LocalSymbol> .Empty,
                                      statements: ImmutableArray.Create <BoundStatement>(@return))
                {
                    WasCompilerGenerated = true
                });
            }

            Binder.ReportUseSiteDiagnostics(updateMethod, diagnostics, syntax);

            BoundThisReference fieldReceiver = eventSymbol.IsStatic ?
                                               null :
                                               new BoundThisReference(syntax, thisParameter.Type)
            {
                WasCompilerGenerated = true
            };

            BoundFieldAccess boundBackingField = new BoundFieldAccess(syntax,
                                                                      receiver: fieldReceiver,
                                                                      fieldSymbol: eventSymbol.AssociatedField,
                                                                      constantValueOpt: null)
            {
                WasCompilerGenerated = true
            };

            BoundParameter boundParameter = new BoundParameter(syntax,
                                                               parameterSymbol: accessor.Parameters[0])
            {
                WasCompilerGenerated = true
            };

            BoundExpression delegateUpdate;

            MethodSymbol compareExchangeMethod = (MethodSymbol)compilation.GetWellKnownTypeMember(WellKnownMember.System_Threading_Interlocked__CompareExchange_T);

            if ((object)compareExchangeMethod == null)
            {
                // (DelegateType)Delegate.Combine(_event, value)
                delegateUpdate = BoundConversion.SynthesizedNonUserDefined(syntax,
                                                                           operand: BoundCall.Synthesized(syntax,
                                                                                                          receiverOpt: null,
                                                                                                          method: updateMethod,
                                                                                                          arguments: ImmutableArray.Create <BoundExpression>(boundBackingField, boundParameter)),
                                                                           kind: ConversionKind.ExplicitReference,
                                                                           type: delegateType);

                // _event = (DelegateType)Delegate.Combine(_event, value);
                BoundStatement eventUpdate = new BoundExpressionStatement(syntax,
                                                                          expression: new BoundAssignmentOperator(syntax,
                                                                                                                  left: boundBackingField,
                                                                                                                  right: delegateUpdate,
                                                                                                                  type: delegateType)
                {
                    WasCompilerGenerated = true
                })
                {
                    WasCompilerGenerated = true
                };

                return(new BoundBlock(syntax,
                                      locals: ImmutableArray <LocalSymbol> .Empty,
                                      statements: ImmutableArray.Create <BoundStatement>(
                                          eventUpdate,
                                          @return))
                {
                    WasCompilerGenerated = true
                });
            }

            compareExchangeMethod = compareExchangeMethod.Construct(ImmutableArray.Create <TypeSymbol>(delegateType));

            Binder.ReportUseSiteDiagnostics(compareExchangeMethod, diagnostics, syntax);

            GeneratedLabelSymbol loopLabel = new GeneratedLabelSymbol("loop");

            const int numTemps = 3;

            LocalSymbol[] tmps      = new LocalSymbol[numTemps];
            BoundLocal[]  boundTmps = new BoundLocal[numTemps];

            for (int i = 0; i < numTemps; i++)
            {
                tmps[i]      = new SynthesizedLocal(accessor, delegateType, SynthesizedLocalKind.LoweringTemp);
                boundTmps[i] = new BoundLocal(syntax, tmps[i], null, delegateType);
            }

            // tmp0 = _event;
            BoundStatement tmp0Init = new BoundExpressionStatement(syntax,
                                                                   expression: new BoundAssignmentOperator(syntax,
                                                                                                           left: boundTmps[0],
                                                                                                           right: boundBackingField,
                                                                                                           type: delegateType)
            {
                WasCompilerGenerated = true
            })
            {
                WasCompilerGenerated = true
            };

            // LOOP:
            BoundStatement loopStart = new BoundLabelStatement(syntax,
                                                               label: loopLabel)
            {
                WasCompilerGenerated = true
            };

            // tmp1 = tmp0;
            BoundStatement tmp1Update = new BoundExpressionStatement(syntax,
                                                                     expression: new BoundAssignmentOperator(syntax,
                                                                                                             left: boundTmps[1],
                                                                                                             right: boundTmps[0],
                                                                                                             type: delegateType)
            {
                WasCompilerGenerated = true
            })
            {
                WasCompilerGenerated = true
            };

            // (DelegateType)Delegate.Combine(tmp1, value)
            delegateUpdate = BoundConversion.SynthesizedNonUserDefined(syntax,
                                                                       operand: BoundCall.Synthesized(syntax,
                                                                                                      receiverOpt: null,
                                                                                                      method: updateMethod,
                                                                                                      arguments: ImmutableArray.Create <BoundExpression>(boundTmps[1], boundParameter)),
                                                                       kind: ConversionKind.ExplicitReference,
                                                                       type: delegateType);

            // tmp2 = (DelegateType)Delegate.Combine(tmp1, value);
            BoundStatement tmp2Update = new BoundExpressionStatement(syntax,
                                                                     expression: new BoundAssignmentOperator(syntax,
                                                                                                             left: boundTmps[2],
                                                                                                             right: delegateUpdate,
                                                                                                             type: delegateType)
            {
                WasCompilerGenerated = true
            })
            {
                WasCompilerGenerated = true
            };

            // Interlocked.CompareExchange<DelegateType>(ref _event, tmp2, tmp1)
            BoundExpression compareExchange = BoundCall.Synthesized(syntax,
                                                                    receiverOpt: null,
                                                                    method: compareExchangeMethod,
                                                                    arguments: ImmutableArray.Create <BoundExpression>(boundBackingField, boundTmps[2], boundTmps[1]));

            // tmp0 = Interlocked.CompareExchange<DelegateType>(ref _event, tmp2, tmp1);
            BoundStatement tmp0Update = new BoundExpressionStatement(syntax,
                                                                     expression: new BoundAssignmentOperator(syntax,
                                                                                                             left: boundTmps[0],
                                                                                                             right: compareExchange,
                                                                                                             type: delegateType)
            {
                WasCompilerGenerated = true
            })
            {
                WasCompilerGenerated = true
            };

            // tmp0 == tmp1 // i.e. exit when they are equal, jump to start otherwise
            BoundExpression loopExitCondition = new BoundBinaryOperator(syntax,
                                                                        operatorKind: BinaryOperatorKind.ObjectEqual,
                                                                        left: boundTmps[0],
                                                                        right: boundTmps[1],
                                                                        constantValueOpt: null,
                                                                        methodOpt: null,
                                                                        resultKind: LookupResultKind.Viable,
                                                                        type: boolType)
            {
                WasCompilerGenerated = true
            };

            // branchfalse (tmp0 == tmp1) LOOP
            BoundStatement loopEnd = new BoundConditionalGoto(syntax,
                                                              condition: loopExitCondition,
                                                              jumpIfTrue: false,
                                                              label: loopLabel)
            {
                WasCompilerGenerated = true
            };

            return(new BoundBlock(syntax,
                                  locals: tmps.AsImmutable(),
                                  statements: ImmutableArray.Create <BoundStatement>(
                                      tmp0Init,
                                      loopStart,
                                      tmp1Update,
                                      tmp2Update,
                                      tmp0Update,
                                      loopEnd,
                                      @return))
            {
                WasCompilerGenerated = true
            });
        }
        private BoundStatement RewriteWhileStatement(
            BoundWhileStatement loop,
            ImmutableArray<LocalSymbol> locals,
            BoundExpression rewrittenCondition,
            BoundStatement rewrittenBody,
            GeneratedLabelSymbol breakLabel,
            GeneratedLabelSymbol continueLabel,
            bool hasErrors)
        {
            if (locals.IsEmpty)
            {
                return RewriteWhileStatement(loop, rewrittenCondition, rewrittenBody, breakLabel, continueLabel, hasErrors);
            }

            // We need to enter scope-block from the top, that is where an instance of a display class will be created
            // if any local is captured within a lambda.

            // while (condition) 
            //   body;
            //
            // becomes
            //
            // continue:
            // {
            //     GotoIfFalse condition break;
            //     body
            //     goto continue;
            // }
            // break:

            SyntaxNode syntax = loop.Syntax;
            BoundStatement continueLabelStatement = new BoundLabelStatement(syntax, continueLabel);
            BoundStatement ifNotConditionGotoBreak = new BoundConditionalGoto(rewrittenCondition.Syntax, rewrittenCondition, false, breakLabel);

            if (this.Instrument && !loop.WasCompilerGenerated)
            {
                ifNotConditionGotoBreak = _instrumenter.InstrumentWhileStatementConditionalGotoStartOrBreak(loop, ifNotConditionGotoBreak);
                continueLabelStatement = new BoundSequencePoint(null, continueLabelStatement);
            }

            return BoundStatementList.Synthesized(syntax, hasErrors,
                continueLabelStatement,
                new BoundBlock(syntax,
                               locals,
                               ImmutableArray.Create(
                                    ifNotConditionGotoBreak,
                                    rewrittenBody,
                                    new BoundGotoStatement(syntax, continueLabel))),
                new BoundLabelStatement(syntax, breakLabel));
        }