public BoundExpression Null(TypeSymbol type)
        {
            BoundExpression nullLiteral = new BoundLiteral(Syntax, ConstantValue.Null, type)
            {
                WasCompilerGenerated = true
            };

            return(type.IsPointerType()
                ? BoundConversion.SynthesizedNonUserDefined(Syntax, nullLiteral, ConversionKind.NullToPointer, type)
                : nullLiteral);
        }
示例#2
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
            });
        }