public sealed override BoundNode VisitBinaryOperator(BoundBinaryOperator node)
{
BoundExpression child = node.Left;
if (child.Kind != BoundKind.BinaryOperator)
{
return(base.VisitBinaryOperator(node));
}
var stack = ArrayBuilder <BoundBinaryOperator> .GetInstance();
stack.Push(node);
BoundBinaryOperator binary = (BoundBinaryOperator)child;
while (true)
{
stack.Push(binary);
child = binary.Left;
if (child.Kind != BoundKind.BinaryOperator)
{
break;
}
binary = (BoundBinaryOperator)child;
}
var left = (BoundExpression)this.Visit(child);
do
{
binary = stack.Pop();
var right = (BoundExpression)this.Visit(binary.Right);
var type = this.VisitType(binary.Type);
left = binary.Update(binary.OperatorKind, binary.ConstantValueOpt, binary.MethodOpt, binary.ResultKind, left, right, type);
}while (stack.Count > 0);
Debug.Assert((object)binary == node);
stack.Free();
return(left);
}
private void CheckRelationals(BoundBinaryOperator node)
{
Debug.Assert(node != null);
if (!node.OperatorKind.IsComparison())
{
return;
}
// Don't bother to check vacuous comparisons where both sides are constant, eg, where someone
// is doing something like "if (0xFFFFFFFFU == 0)" -- these are likely to be machine-
// generated code.
if (node.Left.ConstantValue != null && node.Right.ConstantValue == null && node.Right.Kind == BoundKind.Conversion)
{
CheckVacuousComparisons(node, node.Left.ConstantValue, node.Right);
}
if (node.Right.ConstantValue != null && node.Left.ConstantValue == null && node.Left.Kind == BoundKind.Conversion)
{
CheckVacuousComparisons(node, node.Right.ConstantValue, node.Left);
}
if (node.OperatorKind == BinaryOperatorKind.ObjectEqual || node.OperatorKind == BinaryOperatorKind.ObjectNotEqual)
{
TypeSymbol t;
if (node.Left.Type.SpecialType == SpecialType.System_Object && !IsExplicitCast(node.Left) && !(node.Left.ConstantValue != null && node.Left.ConstantValue.IsNull) && ConvertedHasEqual(node.OperatorKind, node.Right, out t))
{
// Possible unintended reference comparison; to get a value comparison, cast the left hand side to type '{0}'
_diagnostics.Add(ErrorCode.WRN_BadRefCompareLeft, node.Syntax.Location, t);
}
else if (node.Right.Type.SpecialType == SpecialType.System_Object && !IsExplicitCast(node.Right) && !(node.Right.ConstantValue != null && node.Right.ConstantValue.IsNull) && ConvertedHasEqual(node.OperatorKind, node.Left, out t))
{
// Possible unintended reference comparison; to get a value comparison, cast the right hand side to type '{0}'
_diagnostics.Add(ErrorCode.WRN_BadRefCompareRight, node.Syntax.Location, t);
}
}
CheckSelfComparisons(node);
}
public override BoundNode VisitBinaryOperator(BoundBinaryOperator node)
{
BoundSpillSequenceBuilder builder = null;
var right = VisitExpression(ref builder, node.Right);
BoundExpression left;
if (builder == null)
{
left = VisitExpression(ref builder, node.Left);
}
else
{
var leftBuilder = new BoundSpillSequenceBuilder();
left = VisitExpression(ref leftBuilder, node.Left);
left = Spill(leftBuilder, left);
if (node.OperatorKind == BinaryOperatorKind.LogicalBoolOr || node.OperatorKind == BinaryOperatorKind.LogicalBoolAnd)
{
var tmp = _F.SynthesizedLocal(node.Type, kind: SynthesizedLocalKind.Spill, syntax: _F.Syntax);
leftBuilder.AddLocal(tmp);
leftBuilder.AddStatement(_F.Assignment(_F.Local(tmp), left));
leftBuilder.AddStatement(_F.If(
node.OperatorKind == BinaryOperatorKind.LogicalBoolAnd ? _F.Local(tmp) : _F.Not(_F.Local(tmp)),
UpdateStatement(builder, _F.Assignment(_F.Local(tmp), right))));
return(UpdateExpression(leftBuilder, _F.Local(tmp)));
}
else
{
// if the right-hand-side has await, spill the left
leftBuilder.Include(builder);
builder = leftBuilder;
}
}
return(UpdateExpression(builder, node.Update(node.OperatorKind, node.ConstantValue, node.MethodOpt, node.ResultKind, left, right, node.Type)));
}
/// <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<DelegateType>(ref _event, tmp2, tmp1);
/// } while ((object)tmp0 != (object)tmp1);
///
/// Note, if System.Threading.Interlocked.CompareExchange<T> 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.TypeSymbol;
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,
refKind: RefKind.None,
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(BoundBlock.SynthesizedNoLocals(syntax, @return));
}
Binder.ReportUseSiteDiagnostics(updateMethod, diagnostics, syntax);
BoundThisReference fieldReceiver = eventSymbol.IsStatic ?
null :
new BoundThisReference(syntax, thisParameter.Type.TypeSymbol)
{
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)),
conversion: Conversion.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(BoundBlock.SynthesizedNoLocals(syntax,
statements: ImmutableArray.Create <BoundStatement>(
eventUpdate,
@return)));
}
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, TypeSymbolWithAnnotations.Create(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)),
conversion: Conversion.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 void CheckLiftedBinOp(BoundBinaryOperator node)
{
Debug.Assert(node != null);
if (!node.OperatorKind.IsLifted())
{
return;
}
switch (node.OperatorKind.Operator())
{
case BinaryOperatorKind.LessThan:
case BinaryOperatorKind.LessThanOrEqual:
case BinaryOperatorKind.GreaterThan:
case BinaryOperatorKind.GreaterThanOrEqual:
// CS0464: Comparing with null of type '{0}' always produces 'false'
//
// Produce the warning if one (or both) sides are always null.
if (node.Right.NullableNeverHasValue())
{
Error(ErrorCode.WRN_CmpAlwaysFalse, node, GetTypeForLiftedComparisonWarning(node.Right));
}
else if (node.Left.NullableNeverHasValue())
{
Error(ErrorCode.WRN_CmpAlwaysFalse, node, GetTypeForLiftedComparisonWarning(node.Left));
}
break;
case BinaryOperatorKind.Equal:
case BinaryOperatorKind.NotEqual:
// CS0472: The result of the expression is always '{0}' since a value of type '{1}' is never equal to 'null' of type '{2}'
//
// Produce the warning if one side is always null and the other is never null.
// That is, we have something like "if (myInt == null)"
string always = node.OperatorKind.Operator() == BinaryOperatorKind.NotEqual ? "true" : "false";
if (_compilation.FeatureStrictEnabled || !node.OperatorKind.IsUserDefined())
{
if (node.Right.NullableNeverHasValue() && node.Left.NullableAlwaysHasValue())
{
Error(node.OperatorKind.IsUserDefined() ? ErrorCode.WRN_NubExprIsConstBool2 : ErrorCode.WRN_NubExprIsConstBool, node, always, node.Left.Type.GetNullableUnderlyingType(), GetTypeForLiftedComparisonWarning(node.Right));
}
else if (node.Left.NullableNeverHasValue() && node.Right.NullableAlwaysHasValue())
{
Error(node.OperatorKind.IsUserDefined() ? ErrorCode.WRN_NubExprIsConstBool2 : ErrorCode.WRN_NubExprIsConstBool, node, always, node.Right.Type.GetNullableUnderlyingType(), GetTypeForLiftedComparisonWarning(node.Left));
}
}
break;
case BinaryOperatorKind.Or:
case BinaryOperatorKind.And:
// CS0458: The result of the expression is always 'null' of type '{0}'
if ((node.Left.NullableNeverHasValue() && node.Right.IsNullableNonBoolean()) ||
(node.Left.IsNullableNonBoolean() && node.Right.NullableNeverHasValue()))
{
Error(ErrorCode.WRN_AlwaysNull, node, node.Type);
}
break;
default:
// CS0458: The result of the expression is always 'null' of type '{0}'
if (node.Right.NullableNeverHasValue() || node.Left.NullableNeverHasValue())
{
Error(ErrorCode.WRN_AlwaysNull, node, node.Type);
}
break;
}
}
private void CheckVacuousComparisons(BoundBinaryOperator tree, ConstantValue constantValue, BoundNode operand)
{
Debug.Assert(tree != null);
Debug.Assert(constantValue != null);
Debug.Assert(operand != null);
// We wish to detect comparisons between integers and constants which are likely to be wrong
// because we know at compile time whether they will be true or false. For example:
//
// const short s = 1000;
// byte b = whatever;
// if (b < s)
//
// We know that this will always be true because when b and s are both converted to int for
// the comparison, the left side will always be less than the right side.
//
// We only give the warning if there is no explicit conversion involved on the operand.
// For example, if we had:
//
// const uint s = 1000;
// sbyte b = whatever;
// if ((byte)b < s)
//
// Then we do not give a warning.
//
// Note that the native compiler has what looks to be some dead code. It checks to see
// if the conversion on the operand is from an enum type. But this is unnecessary if
// we are rejecting cases with explicit conversions. The only possible cases are:
//
// enum == enumConstant -- enum types must be the same, so it must be in range.
// enum == integralConstant -- not legal unless the constant is zero, which is in range.
// enum == (ENUM)anyConstant -- if the constant is out of range then this is not legal in the first place
// unless we're in an unchecked context, in which case, the user probably does
// not want the warning.
// integral == enumConstant -- never legal in the first place
//
// Since it seems pointless to try to check enums, we simply look for vacuous comparisons of
// integral types here.
for (BoundConversion conversion = operand as BoundConversion;
conversion != null;
conversion = conversion.Operand as BoundConversion)
{
if (conversion.ConversionKind != ConversionKind.ImplicitNumeric &&
conversion.ConversionKind != ConversionKind.ImplicitConstant)
{
return;
}
// As in dev11, we don't dig through explicit casts (see ExpressionBinder::WarnAboutBadRelationals).
if (conversion.ExplicitCastInCode)
{
return;
}
if (!conversion.Operand.Type.SpecialType.IsIntegralType() || !conversion.Type.SpecialType.IsIntegralType())
{
return;
}
if (!Binder.CheckConstantBounds(conversion.Operand.Type.SpecialType, constantValue))
{
Error(ErrorCode.WRN_VacuousIntegralComp, tree, conversion.Operand.Type);
return;
}
}
}
public override BoundNode VisitBinaryOperator(BoundBinaryOperator node)
{
throw ExceptionUtilities.Unreachable;
}
