public override BoundNode VisitNullCoalescingOperator(BoundNullCoalescingOperator node)
{
// TestExpression ?? ElseExpression
if (node.ConstantValue == null && !node.HasErrors)
{
var testExpression = node.TestExpression;
ConstantValue testExpressionConstantValue = testExpression.ConstantValue;
if (testExpressionConstantValue != null)
{
// testExpression is a known compile time constant
if (testExpressionConstantValue == ConstantValue.Null)
{
// testExpression is always null
return(Visit(node.ElseExpression));
}
// testExpression is always non null constant
return(Visit(node.LeftConversion ?? node.TestExpression));
}
else
{
TypeSymbol exprType = node.Type;
BoundExpression elseExpression = node.ElseExpression;
BoundExpression leftConversion = node.LeftConversion; //it's a BoundConversion, but we're passing by ref
// There are two ways that a conversion of the test expression can be represented:
// 1) If it was cast in source, then node.TestExpression could be a BoundConversion, or
// 2) If the compiler generated a conversion to reconcile the types, then node.LeftConversion could be non-null.
if (leftConversion == null)
{
if (IsUpdateRequiredForExplicitConversion(exprType, ref testExpression, ref elseExpression))
{
return(node.Update(
testExpression,
elseExpression,
leftConversion: null,
constantValueOpt: null,
type: exprType));
}
}
else if (IsUpdateRequiredForExplicitConversion(exprType, ref leftConversion, ref elseExpression))
{
return(node.Update(
(BoundExpression)Visit(testExpression),
elseExpression,
(BoundConversion)leftConversion,
constantValueOpt: null,
type: exprType));
}
}
}
return(base.VisitNullCoalescingOperator(node));
}
public override BoundNode VisitNullCoalescingOperator(BoundNullCoalescingOperator node)
{
BoundSpillSequenceBuilder builder = null;
var right = VisitExpression(ref builder, node.RightOperand);
BoundExpression left;
if (builder == null)
{
left = VisitExpression(ref builder, node.LeftOperand);
}
else
{
var leftBuilder = new BoundSpillSequenceBuilder();
left = VisitExpression(ref leftBuilder, node.LeftOperand);
left = Spill(leftBuilder, left);
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(
_F.ObjectEqual(_F.Local(tmp), _F.Null(left.Type)),
UpdateStatement(builder, _F.Assignment(_F.Local(tmp), right))));
return(UpdateExpression(leftBuilder, _F.Local(tmp)));
}
return(UpdateExpression(builder, node.Update(left, right, node.LeftConversion, node.OperatorResultKind, node.Type)));
}
public override BoundNode VisitNullCoalescingOperator(BoundNullCoalescingOperator node)
{
BoundSpillSequenceBuilder builder = null;
var right = VisitExpression(ref builder, node.RightOperand);
BoundExpression left;
if (builder == null)
{
left = VisitExpression(ref builder, node.LeftOperand);
}
else
{
var leftBuilder = new BoundSpillSequenceBuilder();
left = VisitExpression(ref leftBuilder, node.LeftOperand);
left = Spill(leftBuilder, left);
leftBuilder.AddStatement(_F.If(
_F.ObjectEqual(left, _F.Null(left.Type)),
UpdateStatement(builder, _F.Assignment(left, right), substituteTemps: false)));
return(UpdateExpression(leftBuilder, left));
}
return(UpdateExpression(builder, node.Update(left, right, node.LeftConversion, node.Type)));
}
public override BoundNode VisitNullCoalescingOperator(BoundNullCoalescingOperator node)
{
BoundSpillSequence2 ss = null;
var right = VisitExpression(ref ss, node.RightOperand);
BoundExpression left;
if (ss == null)
{
left = VisitExpression(ref ss, node.LeftOperand);
}
else
{
var ssLeft = new BoundSpillSequence2();
left = VisitExpression(ref ssLeft, node.LeftOperand);
left = Spill(ssLeft, left);
ssLeft.Add(F.If(
F.ObjectEqual(left, F.Null(left.Type)),
UpdateStatement(ss, F.Assignment(left, right))
));
return(UpdateExpression(ssLeft, left));
}
return(UpdateExpression(ss, node.Update(left, right, node.LeftConversion, node.Type)));
}
public override BoundNode VisitNullCoalescingOperator(BoundNullCoalescingOperator node)
{
var origStack = StackDepth();
BoundExpression left = (BoundExpression)this.Visit(node.LeftOperand);
var cookie = GetStackStateCookie(); // implicit branch here
// right is evaluated with original stack
// (this is not entirely true, codegen may keep left on the stack as an ephemeral temp, but that is irrelevant here)
SetStackDepth(origStack);
BoundExpression right = (BoundExpression)this.Visit(node.RightOperand);
EnsureStackState(cookie); // implicit label here
return node.Update(left, right, node.LeftConversion, node.Type);
}
public override BoundNode VisitNullCoalescingOperator(BoundNullCoalescingOperator node)
{
// TestExpression ?? ElseExpression
if (node.ConstantValue == null && !node.HasErrors)
{
var testExpression = node.TestExpression;
ConstantValue testExpressionConstantValue = testExpression.ConstantValue;
if (testExpressionConstantValue != null)
{
// testExpression is a known compile time constant
if (testExpressionConstantValue == ConstantValue.Null)
{
// testExpression is always null
return Visit(node.ElseExpression);
}
// testExpression is always non null constant
return Visit(node.LeftConversion ?? node.TestExpression);
}
else
{
TypeSymbol exprType = node.Type;
BoundExpression elseExpression = node.ElseExpression;
BoundExpression leftConversion = node.LeftConversion; //it's a BoundConversion, but we're passing by ref
// There are two ways that a conversion of the test expression can be represented:
// 1) If it was cast in source, then node.TestExpression could be a BoundConversion, or
// 2) If the compiler generated a conversion to reconcile the types, then node.LeftConversion could be non-null.
if (leftConversion == null)
{
if (IsUpdateRequiredForExplicitConversion(exprType, ref testExpression, ref elseExpression))
{
return node.Update(
testExpression,
elseExpression,
leftConversion: null,
constantValueOpt: null,
type: exprType);
}
}
else if (IsUpdateRequiredForExplicitConversion(exprType, ref leftConversion, ref elseExpression))
{
return node.Update(
(BoundExpression)Visit(testExpression),
elseExpression,
(BoundConversion)leftConversion,
constantValueOpt: null,
type: exprType);
}
}
}
return base.VisitNullCoalescingOperator(node);
}