private BoundNode VisitStackAllocArrayCreationBase(
BoundStackAllocArrayCreationBase stackAllocNode
)
{
var rewrittenCount = VisitExpression(stackAllocNode.Count);
var type = stackAllocNode.Type;
Debug.Assert(type is { });
private BoundNode VisitStackAllocArrayCreationBase(BoundStackAllocArrayCreationBase stackAllocNode)
{
var rewrittenCount = VisitExpression(stackAllocNode.Count);
var type = stackAllocNode.Type;
if (rewrittenCount.ConstantValue?.Int32Value == 0)
{
// either default(span) or nullptr
return(_factory.Default(type));
}
var elementType = stackAllocNode.ElementType;
var initializerOpt = stackAllocNode.InitializerOpt;
if (initializerOpt != null)
{
initializerOpt = initializerOpt.Update(VisitList(initializerOpt.Initializers));
}
if (type.IsPointerType())
{
var stackSize = RewriteStackAllocCountToSize(rewrittenCount, elementType);
return(new BoundConvertedStackAllocExpression(stackAllocNode.Syntax, elementType, stackSize, initializerOpt, stackAllocNode.Type));
}
else if (TypeSymbol.Equals(type.OriginalDefinition, _compilation.GetWellKnownType(WellKnownType.System_Span_T), TypeCompareKind.ConsiderEverything2))
{
var spanType = (NamedTypeSymbol)stackAllocNode.Type;
var sideEffects = ArrayBuilder <BoundExpression> .GetInstance();
var locals = ArrayBuilder <LocalSymbol> .GetInstance();
var countTemp = CaptureExpressionInTempIfNeeded(rewrittenCount, sideEffects, locals, SynthesizedLocalKind.Spill);
var stackSize = RewriteStackAllocCountToSize(countTemp, elementType);
stackAllocNode = new BoundConvertedStackAllocExpression(
stackAllocNode.Syntax, elementType, stackSize, initializerOpt, _compilation.CreatePointerTypeSymbol(elementType));
BoundExpression constructorCall;
if (TryGetWellKnownTypeMember(stackAllocNode.Syntax, WellKnownMember.System_Span_T__ctor, out MethodSymbol spanConstructor))
{
constructorCall = _factory.New((MethodSymbol)spanConstructor.SymbolAsMember(spanType), stackAllocNode, countTemp);
}
else
{
constructorCall = new BoundBadExpression(
syntax: stackAllocNode.Syntax,
resultKind: LookupResultKind.NotInvocable,
symbols: ImmutableArray <Symbol> .Empty,
childBoundNodes: ImmutableArray <BoundExpression> .Empty,
type: ErrorTypeSymbol.UnknownResultType);
}
// The stackalloc instruction requires that the evaluation stack contains only its parameter when executed.
// We arrange to clear the stack by wrapping it in a SpillSequence, which will cause pending computations
// to be spilled, and also by storing the result in a temporary local, so that the result does not get
// hoisted/spilled into some state machine. If that temp local needs to be spilled that will result in an
// error.
_needsSpilling = true;
var tempAccess = _factory.StoreToTemp(constructorCall, out BoundAssignmentOperator tempAssignment, syntaxOpt: stackAllocNode.Syntax);
sideEffects.Add(tempAssignment);
locals.Add(tempAccess.LocalSymbol);
return(new BoundSpillSequence(
syntax: stackAllocNode.Syntax,
locals: locals.ToImmutableAndFree(),
sideEffects: sideEffects.ToImmutableAndFree(),
value: tempAccess,
type: spanType));
}
else
{
throw ExceptionUtilities.UnexpectedValue(type);
}
}
