private static ImmutableHashSet <CaptureId> CreateLValueFlowCaptures(ControlFlowGraph cfg)
{
var lvalueFlowCaptureIdBuilder = PooledHashSet <CaptureId> .GetInstance();
#if DEBUG
var rvalueFlowCaptureIds = new Dictionary <CaptureId, HashSet <IFlowCaptureReferenceOperation> >();
#endif
foreach (var flowCaptureReference in cfg.DescendantOperations <IFlowCaptureReferenceOperation>(OperationKind.FlowCaptureReference))
{
if (flowCaptureReference.IsLValueFlowCaptureReference())
{
lvalueFlowCaptureIdBuilder.Add(flowCaptureReference.Id);
}
#if DEBUG
else
{
if (!rvalueFlowCaptureIds.TryGetValue(flowCaptureReference.Id, out var operations))
{
operations = new HashSet <IFlowCaptureReferenceOperation>();
rvalueFlowCaptureIds[flowCaptureReference.Id] = operations;
}
operations.Add(flowCaptureReference);
}
#endif
}
#if DEBUG
if (lvalueFlowCaptureIdBuilder.Count > 0)
{
foreach (var captureId in lvalueFlowCaptureIdBuilder)
{
if (rvalueFlowCaptureIds.ContainsKey(captureId))
{
// Flow capture reference is used on left side as well as right side for
// CFG generated for coalesce assignment operation ('??=')
// Do not fire an assert for this known anomaly.
var operations = rvalueFlowCaptureIds[captureId];
if (operations.Count == 1 &&
operations.Single().Parent?.Kind == OperationKind.FlowCapture)
{
continue;
}
Debug.Fail("Flow capture used as both an r-value and an l-value?");
}
}
}
#endif
return(lvalueFlowCaptureIdBuilder.ToImmutableAndFree());
}
private static ImmutableHashSet <CaptureId> CreateLValueFlowCaptures(ControlFlowGraph cfg)
{
var lvalueFlowCaptureIdBuilder = PooledHashSet <CaptureId> .GetInstance();
#if DEBUG
var rvalueFlowCaptureIds = new HashSet <CaptureId>();
#endif
foreach (var flowCaptureReference in cfg.DescendantOperations <IFlowCaptureReferenceOperation>(OperationKind.FlowCaptureReference))
{
if (flowCaptureReference.Parent is IAssignmentOperation assignment &&
assignment.Target == flowCaptureReference)
{
lvalueFlowCaptureIdBuilder.Add(flowCaptureReference.Id);
}
public static ImmutableDictionary <CaptureId, FlowCaptureKind> CreateLValueFlowCaptures(ControlFlowGraph cfg)
{
// This method identifies flow capture reference operations that are target of an assignment
// and marks them as lvalue flow captures.
// Control flow graph can also contain flow captures
// that are r-value captures at some point and l-values captures at other point in
// the flow graph. Specifically, for an ICoalesceOperation a flow capture acts
// as both an r-value and l-value flow capture.
ImmutableDictionary <CaptureId, FlowCaptureKind> .Builder lvalueFlowCaptureIdBuilder = null;
var rvalueFlowCaptureIds = new HashSet <CaptureId> ();
foreach (var flowCaptureReference in cfg.DescendantOperations <IFlowCaptureReferenceOperation> (OperationKind.FlowCaptureReference))
{
if (flowCaptureReference.Parent is IAssignmentOperation assignment &&
assignment.Target == flowCaptureReference ||
flowCaptureReference.IsInLeftOfDeconstructionAssignment(out _))
{
lvalueFlowCaptureIdBuilder ??= ImmutableDictionary.CreateBuilder <CaptureId, FlowCaptureKind> ();
var captureKind = flowCaptureReference.Parent.IsAnyCompoundAssignment() || rvalueFlowCaptureIds.Contains(flowCaptureReference.Id)
? FlowCaptureKind.LValueAndRValueCapture
: FlowCaptureKind.LValueCapture;
lvalueFlowCaptureIdBuilder.Add(flowCaptureReference.Id, captureKind);
}
public static IEnumerable <T> DescendantOperations <T> (this ControlFlowGraph cfg, OperationKind operationKind)
where T : IOperation
=> cfg.DescendantOperations().Where(d => d?.Kind == operationKind).Cast <T> ();
