public override BoundNode VisitSwitchDispatch(BoundSwitchDispatch node)
{
BoundSpillSequenceBuilder builder = null;
var expression = VisitExpression(ref builder, node.Expression);
return(UpdateStatement(builder, node.Update(expression, node.Cases, node.DefaultLabel, node.EqualityMethod)));
}
public override BoundNode VisitSwitchDispatch(BoundSwitchDispatch node)
{
AddGoto(node.DefaultLabel);
foreach ((_, LabelSymbol label) in node.Cases)
{
AddGoto(label);
}
return(base.VisitSwitchDispatch(node));
}
private bool GenerateSwitchDispatch(BoundDecisionDagNode node, HashSet <BoundDecisionDagNode> loweredNodes)
{
Debug.Assert(!loweredNodes.Contains(node));
// We only generate a switch dispatch if we have two or more value tests in a row
if (!(node is BoundTestDecisionDagNode firstTestNode &&
firstTestNode.Test is BoundDagValueTest firstTest &&
firstTestNode.WhenFalse is BoundTestDecisionDagNode whenFalse &&
whenFalse.Test is BoundDagValueTest secondTest &&
!loweredNodes.Contains(whenFalse) &&
!this._dagNodeLabels.ContainsKey(whenFalse) &&
firstTest.Input == secondTest.Input &&
firstTest.Input.Type.IsValidV6SwitchGoverningType()))
{
// https://github.com/dotnet/roslyn/issues/12509 Could optimize float, double, decimal value switches. For now use if-then-else
return(false);
}
// Gather up the (value, label) pairs, starting with the first one
var cases = ArrayBuilder <(ConstantValue value, LabelSymbol label)> .GetInstance();
cases.Add((value: firstTest.Value, label: GetDagNodeLabel(firstTestNode.WhenTrue)));
BoundTestDecisionDagNode previous = firstTestNode;
while (previous.WhenFalse is BoundTestDecisionDagNode p &&
p.Test is BoundDagValueTest vd &&
vd.Input == firstTest.Input &&
!this._dagNodeLabels.ContainsKey(p) &&
!loweredNodes.Contains(p))
{
cases.Add((value: vd.Value, label: GetDagNodeLabel(p.WhenTrue)));
loweredNodes.Add(p);
previous = p;
}
// If we are emitting a hash table based string switch,
// we need to generate a helper method for computing
// string hash value in <PrivateImplementationDetails> class.
MethodSymbol?stringEquality = null;
if (firstTest.Input.Type.SpecialType == SpecialType.System_String)
{
EnsureStringHashFunction(cases.Count, node.Syntax);
stringEquality = _localRewriter.UnsafeGetSpecialTypeMethod(node.Syntax, SpecialMember.System_String__op_Equality);
}
LabelSymbol defaultLabel = GetDagNodeLabel(previous.WhenFalse);
var dispatch = new BoundSwitchDispatch(
node.Syntax, _tempAllocator.GetTemp(firstTest.Input), cases.ToImmutableAndFree(), defaultLabel, stringEquality);
_loweredDecisionDag.Add(dispatch);
return(true);
}
public override BoundNode VisitSwitchDispatch(BoundSwitchDispatch node)
{
VisitRvalue(node.Expression);
var state = this.State.Clone();
PendingBranches.Add(new PendingBranch(node, state, node.DefaultLabel));
foreach ((_, LabelSymbol label) in node.Cases)
{
PendingBranches.Add(new PendingBranch(node, state, label));
}
SetUnreachable();
return(null);
}
