private BoundExpression LowerSwitchExpression(BoundConvertedSwitchExpression node)
{
// When compiling for Debug (not Release), we produce the most detailed sequence points.
var produceDetailedSequencePoints =
GenerateInstrumentation && _localRewriter._compilation.Options.OptimizationLevel != OptimizationLevel.Release;
_factory.Syntax = node.Syntax;
var result = ArrayBuilder <BoundStatement> .GetInstance();
var outerVariables = ArrayBuilder <LocalSymbol> .GetInstance();
var loweredSwitchGoverningExpression = _localRewriter.VisitExpression(node.Expression);
BoundDecisionDag decisionDag = ShareTempsIfPossibleAndEvaluateInput(
node.DecisionDag, loweredSwitchGoverningExpression, result, out BoundExpression savedInputExpression);
Debug.Assert(savedInputExpression != null);
object restorePointForEnclosingStatement = new object();
object restorePointForSwitchBody = new object();
// lower the decision dag.
(ImmutableArray <BoundStatement> loweredDag, ImmutableDictionary <SyntaxNode, ImmutableArray <BoundStatement> > switchSections) =
LowerDecisionDag(decisionDag);
if (_whenNodeIdentifierLocal is not null)
{
outerVariables.Add(_whenNodeIdentifierLocal);
}
if (produceDetailedSequencePoints)
{
var syntax = (SwitchExpressionSyntax)node.Syntax;
result.Add(new BoundSavePreviousSequencePoint(syntax, restorePointForEnclosingStatement));
// While evaluating the state machine, we highlight the `switch {...}` part.
var spanStart = syntax.SwitchKeyword.Span.Start;
var spanEnd = syntax.Span.End;
var spanForSwitchBody = new TextSpan(spanStart, spanEnd - spanStart);
result.Add(new BoundStepThroughSequencePoint(node.Syntax, span: spanForSwitchBody));
result.Add(new BoundSavePreviousSequencePoint(syntax, restorePointForSwitchBody));
}
// add the rest of the lowered dag that references that input
result.Add(_factory.Block(loweredDag));
// A branch to the default label when no switch case matches is included in the
// decision tree, so the code in result is unreachable at this point.
// Lower each switch expression arm
LocalSymbol resultTemp = _factory.SynthesizedLocal(node.Type, node.Syntax, kind: SynthesizedLocalKind.LoweringTemp);
LabelSymbol afterSwitchExpression = _factory.GenerateLabel("afterSwitchExpression");
foreach (BoundSwitchExpressionArm arm in node.SwitchArms)
{
_factory.Syntax = arm.Syntax;
var sectionBuilder = ArrayBuilder <BoundStatement> .GetInstance();
sectionBuilder.AddRange(switchSections[arm.Syntax]);
sectionBuilder.Add(_factory.Label(arm.Label));
var loweredValue = _localRewriter.VisitExpression(arm.Value);
if (GenerateInstrumentation)
{
loweredValue = this._localRewriter._instrumenter.InstrumentSwitchExpressionArmExpression(arm.Value, loweredValue, _factory);
}
sectionBuilder.Add(_factory.Assignment(_factory.Local(resultTemp), loweredValue));
sectionBuilder.Add(_factory.Goto(afterSwitchExpression));
var statements = sectionBuilder.ToImmutableAndFree();
if (arm.Locals.IsEmpty)
{
result.Add(_factory.StatementList(statements));
}
else
{
// Lifetime of these locals is expanded to the entire switch body, as it is possible to
// share them as temps in the decision dag.
outerVariables.AddRange(arm.Locals);
// Note the language scope of the locals, even though they are included for the purposes of
// lifetime analysis in the enclosing scope.
result.Add(new BoundScope(arm.Syntax, arm.Locals, statements));
}
}
_factory.Syntax = node.Syntax;
if (node.DefaultLabel != null)
{
result.Add(_factory.Label(node.DefaultLabel));
if (produceDetailedSequencePoints)
{
result.Add(new BoundRestorePreviousSequencePoint(node.Syntax, restorePointForSwitchBody));
}
var objectType = _factory.SpecialType(SpecialType.System_Object);
var thrownExpression =
(implicitConversionExists(savedInputExpression, objectType) &&
_factory.WellKnownMember(WellKnownMember.System_Runtime_CompilerServices_SwitchExpressionException__ctorObject, isOptional: true) is MethodSymbol exception1)
? _factory.New(exception1, _factory.Convert(objectType, savedInputExpression)) :
(_factory.WellKnownMember(WellKnownMember.System_Runtime_CompilerServices_SwitchExpressionException__ctor, isOptional: true) is MethodSymbol exception0)
? _factory.New(exception0) :
_factory.New(_factory.WellKnownMethod(WellKnownMember.System_InvalidOperationException__ctor));
result.Add(_factory.Throw(thrownExpression));
}
if (GenerateInstrumentation)
{
result.Add(_factory.HiddenSequencePoint());
}
result.Add(_factory.Label(afterSwitchExpression));
if (produceDetailedSequencePoints)
{
result.Add(new BoundRestorePreviousSequencePoint(node.Syntax, restorePointForEnclosingStatement));
}
outerVariables.Add(resultTemp);
outerVariables.AddRange(_tempAllocator.AllTemps());
return(_factory.SpillSequence(outerVariables.ToImmutableAndFree(), result.ToImmutableAndFree(), _factory.Local(resultTemp)));
bool implicitConversionExists(BoundExpression expression, TypeSymbol type)
{
var discardedUseSiteInfo = CompoundUseSiteInfo <AssemblySymbol> .Discarded;
Conversion c = _localRewriter._compilation.Conversions.ClassifyConversionFromExpression(expression, type, ref discardedUseSiteInfo);
return(c.IsImplicit);
}
}
private SwitchExpressionLocalRewriter(BoundConvertedSwitchExpression node, LocalRewriter localRewriter)
: base(node.Syntax, localRewriter, node.SwitchArms.SelectAsArray(arm => arm.Syntax),
generateInstrumentation: !node.WasCompilerGenerated && localRewriter.Instrument)
{
}
private BoundExpression LowerSwitchExpression(BoundConvertedSwitchExpression node)
{
_factory.Syntax = node.Syntax;
var result = ArrayBuilder <BoundStatement> .GetInstance();
var outerVariables = ArrayBuilder <LocalSymbol> .GetInstance();
var loweredSwitchGoverningExpression = _localRewriter.VisitExpression(node.Expression);
BoundDecisionDag decisionDag = ShareTempsIfPossibleAndEvaluateInput(
node.DecisionDag, loweredSwitchGoverningExpression, result, out BoundExpression savedInputExpression);
Debug.Assert(savedInputExpression != null);
// lower the decision dag.
(ImmutableArray <BoundStatement> loweredDag, ImmutableDictionary <SyntaxNode, ImmutableArray <BoundStatement> > switchSections) =
LowerDecisionDag(decisionDag);
// then add the rest of the lowered dag that references that input
result.Add(_factory.Block(loweredDag));
// A branch to the default label when no switch case matches is included in the
// decision tree, so the code in result is unreachable at this point.
// Lower each switch expression arm
LocalSymbol resultTemp = _factory.SynthesizedLocal(node.Type, node.Syntax, kind: SynthesizedLocalKind.LoweringTemp);
LabelSymbol afterSwitchExpression = _factory.GenerateLabel("afterSwitchExpression");
foreach (BoundSwitchExpressionArm arm in node.SwitchArms)
{
_factory.Syntax = arm.Syntax;
var sectionBuilder = ArrayBuilder <BoundStatement> .GetInstance();
sectionBuilder.AddRange(switchSections[arm.Syntax]);
sectionBuilder.Add(_factory.Label(arm.Label));
sectionBuilder.Add(_factory.Assignment(_factory.Local(resultTemp), _localRewriter.VisitExpression(arm.Value)));
sectionBuilder.Add(_factory.Goto(afterSwitchExpression));
var statements = sectionBuilder.ToImmutableAndFree();
if (arm.Locals.IsEmpty)
{
result.Add(_factory.StatementList(statements));
}
else
{
// Lifetime of these locals is expanded to the entire switch body, as it is possible to
// share them as temps in the decision dag.
outerVariables.AddRange(arm.Locals);
// Note the language scope of the locals, even though they are included for the purposes of
// lifetime analysis in the enclosing scope.
result.Add(new BoundScope(arm.Syntax, arm.Locals, statements));
}
}
_factory.Syntax = node.Syntax;
if (node.DefaultLabel != null)
{
result.Add(_factory.Label(node.DefaultLabel));
var objectType = _factory.SpecialType(SpecialType.System_Object);
var thrownExpression =
(implicitConversionExists(savedInputExpression, objectType) &&
_factory.WellKnownMember(WellKnownMember.System_Runtime_CompilerServices_SwitchExpressionException__ctorObject, isOptional: true) is MethodSymbol exception1)
? _factory.New(exception1, _factory.Convert(objectType, savedInputExpression)) :
(_factory.WellKnownMember(WellKnownMember.System_Runtime_CompilerServices_SwitchExpressionException__ctor, isOptional: true) is MethodSymbol exception0)
? _factory.New(exception0) :
_factory.New(_factory.WellKnownMethod(WellKnownMember.System_InvalidOperationException__ctor));
result.Add(_factory.Throw(thrownExpression));
}
result.Add(_factory.Label(afterSwitchExpression));
outerVariables.Add(resultTemp);
outerVariables.AddRange(_tempAllocator.AllTemps());
return(_factory.SpillSequence(outerVariables.ToImmutableAndFree(), result.ToImmutableAndFree(), _factory.Local(resultTemp)));
bool implicitConversionExists(BoundExpression expression, TypeSymbol type)
{
HashSet <DiagnosticInfo> discarded = null;
Conversion c = _localRewriter._compilation.Conversions.ClassifyConversionFromExpression(expression, type, ref discarded);
return(c.IsImplicit);
}
}
public override BoundNode VisitConvertedSwitchExpression(BoundConvertedSwitchExpression node)
{
return(this.VisitSwitchExpression(node));
}
private SwitchExpressionLocalRewriter(BoundConvertedSwitchExpression node, LocalRewriter localRewriter)
: base(node.Syntax, localRewriter, node.SwitchArms.SelectAsArray(arm => arm.Syntax))
{
}
