/// <summary>
/// Generate the body for <c>MoveNext()</c>.
/// </summary>
internal void GenerateMoveNext(BoundStatement body, MethodSymbol moveNextMethod)
{
F.CurrentMethod = moveNextMethod;
int initialState;
GeneratedLabelSymbol initialLabel;
AddState(out initialState, out initialLabel);
var exceptionLocal = F.SynthesizedLocal(F.WellKnownType(WellKnownType.System_Exception), GeneratedNames.AsyncExceptionFieldName());
var bodyBuilder = ArrayBuilder <BoundStatement> .GetInstance();
bodyBuilder.Add(
F.HiddenSequencePoint());
bodyBuilder.Add(
F.Assignment(F.Local(cachedState), F.Field(F.This(), stateField)));
BoundStatement rewrittenBody = (BoundStatement)Visit(body);
bodyBuilder.Add(
F.Try(
F.Block(
ImmutableArray <LocalSymbol> .Empty,
// switch (state) ...
F.HiddenSequencePoint(),
Dispatch(),
F.Label(initialLabel),
// [body]
rewrittenBody
),
F.CatchBlocks(
F.Catch(
exceptionLocal,
F.Block(
F.NoOp(method.ReturnsVoid ? NoOpStatementFlavor.AsyncMethodCatchHandler : NoOpStatementFlavor.Default),
F.HiddenSequencePoint(),
// this.state = finishedState
F.Assignment(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine)),
// builder.SetException(ex)
F.ExpressionStatement(
F.Call(
F.Field(F.This(), asyncMethodBuilderField),
asyncMethodBuilderMemberCollection.SetException,
F.Local(exceptionLocal))),
GenerateReturn(false)
)
)
)
));
// ReturnLabel (for the rewritten return expressions in the user's method body)
bodyBuilder.Add(F.Label(exprReturnLabel));
// this.state = finishedState
var stateDone = F.Assignment(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine));
var block = body.Syntax as BlockSyntax;
if (block == null)
{
// this happens, for example, in (async () => await e) where there is no block syntax
bodyBuilder.Add(stateDone);
}
else
{
bodyBuilder.Add(F.SequencePointWithSpan(block, block.CloseBraceToken.Span, stateDone));
bodyBuilder.Add(F.HiddenSequencePoint());
// The remaining code is hidden to hide the fact that it can run concurrently with the task's continuation
}
// builder.SetResult([RetVal])
bodyBuilder.Add(
F.ExpressionStatement(
F.Call(
F.Field(F.This(), asyncMethodBuilderField),
asyncMethodBuilderMemberCollection.SetResult,
method.IsGenericTaskReturningAsync(F.Compilation)
? ImmutableArray.Create <BoundExpression>(F.Local(exprRetValue))
: ImmutableArray <BoundExpression> .Empty)));
// this code is hidden behind a hidden sequence point.
bodyBuilder.Add(F.Label(this.exitLabel));
bodyBuilder.Add(F.Return());
var newBody = bodyBuilder.ToImmutableAndFree();
var locals = ArrayBuilder <LocalSymbol> .GetInstance();
locals.Add(cachedState);
if ((object)exprRetValue != null)
{
locals.Add(exprRetValue);
}
F.CloseMethod(
F.SequencePoint(
body.Syntax,
F.Block(
locals.ToImmutableAndFree(),
newBody)));
}
/// <summary>
/// Generate the body for MoveNext()
/// </summary>
internal void GenerateMoveNext(BoundStatement body, MethodSymbol moveNextMethod)
{
F.CurrentMethod = moveNextMethod;
int initialState;
GeneratedLabelSymbol initialLabel;
AddState(out initialState, out initialLabel);
var exceptionLocal = F.SynthesizedLocal(F.WellKnownType(WellKnownType.System_Exception), GeneratedNames.AsyncExceptionFieldName());
BoundStatement rewrittenBody = (BoundStatement)Visit(body);
rewrittenBody = (BoundStatement) new AwaitLoweringRewriterPass1(F).Visit(rewrittenBody);
rewrittenBody = (BoundStatement) new AwaitLoweringRewriterPass2(F, CompilationState).Visit(rewrittenBody);
UnloweredSpillNodeVerifier.Verify(rewrittenBody);
var bodyBuilder = ArrayBuilder <BoundStatement> .GetInstance();
bodyBuilder.Add(
F.Try(
F.Block(
ReadOnlyArray <LocalSymbol> .Empty,
// switch (state) ...
Dispatch(),
// TODO(t-liam) - debugging support...
// dev11(LanguageAnalysis\Compiler\ResumableRewriter.cpp:325) does codegen here to add a
// debug nop and the 'NoCullNormalExit' label
F.Label(initialLabel),
// [body]
rewrittenBody
),
F.CatchBlocks(
// TODO(t-liam) - debugging support...
// dev11(LanguageAnalysis\Compiler\ResumableRewriter.cpp:391)
// // Async void method generated catch handlers have their IL start offset
// // recorded to the PDB for special exception handling in the debugger.
// // Mark the EXPRHANDLER as such so we know to record its offset later.
F.Catch(
F.WellKnownType(WellKnownType.System_Exception),
exceptionLocal,
F.Block(
// state = finishedState
F.Assignment(F.Field(F.This(), state), F.Literal(StateMachineStates.FinishedStateMachine)),
// builder.SetException(ex)
F.ExpressionStatement(
F.Call(
F.Field(F.This(), asyncMethodBuilderField),
asyncMethodBuilderMemberCollection.SetException,
ReadOnlyArray <BoundExpression> .CreateFrom(F.Local(exceptionLocal)))),
F.Return()
)
)
)
));
// ReturnLabel (for the rewritten return expressions in the user's method body)
bodyBuilder.Add(F.Label(exprReturnLabel));
// state = finishedState
bodyBuilder.Add(F.Assignment(F.Field(F.This(), state), F.Literal(StateMachineStates.FinishedStateMachine)));
// builder.SetResult([RetVal])
bodyBuilder.Add(
F.ExpressionStatement(
F.Call(
F.Field(F.This(), asyncMethodBuilderField),
asyncMethodBuilderMemberCollection.SetResult,
method.IsGenericTaskReturningAsync()
? ReadOnlyArray <BoundExpression> .CreateFrom(F.Local(exprRetValue))
: ReadOnlyArray <BoundExpression> .Empty)));
bodyBuilder.Add(F.Return());
var newBody = bodyBuilder.ToReadOnlyAndFree();
F.CloseMethod(
F.SequencePoint(
body.Syntax,
F.Block(
exprRetValue != null ? ReadOnlyArray <LocalSymbol> .CreateFrom(exprRetValue) : ReadOnlyArray <LocalSymbol> .Empty,
newBody)));
}