2 // async.cs: Asynchronous functions
5 // Marek Safar (marek.safar@gmail.com)
7 // Dual licensed under the terms of the MIT X11 or GNU GPL
9 // Copyright 2011 Novell, Inc.
10 // Copyright 2011-2012 Xamarin Inc.
14 using System.Collections.Generic;
16 using System.Collections;
19 using IKVM.Reflection;
20 using IKVM.Reflection.Emit;
22 using System.Reflection;
23 using System.Reflection.Emit;
28 public class Await : ExpressionStatement
33 public Await (Expression expr, Location loc)
39 public Expression Expr {
45 public AwaitStatement Statement {
51 protected override void CloneTo (CloneContext clonectx, Expression target)
53 var t = (Await) target;
55 t.expr = expr.Clone (clonectx);
58 public override Expression CreateExpressionTree (ResolveContext ec)
60 throw new NotImplementedException ("ET");
63 public override bool ContainsEmitWithAwait ()
68 public override void FlowAnalysis (FlowAnalysisContext fc)
70 stmt.Expr.FlowAnalysis (fc);
72 stmt.RegisterResumePoint ();
75 protected override Expression DoResolve (ResolveContext rc)
77 if (rc.HasSet (ResolveContext.Options.LockScope)) {
78 rc.Report.Error (1996, loc,
79 "The `await' operator cannot be used in the body of a lock statement");
83 rc.Report.Error (4004, loc,
84 "The `await' operator cannot be used in an unsafe context");
87 var bc = (BlockContext) rc;
89 stmt = new AwaitStatement (expr, loc);
90 if (!stmt.Resolve (bc))
93 type = stmt.ResultType;
94 eclass = ExprClass.Variable;
98 public override void Emit (EmitContext ec)
100 stmt.EmitPrologue (ec);
102 using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
107 public override Expression EmitToField (EmitContext ec)
109 stmt.EmitPrologue (ec);
110 return stmt.GetResultExpression (ec);
113 public void EmitAssign (EmitContext ec, FieldExpr field)
115 stmt.EmitPrologue (ec);
116 field.InstanceExpression.Emit (ec);
120 public override void EmitStatement (EmitContext ec)
122 stmt.EmitStatement (ec);
125 public override void MarkReachable (Reachability rc)
127 base.MarkReachable (rc);
128 stmt.MarkReachable (rc);
131 public override object Accept (StructuralVisitor visitor)
133 return visitor.Visit (this);
137 public class AwaitStatement : YieldStatement<AsyncInitializer>
139 public sealed class AwaitableMemberAccess : MemberAccess
141 public AwaitableMemberAccess (Expression expr)
142 : base (expr, "GetAwaiter")
146 public bool ProbingMode { get; set; }
148 protected override void Error_TypeDoesNotContainDefinition (ResolveContext rc, TypeSpec type, string name)
150 Error_OperatorCannotBeApplied (rc, type);
153 protected override void Error_OperatorCannotBeApplied (ResolveContext rc, TypeSpec type)
158 var invocation = LeftExpression as Invocation;
159 if (invocation != null && invocation.MethodGroup != null && (invocation.MethodGroup.BestCandidate.Modifiers & Modifiers.ASYNC) != 0) {
160 rc.Report.Error (4008, loc, "Cannot await void method `{0}'. Consider changing method return type to `Task'",
161 invocation.GetSignatureForError ());
163 rc.Report.Error (4001, loc, "Cannot await `{0}' expression", type.GetSignatureForError ());
168 sealed class GetResultInvocation : Invocation
170 public GetResultInvocation (MethodGroupExpr mge, Arguments arguments)
171 : base (null, arguments)
174 type = mg.BestCandidateReturnType;
177 public override Expression EmitToField (EmitContext ec)
184 AwaiterDefinition awaiter_definition;
186 TypeSpec result_type;
188 public AwaitStatement (Expression expr, Location loc)
191 unwind_protect = true;
198 return awaiter_definition == null;
202 public TypeSpec ResultType {
210 protected override void DoEmit (EmitContext ec)
212 using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
213 GetResultExpression (ec).Emit (ec);
217 public Expression GetResultExpression (EmitContext ec)
219 var fe_awaiter = new FieldExpr (awaiter, loc);
220 fe_awaiter.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
223 // result = awaiter.GetResult ();
226 var rc = new ResolveContext (ec.MemberContext);
227 return new Invocation (new MemberAccess (fe_awaiter, "GetResult"), new Arguments (0)).Resolve (rc);
230 var mg_result = MethodGroupExpr.CreatePredefined (awaiter_definition.GetResult, fe_awaiter.Type, loc);
231 mg_result.InstanceExpression = fe_awaiter;
233 return new GetResultInvocation (mg_result, new Arguments (0));
236 public void EmitPrologue (EmitContext ec)
238 awaiter = ((AsyncTaskStorey) machine_initializer.Storey).AddAwaiter (expr.Type);
240 var fe_awaiter = new FieldExpr (awaiter, loc);
241 fe_awaiter.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
243 Label skip_continuation = ec.DefineLabel ();
245 using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
247 // awaiter = expr.GetAwaiter ();
249 fe_awaiter.EmitAssign (ec, expr, false, false);
251 Expression completed_expr;
253 var rc = new ResolveContext (ec.MemberContext);
255 Arguments dargs = new Arguments (1);
256 dargs.Add (new Argument (fe_awaiter));
257 completed_expr = new DynamicMemberBinder ("IsCompleted", dargs, loc).Resolve (rc);
259 dargs = new Arguments (1);
260 dargs.Add (new Argument (completed_expr));
261 completed_expr = new DynamicConversion (ec.Module.Compiler.BuiltinTypes.Bool, 0, dargs, loc).Resolve (rc);
263 var pe = PropertyExpr.CreatePredefined (awaiter_definition.IsCompleted, loc);
264 pe.InstanceExpression = fe_awaiter;
268 completed_expr.EmitBranchable (ec, skip_continuation, true);
274 // The stack has to be empty before calling await continuation. We handle this
275 // by lifting values which would be left on stack into class fields. The process
276 // is quite complicated and quite hard to test because any expression can possibly
277 // leave a value on the stack.
279 // Following assert fails when some of expression called before is missing EmitToField
280 // or parent expression fails to find await in children expressions
282 ec.AssertEmptyStack ();
284 var storey = (AsyncTaskStorey) machine_initializer.Storey;
286 storey.EmitAwaitOnCompletedDynamic (ec, fe_awaiter);
288 storey.EmitAwaitOnCompleted (ec, fe_awaiter);
292 machine_initializer.EmitLeave (ec, unwind_protect);
294 ec.MarkLabel (resume_point);
295 ec.MarkLabel (skip_continuation);
298 public void EmitStatement (EmitContext ec)
303 awaiter.IsAvailableForReuse = true;
305 if (ResultType.Kind != MemberKind.Void)
306 ec.Emit (OpCodes.Pop);
309 void Error_WrongAwaiterPattern (ResolveContext rc, TypeSpec awaiter)
311 rc.Report.Error (4011, loc, "The awaiter type `{0}' must have suitable IsCompleted and GetResult members",
312 awaiter.GetSignatureForError ());
315 public override bool Resolve (BlockContext bc)
317 if (bc.CurrentBlock is Linq.QueryBlock) {
318 bc.Report.Error (1995, loc,
319 "The `await' operator may only be used in a query expression within the first collection expression of the initial `from' clause or within the collection expression of a `join' clause");
323 if (!base.Resolve (bc))
327 Arguments args = new Arguments (0);
330 // The await expression is of dynamic type
332 if (type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
334 expr = new Invocation (new MemberAccess (expr, "GetAwaiter"), args).Resolve (bc);
339 // Check whether the expression is awaitable
341 Expression ama = new AwaitableMemberAccess (expr).Resolve (bc);
345 var errors_printer = new SessionReportPrinter ();
346 var old = bc.Report.SetPrinter (errors_printer);
347 ama = new Invocation (ama, args).Resolve (bc);
348 bc.Report.SetPrinter (old);
350 if (errors_printer.ErrorsCount > 0 || !MemberAccess.IsValidDotExpression (ama.Type)) {
351 bc.Report.Error (1986, expr.Location,
352 "The `await' operand type `{0}' must have suitable GetAwaiter method",
353 expr.Type.GetSignatureForError ());
358 var awaiter_type = ama.Type;
360 awaiter_definition = bc.Module.GetAwaiter (awaiter_type);
362 if (!awaiter_definition.IsValidPattern) {
363 Error_WrongAwaiterPattern (bc, awaiter_type);
367 if (!awaiter_definition.INotifyCompletion) {
368 bc.Report.Error (4027, loc, "The awaiter type `{0}' must implement interface `{1}'",
369 awaiter_type.GetSignatureForError (), bc.Module.PredefinedTypes.INotifyCompletion.GetSignatureForError ());
374 result_type = awaiter_definition.GetResult.ReturnType;
380 class AsyncInitializerStatement : StatementExpression
382 public AsyncInitializerStatement (AsyncInitializer expr)
387 protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
389 base.DoFlowAnalysis (fc);
391 var init = (AsyncInitializer) Expr;
392 var res = !init.Block.HasReachableClosingBrace;
393 var storey = (AsyncTaskStorey) init.Storey;
395 if (storey.ReturnType.IsGenericTask)
401 public override Reachability MarkReachable (Reachability rc)
403 if (!rc.IsUnreachable)
406 var init = (AsyncInitializer) Expr;
407 rc = init.Block.MarkReachable (rc);
409 var storey = (AsyncTaskStorey) init.Storey;
412 // Explicit return is required for Task<T> state machine
414 if (storey.ReturnType != null && storey.ReturnType.IsGenericTask)
417 return Reachability.CreateUnreachable ();
421 public class AsyncInitializer : StateMachineInitializer
423 TypeInferenceContext return_inference;
425 public AsyncInitializer (ParametersBlock block, TypeDefinition host, TypeSpec returnType)
426 : base (block, host, returnType)
432 public override string ContainerType {
434 return "async state machine block";
438 public TypeSpec DelegateType {
442 public StackFieldExpr HoistedReturnState {
446 public override bool IsIterator {
452 public TypeInferenceContext ReturnTypeInference {
454 return return_inference;
460 protected override BlockContext CreateBlockContext (BlockContext bc)
462 var ctx = base.CreateBlockContext (bc);
463 var am = bc.CurrentAnonymousMethod as AnonymousMethodBody;
465 return_inference = am.ReturnTypeInference;
467 ctx.Set (ResolveContext.Options.TryScope);
472 public override void Emit (EmitContext ec)
474 throw new NotImplementedException ();
477 public void EmitCatchBlock (EmitContext ec)
479 var catch_value = LocalVariable.CreateCompilerGenerated (ec.Module.Compiler.BuiltinTypes.Exception, block, Location);
481 ec.BeginCatchBlock (catch_value.Type);
482 catch_value.EmitAssign (ec);
485 ec.EmitInt ((int) IteratorStorey.State.After);
486 ec.Emit (OpCodes.Stfld, storey.PC.Spec);
488 ((AsyncTaskStorey) Storey).EmitSetException (ec, new LocalVariableReference (catch_value, Location));
490 ec.Emit (OpCodes.Leave, move_next_ok);
491 ec.EndExceptionBlock ();
495 protected override void EmitMoveNextEpilogue (EmitContext ec)
497 var storey = (AsyncTaskStorey) Storey;
498 storey.EmitSetResult (ec);
501 public override void EmitStatement (EmitContext ec)
503 var storey = (AsyncTaskStorey) Storey;
504 storey.EmitInitializer (ec);
505 ec.Emit (OpCodes.Ret);
508 public override void MarkReachable (Reachability rc)
511 // Reachability has been done in AsyncInitializerStatement
516 class AsyncTaskStorey : StateMachine
520 readonly TypeSpec return_type;
521 MethodSpec set_result;
522 MethodSpec set_exception;
523 MethodSpec builder_factory;
524 MethodSpec builder_start;
527 Dictionary<TypeSpec, List<Field>> stack_fields;
528 Dictionary<TypeSpec, List<Field>> awaiter_fields;
530 public AsyncTaskStorey (ParametersBlock block, IMemberContext context, AsyncInitializer initializer, TypeSpec type)
531 : base (block, initializer.Host, context.CurrentMemberDefinition as MemberBase, context.CurrentTypeParameters, "async", MemberKind.Struct)
534 awaiter_fields = new Dictionary<TypeSpec, List<Field>> ();
539 public Expression HoistedReturnValue { get; set; }
541 public TypeSpec ReturnType {
547 public PropertySpec Task {
553 protected override TypeAttributes TypeAttr {
555 return base.TypeAttr & ~TypeAttributes.SequentialLayout;
561 public Field AddAwaiter (TypeSpec type)
564 type = mutator.Mutate (type);
566 List<Field> existing_fields;
567 if (awaiter_fields.TryGetValue (type, out existing_fields)) {
568 foreach (var f in existing_fields) {
569 if (f.IsAvailableForReuse) {
570 f.IsAvailableForReuse = false;
576 var field = AddCompilerGeneratedField ("$awaiter" + awaiters++.ToString ("X"), new TypeExpression (type, Location), true);
579 if (existing_fields == null) {
580 existing_fields = new List<Field> ();
581 awaiter_fields.Add (type, existing_fields);
584 existing_fields.Add (field);
588 public Field AddCapturedLocalVariable (TypeSpec type, bool requiresUninitialized = false)
591 type = mutator.Mutate (type);
593 List<Field> existing_fields = null;
594 if (stack_fields == null) {
595 stack_fields = new Dictionary<TypeSpec, List<Field>> ();
596 } else if (stack_fields.TryGetValue (type, out existing_fields) && !requiresUninitialized) {
597 foreach (var f in existing_fields) {
598 if (f.IsAvailableForReuse) {
599 f.IsAvailableForReuse = false;
605 var field = AddCompilerGeneratedField ("$stack" + locals_captured++.ToString ("X"), new TypeExpression (type, Location), true);
608 if (existing_fields == null) {
609 existing_fields = new List<Field> ();
610 stack_fields.Add (type, existing_fields);
613 existing_fields.Add (field);
618 protected override bool DoDefineMembers ()
620 PredefinedType builder_type;
621 PredefinedMember<MethodSpec> bf;
622 PredefinedMember<MethodSpec> bs;
623 PredefinedMember<MethodSpec> sr;
624 PredefinedMember<MethodSpec> se;
625 PredefinedMember<MethodSpec> sm;
626 bool has_task_return_type = false;
627 var pred_members = Module.PredefinedMembers;
629 if (return_type.Kind == MemberKind.Void) {
630 builder_type = Module.PredefinedTypes.AsyncVoidMethodBuilder;
631 bf = pred_members.AsyncVoidMethodBuilderCreate;
632 bs = pred_members.AsyncVoidMethodBuilderStart;
633 sr = pred_members.AsyncVoidMethodBuilderSetResult;
634 se = pred_members.AsyncVoidMethodBuilderSetException;
635 sm = pred_members.AsyncVoidMethodBuilderSetStateMachine;
636 } else if (return_type == Module.PredefinedTypes.Task.TypeSpec) {
637 builder_type = Module.PredefinedTypes.AsyncTaskMethodBuilder;
638 bf = pred_members.AsyncTaskMethodBuilderCreate;
639 bs = pred_members.AsyncTaskMethodBuilderStart;
640 sr = pred_members.AsyncTaskMethodBuilderSetResult;
641 se = pred_members.AsyncTaskMethodBuilderSetException;
642 sm = pred_members.AsyncTaskMethodBuilderSetStateMachine;
643 task = pred_members.AsyncTaskMethodBuilderTask.Get ();
645 builder_type = Module.PredefinedTypes.AsyncTaskMethodBuilderGeneric;
646 bf = pred_members.AsyncTaskMethodBuilderGenericCreate;
647 bs = pred_members.AsyncTaskMethodBuilderGenericStart;
648 sr = pred_members.AsyncTaskMethodBuilderGenericSetResult;
649 se = pred_members.AsyncTaskMethodBuilderGenericSetException;
650 sm = pred_members.AsyncTaskMethodBuilderGenericSetStateMachine;
651 task = pred_members.AsyncTaskMethodBuilderGenericTask.Get ();
652 has_task_return_type = true;
655 set_result = sr.Get ();
656 set_exception = se.Get ();
657 builder_factory = bf.Get ();
658 builder_start = bs.Get ();
660 var istate_machine = Module.PredefinedTypes.IAsyncStateMachine;
661 var set_statemachine = sm.Get ();
663 if (!builder_type.Define () || !istate_machine.Define () || set_result == null || builder_factory == null ||
664 set_exception == null || set_statemachine == null || builder_start == null ||
665 !Module.PredefinedTypes.INotifyCompletion.Define ()) {
666 Report.Error (1993, Location,
667 "Cannot find compiler required types for asynchronous functions support. Are you targeting the wrong framework version?");
668 return base.DoDefineMembers ();
671 var bt = builder_type.TypeSpec;
674 // Inflate generic Task types
676 if (has_task_return_type) {
677 var task_return_type = return_type.TypeArguments;
679 task_return_type = mutator.Mutate (task_return_type);
681 bt = bt.MakeGenericType (Module, task_return_type);
682 set_result = MemberCache.GetMember (bt, set_result);
683 set_exception = MemberCache.GetMember (bt, set_exception);
684 set_statemachine = MemberCache.GetMember (bt, set_statemachine);
687 task = MemberCache.GetMember (bt, task);
690 builder = AddCompilerGeneratedField ("$builder", new TypeExpression (bt, Location));
692 var set_state_machine = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Void, Location),
693 Modifiers.COMPILER_GENERATED | Modifiers.DEBUGGER_HIDDEN | Modifiers.PUBLIC,
694 new MemberName ("SetStateMachine"),
695 ParametersCompiled.CreateFullyResolved (
696 new Parameter (new TypeExpression (istate_machine.TypeSpec, Location), "stateMachine", Parameter.Modifier.NONE, null, Location),
697 istate_machine.TypeSpec),
700 ToplevelBlock block = new ToplevelBlock (Compiler, set_state_machine.ParameterInfo, Location);
701 block.IsCompilerGenerated = true;
702 set_state_machine.Block = block;
704 Members.Add (set_state_machine);
706 if (!base.DoDefineMembers ())
710 // Fabricates SetStateMachine method
712 // public void SetStateMachine (IAsyncStateMachine stateMachine)
714 // $builder.SetStateMachine (stateMachine);
717 var mg = MethodGroupExpr.CreatePredefined (set_statemachine, bt, Location);
718 mg.InstanceExpression = new FieldExpr (builder, Location);
720 var param_reference = block.GetParameterReference (0, Location);
721 param_reference.Type = istate_machine.TypeSpec;
722 param_reference.eclass = ExprClass.Variable;
724 var args = new Arguments (1);
725 args.Add (new Argument (param_reference));
726 set_state_machine.Block.AddStatement (new StatementExpression (new Invocation (mg, args)));
728 if (has_task_return_type) {
729 HoistedReturnValue = TemporaryVariableReference.Create (bt.TypeArguments [0], StateMachineMethod.Block, Location);
735 public void EmitAwaitOnCompletedDynamic (EmitContext ec, FieldExpr awaiter)
737 var critical = Module.PredefinedTypes.ICriticalNotifyCompletion;
738 if (!critical.Define ()) {
739 throw new NotImplementedException ();
742 var temp_critical = new LocalTemporary (critical.TypeSpec);
743 var label_critical = ec.DefineLabel ();
744 var label_end = ec.DefineLabel ();
747 // Special path for dynamic awaiters
749 // var awaiter = this.$awaiter as ICriticalNotifyCompletion;
750 // if (awaiter == null) {
751 // var completion = (INotifyCompletion) this.$awaiter;
752 // this.$builder.AwaitOnCompleted (ref completion, ref this);
754 // this.$builder.AwaitUnsafeOnCompleted (ref awaiter, ref this);
758 ec.Emit (OpCodes.Isinst, critical.TypeSpec);
759 temp_critical.Store (ec);
760 temp_critical.Emit (ec);
761 ec.Emit (OpCodes.Brtrue_S, label_critical);
763 var temp = new LocalTemporary (Module.PredefinedTypes.INotifyCompletion.TypeSpec);
765 ec.Emit (OpCodes.Castclass, temp.Type);
767 EmitOnCompleted (ec, temp, false);
769 ec.Emit (OpCodes.Br_S, label_end);
771 ec.MarkLabel (label_critical);
773 EmitOnCompleted (ec, temp_critical, true);
775 ec.MarkLabel (label_end);
777 temp_critical.Release (ec);
780 public void EmitAwaitOnCompleted (EmitContext ec, FieldExpr awaiter)
782 bool unsafe_version = false;
783 if (Module.PredefinedTypes.ICriticalNotifyCompletion.Define ()) {
784 unsafe_version = awaiter.Type.ImplementsInterface (Module.PredefinedTypes.ICriticalNotifyCompletion.TypeSpec, false);
787 EmitOnCompleted (ec, awaiter, unsafe_version);
790 void EmitOnCompleted (EmitContext ec, Expression awaiter, bool unsafeVersion)
792 var pm = Module.PredefinedMembers;
793 PredefinedMember<MethodSpec> predefined;
794 bool has_task_return_type = false;
795 if (return_type.Kind == MemberKind.Void) {
796 predefined = unsafeVersion ? pm.AsyncVoidMethodBuilderOnCompletedUnsafe : pm.AsyncVoidMethodBuilderOnCompleted;
797 } else if (return_type == Module.PredefinedTypes.Task.TypeSpec) {
798 predefined = unsafeVersion ? pm.AsyncTaskMethodBuilderOnCompletedUnsafe : pm.AsyncTaskMethodBuilderOnCompleted;
800 predefined = unsafeVersion ? pm.AsyncTaskMethodBuilderGenericOnCompletedUnsafe : pm.AsyncTaskMethodBuilderGenericOnCompleted;
801 has_task_return_type = true;
804 var on_completed = predefined.Resolve (Location);
805 if (on_completed == null)
808 if (has_task_return_type)
809 on_completed = MemberCache.GetMember<MethodSpec> (set_result.DeclaringType, on_completed);
811 on_completed = on_completed.MakeGenericMethod (this, awaiter.Type, ec.CurrentType);
813 var mg = MethodGroupExpr.CreatePredefined (on_completed, on_completed.DeclaringType, Location);
814 mg.InstanceExpression = new FieldExpr (builder, Location) {
815 InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location)
818 var args = new Arguments (2);
819 args.Add (new Argument (awaiter, Argument.AType.Ref));
820 args.Add (new Argument (new CompilerGeneratedThis (CurrentType, Location), Argument.AType.Ref));
821 using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
822 mg.EmitCall (ec, args, true);
826 public void EmitInitializer (EmitContext ec)
829 // Some predefined types are missing
834 var instance = (TemporaryVariableReference) Instance;
835 var builder_field = builder.Spec;
836 if (MemberName.Arity > 0) {
837 builder_field = MemberCache.GetMember (instance.Type, builder_field);
841 // Inflated factory method when task is of generic type
843 if (builder_factory.DeclaringType.IsGeneric) {
844 var task_return_type = return_type.TypeArguments;
845 var bt = builder_factory.DeclaringType.MakeGenericType (Module, task_return_type);
846 builder_factory = MemberCache.GetMember (bt, builder_factory);
847 builder_start = MemberCache.GetMember (bt, builder_start);
851 // stateMachine.$builder = AsyncTaskMethodBuilder<{task-type}>.Create();
853 instance.AddressOf (ec, AddressOp.Store);
854 ec.Emit (OpCodes.Call, builder_factory);
855 ec.Emit (OpCodes.Stfld, builder_field);
858 // stateMachine.$builder.Start<{storey-type}>(ref stateMachine);
860 instance.AddressOf (ec, AddressOp.Store);
861 ec.Emit (OpCodes.Ldflda, builder_field);
863 ec.Emit (OpCodes.Dup);
864 instance.AddressOf (ec, AddressOp.Store);
865 ec.Emit (OpCodes.Call, builder_start.MakeGenericMethod (Module, instance.Type));
868 // Emits return stateMachine.$builder.Task;
871 var task_get = Task.Get;
873 if (MemberName.Arity > 0) {
874 task_get = MemberCache.GetMember (builder_field.MemberType, task_get);
877 var pe_task = new PropertyExpr (Task, Location) {
878 InstanceExpression = EmptyExpression.Null, // Comes from the dup above
886 public void EmitSetException (EmitContext ec, LocalVariableReference exceptionVariable)
889 // $builder.SetException (Exception)
891 var mg = MethodGroupExpr.CreatePredefined (set_exception, set_exception.DeclaringType, Location);
892 mg.InstanceExpression = new FieldExpr (builder, Location) {
893 InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location)
896 Arguments args = new Arguments (1);
897 args.Add (new Argument (exceptionVariable));
899 using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
900 mg.EmitCall (ec, args, true);
904 public void EmitSetResult (EmitContext ec)
907 // $builder.SetResult ();
908 // $builder.SetResult<return-type> (value);
910 var mg = MethodGroupExpr.CreatePredefined (set_result, set_result.DeclaringType, Location);
911 mg.InstanceExpression = new FieldExpr (builder, Location) {
912 InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location)
916 if (HoistedReturnValue == null) {
917 args = new Arguments (0);
919 args = new Arguments (1);
920 args.Add (new Argument (HoistedReturnValue));
923 using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
924 mg.EmitCall (ec, args, true);
928 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
930 base_type = Compiler.BuiltinTypes.ValueType;
933 var istate_machine = Module.PredefinedTypes.IAsyncStateMachine;
934 if (istate_machine.Define ()) {
935 return new[] { istate_machine.TypeSpec };
942 public class StackFieldExpr : FieldExpr, IExpressionCleanup
944 public StackFieldExpr (Field field)
945 : base (field, Location.Null)
949 public bool IsAvailableForReuse {
951 var field = (Field) spec.MemberDefinition;
952 return field.IsAvailableForReuse;
955 var field = (Field) spec.MemberDefinition;
956 field.IsAvailableForReuse = value;
960 public override void AddressOf (EmitContext ec, AddressOp mode)
962 base.AddressOf (ec, mode);
964 if (mode == AddressOp.Load) {
965 IsAvailableForReuse = true;
969 public override void Emit (EmitContext ec)
976 public void EmitLoad (EmitContext ec)
981 public void PrepareCleanup (EmitContext ec)
983 IsAvailableForReuse = true;
986 // Release any captured reference type stack variables
987 // to imitate real stack behavour and help GC stuff early
989 if (TypeSpec.IsReferenceType (type)) {
990 ec.AddStatementEpilog (this);
994 void IExpressionCleanup.EmitCleanup (EmitContext ec)
996 EmitAssign (ec, new NullConstant (type, loc), false, false);