Emit async methods #5

jtschuster · 2026-01-16T19:10:12Z

No description provided.

… emit the IL

…Module

…necessary methods

…Module

…c thunks to be inlined.

…ncMethods

…er/runtime into EmitAsyncMethods

…ncMethods

…ilation

Copilot

Pull request overview

This pull request adds support for emitting async methods in the ReadyToRun (R2R) compiler infrastructure. The changes enable async method compilation for ahead-of-time (AOT) scenarios by introducing a new continuation type layout system, async method variant handling, and related JIT interface support.

Changes:

Introduces ELEMENT_TYPE_CONTINUATION (0x46) for representing async continuation types in metadata
Adds R2R fixup kind for continuation layout encoding
Implements AsyncContinuationType with GCPointerMap-based identification
Removes restrictions on compiling async methods in ReadyToRun
Adds cross-module inlining support for async thunks and variants

Reviewed changes

Copilot reviewed 36 out of 37 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
src/tests/profiler/native/rejitprofiler/sigparse.h	Adds ELEMENT_TYPE_CONTINUATION constant definition with alignment fixes
src/tests/async/awaitingnotasync/awaitingnotasync.cs	Comments out all test assertions (work in progress)
src/libraries/System.Private.CoreLib/src/System/Reflection/CorElementType.cs	Adds ELEMENT_TYPE_CONTINUATION enum value
src/coreclr/vm/readytoruninfo.cpp	Removes async variant restrictions from R2R entry point lookup
src/coreclr/vm/jitinterface.cpp	Adds GetContinuationTypeFromLayout for parsing continuation type signatures
src/coreclr/tools/aot/aot.slnx	Adds new solution file for AOT tooling
src/coreclr/tools/aot/ILCompiler.Reflection.ReadyToRun/ReadyToRunSignature.cs	Adds ContinuationLayout fixup parsing and display
src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs	Implements continuation type handling, fixes context type parameters
src/coreclr/tools/aot/ILCompiler.ReadyToRun/ILCompiler.ReadyToRun.csproj	Removes ILStubReferences.cs, adds AsyncMethodVariant.Mangling.cs
src/coreclr/tools/aot/ILCompiler.ReadyToRun/IL/Stubs/ILStubReferences.cs	Deleted file (no longer needed)
src/coreclr/tools/aot/ILCompiler.ReadyToRun/IL/ReadyToRunILProvider.cs	Adds async thunk IL generation and wrapping
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunTableManager.cs	Updates method categorization for async variants
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCompilerContext.cs	Initializes continuation type hashtable, adds layout algorithm
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCompilationModuleGroupBase.cs	Code formatting/whitespace fixes
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs	Adds async reference handling and mutable IL body support
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunSymbolNodeFactory.cs	Adds continuation type fixup symbol creation
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunCodegenNodeFactory.cs	Filters AsyncResumptionStub from enumeration
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/TypeFixupSignature.cs	Implements ContinuationLayout encoding
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/SignatureBuilder.cs	Adds AsyncContinuationType check in type signature emission
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ModuleTokenResolver.cs	Adds GetModuleTokenForField method
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/MethodFixupSignature.cs	Adds comment about async variant handling
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/InstanceEntryPointTableNode.cs	Updates method signature building for async variants
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/InliningInfoNode.cs	Filters async thunks from inlining info
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ExceptionInfoLookupTableNode.cs	Excludes AsyncResumptionStub from EH layout
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/CompilerTypeSystemContext.ReadyToRun.cs	New file: implements R2R-specific continuation type hashtable
src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/JitHelper.cs	Adds helper entry points for continuation allocation
src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/CompilerTypeSystemContext.Aot.cs	Adds AOT continuation type hashtable
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncThunks.cs	Adds ILCompiler namespace import
src/coreclr/tools/Common/TypeSystem/IL/Stubs/AsyncResumptionStub.cs	Moves TargetMethod property declaration
src/coreclr/tools/Common/TypeSystem/IL/InstantiatedMethodIL.cs	Removes assertion that breaks with async variants
src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs	Implements getContinuationType and getAsyncResumptionStub for R2R
src/coreclr/tools/Common/Internal/Runtime/ReadyToRunConstants.cs	Adds ContinuationLayout fixup kind and helper constants
src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.Async.cs	Moves continuation type hashtable to platform-specific files
src/coreclr/tools/Common/Compiler/AsyncMethodVariant.cs	Updates IsAsyncThunk to include AsyncResumptionStub
src/coreclr/tools/Common/Compiler/AsyncContinuationType.cs	Adds OwningMethod for R2R, implements layout algorithm
src/coreclr/tools/.editorconfig	Minor whitespace fix
src/coreclr/inc/readytorun.h	Adds READYTORUN_FIXUP_Continuation_Layout constant

src/coreclr/vm/jitinterface.cpp

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/JitHelper.cs

src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/CompilerTypeSystemContext.ReadyToRun.cs

src/coreclr/tools/Common/Compiler/AsyncContinuationType.cs

src/coreclr/vm/jitinterface.cpp

src/tests/async/awaitingnotasync/awaitingnotasync.cs

Copilot · 2026-01-16T19:20:59Z

src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs

+                    var method = _compilation.NodeFactory.TypeSystemContext.GetCoreLibEntryPoint("System.Runtime.CompilerServices"u8, "AsyncHelpers"u8, "AllocContinuation"u8, null);
+                    var methodWithToken = new MethodWithToken(method, _compilation.CompilationModuleGroup.Resolver.GetModuleTokenForMethod(method, true, true), null, false, null);
+                    return _compilation.NodeFactory.MethodEntrypoint(methodWithToken, false, false, false);
+


Inconsistent handling for CORINFO_HELP_ALLOC_CONTINUATION_METHOD and CORINFO_HELP_ALLOC_CONTINUATION_CLASS. The CORINFO_HELP_ALLOC_CONTINUATION case returns early with a method entrypoint, but the _METHOD and _CLASS variants fall through to throw RequiresRuntimeJitException. This appears to be incomplete implementation - either these cases should have their own implementation or they should be explicitly documented as unimplemented.

Suggested change

// The *_METHOD and *_CLASS variants of continuation allocation are not implemented

// for ReadyToRun. They are expected to fall through to the RequiresRuntimeJitException

// thrown at the end of this switch.

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs

…nCodegenCompilation.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

jtschuster added 30 commits November 15, 2025 18:21

Add known methods that may be unreferenced into the MutableModule.

3dfcffa

Only add types and methods outside of the version bubble, still can't…

13f7d1d

… emit the IL

Fix extra changes

d638752

Fix EntityHandle spacing and use HashSet instead of ImmutableHashSet

80c0a5b

Merge branch 'main' of https://github.com/dotnet/runtime into Mutable…

660f62c

…Module

Add async helper methods to ReadyToRunHelpers

9d35db6

Merge branch 'main' of https://github.com/dotnet/runtime into Mutable…

a9eff16

…Module

Fix build issues

94d8de1

Trigger recompilation for async thunks that don't have references to …

430531c

…necessary methods

Revert changes to helper method enums

f1082d5

Revert files to updated upstream version

003efb0

Use TypeSystemEntity to ensure references to types and methods

0d7a521

Remove unused file

4833400

Revert extraneous changes

305958a

Fix project file, no need to use out param for thunkhelpers

ccc8f9f

Fix build break

2fa0a48

Merge branch 'main' of https://github.com/dotnet/runtime into Mutable…

9f42a55

…Module

Replace AsyncHelpers enum with KnownILStubReferences

7199f97

Missed a couple references to old methods.

88a6d5d

Add references to mutable module before compilation, don't allow asyn…

5a5dc81

…c thunks to be inlined.

Remove unnecessary changes

90e1a52

Typo: Pop should be Push

3297cc8

Emit correct ldloc/ldloca for task/valuetask locals

e708947

Merge branch 'main' of https://github.com/dotnet/runtime into EmitAsy…

651c4d6

…ncMethods

Merge branch 'main' into MutableModule

61cb9cc

Update log message

1112136

Use ILReader to find the references in thunks

70a88f6

Remove KnownReferences enum

b387f78

Merge branch 'MutableModule2' into EmitAsyncMethods

f016d83

Only locals and instatiations can use ELEMENT_TYPE_X

460bb27

jtschuster added 15 commits December 12, 2025 12:34

Account for all il opcodes, add tokens for all TypeDescs

4c04d16

Merge branch 'MutableModule2' into EmitAsyncMethods

bf410fe

Merge branch 'main' of https://github.com/dotnet/runtime into EmitAsy…

bb753d5

…ncMethods

Merge branch 'EmitTaskReturningThunks' into EmitAsyncMethods

218408d

WIP

1a75376

WIP

3d53a80

Merge branch 'EmitTaskReturningThunks' of https://github.com/jtschust…

f5a249e

…er/runtime into EmitAsyncMethods

Merge branch 'main' of https://github.com/dotnet/runtime into EmitAsy…

663f6b7

…ncMethods

Merge branch 'EmitTaskReturningThunks' into EmitAsyncMethods

099b3e8

Merge branch 'EmitTaskReturningThunks' into EmitAsyncMethods

dac8860

Read Continuations from R2R image

6610b81

Emit AsyncContinuationType into R2R image

663f2aa

Use MutableModuleWrappedMethodIL for Async thunks

670b84e

Only add references for getAsyncInfo members in ReadyToRunCodegenComp…

8e59917

…ilation

Clean up extra changes and formatting

897bd40

jtschuster requested a review from Copilot January 16, 2026 19:10

Copilot started reviewing on behalf of jtschuster January 16, 2026 19:11 View session

Copilot AI reviewed Jan 16, 2026

View reviewed changes

jtschuster and others added 4 commits January 16, 2026 12:10

Merge branch 'EmitTaskReturningThunks' into EmitAsyncMethods

8de3d77

Update src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRu…

9941b4e

…nCodegenCompilation.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/JitHelper.cs

02a8208

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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Emit async methods #5

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+                // The *_METHOD and *_CLASS variants of continuation allocation are not implemented
+                // for ReadyToRun. They are expected to fall through to the RequiresRuntimeJitException
+                // thrown at the end of this switch.

Emit async methods #5

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Pull request overview

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