[Async v2] Implement async method variant handling in AddMethod and UpdateMethod by tommcdon · Pull Request #125397 · dotnet/runtime

tommcdon · 2026-03-10T18:33:59Z

This change implements a TODO item in EEClass::AddMethodDesc to support Runtime Async

dotnet-policy-service · 2026-03-10T18:35:00Z

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Copilot

Pull request overview

This PR implements runtime-async method variant support in the Edit-and-Continue (EnC) path by extending EEClass::AddMethodDesc/EEClass::AddMethod to carry async metadata (flags + optional alternate signature) and by updating EnC method update logic to consider async method variants.

Changes:

Extend EEClass::AddMethodDesc to accept async flags and an optional async-variant signature, and plumb that into MethodTableBuilder::InitMethodDesc.
Add async return-type classification and async-variant creation logic to EEClass::AddMethod.
Update EditAndContinueModule::UpdateMethod to also reset the entrypoint for the method’s async counterpart.

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Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/coreclr/vm/encee.cpp	Resets entrypoints for async counterparts during EnC method updates.
src/coreclr/vm/class.h	Extends `AddMethodDesc` signature to accept async flags and optional async signature.
src/coreclr/vm/class.cpp	Implements async return classification and passes async flags/signature into EnC-added `MethodDesc` creation.

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Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

…ejection, generic UpdateMethod comment - class.cpp:579: Update GC violation comment to acknowledge the extern-alias edge case as Won't Fix per reviewer feedback - class.cpp:597: Reject infrastructure async methods (IsMiAsync but not task-returning) on non-system modules with COR_E_BADIMAGEFORMAT, mirroring MethodTableBuilder validation - encee.cpp:388: Add comment explaining that ResetCodeEntryPointForEnC cascades from thunk to async variant automatically, so generic UpdateMethod path does not need explicit async variant handling Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

noahfalk

Looks good 👍 Couple suggestions inline

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

- Update AsyncVariantLookup enum values: AsyncOtherVariant -> Async, MatchingAsyncVariant -> Ordinary - Update ClassifyMethodReturnKind calls to pass new elementTypeLength param - Update FindOrCreateAssociatedMethodDesc call to match new parameter order (AsyncVariantLookup moved before forceRemotableMethod) - Update debugger.cpp: HasAsyncOtherVariant -> IsAsyncThunkMethod, GetAsyncOtherVariantNoCreate -> GetAsyncVariantNoCreate - Add missing variable declarations in methodtablebuilder.cpp - Remove tautological assert in FCAMD lazy creation block Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…cation Reverts the unnecessary variable declaration reordering in EnumerateClassMethods that fell out of the rebase conflict resolution. Keeps the improved comment in InitMethodDesc that clarifies primary thunks use the original metadata signature and do not store one. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

Instead of lazily creating async variant MethodDescs in FindOrCreateAssociatedMethodDesc, create them eagerly alongside the primary thunk in EEClass::AddMethod. The variant signature is computed once from metadata and then AddMethodDesc (GC_NOTRIGGER) creates both MethodDescs. For generic types, each existing instantiation gets its own sig copy from its loader allocator. This eliminates: - Lazy creation block in FCAMD (double-check locking, GCX_COOP, lock) - LoadTypicalMethodDefinition fallback for async variants - EEClass::AddAsyncVariant helper (no longer needed) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Previously AddMethod only created async variants for IsMiAsync methods. Normal type loading (MethodTableBuilder::EnumerateClassMethods) creates variants for all task-returning methods regardless of IsMiAsync. This change aligns EnC with that behavior: - IsMiAsync: primary is thunk, async variant owns the IL - Non-IsMiAsync: primary owns IL, async variant is a thunk Also removes per-instantiation signature copy for generic types since instantiations cannot have longer lifetime than the definition. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace inline NonGenericTask and GenericTask signature rewriting in MethodTableBuilder::EnumerateClassMethods with calls to the shared BuildAsyncVariantSignature function. The ReturnDroppingThunk case (rare covariant override scenario) remains inline since it has unique logic not applicable to the EnC path. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

For task-returning methods with async variants, detect when the primary MethodDesc is a thunk and switch to the async variant that owns the user code before planting remap breakpoints. This eliminates the duplicated breakpoint-planting loop that previously handled the async variant separately. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Per reviewer feedback, inline the sig construction directly in EEClass::AddMethod instead of using a shared BuildAsyncVariantSignature function. Remove the function from method.cpp/method.hpp. Revert all changes to genmeth.cpp and methodtablebuilder.cpp as no modifications are needed in the normal type loading path for the EnC feature. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Per reviewer feedback, return S_OK instead of falling through when GetAsyncVariantNoCreate() returns NULL for an async thunk. There is no user code to plant remap breakpoints on in this case. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Re-add comment explaining the Won't Fix corner cases around the CONTRACT_VIOLATION(GCViolation) in EnC async variant creation: type identity may not match well-known types, and the call may trigger GC even for well-known types. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tommcdon · 2026-04-23T22:26:14Z

/ba-g failures are pre-existing/unrelated

tommcdon added this to the 11.0.0 milestone Mar 10, 2026

tommcdon self-assigned this Mar 10, 2026

tommcdon added the area-Diagnostics-coreclr label Mar 10, 2026

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tommcdon force-pushed the dev/tommcdon/implement_addmethoddesc branch from 76d4eb1 to 437f9ed Compare March 20, 2026 20:08

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build-analysis Bot mentioned this pull request Apr 17, 2026

System.Net.NameResolution.Tests DNS failures: Name or service not known #126641

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tommcdon and others added 3 commits April 23, 2026 14:35

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tommcdon merged commit bd6bb0d into dotnet:main Apr 23, 2026
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build-analysis Bot mentioned this pull request Apr 23, 2026

XHarness package install failure on iOS due to devicectl NSPOSIXErrorDomain error 49 #123796

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dotnet-maestro Bot mentioned this pull request Apr 24, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#6241

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tommcdon commented Mar 10, 2026

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tommcdon commented Apr 23, 2026

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