JIT: Refactor async-to-sync call optimization by jakobbotsch · Pull Request #124798 · dotnet/runtime

jakobbotsch · 2026-02-24T16:19:08Z

Introduce getAsyncOtherVariant JIT-EE API that returns the other async variant of an async/task-returning method
Remove the AwaitVirtual token kind that was used to allow the VM to tell the JIT to prefer a task-returning instead of async variant
Implement the same optimization on the JIT side instead using the getAsyncOtherVariant, when we notice that a call will be direct
Fix ilc.slnx and crossgen2.slnx to compile from VS
ActiveIssue async EH tests under interpreter against Crash in ToString_Async test on Apple mobile with CoreCLR R2R and interpreter #124044

- Introduce `getAsyncOtherVariant` JIT-EE API that returns the other async variant of an async/task-returning method - Remove the `AwaitVirtual` token kind that was used to allow the VM to tell the JIT to prefer a task-returning instead of async variant - Implement the same optimization on the JIT side instead using the `getAsyncOtherVariant`, when we notice that a call will be direct Fix dotnet#124545

dotnet-policy-service · 2026-02-24T16:20:41Z

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Copilot

Pull request overview

Refactors the async-to-sync call optimization by removing VM-driven “prefer task-returning for direct calls” token handling and moving the decision logic into the JIT using a new JIT↔EE API (getAsyncOtherVariant).

Changes:

Add ICorJitInfo::getAsyncOtherVariant API and plumb it through VM, JIT wrappers, NativeAOT JIT interface, and SuperPMI record/replay.
Remove CORINFO_TOKENKIND_AwaitVirtual and simplify await token resolution to always request the async variant from the VM.
Teach the JIT importer to switch back to the synchronous Task-returning call for direct calls when the async variant is a thunk.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/coreclr/vm/jitinterface.cpp	Removes AwaitVirtual-specific resolution logic; adds EE implementation of `getAsyncOtherVariant`.
src/coreclr/jit/importer.cpp	Implements JIT-side “avoid thunk for direct calls” logic using `getAsyncOtherVariant`.
src/coreclr/jit/ee_il_dll.hpp	Replaces `combine(...)` helper with `CORINFO_CALLINFO_FLAGS` `operator
src/coreclr/inc/corinfo.h	Removes `CORINFO_TOKENKIND_AwaitVirtual`; adds `ICorStaticInfo::getAsyncOtherVariant`.
src/coreclr/inc/icorjitinfoimpl_generated.h	Declares the new EE-side virtual method override.
src/coreclr/inc/jiteeversionguid.h	Updates the JIT/EE interface version GUID for the API shape change.
src/coreclr/jit/ICorJitInfo_wrapper_generated.hpp	Adds wrapper forwarding for `getAsyncOtherVariant`.
src/coreclr/jit/ICorJitInfo_names_generated.h	Adds name for the new API.
src/coreclr/tools/superpmi/superpmi/icorjitinfo.cpp	Adds SuperPMI ICJI forwarding/recording hook.
src/coreclr/tools/superpmi/superpmi-shim-simple/icorjitinfo_generated.cpp	Adds shim forwarding for the new API.
src/coreclr/tools/superpmi/superpmi-shim-counter/icorjitinfo_generated.cpp	Adds shim call counting + forwarding for the new API.
src/coreclr/tools/superpmi/superpmi-shim-collector/icorjitinfo.cpp	Records/replays `getAsyncOtherVariant` including `variantIsThunk`.
src/coreclr/tools/superpmi/superpmi-shared/methodcontext.h	Adds record/replay declarations + packet ID for `getAsyncOtherVariant`.
src/coreclr/tools/superpmi/superpmi-shared/methodcontext.cpp	Implements record/replay storage for `getAsyncOtherVariant`.
src/coreclr/tools/superpmi/superpmi-shared/lwmlist.h	Adds LWM map entry for `GetAsyncOtherVariant`.
src/coreclr/tools/Common/JitInterface/ThunkGenerator/ThunkInput.txt	Adds new API to thunk generator inputs.
src/coreclr/tools/Common/JitInterface/CorInfoTypes.cs	Removes `CORINFO_TOKENKIND_AwaitVirtual` from managed enum mirror.
src/coreclr/tools/Common/JitInterface/CorInfoImpl_generated.cs	Adds unmanaged callback plumbing for `getAsyncOtherVariant`.
src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs	Updates await-token handling; adds (currently stubbed) `getAsyncOtherVariant` managed implementation.
src/coreclr/tools/aot/jitinterface/jitinterface_generated.h	Adds callback pointer + wrapper method for `getAsyncOtherVariant`.
src/coreclr/tools/aot/ILCompiler.Compiler/IL/ILImporter.Scanner.cs	Removes NativeAOT scanner-side “avoid thunk for direct calls” logic.
src/coreclr/interpreter/compiler.cpp	Removes AwaitVirtual usage in interpreter async-call peep token resolution.
src/coreclr/tools/aot/ilc.slnx	Adds ILLink.CodeFixProvider project to the solution.
src/coreclr/tools/aot/crossgen2.slnx	Adds ILLink.CodeFixProvider project to the solution.

src/coreclr/tools/aot/crossgen2.slnx

src/coreclr/vm/jitinterface.cpp

src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs

src/coreclr/tools/Common/JitInterface/CorInfoImpl_generated.cs

src/coreclr/interpreter/compiler.cpp

src/coreclr/tools/aot/ilc.slnx

Copilot

Pull request overview

Copilot reviewed 24 out of 24 changed files in this pull request and generated 3 comments.

src/coreclr/jit/importer.cpp

src/coreclr/tools/aot/crossgen2.slnx

…uals-2

Copilot

Pull request overview

Copilot reviewed 27 out of 27 changed files in this pull request and generated 1 comment.

src/coreclr/jit/importercalls.cpp

Copilot

Pull request overview

Copilot reviewed 27 out of 27 changed files in this pull request and generated 1 comment.

src/coreclr/jit/importer.cpp

janvorli

LGTM (I haven't looked at the JIT changes), I have just few nits.

src/coreclr/inc/corinfo.h

janvorli · 2026-02-26T12:36:39Z

src/coreclr/interpreter/compiler.cpp

+                // non-async task-returning call. There is no reason to create
+                // and go through the thunk.
+                ResolveToken(token, CORINFO_TOKENKIND_Method, &resolvedCallToken);
+                m_ip = origIP + 5;


It seems we don't need to save the origIP as at this point the m_ip would always be the same as origIP, unless I am mising something.

m_ip gets changed by AsyncCallPeeps.FindAndApplyPeep above -- this is undoing the change when we decide to not actually dispatch through the async call. Let me add a comment.

Ah, makes sense.

src/coreclr/interpreter/compiler.cpp

Copilot AI review requested due to automatic review settings February 24, 2026 16:19

github-actions bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Feb 24, 2026

dotnet-policy-service bot assigned jakobbotsch Feb 24, 2026

Copilot started reviewing on behalf of jakobbotsch February 24, 2026 16:20 View session

jakobbotsch added 2 commits February 24, 2026 17:22

Managed type system impl

8ef22c8

Fix

1460458

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jakobbotsch added 2 commits February 24, 2026 17:31

Disallow null variantIsThunk

d3f8649

Run jit-format

2a664b1

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jakobbotsch added 3 commits February 25, 2026 12:57

Merge branch 'main' of github.com:dotnet/runtime into fix-static-virt…

15d15c9

…uals-2

Implement in interpreter too

dbf6a5f

ActiveIssue EH tests under interpreter

f65636e

jakobbotsch mentioned this pull request Feb 25, 2026

Crash in ToString_Async test on Apple mobile with CoreCLR R2R and interpreter #124044

Open

Query getAsyncOtherVariant when extra SPMI queries are enabled

52589e4

Copilot AI review requested due to automatic review settings February 25, 2026 14:31

Copilot started reviewing on behalf of jakobbotsch February 25, 2026 14:32 View session

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Feedback, run jit-format

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This was referenced Feb 25, 2026

[FAIL] System.Net.Http.Functional.Tests.SocketsHttpHandler_HttpClientHandlerTest.LargeUriAndHeaders_Works #124487

Open

Android WebSocket failure #121518

Open

jakobbotsch marked this pull request as ready for review February 26, 2026 12:17

jakobbotsch requested review from BrzVlad and MichalStrehovsky as code owners February 26, 2026 12:17

Copilot AI review requested due to automatic review settings February 26, 2026 12:17

jakobbotsch requested review from janvorli and kg as code owners February 26, 2026 12:17

Copilot started reviewing on behalf of jakobbotsch February 26, 2026 12:18 View session

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janvorli approved these changes Feb 26, 2026

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Add some comments

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davidwrighton approved these changes Feb 26, 2026

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jakobbotsch commented Feb 24, 2026 •

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