JIT: don't stress-tailcall named intrinsics (#122479)#128336
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JIT: don't stress-tailcall named intrinsics (#122479)#128336AndyAyersMS wants to merge 1 commit into
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Pull request overview
Updates CoreCLR JIT tailcall-stress handling to avoid treating intrinsic calls as explicit tailcalls, and removes the corresponding temporary runtime workaround.
Changes:
- JIT importer: gate tailcall-stress “explicit tailcall” promotion on
CORINFO_FLG_INTRINSIC. - System.Private.CoreLib: remove the temporary
[MethodImpl(NoInlining | NoOptimization)]workaround onThread.ClearWaitSleepJoinState().
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| src/coreclr/jit/importer.cpp | Skips stress tailcall promotion for intrinsic callees to avoid later-phase inconsistencies/asserts. |
| src/coreclr/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs | Removes prior workaround attributes/comment from ClearWaitSleepJoinState. |
Under STRESS_TAILCALL the importer marks call+ret patterns with PREFIX_TAILCALL_EXPLICIT (and may later add PREFIX_TAILCALL_IMPLICIT) before it knows whether the callee is a named intrinsic. For intrinsics that are imported as non-CALL IR (e.g. GC.KeepAlive -> GT_KEEPALIVE), this leaves a BBJ_RETURN block whose last statement is neither a GT_RETURN nor a GT_CALL, which trips an assert in fgInsertStmtNearEnd when `Insert GC Polls` later runs on methods that contain [SuppressGCTransition] calls (e.g. Thread.ClearWaitSleepJoinState). Fix by treating intrinsic callees as having failed stress-mode validation: set passedStressModeValidation = false so neither the explicit nor the subsequent implicit tailcall promotion is applied to them. Removes the temporary workaround in Thread.CoreCLR.cs added by dotnet#122652, and adds a small JitBlue regression test that exercises the Thread.Sleep -> Thread.ClearWaitSleepJoinState path so the jitstress legs will catch any future regression. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Fixes #122479 |
This was referenced May 19, 2026
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Under STRESS_TAILCALL the importer marks call+ret patterns with PREFIX_TAILCALL_EXPLICIT before it knows whether the callee is a named intrinsic. For intrinsics that are imported as non-CALL IR (e.g. GC.KeepAlive -> GT_KEEPALIVE), this leaves a BBJ_RETURN block whose last statement is neither a GT_RETURN nor a GT_CALL, which trips an assert in fgInsertStmtNearEnd when
Insert GC Pollslater runs on methods that contain [SuppressGCTransition] calls (e.g. Thread.ClearWaitSleepJoinState).Fix by skipping stress-tailcall promotion when the callee has CORINFO_FLG_INTRINSIC set.
Removes the temporary workaround in Thread.CoreCLR.cs added by #122652.
Fixes #122479