[experiment] check generic ctx in gtGetClassHandle#129434
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Recover the exact return type of a non-inlined shared generic call from its instantiation parameter, so the result can be exactly devirtualized. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Just a CI test for an alternative fix #129373 tries to make. |
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@MihuBot -nuget -jitutils-repo EgorBo/jitutils -jitutils-branch pmi-deterministic-cctors |
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
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Pull request overview
This PR adjusts CoreCLR JIT’s Compiler::gtGetClassHandle handling of GT_CALL nodes (specifically CT_USER_FUNC) to attempt to recover a more precise instantiated return type for shared generic calls by using the call’s WellKnownArg::InstParam, similar in spirit to the existing inline-candidate sharpening.
Changes:
- Remove outdated comment implying exact generic context is always unavailable for
CT_USER_FUNCcalls. - When the return type from
eeGetMethodSigis a shared instantiation (e.g.,__Canon), attempt to re-query the signature in the exact context derived fromWellKnownArg::InstParamand use the refined return type when it is no longer shared.
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| // Static method on a generic type (or array method): the | ||
| // generic context is the exact owner class. | ||
| CORINFO_CLASS_HANDLE exactOwner = gtGetHelperArgClassHandle(instParam->GetNode()); |
This was referenced Jun 16, 2026
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Experiment: in gtGetClassHandle's
CT_USER_FUNCbranch, recover the exact return type of a non-inlined shared generic call from its instantiation parameter (WellKnownArg::InstParam), mirroring the sharpening already done for inline candidates. This lets a subsequent virtual call on the result devirtualize exactly (e.g.NoInline(new Foo()).ToString()folds without a GDV guard) instead of seeingSystem.__Canon.Note
This PR was created with assistance from GitHub Copilot.