JIT: Unify to instParamLookup and improve GVM test coverage by hez2010 · Pull Request #126947 · dotnet/runtime

hez2010 · 2026-04-15T12:57:47Z

Extracted from #123323. This PR is the first step in splitting the shared GVM devirtualization work.

It does two things:

expands the generic virtual method test coverage so the later enablement PRs have good coverage
refactors devirtualization a bit to replace multiple ad-hoc flags in CORINFO_DEVIRTUALIZATION_INFO with a single instParamLookup

Contributes to #112596

/cc: @jakobbotsch

dotnet-policy-service · 2026-04-15T12:59:15Z

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Pull request overview

Refactors CoreCLR devirtualization metadata to use a unified instParamLookup and expands JIT test coverage for generic virtual method (GVM) scenarios to support follow-on GVM devirtualization work.

Changes:

Add a new GVM-focused runtime lookup/delegate test to broaden devirtualization coverage.
Replace CORINFO_DEVIRTUALIZATION_INFO ad-hoc flags with instParamLookup, and update JIT devirtualization logic to consume it.
Update SuperPMI and the managed JitInterface type definitions/serialization to match the new CORINFO_DEVIRTUALIZATION_INFO shape (plus bump the JIT/EE versioning GUID).

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Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

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File	Description
src/tests/JIT/Generics/VirtualMethods/generic_virtual_methods.cs	Adds additional GVM/runtime-lookup-related test coverage.
src/coreclr/vm/jitinterface.cpp	Initializes/produces `instParamLookup` for devirtualization results (replacing older flags).
src/coreclr/jit/importercalls.cpp	Plumbs `instParamLookup` through devirtualization + guarded devirtualization candidate tracking and inserts instantiation args when required.
src/coreclr/jit/morph.cpp	Simplifies lookup-tree helpers to take `CORINFO_LOOKUP` directly.
src/coreclr/jit/compiler.h	Updates declarations for the new lookup-tree helper signatures and GDV candidate plumbing.
src/coreclr/inc/corinfo.h	Updates `CORINFO_DEVIRTUALIZATION_INFO` to carry `instParamLookup` instead of legacy flags; documents “no lookup needed” sentinel.
src/coreclr/inc/jiteeversionguid.h	Bumps the JIT/EE version GUID for the interface change.
src/coreclr/tools/Common/JitInterface/CorInfoTypes.cs	Mirrors the `CORINFO_DEVIRTUALIZATION_INFO` layout change in managed definitions.
src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs	Updates managed `resolveVirtualMethod` implementation to populate `instParamLookup` and method-context behavior.
src/coreclr/tools/superpmi/superpmi-shared/agnostic.h	Updates SuperPMI record structs to include `instParamLookup`.
src/coreclr/tools/superpmi/superpmi-shared/methodcontext.cpp	Records/restores/dumps `instParamLookup` in SuperPMI method contexts.

hez2010 · 2026-04-16T03:28:30Z

Test failure seems unrelated.

hez2010 · 2026-04-24T04:28:04Z

Ping @jakobbotsch

This is a refactor only change which is the prerequisites of the upcoming GVM devirt work, please take a look when you get some time.

MichalPetryka · 2026-04-24T04:32:09Z

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Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

hez2010 · 2026-05-23T06:19:59Z

Test failures seem unrelated?

jakobbotsch · 2026-05-23T11:26:24Z

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jakobbotsch · 2026-05-23T11:47:55Z

It seems there are diffs. Can you take a look at why? I was hoping this could be a zero diff change with all diffs coming as follow-ups.

hez2010 · 2026-05-23T11:51:54Z

It seems there are diffs. Can you take a look at why? I was hoping this could be a zero diff change with all diffs coming as follow-ups.

I think it's because this branch is a bit stale? We merged a devirtualization improvement several hours ago but didn't sync that to this branch yet.

hez2010 · 2026-05-23T11:53:56Z

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Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

hez2010 · 2026-05-23T12:55:56Z

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hez2010 · 2026-05-23T15:35:19Z

Previously we only check isExact when the EE sets isInstantiatingStub to true, but now we are checking it unconditionally as long as it's array interface devirt, and the EE no longer returns such a flag. So it rejects more array interface devirt than before.

However, the original "array is inexact" guard was added to workaround a bug in #116771 (comment). But with this PR, we now have the correct instantiating stub in tokenForLookup and we no longer need to do a getInstantiatedEntry round-trip, so the original bug doesn't exist anymore: we now always have the right instantiation here.

For comparison, for this tree

**** Late devirt opportunity
               [000157] --C-G------                         *  CALLV stub ref    System.Collections.Generic.IEnumerable`1[System.__Canon]:GetEnumerator():System.Collections.Generic.IEnumerator`1[System.__Canon]:this
               [000820] --CXG------ this                    \--*  CALL help ref    CORINFO_HELP_CHKCASTANY
               [000819] H------N--- arg0                       +--*  CNS_INT(h) long   0x7ffe0b544f48 class System.Collections.Generic.IEnumerable`1[Span.InlineDataAttribute]
               [000830] --C-G------ arg1                       \--*  CALL      ref    System.Attribute:GetCustomAttributes(System.Reflection.MemberInfo,System.Type,bool):System.Attribute[]
               [000145] ----------- arg0                          +--*  LCL_VAR   ref    V18 tmp5         
               [000827] --C-G------ arg1                          +--*  CALL help ref    CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE
               [000828] H---------- arg0                          |  \--*  CNS_INT(h) long   0x7ffe0b5441d0 class Span.InlineDataAttribute
               [000829] ----------- arg2                          \--*  CNS_INT   int    1

previously we end up with

               [000157] --C-G------                         *  CALL nullcheck ref    System.SZArrayHelper:GetEnumerator[System.__Canon]():System.Collections.Generic.IEnumerator`1[System.__Canon]:this
               [000820] --CXG------ this                    +--*  CALL help ref    CORINFO_HELP_CHKCASTANY
               [000819] H------N--- arg0                    |  +--*  CNS_INT(h) long   0x7ffe0b544f48 class System.Collections.Generic.IEnumerable`1[Span.InlineDataAttribute]
               [000830] --C-G------ arg1                    |  \--*  CALL      ref    System.Attribute:GetCustomAttributes(System.Reflection.MemberInfo,System.Type,bool):System.Attribute[]
               [000145] ----------- arg0                    |     +--*  LCL_VAR   ref    V18 tmp5         
               [000827] --C-G------ arg1                    |     +--*  CALL help ref    CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE
               [000828] H---------- arg0                    |     |  \--*  CNS_INT(h) long   0x7ffe0b5441d0 class Span.InlineDataAttribute
               [000829] ----------- arg2                    |     \--*  CNS_INT   int    1
               [000832] H---------- gctx                    \--*  CNS_INT(h) long   0x7ffe0b5caa68 method System.SZArrayHelper:GetEnumerator[System.Attribute]():System.Collections.Generic.IEnumerator`1[System.Attribute]:this

and now we have

               [000157] --C-G------                         *  CALL nullcheck ref    System.SZArrayHelper:GetEnumerator[System.__Canon]():System.Collections.Generic.IEnumerator`1[System.__Canon]:this
               [000850] --CXG------ this                    +--*  CALL help ref    CORINFO_HELP_CHKCASTANY
               [000849] H------N--- arg0                    |  +--*  CNS_INT(h) long   0x7ffab5805780 class System.Collections.Generic.IEnumerable`1[Span.InlineDataAttribute]
               [000860] --C-G------ arg1                    |  \--*  CALL      ref    System.Attribute:GetCustomAttributes(System.Reflection.MemberInfo,System.Type,bool):System.Attribute[]
               [000145] ----------- arg0                    |     +--*  LCL_VAR   ref    V18 tmp5
               [000857] --C-G------ arg1                    |     +--*  CALL help ref    CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE
               [000858] H---------- arg0                    |     |  \--*  CNS_INT(h) long   0x7ffab5804a18 class Span.InlineDataAttribute
               [000859] ----------- arg2                    |     \--*  CNS_INT   int    1
               [000862] H---------- gctx                    \--*  CNS_INT(h) long   0x7ffab5808a40 method System.SZArrayHelper:GetEnumerator[Span.InlineDataAttribute]():System.Collections.Generic.IEnumerator`1[Span.InlineDataAttribute]:this

We no longer have the issue on incorrect inst param now. So I would recommend removing this invalid guard. (already done in eaca574).

But that's say, to keep this PR zero diff, we will need to introduce the isInstantiatingStub flag back, or checking instParamLookup.constLookup.handle or the signature manually in the JIT. What do you think? @jakobbotsch

hez2010 · 2026-05-23T16:22:03Z

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Copilot reviewed 13 out of 13 changed files in this pull request and generated 4 comments.

hez2010 · 2026-05-23T16:51:16Z

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Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

hez2010 · 2026-05-23T17:10:16Z

Now it's zero diff as expected.

Part 1: add tests and instParamLookup refactor

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hez2010 requested a review from MichalStrehovsky as a code owner April 15, 2026 12:57

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github-actions Bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Apr 15, 2026

Merge branch 'main' into shared-gvm-devirt/1-tests-instparamlookup

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Comment thread src/coreclr/vm/jitinterface.cpp

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This was referenced Apr 22, 2026

slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883

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browser-wasm linux Release LibraryTests queues timing out #117974

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[JitDiff X64] [hez2010] JIT: Unify to instParamLookup and improve GVM test c ... MihuBot/runtime-utils#1850

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hez2010 force-pushed the shared-gvm-devirt/1-tests-instparamlookup branch from 75dec5b to 4da609f Compare April 25, 2026 11:55

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Comment thread src/tests/JIT/Generics/VirtualMethods/generic_virtual_methods.cs

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Merge branch 'main' into shared-gvm-devirt/1-tests-instparamlookup

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hez2010 force-pushed the shared-gvm-devirt/1-tests-instparamlookup branch from 4da609f to 42d5011 Compare April 25, 2026 12:19

Address review feedbacks

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[JitDiff X64] [hez2010] JIT: Unify to instParamLookup and improve GVM test c ... MihuBot/runtime-utils#1926

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hez2010 added 2 commits May 23, 2026 20:53

Remove dead code for now

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Merge branch 'main' into shared-gvm-devirt/1-tests-instparamlookup

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[JitDiff X64] [hez2010] JIT: Unify to instParamLookup and improve GVM test c ... MihuBot/runtime-utils#1927

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Comment thread src/coreclr/jit/morph.cpp

Comment thread src/coreclr/jit/importercalls.cpp Outdated

Comment thread src/tests/JIT/Generics/VirtualMethods/generic_virtual_methods.cs

Address a regression

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[JitDiff X64] [hez2010] JIT: Unify to instParamLookup and improve GVM test c ... MihuBot/runtime-utils#1928

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Comment thread src/coreclr/inc/corinfo.h Outdated

Address some issues that causes non-zero diffs.

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Nit

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[JitDiff X64] [hez2010] JIT: Unify to instParamLookup and improve GVM test c ... MihuBot/runtime-utils#1930

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Comment thread src/coreclr/jit/importercalls.cpp

Comment thread src/coreclr/jit/indirectcalltransformer.cpp

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Comment thread src/tests/JIT/Generics/VirtualMethods/generic_virtual_methods.cs

Fix AV

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hez2010 force-pushed the shared-gvm-devirt/1-tests-instparamlookup branch from aba164b to d02eec1 Compare May 23, 2026 16:49

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[JitDiff X64] [hez2010] JIT: Unify to instParamLookup and improve GVM test c ... MihuBot/runtime-utils#1932

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Checkout failure: "Git fetch failed with exit code 128" dotnet/arcade#9009

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