Support devirtualizing non-shared GVMs in R2R by hez2010 · Pull Request #123183 · dotnet/runtime

hez2010 · 2026-01-14T17:22:36Z

Implement the support for GVM devirtualization in managed type system.

It shares the same issue in #122023 where we are still not able to devirt shared GVMs due to lacking a proper generic context, so let's do the non-shared case first.

NativeAOT still not supported yet as it requires some work in the JIT to stop spilling the helper call for fat pointers.

Contributes to #112596

/cc: @MichalStrehovsky @jakobbotsch

dotnet-policy-service · 2026-01-14T17:23:43Z

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Copilot

Pull request overview

This PR enables devirtualization of non-shared Generic Virtual Methods (GVMs) in ReadyToRun (R2R) compilation by recording the compile-time method handle before embedding it into a lookup, allowing it to be used for devirtualization later. Shared GVMs remain unsupported due to lacking a proper generic context.

Changes:

Added IsConstructed property to Instantiation to determine if all type parameters are concrete types
Removed the early rejection of GVM devirtualization in R2R compilation
Enhanced devirtualization logic to properly handle generic method instantiations
Extended JIT's devirtualization candidate detection to support R2R virtual function pointers
Updated JIT-EE interface version GUID to reflect the API change

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/coreclr/tools/Common/TypeSystem/Common/Instantiation.cs	Adds `IsConstructed` property to check if instantiation contains only concrete types (no generic parameters)
src/coreclr/tools/Common/JitInterface/CorInfoTypes.cs	Removes `CORINFO_DEVIRTUALIZATION_FAILED_GENERIC_VIRTUAL` enum value as GVM devirtualization is now supported
src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs	Removes early rejection check for generic virtual method devirtualization
src/coreclr/tools/Common/Compiler/DevirtualizationManager.cs	Enhances logic to instantiate generic methods and adds check to block shared GVMs
src/coreclr/jit/importer.cpp	Records compile-time method handle for R2R virtual function pointer helper calls
src/coreclr/jit/gentree.h	Adds `compileTimeMethodHandle` union field and extends `IsGenericVirtual` to include R2R helper
src/coreclr/jit/gentree.cpp	Adds R2R-specific logic to extract method handle for devirtualization candidates
src/coreclr/jit/compiler.cpp	Removes error message case for the deleted enum value
src/coreclr/inc/jiteeversionguid.h	Updates JIT-EE version identifier GUID for interface change
src/coreclr/inc/corinfo.h	Removes `CORINFO_DEVIRTUALIZATION_FAILED_GENERIC_VIRTUAL` enum value

hez2010 · 2026-01-16T17:10:40Z

It hit a weird assertion:

Assert failure(PID 4616 [0x00001208], Thread: 3532 [0x0dcc]): Verify_VirtualFunctionOverride Decl Method 'instance int32 [crossgen2smoke] Program+BaseClass::MyGvm()' on type 'BaseClass' is 'instance int32 [crossgen2smoke] Program+BaseClass::MyGvm()'(actual) instead of expected 'instance int32 [crossgen2smoke] Program+BaseClass::MyGvm()'(from compiler)
CORECLR! LoadDynamicInfoEntry + 0x15EC (0x00007ff9`b8340c6c)
CORECLR! Module::FixupNativeEntry + 0x2A3 (0x00007ff9`b8221383)
CORECLR! Module::FixupDelayListAux<Module *,int (__cdecl Module::*)(READYTORUN_IMPORT_SECTION *,unsigned __int64,unsigned __int64 *,int)> + 0x674 (0x00007ff9`b84dcf04)
CORECLR! ReadyToRunInfo::GetEntryPoint + 0x4BE (0x00007ff9`b84e08ce)
CORECLR! MethodDesc::GetPrecompiledR2RCode + 0x11A (0x00007ff9`b842f20a)
CORECLR! MethodDesc::GetPrecompiledCode + 0xFA (0x00007ff9`b842ee3a)
CORECLR! MethodDesc::PrepareILBasedCode + 0x32F (0x00007ff9`b843252f)
CORECLR! MethodDesc::PrepareCode + 0x129 (0x00007ff9`b8432199)
CORECLR! CodeVersionManager::PublishVersionableCodeIfNecessary + 0x4F6 (0x00007ff9`b82812b6)
CORECLR! MethodDesc::DoPrestub + 0xD03 (0x00007ff9`b842b3b3)
File: D:\a\_work\1\s\src\coreclr\vm\jitinterface.cpp:14372
Image: C:\h\w\AA800A0D\p\corerun.exe

aren't the two instance int32 [crossgen2smoke] Program+BaseClass::MyGvm() identical?

hez2010 · 2026-01-16T18:00:34Z

It seems that the failure only happens when specifying --verify-type-and-field-layout in crossgen2.

hez2010 · 2026-01-16T18:45:25Z

It turns out to be a verification-only issue. We need to use the method definition for comparison during verification instead.

hez2010 · 2026-01-17T04:22:09Z

Tests are passing. Please take a look. @MichalStrehovsky

…tion

MichalStrehovsky

Cc @davidwrighton for the JitInterface.cpp change, Cc @jakobbotsch for the RyuJIT change

hez2010 · 2026-01-23T17:27:55Z

@MichalStrehovsky
Addressed feedback comments. Please take another look.

MichalStrehovsky

The managed parts LGTM, but I can't comment on the JIT part or jitinterface.cpp.

Cc @davidwrighton

hez2010 · 2026-01-31T06:38:11Z

I have renamed the PR as it almost changes nothing to the JIT.

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

jakobbotsch

JIT part LGTM

@MichalStrehovsky

Implement the support for GVM devirtualization in managed type system. It shares the same issue in dotnet#122023 where we are still not able to devirt shared GVMs due to lacking a proper generic context, so let's do the non-shared case first. NativeAOT still not supported yet as it requires some work in the JIT to stop spilling the helper call for fat pointers. Contributes to dotnet#112596 /cc: @MichalStrehovsky @jakobbotsch --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

@MichalStrehovsky

Implement the support for GVM devirtualization in managed type system. It shares the same issue in dotnet#122023 where we are still not able to devirt shared GVMs due to lacking a proper generic context, so let's do the non-shared case first. NativeAOT still not supported yet as it requires some work in the JIT to stop spilling the helper call for fat pointers. Contributes to dotnet#112596 /cc: @MichalStrehovsky @jakobbotsch --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

hez2010 requested a review from MichalStrehovsky as a code owner January 14, 2026 17:22

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Copilotstarted reviewing on behalf of hez2010 January 14, 2026 17:23 View session

hez2010 mentioned this pull request Jan 14, 2026
JIT: Devirtualization for generic virtual methods #112596
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hez2010 changed the title ~~Devirtualize non-shared GVMs in R2R~~JIT: Devirtualize non-shared GVMs in R2RJan 14, 2026

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"We stopped hearing from agent Azure Pipelines 32. Verify the agent machine is running and has a healthy network connection" dotnet/dnceng#1886
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Comment threadsrc/coreclr/tools/Common/Compiler/DevirtualizationManager.cs Outdated

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AF: *(_UNCHECKED_OBJECTREF *)handle == NULL (HndCreateHandle called by getJitHandleForObject) #117138
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hez2010 force-pushed the gvm-devirt-r2r branch from 3589e2f to 9efb3c1Compare January 16, 2026 18:44

hez2010 force-pushed the gvm-devirt-r2r branch from 615ddb9 to 8ab7342Compare January 16, 2026 19:01

hez2010 added 7 commits January 23, 2026 00:40

Devirtualize non-shared GVMs in R2R
0247e76

Remove unused failure mode
54a601f

Check null for impl first
5b2e74b

Use IsGenericMethodDefinition
a935bb7

More fixes
2d109f1

Update comments
607b05a

Use typical method definition for R2R generic virtual method verifica…
1113997
…tion

hez2010 force-pushed the gvm-devirt-r2r branch from 8ab7342 to 1113997Compare January 22, 2026 15:42

Update devirtualization detail message
515f39c

MichalStrehovsky reviewed Jan 23, 2026
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Comment threadsrc/coreclr/tools/Common/Compiler/DevirtualizationManager.cs Outdated

hez2010 added 2 commits January 24, 2026 00:47

Reduce nesting per review feedback
c896f15

Nit
ef005bf

Merge branch 'main' into gvm-devirt-r2r
b2e6a96

MichalStrehovsky approved these changes Jan 29, 2026
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hez2010 changed the title ~~JIT: Devirtualize non-shared GVMs in R2R~~Support devirtualizing non-shared GVMs in R2RJan 31, 2026

Merge branch 'main' into gvm-devirt-r2r
4d6ace8

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build-analysisBot mentioned this pull request Jan 31, 2026
XHarness package install failure on iOS due to devicectl NSPOSIXErrorDomain error 49 #123796
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davidwrighton self-assigned this Jan 31, 2026

jakobbotsch approved these changes Feb 2, 2026
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Comment threadsrc/coreclr/vm/jitinterface.cpp

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davidwrighton merged commit da98e91 into dotnet:mainFeb 3, 2026
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[main] Source code updates from dotnet/runtime dotnet/dotnet#4680
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