Support devirtualization for virtual methods that require an instantiating stub

[hez2010]

Enable devirtualization of virtual methods that require an instantiating stub.
We have landed the refactor in the JIT so that now we are able to handle instantiating stub naturally without a JIT change.

This covers both shared generic virtual methods that don't require a runtime lookup, and generic interface methods that have a default implementation.

GVM devirt for NativeAOT requires more changes which is out of scope of this PR.

IGenericA<string> a = new AImpl();
a.B("GVM");
a.C("Generic DIM");

interface IA
{
    void A(object o);
    void B<T>(T o);
}

interface IGenericA<T> : IA
{
    void C(T o) => B(o);
}

class AImpl : IGenericA<string>
{
    public void A(object o)
    {
        Console.WriteLine(o);
    }

    public void B<T>(T o)
    {
        Console.WriteLine(o);
    }
}

Before:

G_M000_IG01:                ;; offset=0x0000
       push     rbx
       sub      rsp, 32
 
G_M000_IG02:                ;; offset=0x0005
       mov      rcx, 0x7FFB383AF518
       call     CORINFO_HELP_NEWSFAST
       mov      rbx, rax
       mov      rcx, rbx
       mov      rdx, 0x7FFB383AF348
       mov      r8, 0x7FFB383AF828
       call     CORINFO_HELP_VIRTUAL_FUNC_PTR
       mov      rcx, rbx
       mov      rdx, 0xA025C36200
       call     rax
       mov      rcx, rbx
       mov      r11, 0x7FFB380E0070
       mov      rdx, 0xA025C36220
       call     [r11]IGenericA`1[System.__Canon]:C(System.__Canon):this
       nop      
 
G_M000_IG03:                ;; offset=0x005D
       add      rsp, 32
       pop      rbx
       ret      
 
; Total bytes of code 99

After:

G_M56640_IG01:  ;; offset=0x0000
       sub      rsp, 40
G_M56640_IG02:  ;; offset=0x0004
       mov      rcx, 0xA0261EE6F0      ; 'GVM'
       call     [System.Console:WriteLine(System.Object)]
       mov      rcx, 0xA0261EE710      ; 'Generic DIM'
       call     [System.Console:WriteLine(System.Object)]
       nop
G_M56640_IG03:  ;; offset=0x0025
       add      rsp, 40
       ret

; Total bytes of code 42

Similar for R2R:

G_M56640_IG01:  ;; offset=0x0000
       push     rbx
       sub      rsp, 32
G_M56640_IG02:  ;; offset=0x0005
       call     [CORINFO_HELP_READYTORUN_NEW]
       mov      rbx, rax
       mov      rcx, qword ptr [(reloc 0x4000000000420148)]      ; const ptr
       mov      rcx, gword ptr [rcx]
       call     [System.Console:WriteLine(System.Object)]
       mov      rdx, qword ptr [(reloc 0x4000000000420150)]      ; const ptr
       mov      rdx, gword ptr [rdx]
       mov      rcx, rbx
       lea      r11, [(reloc 0x40000000004200f8)]      ; function address
       call     [r11]IGenericA`1[System.String]:C(System.String):this
       nop
G_M56640_IG03:  ;; offset=0x0036
       add      rsp, 32
       pop      rbx
       ret

For NativeAOT:

Before:

  G_M000_IG01:                ;; offset=0x0000
         push     rbx
         sub      rsp, 32
   
  G_M000_IG02:                ;; offset=0x0005
         lea      rcx, [(reloc 0x420c38)]
         call     CORINFO_HELP_NEWSFAST
         mov      rbx, rax
         mov      rcx, rbx
         lea      rdx, [(reloc 0x420c48)]
         call     CORINFO_HELP_GVMLOOKUP_FOR_SLOT
         test     al, 2
         je       SHORT G_M000_IG04
   
  G_M000_IG03:                ;; offset=0x0027
         mov      rdx, qword ptr [rax+0x06]
         mov      rcx, rbx
         lea      r8, gword ptr [(reloc 0x420c68)]
         call     [rax-0x02]
         jmp      SHORT G_M000_IG05
   
  G_M000_IG04:                ;; offset=0x003A
         mov      rcx, rbx
         lea      rdx, gword ptr [(reloc 0x420c68)]
         call     rax
   
  G_M000_IG05:                ;; offset=0x0046
         mov      rcx, rbx
         lea      r11, [(reloc 0x420c58)]
         lea      rdx, gword ptr [(reloc 0x420c70)]
         call     [r11]IGenericA`1[System.String]:C(System.String):this
         nop      
   
  G_M000_IG06:                ;; offset=0x005B
         add      rsp, 32
         pop      rbx
         ret      
   
  ; Total bytes of code 97

After:

G_M56640_IG01:  ;; offset=0x0000
       push     rdi
       push     rsi
       push     rbx
       sub      rsp, 32
                                                ;; size=7 bbWeight=1 PerfScore 3.25
G_M56640_IG02:  ;; offset=0x0007
       lea      rcx, [(reloc 0x4000000000420c30)]      ; AImpl
       call     CORINFO_HELP_NEWSFAST
       mov      rbx, rax
       mov      rcx, rbx
       lea      rdx, [(reloc 0x4000000000420c40)]      ; IA:B[System.String](System.String):this
       call     CORINFO_HELP_GVMLOOKUP_FOR_SLOT
       mov      rsi, rax
       mov      edi, eax
       and      edi, 2
       je       SHORT G_M56640_IG04
G_M56640_IG03:  ;; offset=0x002F
       mov      rdx, qword ptr [rax+0x06]
       mov      rcx, rbx
       lea      r8, gword ptr [(reloc 0x4000000000420c90)]      ; '"GVM"'
       call     [rax-0x02]
       jmp      SHORT G_M56640_IG05
G_M56640_IG04:  ;; offset=0x0042
       mov      rcx, rbx
       lea      rdx, gword ptr [(reloc 0x4000000000420c90)]      ; '"GVM"'
       call     rax
G_M56640_IG05:  ;; offset=0x004E
       test     edi, edi
       je       SHORT G_M56640_IG07
G_M56640_IG06:  ;; offset=0x0052
       mov      rdx, qword ptr [rsi+0x06]
       mov      rcx, rbx
       lea      r8, gword ptr [(reloc 0x4000000000420c98)]      ; '"Generic DIM"'
       call     [rsi-0x02]
       jmp      SHORT G_M56640_IG08
G_M56640_IG07:  ;; offset=0x0065
       mov      rcx, rbx
       lea      rdx, gword ptr [(reloc 0x4000000000420c98)]      ; '"Generic DIM"'
       call     rsi
G_M56640_IG08:  ;; offset=0x0071
       nop
G_M56640_IG09:  ;; offset=0x0072
       add      rsp, 32
       pop      rbx
       pop      rsi
       pop      rdi
       ret

; Total bytes of code 122

Also added a couple of tests from #43668.

Closes #9588
Contributes to #112596

/cc: @jakobbotsch @davidwrighton @MichalStrehovsky

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Enables devirtualization of generic virtual methods and default interface methods (DIMs) on generic interfaces, by computing and passing the instantiation argument needed at runtime, instead of failing devirtualization in those cases.

Changes:

• In the VM JIT interface, remove the early bail-out for generic DIMs and shared generic virtual methods, and instead compute instParamLookup / re-resolve via the exact (non-shared) MethodDesc when possible; defer the instantiating-stub unwrap until after tokenLookupContext is set.
• In the managed JIT interface (CorInfoImpl), add parallel logic to populate instParamLookup for generic DIM / generic virtual / array-interface devirtualization (R2R uses TypeDictionary / MethodHandle helpers; NativeAOT path returns FAILED_CANON for now), and switch tokenLookupContext to a method context where appropriate.
• In DevirtualizationManager, drop the unconditional generic-virtual canon bail-out and, for R2R, only fail DIM resolution on variant dispatch (allowing generic DIMs); keep the stricter pre-existing behavior for NativeAOT.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

File	Description
src/coreclr/vm/jitinterface.cpp	Allow devirt to generic DIM / shared GVM by computing exact MD and instParamLookup; move instantiating-stub unwrap after context setup.
src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs	Add instParamLookup population for generic DIM / GVM / array-interface cases; adjust tokenLookupContext; gate AOT vs R2R behavior.
src/coreclr/tools/Common/Compiler/DevirtualizationManager.cs	For R2R, only fail DIM resolution on variant dispatch; remove unconditional shared-GVM canon bail-out.
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/DevirtualizationManager.cs	Update stale comment numbering after removing the DIM-restriction note.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

[hez2010]

@MihuBot

[hez2010]

@MihuBot -nuget

[Copilot]

Pull request overview

Copilot reviewed 28 out of 28 changed files in this pull request and generated 8 comments.

[Copilot]

Pull request overview

Copilot reviewed 28 out of 28 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 7 comments.

[Copilot]

Pull request overview

Copilot reviewed 28 out of 28 changed files in this pull request and generated 6 comments.

[Copilot]

Pull request overview

Copilot reviewed 28 out of 28 changed files in this pull request and generated 5 comments.

[jakobbotsch]

/azp run runtime-coreclr outerloop, runtime-coreclr pgo, runtime-coreclr pgostress, runtime-nativeaot-outerloop

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Azure Pipelines successfully started running 4 pipeline(s).

[hez2010]

All test failures seem unrelated. PTAL.