Improve getExactClasses to support classes as base types

[MichalStrehovsky]

Fixes #88547

using System.Runtime.CompilerServices; public class ClassA { public virtual int GetValue() => 42; } public class ClassB : ClassA { // we don't even need to override GetValue here } class MyClass { static void Main() { Test(new ClassB()); } [MethodImpl(MethodImplOptions.NoInlining)] static int Test(ClassA c) => c.GetValue(); }

Old codegen:

; Method MyClass:Test(ClassA):int (FullOpts)  sub rsp, 40  mov rax, qword ptr [rcx]  call [rax+30H]ClassA:GetValue():int:this  nop  add rsp, 40  ret ; Total bytes of code: 16

New codegen:

00007FF66DD8AFB0 cmp dword ptr [rcx],ecx 00007FF66DD8AFB2 mov eax,2Ah 00007FF66DD8AFB7 ret

Cc @dotnet/ilc-contrib @EgorBo

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Issue Details

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Fixes #88547

using System.Runtime.CompilerServices; public class ClassA { public virtual int GetValue() => 42; } public class ClassB : ClassA { // we don't even need to override GetValue here } class MyClass { static void Main() { Test(new ClassB()); } [MethodImpl(MethodImplOptions.NoInlining)] static int Test(ClassA c) => c.GetValue(); }

Old codegen:

; Method MyClass:Test(ClassA):int (FullOpts) sub rsp, 40 mov rax, qword ptr [rcx] call [rax+30H]ClassA:GetValue():int:this nop add rsp, 40 ret ; Total bytes of code: 16 

New codegen:

00007FF66DD8AFB0 cmp dword ptr [rcx],ecx 00007FF66DD8AFB2 mov eax,2Ah 00007FF66DD8AFB7 ret 

Cc @dotnet/ilc-contrib @EgorBo

Author:	MichalStrehovsky
Assignees:	-
Labels:	area-NativeAOT-coreclr
Milestone:	-

[MichalStrehovsky]

/azp run runtime-nativeaot-outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[EgorBo]

Love it! It should also pick up other jit opts like if (obj is Class1) or multiple-guesses GDV, etc which currently only kick in for interfaces. LGTM if CI passes 🙂

[jkotas]

Thanks