JIT: Handle enums in box-unbox optimization

[EgorBo]

Closes #55355

When we box a enum and unbox it as integer (and vice versa) JIT should be able to optimize it as no-op. E.g. https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABABgAJiBGAOgCUBXAOwwEt8YaBhCfAB1YAbGFADKIgG6swMXAG4AsACgy5UQAtsUPgBlsweszYdFS5cQBMlKgHZlAb2Xln5ANoApVhgDiMJiOkACgwATz4YCAAzQIBRJgZ8KgBKJIBdZwB6DPImCAwnF1cAWRgMdQgAEwBJfkFAkrLKmr5BAHk+NggmXBoAQQBzfthcXFYJGCqmQVYmGf60gudiAGZrJHJgCAhBcgAJPAAxQWx+gB4AFQA+QPPyCWxBBhg0clvI4/nF8kclFz/KGzkQKBGYYJKBCDAABWMDAYPujxg5AAZEDQeDITC4Ul3ickuQALwEtEsDHQ2Fg3H9Ux/AC+ynpZhUqz8CXIcQSVG+5F6LwAQuRaUA==

New codegen:

; Program.HasFlag
       and      ecx, edx
       xor      eax, eax
       cmp      ecx, edx
       sete     al
       ret      
; Total bytes of code: 10

The change is small, the verbosity is due to JIT-EE update, I had to add a flag to compareTypesForEquality because in some places it's still expected to be more conservative around enums vs integers.

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Issue Details

---

Closes #55355

When we box a enum and unbox it as integer (and vice versa) JIT should be able to optimize it as no-op. E.g. https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABABgAJiBGAOgCUBXAOwwEt8YaBhCfAB1YAbGFADKIgG6swMXAG4AsACgy5UQAtsUPgBlsweszYdFS5cQBMlKgHZlAb2Xln5ANoApVhgDiMJiOkACgwATz4YCAAzQIBRJgZ8KgBKJIBdZwB6DPImCAwnF1cAWRgMdQgAEwBJfkFAkrLKmr5BAHk+NggmXBoAQQBzfthcXFYJGCqmQVYmGf60gudiAGZrJHJgCAhBcgAJPAAxQWx+gB4AFQA+QPPyCWxBBhg0clvI4/nF8kclFz/KGzkQKBGYYJKBCDAABWMDAYPujxg5AAZEDQeDITC4Ul3ickuQALwEtEsDHQ2Fg3H9Ux/AC+ynpZhUqz8CXIcQSVG+5F6LwAQuRaUA==

New codegen:

; Program.HasFlag
       and      ecx, edx
       xor      eax, eax
       cmp      ecx, edx
       sete     al
       ret      
; Total bytes of code: 10

The change is small, the verbosity is due to JIT-EE update, I had to add a flag to compareTypesForEquality because in some places it's still expected to be more conservative around enums vs integers.

Author:	EgorBo
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[jakobbotsch]

Can you please take care of #69900 too since you are changing JIT-EE GUID?

[EgorBo]

Can you please take care of #69900 too since you are changing JIT-EE GUID?

Done

[EgorBo]

@dotnet/jit-contrib PTAL, small change (actual change)

[jakobbotsch]

I wonder if we could just call getTypeForPrimitiveValueClass on the classes here. I guess it's not the exact same logic but maybe it is ok?

[EgorBo]

Great idea! addressed 🙂

[MichalStrehovsky]

UnderlyingType returns this if the type is not an enum.

Suggested change

	type1 = type1.IsEnum ? type1.UnderlyingType : type1;
	type2 = type2.IsEnum ? type2.UnderlyingType : type2;
	type1 = type1.UnderlyingType;
	type2 = type2.UnderlyingType;