Intrinsify typeof(T).IsPrimitive

[EgorBo]

Closes #95929

bool Test<T>() => typeof(T).IsPrimitive;

Codegen diff for e.g. Test<int> and Test<string>:

; Assembly listing for method P:Test[int]():ubyte (FullOpts)
-      sub      rsp, 40
-      mov      rcx, 0x27E800054B0      ; 'System.Int32'
-      call     System.RuntimeTypeHandle:GetCorElementType(System.RuntimeType):ubyte
-      mov      ecx, 1
-      shlx     eax, ecx, eax
-      test     eax, 0x3003FFC
-      setne    al
-      movzx    rax, al
-      add      rsp, 40
+      mov      eax, 1
       ret      

; Assembly listing for method P:Test[System.__Canon]():ubyte (FullOpts)
-      sub      rsp, 40
-      mov      qword ptr [rsp+0x20], rcx
-      mov      rcx, qword ptr [rcx+0x38]
-      mov      rcx, qword ptr [rcx]
-      call     CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE
-      mov      rcx, rax
-      call     System.RuntimeTypeHandle:GetCorElementType(System.RuntimeType):ubyte
-      mov      ecx, 1
-      shlx     eax, ecx, eax
-      test     eax, 0x3003FFC
-      setne    al
-      movzx    rax, al
-      add      rsp, 40
+      xor      eax, eax
       ret

Should allow us to avoid listing all primitives by hands for perf reasons (e.g. here)

will add tests.

[ghost]

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Issue Details

---

Seems to be straightforward unless I am missing something (if my CorInfoType -> CorElementType mapping is correct, otherwise it will need a new JIT-EE API).

Closes #95929

bool Test() => typeof(int).IsPrimitive;

; Method P:Test():ubyte:this (FullOpts)
-      sub      rsp, 40
-      mov      rcx, 0x17E001054B0      ; 'System.Int32'
-      call     System.RuntimeTypeHandle:GetCorElementType(System.RuntimeType):ubyte
-      mov      ecx, 1
-      shlx     eax, ecx, eax
-      test     eax, 0x3003FFC
-      setne    al
-      movzx    rax, al
-      add      rsp, 40
+      mov      eax, 1
       ret      
; Total bytes of code: 45

Some other APIs are now constant-folded too, e.g.:

typeof(T).IsFunctionPointer
typeof(T).HasElementType
typeof(T).IsArray
typeof(T).IsSZArray
typeof(T).IsPointer
typeof(T).IsByRef

will add tests.

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

[EgorBo]

@MihuBot

[EgorBo]

@MihuBot

[ShreyasJejurkar]

I love this kind of improvements. ❤🙌

[jkotas]

Any interesting diffs? Any places in this repo to switch over to this intrinsic?

[EgorBo]

Any interesting diffs? Any places in this repo to switch over to this intrinsic?

No diffs in BCL yet but it was requested a few times in different threads so I decided to add it since it's not a lot of efforts after all. The only place in the BCL I know is(https://github.com/dotnet/runtime/blob/main/src/libraries/System.Collections.Immutable/src/System/Collections/Frozen/Constants.cs#L46-L58)

[EgorBo]

@jkotas does it look good to your otherwise?

[jkotas]

LGTM