Intrinsify typeof(T).GetGenericTypeDefinition()

[Sergio0694]

Closes #96898

public static Type? Test1<T>() =>
    typeof(T).IsGenericType
    ? typeof(T).GetGenericTypeDefinition()
    : null;

Codegen diffs:

; Assembly listing for method Foo:Test1[System.Collections.Generic.KeyValuePair`2[System.__Canon,int]]():System.Type (FullOpts)

-   sub      rsp, 40
-   mov      qword ptr [rsp+0x20], rcx
-   mov      rcx, qword ptr [rcx+0x40]
-   mov      rcx, qword ptr [rcx]
-   call     CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE
-   mov      rcx, rax
-   call     [System.RuntimeType:GetGenericTypeDefinition():System.Type:this]
-   nop      
-   add      rsp, 40
+   mov      rax, 0x275000095B0
    ret

public static bool Test2<T>() =>
        typeof(T).IsGenericType &&
        typeof(T).GetGenericTypeDefinition() == typeof(KeyValuePair<,>);

Codegen diffs:

; Assembly listing for method Foo:Test2[System.Collections.Generic.KeyValuePair`2[System.__Canon,int]]():ubyte (FullOpts)

-   sub      rsp, 40
-   mov      qword ptr [rsp+0x20], rcx
-   mov      rcx, qword ptr [rcx+0x40]
-   mov      rcx, qword ptr [rcx]
-   call     CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE
-   mov      rcx, rax
-   call     [System.RuntimeType:GetGenericTypeDefinition():System.Type:this]
-   mov      rcx, 0x19F800095D8      ; 'System.Collections.Generic.KeyValuePair`2[TKey,TValue]'
-   cmp      rax, rcx
-   sete     al
-   movzx    rax, al
-   add      rsp, 40
+   mov      eax, 1
    ret    

Note

Reopening from #97159 because the bot closed that one.

[Sergio0694]

@MihuBot

[En3Tho]

@Sergio0694 wrong command it seems? Box => bot

[Sergio0694]

Oops, typo, thank you! 😅

[Sergio0694]

@MihuBot

[EgorBo]

@MihuBot

[EgorBo]

Failures are unrelated and changes in the recent force push look good, merging