Re: [PATCH v2 0/4] MR375: ntdll: Fixes for runtime 64-bit shift functions.

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about dlls/ntdll/large_int.c:
> +__ASM_GLOBAL_FUNC( _allshl,
> -
>               "xchgl (%esp),%ecx\n\t"
> -
>               "pushl %edx\n\t"
> -
>               "pushl %eax\n\t"
> -
>               "pushl %ecx\n\t"
> -
>               "jmp " __ASM_NAME("__regs__allshl") )
> -
> -
>
> +LONGLONG __regs__allshr( LONGLONG a, unsigned char b )
>  {
> - return a << b;
> - const LARGE_INTEGER x = { .QuadPart = a };
> - LARGE_INTEGER ret;
> -
> - if (b >= 64)
> -
>    return (LONGLONG)(x.HighPart >> 31);

Suggest using `x.HighPart >> (b >= 64 ? 31 : b & 31)` or its equivalent, as per the same reason for `_allshl`.

Compare:

- https://godbolt.org/z/sEd8Th56M (original)

With:

- https://godbolt.org/z/9WxTnbfax (64-bit return ellided).