[PATCH v2 0/4] MR375: ntdll: Fixes for runtime 64-bit shift functions.
Jinoh Kang (@iamahuman)
wine at gitlab.winehq.org
Wed Jul 6 10:50:53 CDT 2022
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).
--
https://gitlab.winehq.org/wine/wine/-/merge_requests/375#note_3461
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