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

[Zebediah Figura (she/her)]

On 7/6/22 10:50, Jinoh Kang (@iamahuman) wrote:
> Jinoh Kang (@iamahuman) commented about dlls/ntdll/large_int.c:
> > - /******************************************************************************
> > -
> >    _allshl   (NTDLL.@)
> > -
> > -
> > -
> > - Shift a 64 bit integer to the left.
> > -
> > -
> > -
> > - PARAMS
> > -
> > - a [I] Initial number.
> > -
> > - b [I] Number to shift a by to the left.
> > -
> > -
> > -
> > - RETURNS
> > -
> > - The left-shifted value.
> > */
> >
> > -LONGLONG WINAPI _allshl( LONGLONG a, LONG b )
> > +__ASM_GLOBAL_FUNC( _allshl,
> > -
> >               "xchgl (%esp),%ecx\n\t"
>
> Maybe a nit, and this pattern also resides in other preëxisting code already, but do we _really_ want to use a full memory barrier in such cases?

I'm inclined to think it's not worth coding more assembly just to 
squeeze every last bit of performance out of these functions.