[PATCH 0/2] Remove some i386 system call optimizations

[H.J. Lu]

On Tue, Jan 11, 2022 at 2:52 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> >> > There are
> >> >
> >> > /* Since GCC 5 and above can properly spill %ebx with PIC when needed,
> >> >    we can inline syscalls with 6 arguments if GCC 5 or above is used
> >> >    to compile glibc.  Disable GCC 5 optimization when compiling for
> >> >    profiling or when -fno-omit-frame-pointer is used since asm ("ebp")
> >> >    can't be used to put the 6th argument in %ebp for syscall.  */
> >> > #if !defined PROF && CAN_USE_REGISTER_ASM_EBP
> >> > # define OPTIMIZE_FOR_GCC_5
> >> > #endif
> >> >
> >> > If we want to support profiling or -fno-omit-frame-pointer,
> >> > we need to keep these codes.
> >>
> >> This is strictly for %ebp, I think, as indicated by the comment.  %ebx
> >> does not need to be special-cased for profiling.
> >>
> >> I assume that building glibc (with profiling) is proof enough that this
> >> works?
> >
> > You need to test glibc build with -fno-omit-frame-pointer.
>
> I tried it, it works (with both patches applied).
> -fno-omit-frame-pointer is about %ebp, not %ebx.
>
> Thanks,
> Florian
>

Do they have to be in glibc 2.35?  If not, I prefer to do it after
2.35 is branched.

Thanks.

-- 
H.J.