Re: [PATCH v2 03/10] i386: Use generic fmod

["H.J. Lu" <hjl.tools@gmail.com>]

On Wed, Mar 27, 2024 at 1:37 PM Adhemerval Zanella Netto
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 27/03/24 16:55, H.J. Lu wrote:
> > On Wed, Mar 27, 2024 at 12:40 PM Adhemerval Zanella
> > <adhemerval.zanella@linaro.org> wrote:
> >>
> >> The benchtest results shows a slight improvement (Ryzen 5900, gcc
> >> 13.2.1):
> >>
> >> * sysdeps/i386/fpu/e_fmod.S:
> >>   "fmod": {
> >>    "subnormals": {
> >>     "duration": 3.68855e+09,
> >>     "iterations": 2.12608e+08,
> >>     "max": 62.012,
> >>     "min": 16.798,
> >>     "mean": 17.349
> >>    },
> >>    "normal": {
> >>     "duration": 3.88459e+09,
> >>     "iterations": 7.168e+06,
> >>     "max": 2879.12,
> >>     "min": 16.909,
> >>     "mean": 541.934
> >>    },
> >>    "close-exponents": {
> >>     "duration": 3.692e+09,
> >>     "iterations": 1.96608e+08,
> >>     "max": 66.452,
> >>     "min": 16.835,
> >>     "mean": 18.7785
> >>    }
> >>   }
> >>
> >> * generic
> >>   "fmod": {
> >>    "subnormals": {
> >>     "duration": 3.68645e+09,
> >>     "iterations": 2.2848e+08,
> >>     "max": 66.896,
> >>     "min": 15.91,
> >>     "mean": 16.1347
> >>    },
> >>    "normal": {
> >>     "duration": 4.1455e+09,
> >>     "iterations": 8.192e+06,
> >>     "max": 3376.18,
> >>     "min": 15.873,
> >>     "mean": 506.043
> >>    },
> >>    "close-exponents": {
> >>     "duration": 3.70197e+09,
> >>     "iterations": 2.08896e+08,
> >>     "max": 69.597,
> >>     "min": 15.947,
> >>     "mean": 17.7216
> >>    }
> >>   }
> >> ---
> >>  sysdeps/i386/fpu/Versions                 |  4 ++++
> >>  sysdeps/i386/fpu/e_fmod.S                 | 18 ------------------
> >>  sysdeps/i386/fpu/e_fmod.c                 |  2 ++
> >>  sysdeps/i386/fpu/math_err.c               |  1 -
> >>  sysdeps/i386/fpu/w_fmod_compat.c          | 15 ---------------
> >>  sysdeps/ieee754/dbl-64/e_fmod.c           |  5 ++++-
> >>  sysdeps/mach/hurd/i386/libm.abilist       |  1 +
> >>  sysdeps/unix/sysv/linux/i386/libm.abilist |  1 +
> >>  8 files changed, 12 insertions(+), 35 deletions(-)
> >>  delete mode 100644 sysdeps/i386/fpu/e_fmod.S
> >>  create mode 100644 sysdeps/i386/fpu/e_fmod.c
> >>  delete mode 100644 sysdeps/i386/fpu/math_err.c
> >>  delete mode 100644 sysdeps/i386/fpu/w_fmod_compat.c
> >>
> >> diff --git a/sysdeps/i386/fpu/Versions b/sysdeps/i386/fpu/Versions
> >> index a2eec371f1..d37bc1eae6 100644
> >> --- a/sysdeps/i386/fpu/Versions
> >> +++ b/sysdeps/i386/fpu/Versions
> >> @@ -3,4 +3,8 @@ libm {
> >>      # functions used in inline functions or macros
> >>      __expl; __expm1l;
> >>    }
> >> +  GLIBC_2.40 {
> >> +    # No SVID compatible error handling.
> >> +    fmod;
> >> +  }
> >
> > This changes the ABI.  I assume that it fixes a real bug.   Is there a bug
> > report open for this?
> >
>
> The new version is the way to provide the system without the SVID compat
> support, which we for all ABIs but i386 on 2.38. For instance:
>
> find . -iname libm.abilist | xargs grep -w fmod
> ./sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist:GLIBC_2.0 fmod F
> ./sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist:GLIBC_2.38 fmod F
> [...]
>
> For i386 specifically, the old SVID symbol will be kept as fmod@GLIBC_2.0.
>

Does it fix a run-time test which fails without the fix?

-- 
H.J.