Re: [PATCH v1] x86: Remove wcsnlen-sse4_1 from wcslen ifunc-impl-list [BZ #28064]

[Noah Goldstein <goldstein.w.n@gmail.com>]

On Thu, Jul 8, 2021 at 11:08 AM H.J. Lu <hjl.tools@gmail.com> wrote:

> On Thu, Jul 8, 2021 at 6:57 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Thu, Jul 8, 2021 at 5:21 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > On Thu, Jul 8, 2021 at 1:22 AM Noah Goldstein <goldstein.w.n@gmail.com>
> wrote:
> > > >
> > > > The following commit
> > > >
> > > > commit 6f573a27b6c8b4236445810a44660612323f5a73
> > > > Author: Noah Goldstein <goldstein.w.n@gmail.com>
> > > > Date:   Wed Jun 23 01:19:34 2021 -0400
> > > >
> > > >     x86-64: Add wcslen optimize for sse4.1
> > > >
> > > > Added wcsnlen-sse4.1 to the wcslen ifunc implementation list and did
> > > > not add wcslen-sse4.1 to wcslen ifunc implementation list. This
> commit
> > > > fixes that by removing wcsnlen-sse4.1 from the wcslen ifunc
> > > > implementation list and adding wcslen-sse4.1 to the ifunc
> > > > implementation list.
> > > >
> > > > Testing:
> > > > test-wcslen.c is passing as well as all other tests in wcsmbs and
> > > > string.
> > > >
> > > > Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
> > > > ---
> > > > I was unable to actually reproduce the bug on my machine, even after
> > > > reordering ifunc-wcslen.h to prefer the sse4.1
> > > > implementation. Although this most definetly is a bug.
> > > >
> > > >
> > > > I ran the following command. Is there an issue with the command? Or
> > > > does rdx happen to always have a len >= actual length of the string?
> > >
> > > That must be the case.   We can do something similar to
> > >
> > > sysdeps/x86_64/x32/tst-size_t-strnlen.c
> > >
> > > to write a testcase.
> >
> > Here is the patch with a testcase.   Please include it in your fix and
> > mention BZ #28064 in your commit log.
>
Done.

>
> Please use this patch passing a pointer to do_strlen for x32.
>
Done. Made it first patch in patchset.

>
> > > > $> rm -rf build; mkdir -p build/glibc; (cd build/glibc/; unset
> LD_LIBRARY_PATH; /absolute/path/to/src/glibc/configure --prefix=/usr; make
> --silent; make xcheck; make -r -C /absolute/path/to/src/glibc/string/
> objdir=`pwd` check; make -r -C /absolute/path/to/src/glibc/wcsmbs/
> objdir=`pwd` check);
> > > >
> > > >
> > > >
> > > >  sysdeps/x86_64/multiarch/ifunc-impl-list.c | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > > > index dbd1ebf298..39ab10613b 100644
> > > > --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > > > +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > > > @@ -684,9 +684,9 @@ __libc_ifunc_impl_list (const char *name, struct
> libc_ifunc_impl *array,
> > > >                                && CPU_FEATURE_USABLE (AVX512BW)
> > > >                                && CPU_FEATURE_USABLE (BMI2)),
> > > >                               __wcslen_evex)
> > > > -             IFUNC_IMPL_ADD (array, i, wcsnlen,
> > > > +             IFUNC_IMPL_ADD (array, i, wcslen,
> > > >                               CPU_FEATURE_USABLE (SSE4_1),
> > > > -                             __wcsnlen_sse4_1)
> > > > +                             __wcslen_sse4_1)
> > > >               IFUNC_IMPL_ADD (array, i, wcslen, 1, __wcslen_sse2))
> > > >
> > > >    /* Support sysdeps/x86_64/multiarch/wcsnlen.c.  */
> > > > --
> > > > 2.25.1
> > > >
> > >
> > > LGTM.
> > >
> > > Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
> > >
> > > --
> > > H.J.
> >
> >
> >
> > --
> > H.J.
>
>
>
> --
> H.J.
>