diff mbox series

[2/4] x86-64: Require BMI2 for AVX2 strn(case)cmp and wcsncmp implementations

Message ID 20221001190911.2994478-3-aurelien@aurel32.net
State Superseded
Headers
Series x86: Fix AVX2 string functions requiring BMI2 or LZCNT (BZ #29611) |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Aurelien Jarno Oct. 1, 2022, 7:09 p.m. UTC 
  The AVX2 strncmp, strncasecmp and wcsncmp implementations use the bzhil
instructions, which belongs to the BMI2 CPU feature.

Fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
Partially resolves: BZ #29611
---
 sysdeps/x86_64/multiarch/ifunc-impl-list.c  | 25 +++++++++++++++------
 sysdeps/x86_64/multiarch/ifunc-strcasecmp.h |  1 +
 sysdeps/x86_64/multiarch/strncmp.c          |  4 ++--
 3 files changed, 21 insertions(+), 9 deletions(-)

Comments

Noah Goldstein Oct. 1, 2022, 10:15 p.m. UTC | #1 
On Sat, Oct 1, 2022 at 12:09 PM Aurelien Jarno <aurelien@aurel32.net> wrote:
>
> The AVX2 strncmp, strncasecmp and wcsncmp implementations use the bzhil
> instructions, which belongs to the BMI2 CPU feature.
>
> Fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
> Partially resolves: BZ #29611
> ---
>  sysdeps/x86_64/multiarch/ifunc-impl-list.c  | 25 +++++++++++++++------
>  sysdeps/x86_64/multiarch/ifunc-strcasecmp.h |  1 +
>  sysdeps/x86_64/multiarch/strncmp.c          |  4 ++--

The ifunc change in strncmp.c and ifunc-strcasecmp.h need to be backport
to 2.33, 2.34, 2.35.

Also separate changes for ifunc need to be backport to strncmp.c:
2.32, 2.31, 2.30, 2.29, 2.28 for a `tzcnt` usage that needs
BMI1.

Finally a corresponding fix is needed for strcmp.c as well (there is
missing BMI2 check in strcmp.c ifunc selection as well as missing
checks in the impl list).

>  3 files changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> index a71444eccb..ec1a8bff5e 100644
> --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> @@ -638,13 +638,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
>    IFUNC_IMPL (i, name, strncasecmp,
>               X86_IFUNC_IMPL_ADD_V4 (array, i, strncasecmp,
>                                      (CPU_FEATURE_USABLE (AVX512VL)
> -                                     && CPU_FEATURE_USABLE (AVX512BW)),
> +                                     && CPU_FEATURE_USABLE (AVX512BW)
> +                                     && CPU_FEATURE_USABLE (BMI2)),
>                                      __strncasecmp_evex)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
> -                                    CPU_FEATURE_USABLE (AVX2),
> +                                    (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)),
>                                      __strncasecmp_avx2)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
>                                      (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)
>                                       && CPU_FEATURE_USABLE (RTM)),
>                                      __strncasecmp_avx2_rtm)
>               X86_IFUNC_IMPL_ADD_V2 (array, i, strncasecmp,
> @@ -660,13 +663,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
>    IFUNC_IMPL (i, name, strncasecmp_l,
>               X86_IFUNC_IMPL_ADD_V4 (array, i, strncasecmp,
>                                      (CPU_FEATURE_USABLE (AVX512VL)
> -                                     && CPU_FEATURE_USABLE (AVX512BW)),
> +                                     & CPU_FEATURE_USABLE (AVX512BW)
> +                                     && CPU_FEATURE_USABLE (BMI2)),
>                                      __strncasecmp_l_evex)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
> -                                    CPU_FEATURE_USABLE (AVX2),
> +                                    (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2),
>                                      __strncasecmp_l_avx2)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
>                                      (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)
>                                       && CPU_FEATURE_USABLE (RTM)),
>                                      __strncasecmp_l_avx2_rtm)
>               X86_IFUNC_IMPL_ADD_V2 (array, i, strncasecmp_l,
> @@ -816,10 +822,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
>                                       && CPU_FEATURE_USABLE (BMI2)),
>                                      __wcsncmp_evex)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
> -                                    CPU_FEATURE_USABLE (AVX2),
> +                                    (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)),
>                                      __wcsncmp_avx2)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
>                                      (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)
>                                       && CPU_FEATURE_USABLE (RTM)),
>                                      __wcsncmp_avx2_rtm)
>               /* ISA V2 wrapper for GENERIC implementation because the
> @@ -1162,13 +1170,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
>    IFUNC_IMPL (i, name, strncmp,
>               X86_IFUNC_IMPL_ADD_V4 (array, i, strncmp,
>                                      (CPU_FEATURE_USABLE (AVX512VL)
> -                                     && CPU_FEATURE_USABLE (AVX512BW)),
> +                                     && CPU_FEATURE_USABLE (AVX512BW)
> +                                     && CPU_FEATURE_USABLE (BMI2)),
>                                      __strncmp_evex)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, strncmp,
> -                                    CPU_FEATURE_USABLE (AVX2),
> +                                    (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)),
>                                      __strncmp_avx2)
>               X86_IFUNC_IMPL_ADD_V3 (array, i, strncmp,
>                                      (CPU_FEATURE_USABLE (AVX2)
> +                                     && CPU_FEATURE_USABLE (BMI2)
>                                       && CPU_FEATURE_USABLE (RTM)),
>                                      __strncmp_avx2_rtm)
>               X86_IFUNC_IMPL_ADD_V2 (array, i, strncmp,
> diff --git a/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h b/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
> index 68646ef199..7622af259c 100644
> --- a/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
> +++ b/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
> @@ -34,6 +34,7 @@ IFUNC_SELECTOR (void)
>    const struct cpu_features *cpu_features = __get_cpu_features ();
>
>    if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> +      && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
>        && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
>                                       AVX_Fast_Unaligned_Load, ))
>      {
> diff --git a/sysdeps/x86_64/multiarch/strncmp.c b/sysdeps/x86_64/multiarch/strncmp.c
> index 4ebe4bde30..c4f8b6bbb5 100644
> --- a/sysdeps/x86_64/multiarch/strncmp.c
> +++ b/sysdeps/x86_64/multiarch/strncmp.c
> @@ -41,12 +41,12 @@ IFUNC_SELECTOR (void)
>    const struct cpu_features *cpu_features = __get_cpu_features ();
>
>    if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> +      && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
>        && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
>                                       AVX_Fast_Unaligned_Load, ))
>      {
>        if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
> -         && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
> -         && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2))
> +         && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
>         return OPTIMIZE (evex);
>
>        if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
> --
> 2.35.1
>
Noah Goldstein Oct. 1, 2022, 10:18 p.m. UTC | #2 
On Sat, Oct 1, 2022 at 3:15 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Sat, Oct 1, 2022 at 12:09 PM Aurelien Jarno <aurelien@aurel32.net> wrote:
> >
> > The AVX2 strncmp, strncasecmp and wcsncmp implementations use the bzhil
> > instructions, which belongs to the BMI2 CPU feature.
> >
> > Fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
> > Partially resolves: BZ #29611
> > ---
> >  sysdeps/x86_64/multiarch/ifunc-impl-list.c  | 25 +++++++++++++++------
> >  sysdeps/x86_64/multiarch/ifunc-strcasecmp.h |  1 +
> >  sysdeps/x86_64/multiarch/strncmp.c          |  4 ++--
>
> The ifunc change in strncmp.c and ifunc-strcasecmp.h need to be backport
> to 2.33, 2.34, 2.35.
>
> Also separate changes for ifunc need to be backport to strncmp.c:
> 2.32, 2.31, 2.30, 2.29, 2.28 for a `tzcnt` usage that needs
> BMI1.
>
> Finally a corresponding fix is needed for strcmp.c as well (there is
> missing BMI2 check in strcmp.c ifunc selection as well as missing
> checks in the impl list).

Don't reply here. Reply (if needed) in main the [0/4] patch thread just
to keep the conversation contained.
>
> >  3 files changed, 21 insertions(+), 9 deletions(-)
> >
> > diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > index a71444eccb..ec1a8bff5e 100644
> > --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> > @@ -638,13 +638,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> >    IFUNC_IMPL (i, name, strncasecmp,
> >               X86_IFUNC_IMPL_ADD_V4 (array, i, strncasecmp,
> >                                      (CPU_FEATURE_USABLE (AVX512VL)
> > -                                     && CPU_FEATURE_USABLE (AVX512BW)),
> > +                                     && CPU_FEATURE_USABLE (AVX512BW)
> > +                                     && CPU_FEATURE_USABLE (BMI2)),
> >                                      __strncasecmp_evex)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
> > -                                    CPU_FEATURE_USABLE (AVX2),
> > +                                    (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)),
> >                                      __strncasecmp_avx2)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
> >                                      (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)
> >                                       && CPU_FEATURE_USABLE (RTM)),
> >                                      __strncasecmp_avx2_rtm)
> >               X86_IFUNC_IMPL_ADD_V2 (array, i, strncasecmp,
> > @@ -660,13 +663,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> >    IFUNC_IMPL (i, name, strncasecmp_l,
> >               X86_IFUNC_IMPL_ADD_V4 (array, i, strncasecmp,
> >                                      (CPU_FEATURE_USABLE (AVX512VL)
> > -                                     && CPU_FEATURE_USABLE (AVX512BW)),
> > +                                     & CPU_FEATURE_USABLE (AVX512BW)
> > +                                     && CPU_FEATURE_USABLE (BMI2)),
> >                                      __strncasecmp_l_evex)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
> > -                                    CPU_FEATURE_USABLE (AVX2),
> > +                                    (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2),
> >                                      __strncasecmp_l_avx2)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
> >                                      (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)
> >                                       && CPU_FEATURE_USABLE (RTM)),
> >                                      __strncasecmp_l_avx2_rtm)
> >               X86_IFUNC_IMPL_ADD_V2 (array, i, strncasecmp_l,
> > @@ -816,10 +822,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> >                                       && CPU_FEATURE_USABLE (BMI2)),
> >                                      __wcsncmp_evex)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
> > -                                    CPU_FEATURE_USABLE (AVX2),
> > +                                    (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)),
> >                                      __wcsncmp_avx2)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
> >                                      (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)
> >                                       && CPU_FEATURE_USABLE (RTM)),
> >                                      __wcsncmp_avx2_rtm)
> >               /* ISA V2 wrapper for GENERIC implementation because the
> > @@ -1162,13 +1170,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> >    IFUNC_IMPL (i, name, strncmp,
> >               X86_IFUNC_IMPL_ADD_V4 (array, i, strncmp,
> >                                      (CPU_FEATURE_USABLE (AVX512VL)
> > -                                     && CPU_FEATURE_USABLE (AVX512BW)),
> > +                                     && CPU_FEATURE_USABLE (AVX512BW)
> > +                                     && CPU_FEATURE_USABLE (BMI2)),
> >                                      __strncmp_evex)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, strncmp,
> > -                                    CPU_FEATURE_USABLE (AVX2),
> > +                                    (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)),
> >                                      __strncmp_avx2)
> >               X86_IFUNC_IMPL_ADD_V3 (array, i, strncmp,
> >                                      (CPU_FEATURE_USABLE (AVX2)
> > +                                     && CPU_FEATURE_USABLE (BMI2)
> >                                       && CPU_FEATURE_USABLE (RTM)),
> >                                      __strncmp_avx2_rtm)
> >               X86_IFUNC_IMPL_ADD_V2 (array, i, strncmp,
> > diff --git a/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h b/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
> > index 68646ef199..7622af259c 100644
> > --- a/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
> > +++ b/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
> > @@ -34,6 +34,7 @@ IFUNC_SELECTOR (void)
> >    const struct cpu_features *cpu_features = __get_cpu_features ();
> >
> >    if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> > +      && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
> >        && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
> >                                       AVX_Fast_Unaligned_Load, ))
> >      {
> > diff --git a/sysdeps/x86_64/multiarch/strncmp.c b/sysdeps/x86_64/multiarch/strncmp.c
> > index 4ebe4bde30..c4f8b6bbb5 100644
> > --- a/sysdeps/x86_64/multiarch/strncmp.c
> > +++ b/sysdeps/x86_64/multiarch/strncmp.c
> > @@ -41,12 +41,12 @@ IFUNC_SELECTOR (void)
> >    const struct cpu_features *cpu_features = __get_cpu_features ();
> >
> >    if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> > +      && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
> >        && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
> >                                       AVX_Fast_Unaligned_Load, ))
> >      {
> >        if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
> > -         && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
> > -         && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2))
> > +         && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
> >         return OPTIMIZE (evex);
> >
> >        if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
> > --
> > 2.35.1
> >
diff mbox series

Patch

diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index a71444eccb..ec1a8bff5e 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -638,13 +638,16 @@  __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   IFUNC_IMPL (i, name, strncasecmp,
 	      X86_IFUNC_IMPL_ADD_V4 (array, i, strncasecmp,
 				     (CPU_FEATURE_USABLE (AVX512VL)
-				      && CPU_FEATURE_USABLE (AVX512BW)),
+				      && CPU_FEATURE_USABLE (AVX512BW)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __strncasecmp_evex)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
-				     CPU_FEATURE_USABLE (AVX2),
+				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __strncasecmp_avx2)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
 				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)
 				      && CPU_FEATURE_USABLE (RTM)),
 				     __strncasecmp_avx2_rtm)
 	      X86_IFUNC_IMPL_ADD_V2 (array, i, strncasecmp,
@@ -660,13 +663,16 @@  __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   IFUNC_IMPL (i, name, strncasecmp_l,
 	      X86_IFUNC_IMPL_ADD_V4 (array, i, strncasecmp,
 				     (CPU_FEATURE_USABLE (AVX512VL)
-				      && CPU_FEATURE_USABLE (AVX512BW)),
+				      & CPU_FEATURE_USABLE (AVX512BW)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __strncasecmp_l_evex)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
-				     CPU_FEATURE_USABLE (AVX2),
+				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2),
 				     __strncasecmp_l_avx2)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, strncasecmp,
 				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)
 				      && CPU_FEATURE_USABLE (RTM)),
 				     __strncasecmp_l_avx2_rtm)
 	      X86_IFUNC_IMPL_ADD_V2 (array, i, strncasecmp_l,
@@ -816,10 +822,12 @@  __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 				      && CPU_FEATURE_USABLE (BMI2)),
 				     __wcsncmp_evex)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
-				     CPU_FEATURE_USABLE (AVX2),
+				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __wcsncmp_avx2)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
 				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)
 				      && CPU_FEATURE_USABLE (RTM)),
 				     __wcsncmp_avx2_rtm)
 	      /* ISA V2 wrapper for GENERIC implementation because the
@@ -1162,13 +1170,16 @@  __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   IFUNC_IMPL (i, name, strncmp,
 	      X86_IFUNC_IMPL_ADD_V4 (array, i, strncmp,
 				     (CPU_FEATURE_USABLE (AVX512VL)
-				      && CPU_FEATURE_USABLE (AVX512BW)),
+				      && CPU_FEATURE_USABLE (AVX512BW)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __strncmp_evex)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, strncmp,
-				     CPU_FEATURE_USABLE (AVX2),
+				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)),
 				     __strncmp_avx2)
 	      X86_IFUNC_IMPL_ADD_V3 (array, i, strncmp,
 				     (CPU_FEATURE_USABLE (AVX2)
+				      && CPU_FEATURE_USABLE (BMI2)
 				      && CPU_FEATURE_USABLE (RTM)),
 				     __strncmp_avx2_rtm)
 	      X86_IFUNC_IMPL_ADD_V2 (array, i, strncmp,
diff --git a/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h b/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
index 68646ef199..7622af259c 100644
--- a/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
+++ b/sysdeps/x86_64/multiarch/ifunc-strcasecmp.h
@@ -34,6 +34,7 @@  IFUNC_SELECTOR (void)
   const struct cpu_features *cpu_features = __get_cpu_features ();
 
   if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
+      && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
       && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
 				      AVX_Fast_Unaligned_Load, ))
     {
diff --git a/sysdeps/x86_64/multiarch/strncmp.c b/sysdeps/x86_64/multiarch/strncmp.c
index 4ebe4bde30..c4f8b6bbb5 100644
--- a/sysdeps/x86_64/multiarch/strncmp.c
+++ b/sysdeps/x86_64/multiarch/strncmp.c
@@ -41,12 +41,12 @@  IFUNC_SELECTOR (void)
   const struct cpu_features *cpu_features = __get_cpu_features ();
 
   if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
+      && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
       && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
 				      AVX_Fast_Unaligned_Load, ))
     {
       if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
-	  && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
-	  && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2))
+	  && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
 	return OPTIMIZE (evex);
 
       if (CPU_FEATURE_USABLE_P (cpu_features, RTM))