[PATCH] x86-64: Require BMI2 for strchr-avx2.S

[PATCH] x86-64: Require BMI2 for strchr-avx2.S

[H.J. Lu]

Since strchr-avx2.S updated by

commit 1f745ecc2109890886b161d4791e1406fdfc29b8
Author: noah <goldstein.w.n@gmail.com>
Date:   Wed Feb 3 00:38:59 2021 -0500

    x86-64: Refactor and improve performance of strchr-avx2.S

uses sarx:

c4 e2 72 f7 c0       	sarx   %ecx,%eax,%eax

for strchr-avx2 family functions, require BMI2 in ifunc-impl-list.c and
ifunc-avx2.h.
---
 sysdeps/x86_64/multiarch/ifunc-avx2.h      |  4 ++--
 sysdeps/x86_64/multiarch/ifunc-impl-list.c | 12 +++++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/sysdeps/x86_64/multiarch/ifunc-avx2.h b/sysdeps/x86_64/multiarch/ifunc-avx2.h
index e3ec62ca5e..6de72f7272 100644
--- a/sysdeps/x86_64/multiarch/ifunc-avx2.h
+++ b/sysdeps/x86_64/multiarch/ifunc-avx2.h
@@ -30,11 +30,11 @@ IFUNC_SELECTOR (void)
   const struct cpu_features* cpu_features = __get_cpu_features ();
 
   if (CPU_FEATURE_USABLE_P (cpu_features, AVX2)
+      && CPU_FEATURE_USABLE_P (cpu_features, BMI2)
       && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
     {
       if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
-	  && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
-	  && CPU_FEATURE_USABLE_P (cpu_features, BMI2))
+	  && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
 	return OPTIMIZE (evex);
 
       if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index f1a755b1d6..0b0927b124 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -396,10 +396,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/strchr.c.  */
   IFUNC_IMPL (i, name, strchr,
 	      IFUNC_IMPL_ADD (array, i, strchr,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __strchr_avx2)
 	      IFUNC_IMPL_ADD (array, i, strchr,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __strchr_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, strchr,
@@ -413,10 +415,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/strchrnul.c.  */
   IFUNC_IMPL (i, name, strchrnul,
 	      IFUNC_IMPL_ADD (array, i, strchrnul,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __strchrnul_avx2)
 	      IFUNC_IMPL_ADD (array, i, strchrnul,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __strchrnul_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, strchrnul,
@@ -570,10 +574,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/wcschr.c.  */
   IFUNC_IMPL (i, name, wcschr,
 	      IFUNC_IMPL_ADD (array, i, wcschr,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __wcschr_avx2)
 	      IFUNC_IMPL_ADD (array, i, wcschr,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __wcschr_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, wcschr,
-- 
2.30.2

Re: [PATCH] x86-64: Require BMI2 for strchr-avx2.S

[Florian Weimer]

* H. J. Lu via Libc-alpha:

> Since strchr-avx2.S updated by
>
> commit 1f745ecc2109890886b161d4791e1406fdfc29b8
> Author: noah <goldstein.w.n@gmail.com>
> Date:   Wed Feb 3 00:38:59 2021 -0500
>
>     x86-64: Refactor and improve performance of strchr-avx2.S
>
> uses sarx:
>
> c4 e2 72 f7 c0       	sarx   %ecx,%eax,%eax
>
> for strchr-avx2 family functions, require BMI2 in ifunc-impl-list.c and
> ifunc-avx2.h.

Seems reasonable, thanks.

Florian

Re: [PATCH] x86-64: Require BMI2 for strchr-avx2.S

[Sunil Pandey]

On Mon, Apr 19, 2021 at 11:50 AM Florian Weimer via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> * H. J. Lu via Libc-alpha:
>
> > Since strchr-avx2.S updated by
> >
> > commit 1f745ecc2109890886b161d4791e1406fdfc29b8
> > Author: noah <goldstein.w.n@gmail.com>
> > Date:   Wed Feb 3 00:38:59 2021 -0500
> >
> >     x86-64: Refactor and improve performance of strchr-avx2.S
> >
> > uses sarx:
> >
> > c4 e2 72 f7 c0        sarx   %ecx,%eax,%eax
> >
> > for strchr-avx2 family functions, require BMI2 in ifunc-impl-list.c and
> > ifunc-avx2.h.
>
> Seems reasonable, thanks.
>
> Florian
>

I would like to backport this patch to release branches.
Any comments or objections?

--Sunil

Re: [PATCH] x86-64: Require BMI2 for strchr-avx2.S

[Florian Weimer]

* Sunil Pandey:

> On Mon, Apr 19, 2021 at 11:50 AM Florian Weimer via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
>>
>> * H. J. Lu via Libc-alpha:
>>
>> > Since strchr-avx2.S updated by
>> >
>> > commit 1f745ecc2109890886b161d4791e1406fdfc29b8
>> > Author: noah <goldstein.w.n@gmail.com>
>> > Date:   Wed Feb 3 00:38:59 2021 -0500
>> >
>> >     x86-64: Refactor and improve performance of strchr-avx2.S
>> >
>> > uses sarx:
>> >
>> > c4 e2 72 f7 c0        sarx   %ecx,%eax,%eax
>> >
>> > for strchr-avx2 family functions, require BMI2 in ifunc-impl-list.c and
>> > ifunc-avx2.h.
>>
>> Seems reasonable, thanks.
>>
>> Florian
>>
>
> I would like to backport this patch to release branches.
> Any comments or objections?

Please backport.

Thanks,
Florian