glibc/SOURCES/glibc-upstream-2.34-341.patch

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2023-05-09 05:36:28 +00:00
commit 67e863742d98c990b3d3b814b80042c0fa0d50a5
Author: Aurelien Jarno <aurelien@aurel32.net>
Date: Mon Oct 3 23:16:46 2022 +0200
x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations
The AVX2 wcs(n)cmp implementations use the 'bzhi' instruction, which
belongs to the BMI2 CPU feature.
NB: It also uses the 'tzcnt' BMI1 instruction, but it is executed as BSF
as BSF if the CPU doesn't support TZCNT, and produces the same result
for non-zero input.
Partially fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
Partially resolves: BZ #29611
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
(cherry picked from commit f31a5a884ed84bd37032729d4d1eb9d06c9f3c29)
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index 34d5f6efe5421014..e76a991dc671c1a9 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -693,10 +693,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
/* Support sysdeps/x86_64/multiarch/wcscmp.c. */
IFUNC_IMPL (i, name, wcscmp,
IFUNC_IMPL_ADD (array, i, wcscmp,
- CPU_FEATURE_USABLE (AVX2),
+ (CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)),
__wcscmp_avx2)
IFUNC_IMPL_ADD (array, i, wcscmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (RTM)),
__wcscmp_avx2_rtm)
IFUNC_IMPL_ADD (array, i, wcscmp,
@@ -709,10 +711,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
/* Support sysdeps/x86_64/multiarch/wcsncmp.c. */
IFUNC_IMPL (i, name, wcsncmp,
IFUNC_IMPL_ADD (array, i, wcsncmp,
- CPU_FEATURE_USABLE (AVX2),
+ (CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)),
__wcsncmp_avx2)
IFUNC_IMPL_ADD (array, i, wcsncmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (RTM)),
__wcsncmp_avx2_rtm)
IFUNC_IMPL_ADD (array, i, wcsncmp,