| Message ID | 20221003195944.3274548-6-aurelien@aurel32.net |
|---|---|
| State | New |
| Headers | show |
| Series | x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) | expand |
On Mon, Oct 3, 2022 at 12:59 PM Aurelien Jarno <aurelien@aurel32.net> wrote: > > 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 > --- > sysdeps/x86_64/multiarch/ifunc-impl-list.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c > index aebef3daaf..fec8790c11 100644 > --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c > +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c > @@ -810,10 +810,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array, > && CPU_FEATURE_USABLE (BMI2)), > __wcscmp_evex) > X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp, > - CPU_FEATURE_USABLE (AVX2), > + (CPU_FEATURE_USABLE (AVX2) > + && CPU_FEATURE_USABLE (BMI2)), > __wcscmp_avx2) > X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp, > (CPU_FEATURE_USABLE (AVX2) > + && CPU_FEATURE_USABLE (BMI2) > && CPU_FEATURE_USABLE (RTM)), > __wcscmp_avx2_rtm) > /* ISA V2 wrapper for SSE2 implementation because the SSE2 > @@ -830,10 +832,12 @@ __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 > -- > 2.35.1 > LGTM. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c index aebef3daaf..fec8790c11 100644 --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c @@ -810,10 +810,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array, && CPU_FEATURE_USABLE (BMI2)), __wcscmp_evex) X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp, - CPU_FEATURE_USABLE (AVX2), + (CPU_FEATURE_USABLE (AVX2) + && CPU_FEATURE_USABLE (BMI2)), __wcscmp_avx2) X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp, (CPU_FEATURE_USABLE (AVX2) + && CPU_FEATURE_USABLE (BMI2) && CPU_FEATURE_USABLE (RTM)), __wcscmp_avx2_rtm) /* ISA V2 wrapper for SSE2 implementation because the SSE2 @@ -830,10 +832,12 @@ __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
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 --- sysdeps/x86_64/multiarch/ifunc-impl-list.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)