From: Noah Goldstein <goldstein.w.n@gmail.com>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: libc-alpha@sourceware.org, "H . J . Lu" <hjl.tools@gmail.com>,
Sunil K Pandey <skpgkp2@gmail.com>
Subject: Re: [PATCH v2 4/6] x86-64: Require LZCNT for AVX2 memrchr implementation
Date: Sun, 2 Oct 2022 17:08:43 -0400 [thread overview]
Message-ID: <CAFUsyfKQdBRZYbyL5BrKgmeyiHqBw73LMn8Q8eGtxrP7hjChGg@mail.gmail.com> (raw)
In-Reply-To: <20221002123424.3079805-5-aurelien@aurel32.net>
On Sun, Oct 2, 2022 at 8:34 AM Aurelien Jarno <aurelien@aurel32.net> wrote:
>
> The AVX2 memrchr implementation uses the 'lzcnt' instruction, which
> belongs to the LZCNT CPU feature.
>
> Fixes: af5306a735eb ("x86: Optimize memrchr-avx2.S")
> Partially resolves: BZ #29611
> ---
> sysdeps/x86/isa-level.h | 1 +
> sysdeps/x86_64/multiarch/ifunc-avx2.h | 1 +
> sysdeps/x86_64/multiarch/ifunc-impl-list.c | 7 +++++--
> 3 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/x86/isa-level.h b/sysdeps/x86/isa-level.h
> index 3c4480aba7..bbb90f5c5e 100644
> --- a/sysdeps/x86/isa-level.h
> +++ b/sysdeps/x86/isa-level.h
> @@ -80,6 +80,7 @@
> #define AVX_X86_ISA_LEVEL 3
> #define AVX2_X86_ISA_LEVEL 3
> #define BMI2_X86_ISA_LEVEL 3
> +#define LZCNT_X86_ISA_LEVEL 3
> #define MOVBE_X86_ISA_LEVEL 3
>
> /* ISA level >= 2 guaranteed includes. */
> diff --git a/sysdeps/x86_64/multiarch/ifunc-avx2.h b/sysdeps/x86_64/multiarch/ifunc-avx2.h
> index a57a9952f3..f1741083fd 100644
> --- a/sysdeps/x86_64/multiarch/ifunc-avx2.h
> +++ b/sysdeps/x86_64/multiarch/ifunc-avx2.h
> @@ -37,6 +37,7 @@ IFUNC_SELECTOR (void)
>
> if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
> + && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, LZCNT)
> && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
> AVX_Fast_Unaligned_Load, ))
> {
> diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> index 7c84963d92..4ee28c99bd 100644
> --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> @@ -209,13 +209,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> IFUNC_IMPL (i, name, memrchr,
> X86_IFUNC_IMPL_ADD_V4 (array, i, memrchr,
> (CPU_FEATURE_USABLE (AVX512VL)
> - && CPU_FEATURE_USABLE (AVX512BW)),
> + && CPU_FEATURE_USABLE (AVX512BW)
> + && CPU_FEATURE_USABLE (LZCNT)),
> __memrchr_evex)
> X86_IFUNC_IMPL_ADD_V3 (array, i, memrchr,
> - CPU_FEATURE_USABLE (AVX2),
> + (CPU_FEATURE_USABLE (AVX2)
> + && CPU_FEATURE_USABLE (LZCNT)),
> __memrchr_avx2)
> X86_IFUNC_IMPL_ADD_V3 (array, i, memrchr,
> (CPU_FEATURE_USABLE (AVX2)
> + && CPU_FEATURE_USABLE (LZCNT)
> && CPU_FEATURE_USABLE (RTM)),
> __memrchr_avx2_rtm)
> /* ISA V2 wrapper for SSE2 implementation because the SSE2
> --
> 2.35.1
>
LGTM.
next prev parent reply other threads:[~2022-10-02 21:08 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-02 12:34 [PATCH v2 0/6] x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) Aurelien Jarno
2022-10-02 12:34 ` [PATCH v2 1/6] x86: include BMI1 and BMI2 in x86-64-v3 level Aurelien Jarno
2022-10-02 21:07 ` Noah Goldstein
2022-10-02 12:34 ` [PATCH v2 2/6] x86-64: Require BMI2 for AVX2 str*cmp and wcs(n)cmp implementations Aurelien Jarno
2022-10-02 21:08 ` Noah Goldstein
2022-10-03 16:19 ` Sunil Pandey
2022-10-03 17:35 ` Aurelien Jarno
2022-10-03 17:50 ` Noah Goldstein
2022-10-03 18:43 ` Sunil Pandey
2022-10-03 19:21 ` Aurelien Jarno
2022-10-03 19:59 ` Aurelien Jarno
2022-10-03 20:51 ` Sunil Pandey
2022-10-02 12:34 ` [PATCH v2 3/6] x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations Aurelien Jarno
2022-10-02 21:08 ` Noah Goldstein
2022-10-02 12:34 ` [PATCH v2 4/6] x86-64: Require LZCNT for AVX2 memrchr implementation Aurelien Jarno
2022-10-02 21:08 ` Noah Goldstein [this message]
2022-10-02 12:34 ` [PATCH v2 5/6] x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations Aurelien Jarno
2022-10-02 21:08 ` Noah Goldstein
2022-10-02 12:34 ` [PATCH v2 6/6] x86-64: Require BMI2 for AVX2 memrchr implementation Aurelien Jarno
2022-10-02 21:09 ` Noah Goldstein
2022-10-02 16:21 ` [PATCH v2 0/6] x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) Noah Goldstein
2022-10-02 18:09 ` Aurelien Jarno
2022-10-02 21:11 ` Noah Goldstein
2022-10-03 17:36 ` Aurelien Jarno
2022-10-03 17:51 ` Noah Goldstein
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