From 02aa1f4a5b6955f2cb384daa4e520d9c8078a078 Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Mon, 3 Oct 2022 23:16:46 +0200 Subject: [PATCH] x86-64: Require BMI2 and LZCNT for AVX2 memrchr implementation The AVX2 memrchr implementation uses the 'shlxl' instruction, which belongs to the BMI2 CPU feature and uses the 'lzcnt' instruction, which belongs to the LZCNT CPU feature. Fixes: af5306a735eb ("x86: Optimize memrchr-avx2.S") Partially resolves: BZ #29611 Reviewed-by: Noah Goldstein (cherry picked from commit 3c0c78afabfed4b6fc161c159e628fbf14ff370b) --- sysdeps/x86_64/multiarch/ifunc-avx2.h | 1 + sysdeps/x86_64/multiarch/ifunc-impl-list.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/sysdeps/x86_64/multiarch/ifunc-avx2.h b/sysdeps/x86_64/multiarch/ifunc-avx2.h index 4289df29ecb..5cc1e4b0bc3 100644 --- a/sysdeps/x86_64/multiarch/ifunc-avx2.h +++ b/sysdeps/x86_64/multiarch/ifunc-avx2.h @@ -31,6 +31,7 @@ IFUNC_SELECTOR (void) if (CPU_FEATURE_USABLE_P (cpu_features, AVX2) && CPU_FEATURE_USABLE_P (cpu_features, BMI2) + && CPU_FEATURE_USABLE_P (cpu_features, LZCNT) && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load)) { if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL) diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c index 9959f7b2286..a7c8ebbe850 100644 --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c @@ -192,15 +192,21 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array, /* Support sysdeps/x86_64/multiarch/memrchr.c. */ IFUNC_IMPL (i, name, memrchr, IFUNC_IMPL_ADD (array, i, memrchr, - CPU_FEATURE_USABLE (AVX2), + (CPU_FEATURE_USABLE (AVX2) + && CPU_FEATURE_USABLE (BMI2) + && CPU_FEATURE_USABLE (LZCNT)), __memrchr_avx2) IFUNC_IMPL_ADD (array, i, memrchr, (CPU_FEATURE_USABLE (AVX2) + && CPU_FEATURE_USABLE (BMI2) + && CPU_FEATURE_USABLE (LZCNT) && CPU_FEATURE_USABLE (RTM)), __memrchr_avx2_rtm) IFUNC_IMPL_ADD (array, i, memrchr, (CPU_FEATURE_USABLE (AVX512VL) - && CPU_FEATURE_USABLE (AVX512BW)), + && CPU_FEATURE_USABLE (AVX512BW) + && CPU_FEATURE_USABLE (BMI2) + && CPU_FEATURE_USABLE (LZCNT)), __memrchr_evex) IFUNC_IMPL_ADD (array, i, memrchr, 1, __memrchr_sse2)) -- 2.47.3