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From: Aurelien Jarno <aurel32@sourceware.org>
To: glibc-cvs@sourceware.org
Subject: [glibc/release/2.34/master] x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations
Date: Mon,  3 Oct 2022 22:02:42 +0000 (GMT)	[thread overview]
Message-ID: <20221003220242.5BC70385381B@sourceware.org> (raw)

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e570b865b53f33453d97160791a7d97e38bcc6e8

commit e570b865b53f33453d97160791a7d97e38bcc6e8
Author: Aurelien Jarno <aurelien@aurel32.net>
Date:   Mon Oct 3 23:16:46 2022 +0200

    x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations
    
    The AVX2 strrchr and wcsrchr implementation uses the 'blsmsk'
    instruction which belongs to the BMI1 CPU feature and the 'shrx'
    instruction, which belongs to the BMI2 CPU feature.
    
    Fixes: df7e295d18ff ("x86: Optimize {str|wcs}rchr-avx2")
    Partially resolves: BZ #29611
    
    Reviewed-by: Noah Goldstein  <goldstein.w.n@gmail.com>
    (cherry picked from commit 7e8283170c5d6805b609a040801d819e362a6292)

Diff:
---
 sysdeps/x86_64/multiarch/ifunc-avx2.h      |  1 +
 sysdeps/x86_64/multiarch/ifunc-impl-list.c | 17 ++++++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/sysdeps/x86_64/multiarch/ifunc-avx2.h b/sysdeps/x86_64/multiarch/ifunc-avx2.h
index 52bd00ea5c..877f007dd6 100644
--- a/sysdeps/x86_64/multiarch/ifunc-avx2.h
+++ b/sysdeps/x86_64/multiarch/ifunc-avx2.h
@@ -30,6 +30,7 @@ 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, BMI1)
       && CPU_FEATURE_USABLE_P (cpu_features, BMI2)
       && CPU_FEATURE_USABLE_P (cpu_features, LZCNT)
       && 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 d1fc1e75d6..84f9e73e2b 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -498,15 +498,21 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/strrchr.c.  */
   IFUNC_IMPL (i, name, strrchr,
 	      IFUNC_IMPL_ADD (array, i, strrchr,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __strrchr_avx2)
 	      IFUNC_IMPL_ADD (array, i, strrchr,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __strrchr_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, strrchr,
 			      (CPU_FEATURE_USABLE (AVX512VL)
-			       && CPU_FEATURE_USABLE (AVX512BW)),
+			       && CPU_FEATURE_USABLE (AVX512BW)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __strrchr_evex)
 	      IFUNC_IMPL_ADD (array, i, strrchr, 1, __strrchr_sse2))
 
@@ -687,15 +693,20 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/wcsrchr.c.  */
   IFUNC_IMPL (i, name, wcsrchr,
 	      IFUNC_IMPL_ADD (array, i, wcsrchr,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __wcsrchr_avx2)
 	      IFUNC_IMPL_ADD (array, i, wcsrchr,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __wcsrchr_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, wcsrchr,
 			      (CPU_FEATURE_USABLE (AVX512VL)
 			       && CPU_FEATURE_USABLE (AVX512BW)
+			       && CPU_FEATURE_USABLE (BMI1)
 			       && CPU_FEATURE_USABLE (BMI2)),
 			      __wcsrchr_evex)
 	      IFUNC_IMPL_ADD (array, i, wcsrchr, 1, __wcsrchr_sse2))

                 reply	other threads:[~2022-10-03 22:02 UTC|newest]

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