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 --git a/sysdeps/x86_64/multiarch/ifunc-avx2.h b/sysdeps/x86_64/multiarch/ifunc-avx2.h
index 5cc1e4b0bc32abd1a0082b63805286232a7a65da..0456fa6efe1e2db34828fe932e8d8742b41de27b 100644 (file)
--- 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 a7c8ebbe850d654dd0dede6df1b5fc20e97fad4b..b224e6a644fc7c3215914f9223f23cd5ed2eb282 100644 (file)
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -516,15 +516,21 @@ __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))
 
@@ -705,15 +711,20 @@ __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))