diff options
| -rw-r--r-- | sysdeps/x86_64/multiarch/ifunc-sse4_2.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/sysdeps/x86_64/multiarch/ifunc-sse4_2.h b/sysdeps/x86_64/multiarch/ifunc-sse4_2.h index ee36525..f8b5693 100644 --- a/sysdeps/x86_64/multiarch/ifunc-sse4_2.h +++ b/sysdeps/x86_64/multiarch/ifunc-sse4_2.h @@ -27,6 +27,12 @@ IFUNC_SELECTOR (void) { const struct cpu_features* cpu_features = __get_cpu_features (); + /* This function uses the `pcmpstri` sse4.2 instruction which can be + slow on some CPUs. This normally would be guarded by a + Slow_SSE4_2 check, but since there is no other optimized + implementation its best to keep it regardless. If an optimized + fallback is added add a X86_ISA_CPU_FEATURE_ARCH_P (cpu_features, + Slow_SSE4_2) check. */ if (CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)) return OPTIMIZE (sse42); |