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commit 9d50e162eef88e1f870a941b0a973060e984e7ca
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Tue Jun 14 15:37:28 2022 -0700
x86: Add sse42 implementation to strcmp's ifunc
This has been missing since the the ifuncs where added.
The performance of SSE4.2 is preferable to to SSE2.
Measured on Tigerlake with N = 20 runs.
Geometric Mean of all benchmarks SSE4.2 / SSE2: 0.906
(cherry picked from commit ff439c47173565fbff4f0f78d07b0f14e4a7db05)
diff --git a/sysdeps/x86_64/multiarch/strcmp.c b/sysdeps/x86_64/multiarch/strcmp.c
index 7c2901bf44456259..b457fb4c150e4407 100644
--- a/sysdeps/x86_64/multiarch/strcmp.c
+++ b/sysdeps/x86_64/multiarch/strcmp.c
@@ -29,6 +29,7 @@
extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_unaligned) attribute_hidden;
extern __typeof (REDIRECT_NAME) OPTIMIZE (ssse3) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse42) attribute_hidden;
extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2_rtm) attribute_hidden;
extern __typeof (REDIRECT_NAME) OPTIMIZE (evex) attribute_hidden;
@@ -53,6 +54,10 @@ IFUNC_SELECTOR (void)
return OPTIMIZE (avx2);
}
+ if (CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)
+ && !CPU_FEATURES_ARCH_P (cpu_features, Slow_SSE4_2))
+ return OPTIMIZE (sse42);
+
if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
return OPTIMIZE (sse2_unaligned);