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