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(parent: c46e9af) | patch
x86-64: Remove Prefer_AVX2_STRCMP
authorH.J. Lu <hjl.tools@gmail.com>
Fri, 29 Oct 2021 19:56:53 +0000 (12:56 -0700)
committerH.J. Lu <hjl.tools@gmail.com>
Mon, 1 Nov 2021 14:53:04 +0000 (07:53 -0700)
commit14dbbf46a007ae5df36646b51ad0c9e5f5259f30
tree7e0470499bd6cea64b76b1f0392bf23aeea2a19etree | snapshot
parentc46e9afb2df5fc9e39ff4d13777e4b4c26e04e55commit | diff
x86-64: Remove Prefer_AVX2_STRCMP

Remove Prefer_AVX2_STRCMP to enable EVEX strcmp.  When comparing 2 32-byte
strings, EVEX strcmp has been improved to require 1 load, 1 VPTESTM, 1
VPCMP, 1 KMOVD and 1 INCL instead of 2 loads, 3 VPCMPs, 2 KORDs, 1 KMOVD
and 1 TESTL while AVX2 strcmp requires 1 load, 2 VPCMPEQs, 1 VPMINU, 1
VPMOVMSKB and 1 TESTL.  EVEX strcmp is now faster than AVX2 strcmp by up
to 40% on Tiger Lake and Ice Lake.
sysdeps/x86/cpu-features.c diff | blob | blame | history
sysdeps/x86/cpu-tunables.c diff | blob | blame | history
sysdeps/x86/include/cpu-features-preferred_feature_index_1.def diff | blob | blame | history
sysdeps/x86_64/multiarch/strcmp.c diff | blob | blame | history
sysdeps/x86_64/multiarch/strncmp.c diff | blob | blame | history
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