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author | Ondřej Bílka <neleai@seznam.cz> | 2014-03-18 11:01:38 +0100 |
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committer | Ondřej Bílka <neleai@seznam.cz> | 2015-05-12 20:18:51 +0200 |
commit | 0f4840be2528b3e3f2ecea009ab08e753701e9be (patch) | |
tree | fc4eafdf024c8eccba2724f48153a6ccc7166121 /localedata | |
parent | 7327b333e56926d7d79bb9e01b839d3618bf750f (diff) | |
download | glibc-0f4840be2528b3e3f2ecea009ab08e753701e9be.tar.gz glibc-0f4840be2528b3e3f2ecea009ab08e753701e9be.tar.xz glibc-0f4840be2528b3e3f2ecea009ab08e753701e9be.zip |
Use strspn/strcspn/strpbrk ifunc in internal calls.
To make a strtok faster and improve performance in general we need to do one additional change. A comment: /* It doesn't make sense to send libc-internal strcspn calls through a PLT. The speedup we get from using SSE4.2 instruction is likely eaten away by the indirect call in the PLT. */ Does not make sense at all because nobody bothered to check it. Gap between these implementations is quite big, when haystack is empty a sse2 is around 40 cycles slower because it needs to populate a lookup table and difference only increases with size. That is much bigger than plt slowdown which is few cycles. Even benchtest show a gap which also may be reverse by branch misprediction but my internal benchmark shown. simple_strspn stupid_strspn __strspn_sse42 __strspn_sse2 Length 0, alignment 0, acc len 6: 18.6562 35.2344 17.0469 61.6719 Length 6, alignment 0, acc len 6: 59.5469 72.5781 16.4219 73.625 This patch also handles strpbrk which is implemented by including a x86_64/multiarch/strcspn.S file. * sysdeps/x86_64/multiarch/strspn.S: Remove plt indirection. * sysdeps/x86_64/multiarch/strcspn.S: Likewise.
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