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author | Wilco Dijkstra <wdijkstr@arm.com> | 2016-03-25 16:44:26 -0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2016-04-01 10:44:40 -0300 |
commit | d3496c9f4f27d3009b71be87f6108b4fed7314bd (patch) | |
tree | eefcd05beb1f6ed269167433a763c234483b7c0b /WUR-REPORT | |
parent | d8a012c5c9e4bfc1b8db2bc6deacb85b44a2e1eb (diff) | |
download | glibc-d3496c9f4f27d3009b71be87f6108b4fed7314bd.tar.gz glibc-d3496c9f4f27d3009b71be87f6108b4fed7314bd.tar.xz glibc-d3496c9f4f27d3009b71be87f6108b4fed7314bd.zip |
Improve generic strcspn performance
Improve strcspn performance using a much faster algorithm. It is kept simple so it works well on most targets. It is generally at least 10 times faster than the existing implementation on bench-strcspn on a few AArch64 implementations, and for some tests 100 times as fast (repeatedly calling strchr on a small string is extremely slow...). In fact the string/bits/string2.h inlines make no longer sense, as GCC already uses strlen if reject is an empty string, strchrnul is 5 times as fast as __strcspn_c1, while __strcspn_c2 and __strcspn_c3 are slower than the strcspn main loop for large strings (though reject length 2-4 could be special cased in the future to gain even more performance). Tested on x86_64, i686, and aarch64. * string/Version (libc): Add GLIBC_2.24. * string/strcspn.c (strcspn): Rewrite function. * string/bits/string2.h (strcspn): Use __builtin_strcspn. (__strcspn_c1): Remove inline function. (__strcspn_c2): Likewise. (__strcspn_c3): Likewise. * string/string-inline.c [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strcspn_c1): Add compatibility symbol. [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strcspn_c2): Likewise. [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strcspn_c3): Likewise. * sysdeps/i386/string-inlines.c: Include generic string-inlines.c.
Diffstat (limited to 'WUR-REPORT')
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