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authorWilco Dijkstra <wdijkstr@arm.com>2016-03-25 16:44:26 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2016-04-01 10:44:40 -0300
commitd3496c9f4f27d3009b71be87f6108b4fed7314bd (patch)
treeeefcd05beb1f6ed269167433a763c234483b7c0b /intl
parentd8a012c5c9e4bfc1b8db2bc6deacb85b44a2e1eb (diff)
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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 'intl')
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