353ebae304
This patch significantly improves performance of memmem using a novel modified Horspool algorithm. Needles up to size 256 use a bad-character table indexed by hashed pairs of characters to quickly skip past mismatches. Long needles use a self-adapting filtering step to avoid comparing the whole needle repeatedly. By limiting the needle length to 256, the shift table only requires 8 bits per entry, lowering preprocessing overhead and minimizing cache effects. This limit also implies worst-case performance is linear. Small needles up to size 2 use a dedicated linear search. Very long needles use the Two-Way algorithm (to avoid increasing stack size inlining is now disabled). The performance gain is 6.6 times on English text on AArch64 using random needles with average size 8 (this is even faster than the recently improved strstr algorithm, so I'll update that in the near future). The size-optimized memmem has also been rewritten from scratch to get a 2.7x performance gain. Tested against GLIBC testsuite and randomized tests. Message-Id: <DB5PR08MB1030649D051FA8532A4512C883B20@DB5PR08MB1030.eurprd08.prod.outlook.com> |
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config | ||
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include | ||
libgloss | ||
newlib | ||
texinfo | ||
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COPYING | ||
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COPYING.LIBGLOSS | ||
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COPYING3 | ||
COPYING3.LIB | ||
ChangeLog | ||
MAINTAINERS | ||
Makefile.def | ||
Makefile.in | ||
Makefile.tpl | ||
README | ||
README-maintainer-mode | ||
compile | ||
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config.guess | ||
config.rpath | ||
config.sub | ||
configure | ||
configure.ac | ||
depcomp | ||
djunpack.bat | ||
install-sh | ||
libtool.m4 | ||
ltgcc.m4 | ||
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missing | ||
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setup.com | ||
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ylwrap |
README
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.