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Wilco Dijkstra
c86063bdc0
Optimized memcmp
This is an optimized memcmp for AArch64. This is a complete rewrite using a different algorithm. The previous version split into cases where both inputs were aligned, the inputs were mutually aligned and unaligned using a byte loop. The new version combines all these cases, while small inputs of less than 8 bytes are handled separately. This allows the main code to be sped up using unaligned loads since there are now at least 8 bytes to be compared. After the first 8 bytes, align the first input. This ensures each iteration does at most one unaligned access and mutually aligned inputs behave as aligned. After the main loop, process the last 8 bytes using unaligned accesses. This improves performance of (mutually) aligned cases by 25% and unaligned by >500% (yes >6 times faster) on large inputs. ChangeLog: 2017-06-28 Wilco Dijkstra <wdijkstr@arm.com> * newlib/libc/machine/aarch64/memcmp.S (memcmp): Rewrite of optimized memcmp. GLIBC benchtests/bench-memcmp.c performance comparison for Cortex-A53: Length 1, alignment 1/ 1: 153% Length 1, alignment 1/ 1: 119% Length 1, alignment 1/ 1: 154% Length 2, alignment 2/ 2: 121% Length 2, alignment 2/ 2: 140% Length 2, alignment 2/ 2: 121% Length 3, alignment 3/ 3: 105% Length 3, alignment 3/ 3: 105% Length 3, alignment 3/ 3: 105% Length 4, alignment 4/ 4: 155% Length 4, alignment 4/ 4: 154% Length 4, alignment 4/ 4: 161% Length 5, alignment 5/ 5: 173% Length 5, alignment 5/ 5: 173% Length 5, alignment 5/ 5: 173% Length 6, alignment 6/ 6: 145% Length 6, alignment 6/ 6: 145% Length 6, alignment 6/ 6: 145% Length 7, alignment 7/ 7: 125% Length 7, alignment 7/ 7: 125% Length 7, alignment 7/ 7: 125% Length 8, alignment 8/ 8: 111% Length 8, alignment 8/ 8: 130% Length 8, alignment 8/ 8: 124% Length 9, alignment 9/ 9: 160% Length 9, alignment 9/ 9: 160% Length 9, alignment 9/ 9: 150% Length 10, alignment 10/10: 170% Length 10, alignment 10/10: 137% Length 10, alignment 10/10: 150% Length 11, alignment 11/11: 160% Length 11, alignment 11/11: 160% Length 11, alignment 11/11: 160% Length 12, alignment 12/12: 146% Length 12, alignment 12/12: 168% Length 12, alignment 12/12: 156% Length 13, alignment 13/13: 167% Length 13, alignment 13/13: 167% Length 13, alignment 13/13: 173% Length 14, alignment 14/14: 167% Length 14, alignment 14/14: 168% Length 14, alignment 14/14: 168% Length 15, alignment 15/15: 168% Length 15, alignment 15/15: 173% Length 15, alignment 15/15: 173% Length 1, alignment 0/ 0: 134% Length 1, alignment 0/ 0: 127% Length 1, alignment 0/ 0: 119% Length 2, alignment 0/ 0: 94% Length 2, alignment 0/ 0: 94% Length 2, alignment 0/ 0: 106% Length 3, alignment 0/ 0: 82% Length 3, alignment 0/ 0: 87% Length 3, alignment 0/ 0: 82% Length 4, alignment 0/ 0: 115% Length 4, alignment 0/ 0: 115% Length 4, alignment 0/ 0: 122% Length 5, alignment 0/ 0: 127% Length 5, alignment 0/ 0: 119% Length 5, alignment 0/ 0: 127% Length 6, alignment 0/ 0: 103% Length 6, alignment 0/ 0: 100% Length 6, alignment 0/ 0: 100% Length 7, alignment 0/ 0: 82% Length 7, alignment 0/ 0: 91% Length 7, alignment 0/ 0: 87% Length 8, alignment 0/ 0: 111% Length 8, alignment 0/ 0: 124% Length 8, alignment 0/ 0: 124% Length 9, alignment 0/ 0: 136% Length 9, alignment 0/ 0: 136% Length 9, alignment 0/ 0: 136% Length 10, alignment 0/ 0: 136% Length 10, alignment 0/ 0: 135% Length 10, alignment 0/ 0: 136% Length 11, alignment 0/ 0: 136% Length 11, alignment 0/ 0: 136% Length 11, alignment 0/ 0: 135% Length 12, alignment 0/ 0: 136% Length 12, alignment 0/ 0: 136% Length 12, alignment 0/ 0: 136% Length 13, alignment 0/ 0: 135% Length 13, alignment 0/ 0: 136% Length 13, alignment 0/ 0: 136% Length 14, alignment 0/ 0: 136% Length 14, alignment 0/ 0: 136% Length 14, alignment 0/ 0: 136% Length 15, alignment 0/ 0: 136% Length 15, alignment 0/ 0: 136% Length 15, alignment 0/ 0: 136% Length 4, alignment 0/ 0: 115% Length 4, alignment 0/ 0: 115% Length 4, alignment 0/ 0: 115% Length 32, alignment 0/ 0: 127% Length 32, alignment 7/ 2: 395% Length 32, alignment 0/ 0: 127% Length 32, alignment 0/ 0: 127% Length 8, alignment 0/ 0: 111% Length 8, alignment 0/ 0: 124% Length 8, alignment 0/ 0: 124% Length 64, alignment 0/ 0: 128% Length 64, alignment 6/ 4: 475% Length 64, alignment 0/ 0: 131% Length 64, alignment 0/ 0: 134% Length 16, alignment 0/ 0: 128% Length 16, alignment 0/ 0: 119% Length 16, alignment 0/ 0: 128% Length 128, alignment 0/ 0: 129% Length 128, alignment 5/ 6: 475% Length 128, alignment 0/ 0: 130% Length 128, alignment 0/ 0: 129% Length 32, alignment 0/ 0: 126% Length 32, alignment 0/ 0: 126% Length 32, alignment 0/ 0: 126% Length 256, alignment 0/ 0: 127% Length 256, alignment 4/ 8: 545% Length 256, alignment 0/ 0: 126% Length 256, alignment 0/ 0: 128% Length 64, alignment 0/ 0: 171% Length 64, alignment 0/ 0: 171% Length 64, alignment 0/ 0: 174% Length 512, alignment 0/ 0: 126% Length 512, alignment 3/10: 585% Length 512, alignment 0/ 0: 126% Length 512, alignment 0/ 0: 127% Length 128, alignment 0/ 0: 129% Length 128, alignment 0/ 0: 128% Length 128, alignment 0/ 0: 129% Length 1024, alignment 0/ 0: 125% Length 1024, alignment 2/12: 611% Length 1024, alignment 0/ 0: 126% Length 1024, alignment 0/ 0: 126% Length 256, alignment 0/ 0: 128% Length 256, alignment 0/ 0: 127% Length 256, alignment 0/ 0: 128% Length 2048, alignment 0/ 0: 125% Length 2048, alignment 1/14: 625% Length 2048, alignment 0/ 0: 125% Length 2048, alignment 0/ 0: 125% Length 512, alignment 0/ 0: 126% Length 512, alignment 0/ 0: 127% Length 512, alignment 0/ 0: 127% Length 4096, alignment 0/ 0: 125% Length 4096, alignment 0/16: 125% Length 4096, alignment 0/ 0: 125% Length 4096, alignment 0/ 0: 125% Length 1024, alignment 0/ 0: 126% Length 1024, alignment 0/ 0: 126% Length 1024, alignment 0/ 0: 126% Length 8192, alignment 0/ 0: 125% Length 8192, alignment 63/18: 636% Length 8192, alignment 0/ 0: 125% Length 8192, alignment 0/ 0: 125% Length 16, alignment 1/ 2: 317% Length 16, alignment 1/ 2: 317% Length 16, alignment 1/ 2: 317% Length 32, alignment 2/ 4: 395% Length 32, alignment 2/ 4: 395% Length 32, alignment 2/ 4: 398% Length 64, alignment 3/ 6: 475% Length 64, alignment 3/ 6: 475% Length 64, alignment 3/ 6: 477% Length 128, alignment 4/ 8: 479% Length 128, alignment 4/ 8: 479% Length 128, alignment 4/ 8: 479% Length 256, alignment 5/10: 543% Length 256, alignment 5/10: 539% Length 256, alignment 5/10: 543% Length 512, alignment 6/12: 585% Length 512, alignment 6/12: 585% Length 512, alignment 6/12: 585% Length 1024, alignment 7/14: 611% Length 1024, alignment 7/14: 611% Length 1024, alignment 7/14: 611%
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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.
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