glibc/sysdeps/aarch64/multiarch/memmove.c

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/* Multiple versions of memmove. AARCH64 version.
Copyright (C) 2017-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* Define multiple versions only for the definition in libc. */
#if IS_IN (libc)
/* Redefine memmove so that the compiler won't complain about the type
mismatch with the IFUNC selector in strong_alias, below. */
# undef memmove
# define memmove __redirect_memmove
# include <string.h>
# include <init-arch.h>
extern __typeof (__redirect_memmove) __libc_memmove;
extern __typeof (__redirect_memmove) __memmove_generic attribute_hidden;
extern __typeof (__redirect_memmove) __memmove_thunderx attribute_hidden;
aarch64: Optimized implementation of memmove for Qualcomm Falkor This is an optimized memmove implementation for the Qualcomm Falkor processor core. Due to the way the falkor memcpy needs to be written, code cannot be easily shared between memmove and memcpy like in case of other aarch64 memcpy implementations due to which this routine is separate. The underlying principle is the same as that of memcpy where it tries to use registers with the same lower 4 bits for fetching the same stream, thus optimizing hardware prefetcher performance. The memcpy copy loop copies 64 bytes at a time using the same register pair since that's the way to train the hardware prefetcher on the falkor core. memmove cannot quite do that since it needs to avoid overlaps, so it does the next best thing, i.e. has a 32 byte loop with a 32 byte end (prefetch a loop ahead to account for overlapping locations) with register pairs that alias so that they hit the same prefetcher. Due to this difference in loop size, they have to currently be separate implementations but efforts are on to try and get memmove to fall back into memcpy whenever it can without simply duplicating all of the code. Performance: The routine fares around 20-25% better than the generic memmove for most medium to large sizes (i.e. > 128 bytes) for the new walking memmove benchmark (memmove-walk) with an unexplained regression between 1K and 2K. The minor regression is something worth looking into for us, but the remaining gains are significant enough that we would like this included upstream as we looking into the cause for the regression. Here is a snippet of the numbers as generated from the microbenchmark by the compare_strings script. Comparisons are against __memmove_generic: Function: memmove Variant: walk __memmove_thunderx __memmove_falkor __memmove_generic ======================================================================================================================== <snip> length=16384: 12508800.00 ( 6.09%) 11486800.00 ( 13.76%) 13319600.00 length=16400: 13614200.00 ( -0.67%) 11585000.00 ( 14.33%) 13523600.00 length=16385: 13448400.00 ( 0.10%) 11732700.00 ( 12.84%) 13461200.00 length=16399: 13594100.00 ( -0.22%) 11859600.00 ( 12.57%) 13564400.00 length=16386: 13211600.00 ( 1.13%) 11503800.00 ( 13.91%) 13362400.00 length=16398: 13218600.00 ( 2.12%) 11573200.00 ( 14.30%) 13504700.00 length=16387: 13510900.00 ( -0.37%) 11744200.00 ( 12.76%) 13461300.00 length=16397: 13603700.00 ( -0.15%) 11878200.00 ( 12.55%) 13583200.00 length=16388: 13461700.00 ( -0.13%) 11558000.00 ( 14.03%) 13444100.00 length=16396: 13517500.00 ( -0.03%) 11561300.00 ( 14.45%) 13513900.00 length=16389: 13534100.00 ( 0.17%) 11756800.00 ( 13.28%) 13556900.00 length=16395: 13585600.00 ( 0.11%) 11791800.00 ( 13.30%) 13601200.00 length=16390: 13480100.00 ( -0.13%) 11685500.00 ( 13.20%) 13462100.00 length=16394: 13529900.00 ( -0.23%) 11549800.00 ( 14.43%) 13498200.00 length=16391: 13595400.00 ( -0.26%) 11768200.00 ( 13.22%) 13560600.00 length=16393: 13567000.00 ( 0.20%) 11779700.00 ( 13.35%) 13594700.00 length=32768: 71308800.00 ( -6.53%) 50220800.00 ( 24.98%) 66939200.00 length=32784: 72100800.00 (-11.55%) 50114100.00 ( 22.47%) 64636300.00 length=32769: 71767000.00 ( -7.10%) 51238400.00 ( 23.54%) 67010000.00 length=32783: 70113700.00 (-40.95%) 51129000.00 ( -2.78%) 49744400.00 length=32770: 71367600.00 ( -6.52%) 50244700.00 ( 25.01%) 67000900.00 length=32782: 64366700.00 ( 4.71%) 50101400.00 ( 25.83%) 67545600.00 length=32771: 71440100.00 ( -6.51%) 51263900.00 ( 23.57%) 67074900.00 length=32781: 66993000.00 ( 0.34%) 51108300.00 ( 23.97%) 67220300.00 length=32772: 71443900.00 (-60.50%) 50062100.00 (-12.47%) 44512600.00 length=32780: 71759100.00 ( -6.58%) 50263200.00 ( 25.35%) 67328600.00 length=32773: 71714900.00 (-33.21%) 51076600.00 ( 5.12%) 53835400.00 length=32779: 71756900.00 ( -6.56%) 51290800.00 ( 23.83%) 67337800.00 length=32774: 59689300.00 (-34.55%) 50068400.00 (-12.86%) 44363300.00 length=32778: 71847500.00 (-18.20%) 50084100.00 ( 17.61%) 60786500.00 length=32775: 71599300.00 ( -6.54%) 51278200.00 ( 23.70%) 67204800.00 length=32777: 71862900.00 (-60.85%) 51094000.00 (-14.36%) 44677900.00 length=65536: 282848000.00 ( -6.60%) 199187000.00 ( 24.93%) 265325000.00 length=65552: 243285000.00 (-41.61%) 198512000.00 (-15.54%) 171805000.00 length=65537: 255415000.00 (-23.47%) 202499000.00 ( 2.11%) 206858000.00 length=65551: 280122000.00 (-62.95%) 203349000.00 (-18.29%) 171911000.00 length=65538: 283676000.00 (-14.46%) 198368000.00 ( 19.96%) 247848000.00 length=65550: 275566000.00 (-51.76%) 198494000.00 ( -9.31%) 181581000.00 length=65539: 283699000.00 ( -6.58%) 203453000.00 ( 23.57%) 266195000.00 length=65549: 286572000.00 ( -6.65%) 202607000.00 ( 24.60%) 268712000.00 length=65540: 283710000.00 ( -6.59%) 199161000.00 ( 25.17%) 266160000.00 length=65548: 237573000.00 ( 11.48%) 198462000.00 ( 26.06%) 268395000.00 length=65541: 284150000.00 ( -6.58%) 203273000.00 ( 23.75%) 266600000.00 length=65547: 286250000.00 ( -6.70%) 202594000.00 ( 24.48%) 268263000.00 length=65542: 284167000.00 ( -6.60%) 199122000.00 ( 25.31%) 266584000.00 length=65546: 285656000.00 ( -6.59%) 198443000.00 ( 25.95%) 268002000.00 length=65543: 284600000.00 ( -6.58%) 203247000.00 ( 23.89%) 267030000.00 length=65545: 285665000.00 ( -6.40%) 202575000.00 ( 24.55%) 268472000.00 <snip> * sysdeps/aarch64/multiarch/Makefile (sysdep_routines): Add memmove_falkor. * sysdeps/aarch64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Likewise. * sysdeps/aarch64/multiarch/memmove.c: Likewise. * sysdeps/aarch64/multiarch/memmove_falkor.S: New file.
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extern __typeof (__redirect_memmove) __memmove_falkor attribute_hidden;
libc_ifunc (__libc_memmove,
aarch64: Optimized implementation of memmove for Qualcomm Falkor This is an optimized memmove implementation for the Qualcomm Falkor processor core. Due to the way the falkor memcpy needs to be written, code cannot be easily shared between memmove and memcpy like in case of other aarch64 memcpy implementations due to which this routine is separate. The underlying principle is the same as that of memcpy where it tries to use registers with the same lower 4 bits for fetching the same stream, thus optimizing hardware prefetcher performance. The memcpy copy loop copies 64 bytes at a time using the same register pair since that's the way to train the hardware prefetcher on the falkor core. memmove cannot quite do that since it needs to avoid overlaps, so it does the next best thing, i.e. has a 32 byte loop with a 32 byte end (prefetch a loop ahead to account for overlapping locations) with register pairs that alias so that they hit the same prefetcher. Due to this difference in loop size, they have to currently be separate implementations but efforts are on to try and get memmove to fall back into memcpy whenever it can without simply duplicating all of the code. Performance: The routine fares around 20-25% better than the generic memmove for most medium to large sizes (i.e. > 128 bytes) for the new walking memmove benchmark (memmove-walk) with an unexplained regression between 1K and 2K. The minor regression is something worth looking into for us, but the remaining gains are significant enough that we would like this included upstream as we looking into the cause for the regression. Here is a snippet of the numbers as generated from the microbenchmark by the compare_strings script. Comparisons are against __memmove_generic: Function: memmove Variant: walk __memmove_thunderx __memmove_falkor __memmove_generic ======================================================================================================================== <snip> length=16384: 12508800.00 ( 6.09%) 11486800.00 ( 13.76%) 13319600.00 length=16400: 13614200.00 ( -0.67%) 11585000.00 ( 14.33%) 13523600.00 length=16385: 13448400.00 ( 0.10%) 11732700.00 ( 12.84%) 13461200.00 length=16399: 13594100.00 ( -0.22%) 11859600.00 ( 12.57%) 13564400.00 length=16386: 13211600.00 ( 1.13%) 11503800.00 ( 13.91%) 13362400.00 length=16398: 13218600.00 ( 2.12%) 11573200.00 ( 14.30%) 13504700.00 length=16387: 13510900.00 ( -0.37%) 11744200.00 ( 12.76%) 13461300.00 length=16397: 13603700.00 ( -0.15%) 11878200.00 ( 12.55%) 13583200.00 length=16388: 13461700.00 ( -0.13%) 11558000.00 ( 14.03%) 13444100.00 length=16396: 13517500.00 ( -0.03%) 11561300.00 ( 14.45%) 13513900.00 length=16389: 13534100.00 ( 0.17%) 11756800.00 ( 13.28%) 13556900.00 length=16395: 13585600.00 ( 0.11%) 11791800.00 ( 13.30%) 13601200.00 length=16390: 13480100.00 ( -0.13%) 11685500.00 ( 13.20%) 13462100.00 length=16394: 13529900.00 ( -0.23%) 11549800.00 ( 14.43%) 13498200.00 length=16391: 13595400.00 ( -0.26%) 11768200.00 ( 13.22%) 13560600.00 length=16393: 13567000.00 ( 0.20%) 11779700.00 ( 13.35%) 13594700.00 length=32768: 71308800.00 ( -6.53%) 50220800.00 ( 24.98%) 66939200.00 length=32784: 72100800.00 (-11.55%) 50114100.00 ( 22.47%) 64636300.00 length=32769: 71767000.00 ( -7.10%) 51238400.00 ( 23.54%) 67010000.00 length=32783: 70113700.00 (-40.95%) 51129000.00 ( -2.78%) 49744400.00 length=32770: 71367600.00 ( -6.52%) 50244700.00 ( 25.01%) 67000900.00 length=32782: 64366700.00 ( 4.71%) 50101400.00 ( 25.83%) 67545600.00 length=32771: 71440100.00 ( -6.51%) 51263900.00 ( 23.57%) 67074900.00 length=32781: 66993000.00 ( 0.34%) 51108300.00 ( 23.97%) 67220300.00 length=32772: 71443900.00 (-60.50%) 50062100.00 (-12.47%) 44512600.00 length=32780: 71759100.00 ( -6.58%) 50263200.00 ( 25.35%) 67328600.00 length=32773: 71714900.00 (-33.21%) 51076600.00 ( 5.12%) 53835400.00 length=32779: 71756900.00 ( -6.56%) 51290800.00 ( 23.83%) 67337800.00 length=32774: 59689300.00 (-34.55%) 50068400.00 (-12.86%) 44363300.00 length=32778: 71847500.00 (-18.20%) 50084100.00 ( 17.61%) 60786500.00 length=32775: 71599300.00 ( -6.54%) 51278200.00 ( 23.70%) 67204800.00 length=32777: 71862900.00 (-60.85%) 51094000.00 (-14.36%) 44677900.00 length=65536: 282848000.00 ( -6.60%) 199187000.00 ( 24.93%) 265325000.00 length=65552: 243285000.00 (-41.61%) 198512000.00 (-15.54%) 171805000.00 length=65537: 255415000.00 (-23.47%) 202499000.00 ( 2.11%) 206858000.00 length=65551: 280122000.00 (-62.95%) 203349000.00 (-18.29%) 171911000.00 length=65538: 283676000.00 (-14.46%) 198368000.00 ( 19.96%) 247848000.00 length=65550: 275566000.00 (-51.76%) 198494000.00 ( -9.31%) 181581000.00 length=65539: 283699000.00 ( -6.58%) 203453000.00 ( 23.57%) 266195000.00 length=65549: 286572000.00 ( -6.65%) 202607000.00 ( 24.60%) 268712000.00 length=65540: 283710000.00 ( -6.59%) 199161000.00 ( 25.17%) 266160000.00 length=65548: 237573000.00 ( 11.48%) 198462000.00 ( 26.06%) 268395000.00 length=65541: 284150000.00 ( -6.58%) 203273000.00 ( 23.75%) 266600000.00 length=65547: 286250000.00 ( -6.70%) 202594000.00 ( 24.48%) 268263000.00 length=65542: 284167000.00 ( -6.60%) 199122000.00 ( 25.31%) 266584000.00 length=65546: 285656000.00 ( -6.59%) 198443000.00 ( 25.95%) 268002000.00 length=65543: 284600000.00 ( -6.58%) 203247000.00 ( 23.89%) 267030000.00 length=65545: 285665000.00 ( -6.40%) 202575000.00 ( 24.55%) 268472000.00 <snip> * sysdeps/aarch64/multiarch/Makefile (sysdep_routines): Add memmove_falkor. * sysdeps/aarch64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Likewise. * sysdeps/aarch64/multiarch/memmove.c: Likewise. * sysdeps/aarch64/multiarch/memmove_falkor.S: New file.
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(IS_THUNDERX (midr)
? __memmove_thunderx
: (IS_FALKOR (midr) || IS_PHECDA (midr)
aarch64: Optimized implementation of memmove for Qualcomm Falkor This is an optimized memmove implementation for the Qualcomm Falkor processor core. Due to the way the falkor memcpy needs to be written, code cannot be easily shared between memmove and memcpy like in case of other aarch64 memcpy implementations due to which this routine is separate. The underlying principle is the same as that of memcpy where it tries to use registers with the same lower 4 bits for fetching the same stream, thus optimizing hardware prefetcher performance. The memcpy copy loop copies 64 bytes at a time using the same register pair since that's the way to train the hardware prefetcher on the falkor core. memmove cannot quite do that since it needs to avoid overlaps, so it does the next best thing, i.e. has a 32 byte loop with a 32 byte end (prefetch a loop ahead to account for overlapping locations) with register pairs that alias so that they hit the same prefetcher. Due to this difference in loop size, they have to currently be separate implementations but efforts are on to try and get memmove to fall back into memcpy whenever it can without simply duplicating all of the code. Performance: The routine fares around 20-25% better than the generic memmove for most medium to large sizes (i.e. > 128 bytes) for the new walking memmove benchmark (memmove-walk) with an unexplained regression between 1K and 2K. The minor regression is something worth looking into for us, but the remaining gains are significant enough that we would like this included upstream as we looking into the cause for the regression. Here is a snippet of the numbers as generated from the microbenchmark by the compare_strings script. Comparisons are against __memmove_generic: Function: memmove Variant: walk __memmove_thunderx __memmove_falkor __memmove_generic ======================================================================================================================== <snip> length=16384: 12508800.00 ( 6.09%) 11486800.00 ( 13.76%) 13319600.00 length=16400: 13614200.00 ( -0.67%) 11585000.00 ( 14.33%) 13523600.00 length=16385: 13448400.00 ( 0.10%) 11732700.00 ( 12.84%) 13461200.00 length=16399: 13594100.00 ( -0.22%) 11859600.00 ( 12.57%) 13564400.00 length=16386: 13211600.00 ( 1.13%) 11503800.00 ( 13.91%) 13362400.00 length=16398: 13218600.00 ( 2.12%) 11573200.00 ( 14.30%) 13504700.00 length=16387: 13510900.00 ( -0.37%) 11744200.00 ( 12.76%) 13461300.00 length=16397: 13603700.00 ( -0.15%) 11878200.00 ( 12.55%) 13583200.00 length=16388: 13461700.00 ( -0.13%) 11558000.00 ( 14.03%) 13444100.00 length=16396: 13517500.00 ( -0.03%) 11561300.00 ( 14.45%) 13513900.00 length=16389: 13534100.00 ( 0.17%) 11756800.00 ( 13.28%) 13556900.00 length=16395: 13585600.00 ( 0.11%) 11791800.00 ( 13.30%) 13601200.00 length=16390: 13480100.00 ( -0.13%) 11685500.00 ( 13.20%) 13462100.00 length=16394: 13529900.00 ( -0.23%) 11549800.00 ( 14.43%) 13498200.00 length=16391: 13595400.00 ( -0.26%) 11768200.00 ( 13.22%) 13560600.00 length=16393: 13567000.00 ( 0.20%) 11779700.00 ( 13.35%) 13594700.00 length=32768: 71308800.00 ( -6.53%) 50220800.00 ( 24.98%) 66939200.00 length=32784: 72100800.00 (-11.55%) 50114100.00 ( 22.47%) 64636300.00 length=32769: 71767000.00 ( -7.10%) 51238400.00 ( 23.54%) 67010000.00 length=32783: 70113700.00 (-40.95%) 51129000.00 ( -2.78%) 49744400.00 length=32770: 71367600.00 ( -6.52%) 50244700.00 ( 25.01%) 67000900.00 length=32782: 64366700.00 ( 4.71%) 50101400.00 ( 25.83%) 67545600.00 length=32771: 71440100.00 ( -6.51%) 51263900.00 ( 23.57%) 67074900.00 length=32781: 66993000.00 ( 0.34%) 51108300.00 ( 23.97%) 67220300.00 length=32772: 71443900.00 (-60.50%) 50062100.00 (-12.47%) 44512600.00 length=32780: 71759100.00 ( -6.58%) 50263200.00 ( 25.35%) 67328600.00 length=32773: 71714900.00 (-33.21%) 51076600.00 ( 5.12%) 53835400.00 length=32779: 71756900.00 ( -6.56%) 51290800.00 ( 23.83%) 67337800.00 length=32774: 59689300.00 (-34.55%) 50068400.00 (-12.86%) 44363300.00 length=32778: 71847500.00 (-18.20%) 50084100.00 ( 17.61%) 60786500.00 length=32775: 71599300.00 ( -6.54%) 51278200.00 ( 23.70%) 67204800.00 length=32777: 71862900.00 (-60.85%) 51094000.00 (-14.36%) 44677900.00 length=65536: 282848000.00 ( -6.60%) 199187000.00 ( 24.93%) 265325000.00 length=65552: 243285000.00 (-41.61%) 198512000.00 (-15.54%) 171805000.00 length=65537: 255415000.00 (-23.47%) 202499000.00 ( 2.11%) 206858000.00 length=65551: 280122000.00 (-62.95%) 203349000.00 (-18.29%) 171911000.00 length=65538: 283676000.00 (-14.46%) 198368000.00 ( 19.96%) 247848000.00 length=65550: 275566000.00 (-51.76%) 198494000.00 ( -9.31%) 181581000.00 length=65539: 283699000.00 ( -6.58%) 203453000.00 ( 23.57%) 266195000.00 length=65549: 286572000.00 ( -6.65%) 202607000.00 ( 24.60%) 268712000.00 length=65540: 283710000.00 ( -6.59%) 199161000.00 ( 25.17%) 266160000.00 length=65548: 237573000.00 ( 11.48%) 198462000.00 ( 26.06%) 268395000.00 length=65541: 284150000.00 ( -6.58%) 203273000.00 ( 23.75%) 266600000.00 length=65547: 286250000.00 ( -6.70%) 202594000.00 ( 24.48%) 268263000.00 length=65542: 284167000.00 ( -6.60%) 199122000.00 ( 25.31%) 266584000.00 length=65546: 285656000.00 ( -6.59%) 198443000.00 ( 25.95%) 268002000.00 length=65543: 284600000.00 ( -6.58%) 203247000.00 ( 23.89%) 267030000.00 length=65545: 285665000.00 ( -6.40%) 202575000.00 ( 24.55%) 268472000.00 <snip> * sysdeps/aarch64/multiarch/Makefile (sysdep_routines): Add memmove_falkor. * sysdeps/aarch64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Likewise. * sysdeps/aarch64/multiarch/memmove.c: Likewise. * sysdeps/aarch64/multiarch/memmove_falkor.S: New file.
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? __memmove_falkor
: __memmove_generic)));
# undef memmove
strong_alias (__libc_memmove, memmove);
#endif