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glibc/sysdeps/x86/dl-new-hash.h

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elf: Refactor dl_new_hash so it can be tested / benchmarked No change to the code other than moving the function to dl-new-hash.h. Changed name so its now in the reserved namespace. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-05-19 22:17:58 +00:00
/* _dl_new_hash for elf symbol lookup
Copyright (C) 2022 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
<https://www.gnu.org/licenses/>. */
elf: Optimize _dl_new_hash in dl-new-hash.h Unroll slightly and enforce good instruction scheduling. This improves performance on out-of-order machines. The unrolling allows for pipelined multiplies. As well, as an optional sysdep, reorder the operations and prevent reassosiation for better scheduling and higher ILP. This commit only adds the barrier for x86, although it should be either no change or a win for any architecture. Unrolling further started to induce slowdowns for sizes [0, 4] but can help the loop so if larger sizes are the target further unrolling can be beneficial. Results for _dl_new_hash Benchmarked on Tigerlake: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz Time as Geometric Mean of N=30 runs Geometric of all benchmark New / Old: 0.674 type, length, New Time, Old Time, New Time / Old Time fixed, 0, 2.865, 2.72, 1.053 fixed, 1, 3.567, 2.489, 1.433 fixed, 2, 2.577, 3.649, 0.706 fixed, 3, 3.644, 5.983, 0.609 fixed, 4, 4.211, 6.833, 0.616 fixed, 5, 4.741, 9.372, 0.506 fixed, 6, 5.415, 9.561, 0.566 fixed, 7, 6.649, 10.789, 0.616 fixed, 8, 8.081, 11.808, 0.684 fixed, 9, 8.427, 12.935, 0.651 fixed, 10, 8.673, 14.134, 0.614 fixed, 11, 10.69, 15.408, 0.694 fixed, 12, 10.789, 16.982, 0.635 fixed, 13, 12.169, 18.411, 0.661 fixed, 14, 12.659, 19.914, 0.636 fixed, 15, 13.526, 21.541, 0.628 fixed, 16, 14.211, 23.088, 0.616 fixed, 32, 29.412, 52.722, 0.558 fixed, 64, 65.41, 142.351, 0.459 fixed, 128, 138.505, 295.625, 0.469 fixed, 256, 291.707, 601.983, 0.485 random, 2, 12.698, 12.849, 0.988 random, 4, 16.065, 15.857, 1.013 random, 8, 19.564, 21.105, 0.927 random, 16, 23.919, 26.823, 0.892 random, 32, 31.987, 39.591, 0.808 random, 64, 49.282, 71.487, 0.689 random, 128, 82.23, 145.364, 0.566 random, 256, 152.209, 298.434, 0.51 Co-authored-by: Alexander Monakov <amonakov@ispras.ru> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-05-19 22:18:03 +00:00
#ifdef __asm_reassociation_barrier
# error "__asm_reassociation_barrier should never already be defined."
#endif
elf: Refactor dl_new_hash so it can be tested / benchmarked No change to the code other than moving the function to dl-new-hash.h. Changed name so its now in the reserved namespace. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-05-19 22:17:58 +00:00
elf: Optimize _dl_new_hash in dl-new-hash.h Unroll slightly and enforce good instruction scheduling. This improves performance on out-of-order machines. The unrolling allows for pipelined multiplies. As well, as an optional sysdep, reorder the operations and prevent reassosiation for better scheduling and higher ILP. This commit only adds the barrier for x86, although it should be either no change or a win for any architecture. Unrolling further started to induce slowdowns for sizes [0, 4] but can help the loop so if larger sizes are the target further unrolling can be beneficial. Results for _dl_new_hash Benchmarked on Tigerlake: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz Time as Geometric Mean of N=30 runs Geometric of all benchmark New / Old: 0.674 type, length, New Time, Old Time, New Time / Old Time fixed, 0, 2.865, 2.72, 1.053 fixed, 1, 3.567, 2.489, 1.433 fixed, 2, 2.577, 3.649, 0.706 fixed, 3, 3.644, 5.983, 0.609 fixed, 4, 4.211, 6.833, 0.616 fixed, 5, 4.741, 9.372, 0.506 fixed, 6, 5.415, 9.561, 0.566 fixed, 7, 6.649, 10.789, 0.616 fixed, 8, 8.081, 11.808, 0.684 fixed, 9, 8.427, 12.935, 0.651 fixed, 10, 8.673, 14.134, 0.614 fixed, 11, 10.69, 15.408, 0.694 fixed, 12, 10.789, 16.982, 0.635 fixed, 13, 12.169, 18.411, 0.661 fixed, 14, 12.659, 19.914, 0.636 fixed, 15, 13.526, 21.541, 0.628 fixed, 16, 14.211, 23.088, 0.616 fixed, 32, 29.412, 52.722, 0.558 fixed, 64, 65.41, 142.351, 0.459 fixed, 128, 138.505, 295.625, 0.469 fixed, 256, 291.707, 601.983, 0.485 random, 2, 12.698, 12.849, 0.988 random, 4, 16.065, 15.857, 1.013 random, 8, 19.564, 21.105, 0.927 random, 16, 23.919, 26.823, 0.892 random, 32, 31.987, 39.591, 0.808 random, 64, 49.282, 71.487, 0.689 random, 128, 82.23, 145.364, 0.566 random, 256, 152.209, 298.434, 0.51 Co-authored-by: Alexander Monakov <amonakov@ispras.ru> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-05-19 22:18:03 +00:00
#define __asm_reassociation_barrier __asm__
#include <sysdeps/generic/dl-new-hash.h>
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