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author | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-11-08 17:38:38 -0800 |
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committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-11-08 19:22:33 -0800 |
commit | f049f52dfeed8129c11ab1641a815705d09ff7e8 (patch) | |
tree | a6c13dc462411b308467b26a3a0f1062e0597bbd /sysdeps/x86_64/multiarch/strcat-evex.S | |
parent | d44e116428fefa0c2d01151af11f7a41fb525536 (diff) | |
download | glibc-f049f52dfeed8129c11ab1641a815705d09ff7e8.tar.gz glibc-f049f52dfeed8129c11ab1641a815705d09ff7e8.tar.xz glibc-f049f52dfeed8129c11ab1641a815705d09ff7e8.zip |
x86: Optimize and shrink st{r|p}{n}{cat|cpy}-evex functions
Optimizations are: 1. Use more overlapping stores to avoid branches. 2. Reduce how unrolled the aligning copies are (this is more of a code-size save, its a negative for some sizes in terms of perf). 3. Improve the loop a bit (similiar to what we do in strlen with 2x vpminu + kortest instead of 3x vpminu + kmov + test). 4. For st{r|p}n{cat|cpy} re-order the branches to minimize the number that are taken. Performance Changes: Times are from N = 10 runs of the benchmark suite and are reported as geometric mean of all ratios of New Implementation / Old Implementation. stpcpy-evex -> 0.922 strcat-evex -> 0.985 strcpy-evex -> 0.880 strncpy-evex -> 0.831 stpncpy-evex -> 0.780 strncat-evex -> 0.958 Code Size Changes: function -> Bytes New / Bytes Old -> Ratio strcat-evex -> 819 / 1874 -> 0.437 strcpy-evex -> 700 / 1074 -> 0.652 stpcpy-evex -> 735 / 1094 -> 0.672 strncpy-evex -> 1397 / 2611 -> 0.535 stpncpy-evex -> 1489 / 2691 -> 0.553 strncat-evex -> 1184 / 2832 -> 0.418 Notes: 1. Because of the significant difference between the implementations they are split into three files. strcpy-evex.S -> strcpy, stpcpy, strcat strncpy-evex.S -> strncpy strncat-evex.S > strncat I couldn't find a way to merge them without making the ifdefs incredibly difficult to follow. 2. All implementations can be made evex512 by including "x86-evex512-vecs.h" at the top. 3. All implementations have an optional define: `USE_EVEX_MASKED_STORE` Setting to one uses evex-masked stores for handling short strings. This saves code size and branches. It's disabled for all implementations are the moment as there are some serious drawbacks to masked stores in certain cases, but that may be fixed on future architectures. Full check passes on x86-64 and build succeeds for all ISA levels w/ and w/o multiarch.
Diffstat (limited to 'sysdeps/x86_64/multiarch/strcat-evex.S')
-rw-r--r-- | sysdeps/x86_64/multiarch/strcat-evex.S | 291 |
1 files changed, 6 insertions, 285 deletions
diff --git a/sysdeps/x86_64/multiarch/strcat-evex.S b/sysdeps/x86_64/multiarch/strcat-evex.S index 0e2df947e9..b4207b7889 100644 --- a/sysdeps/x86_64/multiarch/strcat-evex.S +++ b/sysdeps/x86_64/multiarch/strcat-evex.S @@ -1,286 +1,7 @@ -/* strcat with 256-bit EVEX instructions. - Copyright (C) 2021-2022 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/>. */ - -#include <isa-level.h> - -#if ISA_SHOULD_BUILD (4) - - -# include <sysdep.h> - -# ifndef STRCAT -# define STRCAT __strcat_evex -# endif - -# define VMOVU vmovdqu64 -# define VMOVA vmovdqa64 - -/* zero register */ -# define XMMZERO xmm16 -# define YMMZERO ymm16 -# define YMM0 ymm17 -# define YMM1 ymm18 - -# define USE_AS_STRCAT - -/* Number of bytes in a vector register */ -# define VEC_SIZE 32 - - .section .text.evex,"ax",@progbits -ENTRY (STRCAT) - mov %rdi, %r9 -# ifdef USE_AS_STRNCAT - mov %rdx, %r8 -# endif - - xor %eax, %eax - mov %edi, %ecx - and $((VEC_SIZE * 4) - 1), %ecx - vpxorq %XMMZERO, %XMMZERO, %XMMZERO - cmp $(VEC_SIZE * 3), %ecx - ja L(fourth_vector_boundary) - vpcmpb $0, (%rdi), %YMMZERO, %k0 - kmovd %k0, %edx - test %edx, %edx - jnz L(exit_null_on_first_vector) - mov %rdi, %rax - and $-VEC_SIZE, %rax - jmp L(align_vec_size_start) -L(fourth_vector_boundary): - mov %rdi, %rax - and $-VEC_SIZE, %rax - vpcmpb $0, (%rax), %YMMZERO, %k0 - mov $-1, %r10d - sub %rax, %rcx - shl %cl, %r10d - kmovd %k0, %edx - and %r10d, %edx - jnz L(exit) - -L(align_vec_size_start): - vpcmpb $0, VEC_SIZE(%rax), %YMMZERO, %k0 - kmovd %k0, %edx - test %edx, %edx - jnz L(exit_null_on_second_vector) - - vpcmpb $0, (VEC_SIZE * 2)(%rax), %YMMZERO, %k1 - kmovd %k1, %edx - test %edx, %edx - jnz L(exit_null_on_third_vector) - - vpcmpb $0, (VEC_SIZE * 3)(%rax), %YMMZERO, %k2 - kmovd %k2, %edx - test %edx, %edx - jnz L(exit_null_on_fourth_vector) - - vpcmpb $0, (VEC_SIZE * 4)(%rax), %YMMZERO, %k3 - kmovd %k3, %edx - test %edx, %edx - jnz L(exit_null_on_fifth_vector) - - vpcmpb $0, (VEC_SIZE * 5)(%rax), %YMMZERO, %k4 - add $(VEC_SIZE * 4), %rax - kmovd %k4, %edx - test %edx, %edx - jnz L(exit_null_on_second_vector) - - vpcmpb $0, (VEC_SIZE * 2)(%rax), %YMMZERO, %k1 - kmovd %k1, %edx - test %edx, %edx - jnz L(exit_null_on_third_vector) - - vpcmpb $0, (VEC_SIZE * 3)(%rax), %YMMZERO, %k2 - kmovd %k2, %edx - test %edx, %edx - jnz L(exit_null_on_fourth_vector) - - vpcmpb $0, (VEC_SIZE * 4)(%rax), %YMMZERO, %k3 - kmovd %k3, %edx - test %edx, %edx - jnz L(exit_null_on_fifth_vector) - - vpcmpb $0, (VEC_SIZE * 5)(%rax), %YMMZERO, %k4 - kmovd %k4, %edx - add $(VEC_SIZE * 4), %rax - test %edx, %edx - jnz L(exit_null_on_second_vector) - - vpcmpb $0, (VEC_SIZE * 2)(%rax), %YMMZERO, %k1 - kmovd %k1, %edx - test %edx, %edx - jnz L(exit_null_on_third_vector) - - vpcmpb $0, (VEC_SIZE * 3)(%rax), %YMMZERO, %k2 - kmovd %k2, %edx - test %edx, %edx - jnz L(exit_null_on_fourth_vector) - - vpcmpb $0, (VEC_SIZE * 4)(%rax), %YMMZERO, %k3 - kmovd %k3, %edx - test %edx, %edx - jnz L(exit_null_on_fifth_vector) - - vpcmpb $0, (VEC_SIZE * 5)(%rax), %YMMZERO, %k4 - add $(VEC_SIZE * 4), %rax - kmovd %k4, %edx - test %edx, %edx - jnz L(exit_null_on_second_vector) - - vpcmpb $0, (VEC_SIZE * 2)(%rax), %YMMZERO, %k1 - kmovd %k1, %edx - test %edx, %edx - jnz L(exit_null_on_third_vector) - - vpcmpb $0, (VEC_SIZE * 3)(%rax), %YMMZERO, %k2 - kmovd %k2, %edx - test %edx, %edx - jnz L(exit_null_on_fourth_vector) - - vpcmpb $0, (VEC_SIZE * 4)(%rax), %YMMZERO, %k3 - kmovd %k3, %edx - test %edx, %edx - jnz L(exit_null_on_fifth_vector) - - test $((VEC_SIZE * 4) - 1), %rax - jz L(align_four_vec_loop) - - vpcmpb $0, (VEC_SIZE * 5)(%rax), %YMMZERO, %k4 - add $(VEC_SIZE * 5), %rax - kmovd %k4, %edx - test %edx, %edx - jnz L(exit) - - test $((VEC_SIZE * 4) - 1), %rax - jz L(align_four_vec_loop) - - vpcmpb $0, VEC_SIZE(%rax), %YMMZERO, %k0 - add $VEC_SIZE, %rax - kmovd %k0, %edx - test %edx, %edx - jnz L(exit) - - test $((VEC_SIZE * 4) - 1), %rax - jz L(align_four_vec_loop) - - vpcmpb $0, VEC_SIZE(%rax), %YMMZERO, %k0 - add $VEC_SIZE, %rax - kmovd %k0, %edx - test %edx, %edx - jnz L(exit) - - test $((VEC_SIZE * 4) - 1), %rax - jz L(align_four_vec_loop) - - vpcmpb $0, VEC_SIZE(%rax), %YMMZERO, %k1 - add $VEC_SIZE, %rax - kmovd %k1, %edx - test %edx, %edx - jnz L(exit) - - add $VEC_SIZE, %rax - - .p2align 4 -L(align_four_vec_loop): - VMOVA (%rax), %YMM0 - VMOVA (VEC_SIZE * 2)(%rax), %YMM1 - vpminub VEC_SIZE(%rax), %YMM0, %YMM0 - vpminub (VEC_SIZE * 3)(%rax), %YMM1, %YMM1 - vpminub %YMM0, %YMM1, %YMM0 - /* If K0 != 0, there is a null byte. */ - vpcmpb $0, %YMM0, %YMMZERO, %k0 - add $(VEC_SIZE * 4), %rax - ktestd %k0, %k0 - jz L(align_four_vec_loop) - - vpcmpb $0, -(VEC_SIZE * 4)(%rax), %YMMZERO, %k0 - sub $(VEC_SIZE * 5), %rax - kmovd %k0, %edx - test %edx, %edx - jnz L(exit_null_on_second_vector) - - vpcmpb $0, (VEC_SIZE * 2)(%rax), %YMMZERO, %k1 - kmovd %k1, %edx - test %edx, %edx - jnz L(exit_null_on_third_vector) - - vpcmpb $0, (VEC_SIZE * 3)(%rax), %YMMZERO, %k2 - kmovd %k2, %edx - test %edx, %edx - jnz L(exit_null_on_fourth_vector) - - vpcmpb $0, (VEC_SIZE * 4)(%rax), %YMMZERO, %k3 - kmovd %k3, %edx - sub %rdi, %rax - bsf %rdx, %rdx - add %rdx, %rax - add $(VEC_SIZE * 4), %rax - jmp L(StartStrcpyPart) - - .p2align 4 -L(exit): - sub %rdi, %rax -L(exit_null_on_first_vector): - bsf %rdx, %rdx - add %rdx, %rax - jmp L(StartStrcpyPart) - - .p2align 4 -L(exit_null_on_second_vector): - sub %rdi, %rax - bsf %rdx, %rdx - add %rdx, %rax - add $VEC_SIZE, %rax - jmp L(StartStrcpyPart) - - .p2align 4 -L(exit_null_on_third_vector): - sub %rdi, %rax - bsf %rdx, %rdx - add %rdx, %rax - add $(VEC_SIZE * 2), %rax - jmp L(StartStrcpyPart) - - .p2align 4 -L(exit_null_on_fourth_vector): - sub %rdi, %rax - bsf %rdx, %rdx - add %rdx, %rax - add $(VEC_SIZE * 3), %rax - jmp L(StartStrcpyPart) - - .p2align 4 -L(exit_null_on_fifth_vector): - sub %rdi, %rax - bsf %rdx, %rdx - add %rdx, %rax - add $(VEC_SIZE * 4), %rax - - .p2align 4 -L(StartStrcpyPart): - lea (%r9, %rax), %rdi - mov %rsi, %rcx - mov %r9, %rax /* save result */ - -# ifdef USE_AS_STRNCAT - test %r8, %r8 - jz L(ExitZero) -# define USE_AS_STRNCPY -# endif - -# include "strcpy-evex.S" +#ifndef STRCAT +# define STRCAT __strcat_evex #endif + +#define USE_AS_STRCAT +#define STRCPY STRCAT +#include "strcpy-evex.S" |