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glibc/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
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/* memset/bzero with unaligned store and rep stosb | |
Copyright (C) 2016 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/>. */ | |
/* memset is implemented as: | |
1. Use overlapping store to avoid branch. | |
2. Force 32-bit displacement for branches to avoid long nop between | |
instructions. | |
3. If size is less than VEC, use integer register stores. | |
4. If size is from VEC_SIZE to 2 * VEC_SIZE, use 2 VEC stores. | |
5. If size is from 2 * VEC_SIZE to 4 * VEC_SIZE, use 4 VEC stores. | |
6. If size is more to 4 * VEC_SIZE, align to 4 * VEC_SIZE with | |
4 VEC stores and store 4 * VEC at a time until done. */ | |
#include <sysdep.h> | |
#ifndef MEMSET_CHK_SYMBOL | |
# define MEMSET_CHK_SYMBOL(p,s) MEMSET_SYMBOL(p, s) | |
#endif | |
#ifndef VZEROUPPER | |
# if VEC_SIZE > 16 | |
# define VZEROUPPER vzeroupper | |
# else | |
# define VZEROUPPER | |
# endif | |
#endif | |
#ifndef VZEROUPPER_SHORT_RETURN | |
# if VEC_SIZE > 16 | |
# define VZEROUPPER_SHORT_RETURN vzeroupper | |
# else | |
# define VZEROUPPER_SHORT_RETURN rep | |
# endif | |
#endif | |
#ifndef MOVQ | |
# if VEC_SIZE > 16 | |
# define MOVQ vmovq | |
# else | |
# define MOVQ movq | |
# endif | |
#endif | |
/* Threshold to use Enhanced REP STOSB. Since there is overhead to set | |
up REP STOSB operation, REP STOSB isn't faster on short data. The | |
memset micro benchmark in glibc shows that 2KB is the approximate | |
value above which REP STOSB becomes faster on processors with | |
Enhanced REP STOSB. Since the stored value is fixed, larger register | |
size has minimal impact on threshold. */ | |
#ifndef REP_STOSB_THRESHOLD | |
# define REP_STOSB_THRESHOLD 2048 | |
#endif | |
#ifndef SECTION | |
# error SECTION is not defined! | |
#endif | |
.section SECTION(.text),"ax",@progbits | |
#if VEC_SIZE == 16 && IS_IN (libc) && 0 | |
ENTRY (__bzero) | |
movq %rdi, %rax /* Set return value. */ | |
movq %rsi, %rdx /* Set n. */ | |
pxor %xmm0, %xmm0 | |
jmp L(entry_from_bzero) | |
END (__bzero) | |
weak_alias (__bzero, bzero) | |
#endif | |
#if defined SHARED && IS_IN (libc) | |
ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned)) | |
cmpq %rdx, %rcx | |
jb HIDDEN_JUMPTARGET (__chk_fail) | |
END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned)) | |
#endif | |
ENTRY (MEMSET_SYMBOL (__memset, unaligned)) | |
L(memset_entry): | |
VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi) | |
L(entry_from_bzero): | |
cmpq $VEC_SIZE, %rdx | |
jb L(less_vec) | |
cmpq $(VEC_SIZE * 2), %rdx | |
ja L(more_2x_vec) | |
/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */ | |
VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx) | |
VMOVU %VEC(0), (%rdi) | |
VZEROUPPER | |
ret | |
#if defined USE_MULTIARCH && IS_IN (libc) | |
END (MEMSET_SYMBOL (__memset, unaligned)) | |
# if VEC_SIZE == 16 | |
/* Only used to measure performance of REP STOSB. */ | |
ENTRY (__memset_erms) | |
# else | |
/* Provide a symbol to debugger. */ | |
ENTRY (MEMSET_SYMBOL (__memset, erms)) | |
# endif | |
L(stosb): | |
movq %rdx, %rcx | |
movzbl %sil, %eax | |
movq %rdi, %rdx | |
rep stosb | |
movq %rdx, %rax | |
ret | |
# if VEC_SIZE == 16 | |
END (__memset_erms) | |
# else | |
END (MEMSET_SYMBOL (__memset, erms)) | |
# endif | |
# if defined SHARED && IS_IN (libc) | |
ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms)) | |
cmpq %rdx, %rcx | |
jb HIDDEN_JUMPTARGET (__chk_fail) | |
END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms)) | |
# endif | |
ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms)) | |
VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi) | |
cmpq $VEC_SIZE, %rdx | |
jb L(less_vec) | |
cmpq $(VEC_SIZE * 2), %rdx | |
ja L(stosb_more_2x_vec) | |
/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */ | |
VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx) | |
VMOVU %VEC(0), (%rdi) | |
VZEROUPPER | |
ret | |
.p2align 4 | |
L(stosb_more_2x_vec): | |
cmpq $REP_STOSB_THRESHOLD, %rdx | |
/* Force 32-bit displacement to avoid long nop between | |
instructions. */ | |
ja.d32 L(stosb) | |
#endif | |
.p2align 4 | |
L(more_2x_vec): | |
cmpq $(VEC_SIZE * 4), %rdx | |
ja L(loop_start) | |
VMOVU %VEC(0), (%rdi) | |
VMOVU %VEC(0), VEC_SIZE(%rdi) | |
VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx) | |
VMOVU %VEC(0), -(VEC_SIZE * 2)(%rdi,%rdx) | |
L(return): | |
VZEROUPPER | |
ret | |
.p2align 4 | |
L(loop_start): | |
leaq (VEC_SIZE * 4)(%rdi), %rcx | |
# if VEC_SIZE == 32 || VEC_SIZE == 64 | |
/* Force 32-bit displacement to avoid long nop between | |
instructions. */ | |
VMOVU.d32 %VEC(0), (%rdi) | |
# else | |
VMOVU %VEC(0), (%rdi) | |
# endif | |
andq $-(VEC_SIZE * 4), %rcx | |
# if VEC_SIZE == 32 | |
/* Force 32-bit displacement to avoid long nop between | |
instructions. */ | |
VMOVU.d32 %VEC(0), -VEC_SIZE(%rdi,%rdx) | |
VMOVU.d32 %VEC(0), VEC_SIZE(%rdi) | |
# else | |
VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx) | |
VMOVU %VEC(0), VEC_SIZE(%rdi) | |
# endif | |
VMOVU %VEC(0), -(VEC_SIZE * 2)(%rdi,%rdx) | |
VMOVU %VEC(0), (VEC_SIZE * 2)(%rdi) | |
VMOVU %VEC(0), -(VEC_SIZE * 3)(%rdi,%rdx) | |
VMOVU %VEC(0), (VEC_SIZE * 3)(%rdi) | |
VMOVU %VEC(0), -(VEC_SIZE * 4)(%rdi,%rdx) | |
addq %rdi, %rdx | |
andq $-(VEC_SIZE * 4), %rdx | |
cmpq %rdx, %rcx | |
# if VEC_SIZE == 32 || VEC_SIZE == 64 | |
/* Force 32-bit displacement to avoid long nop between | |
instructions. */ | |
je.d32 L(return) | |
# else | |
je L(return) | |
# endif | |
.p2align 4 | |
L(loop): | |
VMOVA %VEC(0), (%rcx) | |
VMOVA %VEC(0), VEC_SIZE(%rcx) | |
VMOVA %VEC(0), (VEC_SIZE * 2)(%rcx) | |
VMOVA %VEC(0), (VEC_SIZE * 3)(%rcx) | |
addq $(VEC_SIZE * 4), %rcx | |
cmpq %rcx, %rdx | |
jne L(loop) | |
VZEROUPPER_SHORT_RETURN | |
ret | |
L(less_vec): | |
/* Less than 1 VEC. */ | |
# if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64 | |
# error Unsupported VEC_SIZE! | |
# endif | |
# if VEC_SIZE > 32 | |
cmpb $32, %dl | |
jae L(between_32_63) | |
# endif | |
# if VEC_SIZE > 16 | |
cmpb $16, %dl | |
jae L(between_16_31) | |
# endif | |
MOVQ %xmm0, %rcx | |
cmpb $8, %dl | |
jae L(between_8_15) | |
cmpb $4, %dl | |
jae L(between_4_7) | |
cmpb $1, %dl | |
ja L(between_2_3) | |
jb 1f | |
movb %cl, (%rdi) | |
1: | |
VZEROUPPER | |
ret | |
# if VEC_SIZE > 32 | |
/* From 32 to 63. No branch when size == 32. */ | |
L(between_32_63): | |
vmovdqu %ymm0, -32(%rdi,%rdx) | |
vmovdqu %ymm0, (%rdi) | |
VZEROUPPER | |
ret | |
# endif | |
# if VEC_SIZE > 16 | |
/* From 16 to 31. No branch when size == 16. */ | |
L(between_16_31): | |
vmovdqu %xmm0, -16(%rdi,%rdx) | |
vmovdqu %xmm0, (%rdi) | |
VZEROUPPER | |
ret | |
# endif | |
/* From 8 to 15. No branch when size == 8. */ | |
L(between_8_15): | |
movq %rcx, -8(%rdi,%rdx) | |
movq %rcx, (%rdi) | |
VZEROUPPER | |
ret | |
L(between_4_7): | |
/* From 4 to 7. No branch when size == 4. */ | |
movl %ecx, -4(%rdi,%rdx) | |
movl %ecx, (%rdi) | |
VZEROUPPER | |
ret | |
L(between_2_3): | |
/* From 2 to 3. No branch when size == 2. */ | |
movw %cx, -2(%rdi,%rdx) | |
movw %cx, (%rdi) | |
VZEROUPPER | |
ret | |
END (MEMSET_SYMBOL (__memset, unaligned_erms)) |