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/* memset/bzero with unaligned store and rep stosb
Copyright (C) 2016-2021 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/>. */
/* memset is implemented as:
1. Use overlapping store to avoid branch.
2. If size is less than VEC, use integer register stores.
3. If size is from VEC_SIZE to 2 * VEC_SIZE, use 2 VEC stores.
4. If size is from 2 * VEC_SIZE to 4 * VEC_SIZE, use 4 VEC stores.
5. 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 WMEMSET_CHK_SYMBOL
# define WMEMSET_CHK_SYMBOL(p,s) WMEMSET_SYMBOL(p, s)
#endif
#ifndef XMM0
# define XMM0 xmm0
#endif
#ifndef YMM0
# define YMM0 ymm0
#endif
#ifndef VZEROUPPER
# if VEC_SIZE > 16
# define VZEROUPPER vzeroupper
# define VZEROUPPER_SHORT_RETURN vzeroupper; ret
# else
# define VZEROUPPER
# endif
#endif
#ifndef VZEROUPPER_SHORT_RETURN
# define VZEROUPPER_SHORT_RETURN rep; ret
#endif
#ifndef MOVQ
# if VEC_SIZE > 16
# define MOVQ vmovq
# else
# define MOVQ movq
# endif
#endif
#define PAGE_SIZE 4096
#ifndef SECTION
# error SECTION is not defined!
#endif
.section SECTION(.text),"ax",@progbits
#if VEC_SIZE == 16 && IS_IN (libc)
ENTRY (__bzero)
mov %RDI_LP, %RAX_LP /* Set return value. */
mov %RSI_LP, %RDX_LP /* Set n. */
pxor %XMM0, %XMM0
jmp L(entry_from_bzero)
END (__bzero)
weak_alias (__bzero, bzero)
#endif
#if IS_IN (libc)
# if defined SHARED
ENTRY_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))
# endif
ENTRY (WMEMSET_SYMBOL (__wmemset, unaligned))
shl $2, %RDX_LP
WMEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
jmp L(entry_from_bzero)
END (WMEMSET_SYMBOL (__wmemset, unaligned))
#endif
#if defined SHARED && IS_IN (libc)
ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
#endif
ENTRY (MEMSET_SYMBOL (__memset, unaligned))
MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
# ifdef __ILP32__
/* Clear the upper 32 bits. */
mov %edx, %edx
# endif
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_RETURN
#if defined USE_MULTIARCH && IS_IN (libc)
END (MEMSET_SYMBOL (__memset, unaligned))
# if VEC_SIZE == 16
ENTRY (__memset_chk_erms)
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (__memset_chk_erms)
/* Only used to measure performance of REP STOSB. */
ENTRY (__memset_erms)
/* Skip zero length. */
test %RDX_LP, %RDX_LP
jnz L(stosb)
movq %rdi, %rax
ret
# else
/* Provide a hidden symbol to debugger. */
.hidden MEMSET_SYMBOL (__memset, erms)
ENTRY (MEMSET_SYMBOL (__memset, erms))
# endif
L(stosb):
mov %RDX_LP, %RCX_LP
movzbl %sil, %eax
mov %RDI_LP, %RDX_LP
rep stosb
mov %RDX_LP, %RAX_LP
VZEROUPPER_RETURN
# 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))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
# endif
ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms))
MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
# ifdef __ILP32__
/* Clear the upper 32 bits. */
mov %edx, %edx
# endif
cmp $VEC_SIZE, %RDX_LP
jb L(less_vec)
cmp $(VEC_SIZE * 2), %RDX_LP
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_RETURN
L(stosb_more_2x_vec):
cmp __x86_rep_stosb_threshold(%rip), %RDX_LP
ja L(stosb)
#endif
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):
#if VEC_SIZE > 16
ZERO_UPPER_VEC_REGISTERS_RETURN
#else
ret
#endif
L(loop_start):
leaq (VEC_SIZE * 4)(%rdi), %rcx
VMOVU %VEC(0), (%rdi)
andq $-(VEC_SIZE * 4), %rcx
VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx)
VMOVU %VEC(0), VEC_SIZE(%rdi)
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
je L(return)
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
.p2align 4
L(less_vec):
/* Less than 1 VEC. */
# if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64
# error Unsupported VEC_SIZE!
# endif
# ifdef USE_LESS_VEC_MASK_STORE
/* Clear high bits from edi. Only keeping bits relevant to page
cross check. Note that we are using rax which is set in
MEMSET_VDUP_TO_VEC0_AND_SET_RETURN as ptr from here on out.
*/
andl $(PAGE_SIZE - 1), %edi
/* Check if VEC_SIZE store cross page. Mask stores suffer serious
performance degradation when it has to fault supress. */
cmpl $(PAGE_SIZE - VEC_SIZE), %edi
ja L(cross_page)
# if VEC_SIZE > 32
movq $-1, %rcx
bzhiq %rdx, %rcx, %rcx
kmovq %rcx, %k1
# else
movl $-1, %ecx
bzhil %edx, %ecx, %ecx
kmovd %ecx, %k1
# endif
vmovdqu8 %VEC(0), (%rax) {%k1}
VZEROUPPER_RETURN
.p2align 4
L(cross_page):
# 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, (%rax)
1:
VZEROUPPER_RETURN
# if VEC_SIZE > 32
/* From 32 to 63. No branch when size == 32. */
L(between_32_63):
VMOVU %YMM0, -32(%rax,%rdx)
VMOVU %YMM0, (%rax)
VZEROUPPER_RETURN
# endif
# if VEC_SIZE > 16
/* From 16 to 31. No branch when size == 16. */
L(between_16_31):
VMOVU %XMM0, -16(%rax,%rdx)
VMOVU %XMM0, (%rax)
VZEROUPPER_RETURN
# endif
/* From 8 to 15. No branch when size == 8. */
L(between_8_15):
movq %rcx, -8(%rax,%rdx)
movq %rcx, (%rax)
VZEROUPPER_RETURN
L(between_4_7):
/* From 4 to 7. No branch when size == 4. */
movl %ecx, -4(%rax,%rdx)
movl %ecx, (%rax)
VZEROUPPER_RETURN
L(between_2_3):
/* From 2 to 3. No branch when size == 2. */
movw %cx, -2(%rax,%rdx)
movw %cx, (%rax)
VZEROUPPER_RETURN
END (MEMSET_SYMBOL (__memset, unaligned_erms))
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