mirror of
https://sourceware.org/git/glibc.git
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eb9aa96fac
Both symbols are marked as legacy in POSIX.1-2001 and removed on
POSIX.1-2008, although the prototypes are defined for _GNU_SOURCE
or _DEFAULT_SOURCE.
GCC also replaces bcopy with a memmove and bzero with memset on default
configuration (to actually get a bzero libc call the code requires
to omit string.h inclusion and built with -fno-builtin), so it is
highly unlikely programs are actually calling libc bzero symbol.
On a recent Linux distro (Ubuntu 22.04), there is no bzero calls
by the installed binaries.
$ cat count_bstring.sh
#!/bin/bash
files=`IFS=':';for i in $PATH; do test -d "$i" && find "$i" -maxdepth 1 -executable -type f; done`
total=0
for file in $files; do
symbols=`objdump -R $file 2>&1`
if [ $? -eq 0 ]; then
ncalls=`echo $symbols | grep -w $1 | wc -l`
((total=total+ncalls))
if [ $ncalls -gt 0 ]; then
echo "$file: $ncalls"
fi
fi
done
echo "TOTAL=$total"
$ ./count_bstring.sh bzero
TOTAL=0
Checked on x86_64-linux-gnu.
(cherry picked from commit 9403b71ae9)
464 lines
12 KiB
ArmAsm
464 lines
12 KiB
ArmAsm
/* memset with unaligned store and rep stosb
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Copyright (C) 2016-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* memset is implemented as:
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1. Use overlapping store to avoid branch.
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2. If size is less than VEC, use integer register stores.
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3. If size is from VEC_SIZE to 2 * VEC_SIZE, use 2 VEC stores.
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4. If size is from 2 * VEC_SIZE to 4 * VEC_SIZE, use 4 VEC stores.
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5. If size is more to 4 * VEC_SIZE, align to 4 * VEC_SIZE with
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4 VEC stores and store 4 * VEC at a time until done. */
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#include <sysdep.h>
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#ifndef MEMSET_CHK_SYMBOL
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# define MEMSET_CHK_SYMBOL(p,s) MEMSET_SYMBOL(p, s)
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#endif
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#ifndef WMEMSET_CHK_SYMBOL
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# define WMEMSET_CHK_SYMBOL(p,s) WMEMSET_SYMBOL(p, s)
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#endif
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#ifndef XMM0
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# define XMM0 xmm0
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#endif
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#ifndef YMM0
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# define YMM0 ymm0
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#endif
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#ifndef VZEROUPPER
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# if VEC_SIZE > 16
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# define VZEROUPPER vzeroupper
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# define VZEROUPPER_SHORT_RETURN vzeroupper; ret
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# else
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# define VZEROUPPER
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# endif
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#endif
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#ifndef VZEROUPPER_SHORT_RETURN
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# define VZEROUPPER_SHORT_RETURN rep; ret
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#endif
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#ifndef MOVQ
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# if VEC_SIZE > 16
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# define MOVQ vmovq
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# define MOVD vmovd
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# else
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# define MOVQ movq
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# define MOVD movd
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# endif
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#endif
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#if VEC_SIZE == 64
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# define LOOP_4X_OFFSET (VEC_SIZE * 4)
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#else
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# define LOOP_4X_OFFSET (0)
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#endif
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#if defined USE_WITH_EVEX || defined USE_WITH_AVX512
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# define END_REG rcx
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# define LOOP_REG rdi
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# define LESS_VEC_REG rax
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#else
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# define END_REG rdi
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# define LOOP_REG rdx
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# define LESS_VEC_REG rdi
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#endif
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#ifdef USE_XMM_LESS_VEC
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# define XMM_SMALL 1
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#else
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# define XMM_SMALL 0
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#endif
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#ifdef USE_LESS_VEC_MASK_STORE
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# define SET_REG64 rcx
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# define SET_REG32 ecx
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# define SET_REG16 cx
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# define SET_REG8 cl
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#else
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# define SET_REG64 rsi
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# define SET_REG32 esi
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# define SET_REG16 si
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# define SET_REG8 sil
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#endif
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#define PAGE_SIZE 4096
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/* Macro to calculate size of small memset block for aligning
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purposes. */
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#define SMALL_MEMSET_ALIGN(mov_sz, ret_sz) (2 * (mov_sz) + (ret_sz) + 1)
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#ifndef SECTION
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# error SECTION is not defined!
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#endif
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.section SECTION(.text), "ax", @progbits
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#if IS_IN (libc)
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# if defined SHARED
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ENTRY_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))
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cmp %RDX_LP, %RCX_LP
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jb HIDDEN_JUMPTARGET (__chk_fail)
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END_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))
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# endif
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ENTRY (WMEMSET_SYMBOL (__wmemset, unaligned))
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shl $2, %RDX_LP
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WMEMSET_SET_VEC0_AND_SET_RETURN (%esi, %rdi)
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WMEMSET_VDUP_TO_VEC0_LOW()
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cmpq $VEC_SIZE, %rdx
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jb L(less_vec_from_wmemset)
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WMEMSET_VDUP_TO_VEC0_HIGH()
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jmp L(entry_from_wmemset)
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END (WMEMSET_SYMBOL (__wmemset, unaligned))
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#endif
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#if defined SHARED && IS_IN (libc)
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ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
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cmp %RDX_LP, %RCX_LP
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jb HIDDEN_JUMPTARGET (__chk_fail)
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END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
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#endif
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ENTRY (MEMSET_SYMBOL (__memset, unaligned))
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MEMSET_SET_VEC0_AND_SET_RETURN (%esi, %rdi)
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# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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mov %edx, %edx
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# endif
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cmpq $VEC_SIZE, %rdx
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jb L(less_vec)
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MEMSET_VDUP_TO_VEC0_HIGH()
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L(entry_from_wmemset):
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cmpq $(VEC_SIZE * 2), %rdx
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ja L(more_2x_vec)
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/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */
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VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx)
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VMOVU %VEC(0), (%rdi)
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VZEROUPPER_RETURN
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#if defined USE_MULTIARCH && IS_IN (libc)
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END (MEMSET_SYMBOL (__memset, unaligned))
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# if VEC_SIZE == 16
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ENTRY (__memset_chk_erms)
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cmp %RDX_LP, %RCX_LP
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jb HIDDEN_JUMPTARGET (__chk_fail)
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END (__memset_chk_erms)
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/* Only used to measure performance of REP STOSB. */
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ENTRY (__memset_erms)
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/* Skip zero length. */
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test %RDX_LP, %RDX_LP
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jnz L(stosb)
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movq %rdi, %rax
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ret
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# else
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/* Provide a hidden symbol to debugger. */
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.hidden MEMSET_SYMBOL (__memset, erms)
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ENTRY (MEMSET_SYMBOL (__memset, erms))
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# endif
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L(stosb):
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mov %RDX_LP, %RCX_LP
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movzbl %sil, %eax
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mov %RDI_LP, %RDX_LP
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rep stosb
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mov %RDX_LP, %RAX_LP
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VZEROUPPER_RETURN
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# if VEC_SIZE == 16
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END (__memset_erms)
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# else
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END (MEMSET_SYMBOL (__memset, erms))
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# endif
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# if defined SHARED && IS_IN (libc)
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ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
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cmp %RDX_LP, %RCX_LP
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jb HIDDEN_JUMPTARGET (__chk_fail)
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END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
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# endif
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ENTRY_P2ALIGN (MEMSET_SYMBOL (__memset, unaligned_erms), 6)
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MEMSET_SET_VEC0_AND_SET_RETURN (%esi, %rdi)
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# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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mov %edx, %edx
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# endif
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cmp $VEC_SIZE, %RDX_LP
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jb L(less_vec)
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MEMSET_VDUP_TO_VEC0_HIGH ()
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cmp $(VEC_SIZE * 2), %RDX_LP
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ja L(stosb_more_2x_vec)
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/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */
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VMOVU %VEC(0), (%rdi)
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VMOVU %VEC(0), (VEC_SIZE * -1)(%rdi, %rdx)
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VZEROUPPER_RETURN
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#endif
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.p2align 4,, 4
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L(last_2x_vec):
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#ifdef USE_LESS_VEC_MASK_STORE
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VMOVU %VEC(0), (VEC_SIZE * -2)(%rdi, %rdx)
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VMOVU %VEC(0), (VEC_SIZE * -1)(%rdi, %rdx)
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#else
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VMOVU %VEC(0), (VEC_SIZE * -2)(%rdi)
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VMOVU %VEC(0), (VEC_SIZE * -1)(%rdi)
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#endif
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VZEROUPPER_RETURN
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/* If have AVX512 mask instructions put L(less_vec) close to
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entry as it doesn't take much space and is likely a hot target.
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*/
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#ifdef USE_LESS_VEC_MASK_STORE
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.p2align 4,, 10
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L(less_vec):
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L(less_vec_from_wmemset):
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/* Less than 1 VEC. */
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# if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64
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# error Unsupported VEC_SIZE!
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# endif
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/* Clear high bits from edi. Only keeping bits relevant to page
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cross check. Note that we are using rax which is set in
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MEMSET_VDUP_TO_VEC0_AND_SET_RETURN as ptr from here on out. */
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andl $(PAGE_SIZE - 1), %edi
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/* Check if VEC_SIZE store cross page. Mask stores suffer
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serious performance degradation when it has to fault supress.
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*/
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cmpl $(PAGE_SIZE - VEC_SIZE), %edi
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/* This is generally considered a cold target. */
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ja L(cross_page)
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# if VEC_SIZE > 32
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movq $-1, %rcx
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bzhiq %rdx, %rcx, %rcx
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kmovq %rcx, %k1
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# else
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movl $-1, %ecx
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bzhil %edx, %ecx, %ecx
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kmovd %ecx, %k1
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# endif
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vmovdqu8 %VEC(0), (%rax){%k1}
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VZEROUPPER_RETURN
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# if defined USE_MULTIARCH && IS_IN (libc)
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/* Include L(stosb_local) here if including L(less_vec) between
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L(stosb_more_2x_vec) and ENTRY. This is to cache align the
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L(stosb_more_2x_vec) target. */
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.p2align 4,, 10
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L(stosb_local):
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movzbl %sil, %eax
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mov %RDX_LP, %RCX_LP
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mov %RDI_LP, %RDX_LP
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rep stosb
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mov %RDX_LP, %RAX_LP
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VZEROUPPER_RETURN
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# endif
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#endif
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#if defined USE_MULTIARCH && IS_IN (libc)
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.p2align 4
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L(stosb_more_2x_vec):
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cmp __x86_rep_stosb_threshold(%rip), %RDX_LP
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ja L(stosb_local)
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#endif
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/* Fallthrough goes to L(loop_4x_vec). Tests for memset (2x, 4x]
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and (4x, 8x] jump to target. */
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L(more_2x_vec):
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/* Store next 2x vec regardless. */
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VMOVU %VEC(0), (%rdi)
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VMOVU %VEC(0), (VEC_SIZE * 1)(%rdi)
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/* Two different methods of setting up pointers / compare. The two
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methods are based on the fact that EVEX/AVX512 mov instructions take
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more bytes then AVX2/SSE2 mov instructions. As well that EVEX/AVX512
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machines also have fast LEA_BID. Both setup and END_REG to avoid complex
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address mode. For EVEX/AVX512 this saves code size and keeps a few
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targets in one fetch block. For AVX2/SSE2 this helps prevent AGU
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bottlenecks. */
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#if !(defined USE_WITH_EVEX || defined USE_WITH_AVX512)
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/* If AVX2/SSE2 compute END_REG (rdi) with ALU. */
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addq %rdx, %END_REG
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#endif
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cmpq $(VEC_SIZE * 4), %rdx
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jbe L(last_2x_vec)
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#if defined USE_WITH_EVEX || defined USE_WITH_AVX512
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/* If EVEX/AVX512 compute END_REG - (VEC_SIZE * 4 + LOOP_4X_OFFSET) with
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LEA_BID. */
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/* END_REG is rcx for EVEX/AVX512. */
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leaq -(VEC_SIZE * 4 + LOOP_4X_OFFSET)(%rdi, %rdx), %END_REG
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#endif
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/* Store next 2x vec regardless. */
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VMOVU %VEC(0), (VEC_SIZE * 2)(%rax)
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VMOVU %VEC(0), (VEC_SIZE * 3)(%rax)
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#if defined USE_WITH_EVEX || defined USE_WITH_AVX512
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/* If LOOP_4X_OFFSET don't readjust LOOP_REG (rdi), just add
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extra offset to addresses in loop. Used for AVX512 to save space
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as no way to get (VEC_SIZE * 4) in imm8. */
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# if LOOP_4X_OFFSET == 0
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subq $-(VEC_SIZE * 4), %LOOP_REG
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# endif
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/* Avoid imm32 compare here to save code size. */
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cmpq %rdi, %rcx
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#else
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addq $-(VEC_SIZE * 4), %END_REG
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cmpq $(VEC_SIZE * 8), %rdx
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#endif
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jbe L(last_4x_vec)
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#if !(defined USE_WITH_EVEX || defined USE_WITH_AVX512)
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/* Set LOOP_REG (rdx). */
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leaq (VEC_SIZE * 4)(%rax), %LOOP_REG
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#endif
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/* Align dst for loop. */
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andq $(VEC_SIZE * -2), %LOOP_REG
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.p2align 4
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L(loop):
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VMOVA %VEC(0), LOOP_4X_OFFSET(%LOOP_REG)
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VMOVA %VEC(0), (VEC_SIZE + LOOP_4X_OFFSET)(%LOOP_REG)
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VMOVA %VEC(0), (VEC_SIZE * 2 + LOOP_4X_OFFSET)(%LOOP_REG)
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VMOVA %VEC(0), (VEC_SIZE * 3 + LOOP_4X_OFFSET)(%LOOP_REG)
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subq $-(VEC_SIZE * 4), %LOOP_REG
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cmpq %END_REG, %LOOP_REG
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jb L(loop)
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.p2align 4,, MOV_SIZE
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L(last_4x_vec):
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VMOVU %VEC(0), LOOP_4X_OFFSET(%END_REG)
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VMOVU %VEC(0), (VEC_SIZE + LOOP_4X_OFFSET)(%END_REG)
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VMOVU %VEC(0), (VEC_SIZE * 2 + LOOP_4X_OFFSET)(%END_REG)
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VMOVU %VEC(0), (VEC_SIZE * 3 + LOOP_4X_OFFSET)(%END_REG)
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L(return):
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#if VEC_SIZE > 16
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ZERO_UPPER_VEC_REGISTERS_RETURN
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#else
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ret
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#endif
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.p2align 4,, 10
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#ifndef USE_LESS_VEC_MASK_STORE
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# if defined USE_MULTIARCH && IS_IN (libc)
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/* If no USE_LESS_VEC_MASK put L(stosb_local) here. Will be in
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range for 2-byte jump encoding. */
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L(stosb_local):
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movzbl %sil, %eax
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mov %RDX_LP, %RCX_LP
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mov %RDI_LP, %RDX_LP
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rep stosb
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mov %RDX_LP, %RAX_LP
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VZEROUPPER_RETURN
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# endif
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/* Define L(less_vec) only if not otherwise defined. */
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.p2align 4
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L(less_vec):
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/* Broadcast esi to partial register (i.e VEC_SIZE == 32 broadcast to
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xmm). This is only does anything for AVX2. */
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MEMSET_VDUP_TO_VEC0_LOW ()
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L(less_vec_from_wmemset):
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#endif
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L(cross_page):
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#if VEC_SIZE > 32
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cmpl $32, %edx
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jge L(between_32_63)
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#endif
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#if VEC_SIZE > 16
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cmpl $16, %edx
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jge L(between_16_31)
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#endif
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#ifndef USE_XMM_LESS_VEC
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MOVQ %XMM0, %SET_REG64
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#endif
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cmpl $8, %edx
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jge L(between_8_15)
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cmpl $4, %edx
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jge L(between_4_7)
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cmpl $1, %edx
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jg L(between_2_3)
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jl L(between_0_0)
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movb %SET_REG8, (%LESS_VEC_REG)
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L(between_0_0):
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ret
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/* Align small targets only if not doing so would cross a fetch line.
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*/
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#if VEC_SIZE > 32
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.p2align 4,, SMALL_MEMSET_ALIGN(MOV_SIZE, RET_SIZE)
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/* From 32 to 63. No branch when size == 32. */
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L(between_32_63):
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VMOVU %YMM0, (%LESS_VEC_REG)
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VMOVU %YMM0, -32(%LESS_VEC_REG, %rdx)
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VZEROUPPER_RETURN
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#endif
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#if VEC_SIZE >= 32
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.p2align 4,, SMALL_MEMSET_ALIGN(MOV_SIZE, 1)
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L(between_16_31):
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/* From 16 to 31. No branch when size == 16. */
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VMOVU %XMM0, (%LESS_VEC_REG)
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VMOVU %XMM0, -16(%LESS_VEC_REG, %rdx)
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ret
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#endif
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/* Move size is 3 for SSE2, EVEX, and AVX512. Move size is 4 for AVX2.
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*/
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.p2align 4,, SMALL_MEMSET_ALIGN(3 + XMM_SMALL, 1)
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L(between_8_15):
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/* From 8 to 15. No branch when size == 8. */
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#ifdef USE_XMM_LESS_VEC
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MOVQ %XMM0, (%rdi)
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MOVQ %XMM0, -8(%rdi, %rdx)
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#else
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movq %SET_REG64, (%LESS_VEC_REG)
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movq %SET_REG64, -8(%LESS_VEC_REG, %rdx)
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#endif
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ret
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/* Move size is 2 for SSE2, EVEX, and AVX512. Move size is 4 for AVX2.
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*/
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.p2align 4,, SMALL_MEMSET_ALIGN(2 << XMM_SMALL, 1)
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L(between_4_7):
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/* From 4 to 7. No branch when size == 4. */
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#ifdef USE_XMM_LESS_VEC
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MOVD %XMM0, (%rdi)
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MOVD %XMM0, -4(%rdi, %rdx)
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#else
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movl %SET_REG32, (%LESS_VEC_REG)
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movl %SET_REG32, -4(%LESS_VEC_REG, %rdx)
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#endif
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ret
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/* 4 * XMM_SMALL for the third mov for AVX2. */
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.p2align 4,, 4 * XMM_SMALL + SMALL_MEMSET_ALIGN(3, 1)
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L(between_2_3):
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/* From 2 to 3. No branch when size == 2. */
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#ifdef USE_XMM_LESS_VEC
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|
movb %SET_REG8, (%rdi)
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movb %SET_REG8, 1(%rdi)
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movb %SET_REG8, -1(%rdi, %rdx)
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#else
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movw %SET_REG16, (%LESS_VEC_REG)
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movb %SET_REG8, -1(%LESS_VEC_REG, %rdx)
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#endif
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ret
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END (MEMSET_SYMBOL (__memset, unaligned_erms))
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