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glibc/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
Noah Goldstein 89a25c6f64 x86: Cleanup bounds checking in large memcpy case 
1. Fix incorrect lower-bound threshold in L(large_memcpy_2x).
   Previously was using `__x86_rep_movsb_threshold` and should
   have been using `__x86_shared_non_temporal_threshold`.

2. Avoid reloading __x86_shared_non_temporal_threshold before
   the L(large_memcpy_4x) bounds check.

3. Document the second bounds check for L(large_memcpy_4x)
   more clearly.
2022-06-15 14:25:55 -07:00

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/* memmove/memcpy/mempcpy with unaligned load/store and rep movsb
Copyright (C) 2016-2022 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/>. */
/* memmove/memcpy/mempcpy is implemented as:
1. Use overlapping load and store to avoid branch.
2. Load all sources into registers and store them together to avoid
possible address overlap between source and destination.
3. If size is 8 * VEC_SIZE or less, load all sources into registers
and store them together.
4. If address of destination > address of source, backward copy
4 * VEC_SIZE at a time with unaligned load and aligned store.
Load the first 4 * VEC and last VEC before the loop and store
them after the loop to support overlapping addresses.
5. Otherwise, forward copy 4 * VEC_SIZE at a time with unaligned
load and aligned store. Load the last 4 * VEC and first VEC
before the loop and store them after the loop to support
overlapping addresses.
6. On machines with ERMS feature, if size greater than equal or to
__x86_rep_movsb_threshold and less than
__x86_rep_movsb_stop_threshold, then REP MOVSB will be used.
7. If size >= __x86_shared_non_temporal_threshold and there is no
overlap between destination and source, use non-temporal store
instead of aligned store copying from either 2 or 4 pages at
once.
8. For point 7) if size < 16 * __x86_shared_non_temporal_threshold
and source and destination do not page alias, copy from 2 pages
at once using non-temporal stores. Page aliasing in this case is
considered true if destination's page alignment - sources' page
alignment is less than 8 * VEC_SIZE.
9. If size >= 16 * __x86_shared_non_temporal_threshold or source
and destination do page alias copy from 4 pages at once using
non-temporal stores. */
#include <sysdep.h>
#ifndef MEMCPY_SYMBOL
# define MEMCPY_SYMBOL(p,s) MEMMOVE_SYMBOL(p, s)
#endif
#ifndef MEMPCPY_SYMBOL
# define MEMPCPY_SYMBOL(p,s) MEMMOVE_SYMBOL(p, s)
#endif
#ifndef MEMMOVE_CHK_SYMBOL
# define MEMMOVE_CHK_SYMBOL(p,s) MEMMOVE_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
# else
# define VZEROUPPER
# endif
#endif
/* Whether to align before movsb. Ultimately we want 64 byte
align and not worth it to load 4x VEC for VEC_SIZE == 16. */
#define ALIGN_MOVSB (VEC_SIZE > 16)
/* Number of bytes to align movsb to. */
#define MOVSB_ALIGN_TO 64
#define SMALL_MOV_SIZE (MOV_SIZE <= 4)
#define LARGE_MOV_SIZE (MOV_SIZE > 4)
#if SMALL_MOV_SIZE + LARGE_MOV_SIZE != 1
# error MOV_SIZE Unknown
#endif
#if LARGE_MOV_SIZE
# define SMALL_SIZE_OFFSET (4)
#else
# define SMALL_SIZE_OFFSET (0)
#endif
#ifndef PAGE_SIZE
# define PAGE_SIZE 4096
#endif
#if PAGE_SIZE != 4096
# error Unsupported PAGE_SIZE
#endif
#ifndef LOG_PAGE_SIZE
# define LOG_PAGE_SIZE 12
#endif
#if PAGE_SIZE != (1 << LOG_PAGE_SIZE)
# error Invalid LOG_PAGE_SIZE
#endif
/* Byte per page for large_memcpy inner loop. */
#if VEC_SIZE == 64
# define LARGE_LOAD_SIZE (VEC_SIZE * 2)
#else
# define LARGE_LOAD_SIZE (VEC_SIZE * 4)
#endif
/* Amount to shift __x86_shared_non_temporal_threshold by for
bound for memcpy_large_4x. This is essentially use to to
indicate that the copy is far beyond the scope of L3
(assuming no user config x86_non_temporal_threshold) and to
use a more aggressively unrolled loop. NB: before
increasing the value also update initialization of
x86_non_temporal_threshold. */
#ifndef LOG_4X_MEMCPY_THRESH
# define LOG_4X_MEMCPY_THRESH 4
#endif
/* Avoid short distance rep movsb only with non-SSE vector. */
#ifndef AVOID_SHORT_DISTANCE_REP_MOVSB
# define AVOID_SHORT_DISTANCE_REP_MOVSB (VEC_SIZE > 16)
#else
# define AVOID_SHORT_DISTANCE_REP_MOVSB 0
#endif
#ifndef PREFETCH
# define PREFETCH(addr) prefetcht0 addr
#endif
/* Assume 64-byte prefetch size. */
#ifndef PREFETCH_SIZE
# define PREFETCH_SIZE 64
#endif
#define PREFETCHED_LOAD_SIZE (VEC_SIZE * 4)
#if PREFETCH_SIZE == 64
# if PREFETCHED_LOAD_SIZE == PREFETCH_SIZE
# define PREFETCH_ONE_SET(dir, base, offset) \
PREFETCH ((offset)base)
# elif PREFETCHED_LOAD_SIZE == 2 * PREFETCH_SIZE
# define PREFETCH_ONE_SET(dir, base, offset) \
PREFETCH ((offset)base); \
PREFETCH ((offset + dir * PREFETCH_SIZE)base)
# elif PREFETCHED_LOAD_SIZE == 4 * PREFETCH_SIZE
# define PREFETCH_ONE_SET(dir, base, offset) \
PREFETCH ((offset)base); \
PREFETCH ((offset + dir * PREFETCH_SIZE)base); \
PREFETCH ((offset + dir * PREFETCH_SIZE * 2)base); \
PREFETCH ((offset + dir * PREFETCH_SIZE * 3)base)
# else
# error Unsupported PREFETCHED_LOAD_SIZE!
# endif
#else
# error Unsupported PREFETCH_SIZE!
#endif
#if LARGE_LOAD_SIZE == (VEC_SIZE * 2)
# define LOAD_ONE_SET(base, offset, vec0, vec1, ...) \
VMOVU (offset)base, vec0; \
VMOVU ((offset) + VEC_SIZE)base, vec1;
# define STORE_ONE_SET(base, offset, vec0, vec1, ...) \
VMOVNT vec0, (offset)base; \
VMOVNT vec1, ((offset) + VEC_SIZE)base;
#elif LARGE_LOAD_SIZE == (VEC_SIZE * 4)
# define LOAD_ONE_SET(base, offset, vec0, vec1, vec2, vec3) \
VMOVU (offset)base, vec0; \
VMOVU ((offset) + VEC_SIZE)base, vec1; \
VMOVU ((offset) + VEC_SIZE * 2)base, vec2; \
VMOVU ((offset) + VEC_SIZE * 3)base, vec3;
# define STORE_ONE_SET(base, offset, vec0, vec1, vec2, vec3) \
VMOVNT vec0, (offset)base; \
VMOVNT vec1, ((offset) + VEC_SIZE)base; \
VMOVNT vec2, ((offset) + VEC_SIZE * 2)base; \
VMOVNT vec3, ((offset) + VEC_SIZE * 3)base;
#else
# error Invalid LARGE_LOAD_SIZE
#endif
#ifndef SECTION
# error SECTION is not defined!
#endif
.section SECTION(.text),"ax",@progbits
#if defined SHARED && IS_IN (libc)
ENTRY (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned))
#endif
ENTRY (MEMPCPY_SYMBOL (__mempcpy, unaligned))
mov %RDI_LP, %RAX_LP
add %RDX_LP, %RAX_LP
jmp L(start)
END (MEMPCPY_SYMBOL (__mempcpy, unaligned))
#if defined SHARED && IS_IN (libc)
ENTRY (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned))
#endif
ENTRY (MEMMOVE_SYMBOL (__memmove, unaligned))
movq %rdi, %rax
L(start):
# ifdef __ILP32__
/* Clear the upper 32 bits. */
movl %edx, %edx
# endif
cmp $VEC_SIZE, %RDX_LP
jb L(less_vec)
/* Load regardless. */
VMOVU (%rsi), %VEC(0)
cmp $(VEC_SIZE * 2), %RDX_LP
ja L(more_2x_vec)
/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */
VMOVU -VEC_SIZE(%rsi,%rdx), %VEC(1)
VMOVU %VEC(0), (%rdi)
VMOVU %VEC(1), -VEC_SIZE(%rdi,%rdx)
#if !(defined USE_MULTIARCH && IS_IN (libc))
ZERO_UPPER_VEC_REGISTERS_RETURN
#else
VZEROUPPER_RETURN
#endif
#if defined USE_MULTIARCH && IS_IN (libc)
END (MEMMOVE_SYMBOL (__memmove, unaligned))
# if VEC_SIZE == 16
ENTRY (__mempcpy_chk_erms)
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (__mempcpy_chk_erms)
/* Only used to measure performance of REP MOVSB. */
ENTRY (__mempcpy_erms)
mov %RDI_LP, %RAX_LP
/* Skip zero length. */
test %RDX_LP, %RDX_LP
jz 2f
add %RDX_LP, %RAX_LP
jmp L(start_movsb)
END (__mempcpy_erms)
ENTRY (__memmove_chk_erms)
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (__memmove_chk_erms)
ENTRY (__memmove_erms)
movq %rdi, %rax
/* Skip zero length. */
test %RDX_LP, %RDX_LP
jz 2f
L(start_movsb):
mov %RDX_LP, %RCX_LP
cmp %RSI_LP, %RDI_LP
jb 1f
/* Source == destination is less common. */
je 2f
lea (%rsi,%rcx), %RDX_LP
cmp %RDX_LP, %RDI_LP
jb L(movsb_backward)
1:
rep movsb
2:
ret
L(movsb_backward):
leaq -1(%rdi,%rcx), %rdi
leaq -1(%rsi,%rcx), %rsi
std
rep movsb
cld
ret
END (__memmove_erms)
strong_alias (__memmove_erms, __memcpy_erms)
strong_alias (__memmove_chk_erms, __memcpy_chk_erms)
# endif
# ifdef SHARED
ENTRY (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned_erms))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned_erms))
# endif
ENTRY (MEMMOVE_SYMBOL (__mempcpy, unaligned_erms))
mov %RDI_LP, %RAX_LP
add %RDX_LP, %RAX_LP
jmp L(start_erms)
END (MEMMOVE_SYMBOL (__mempcpy, unaligned_erms))
# ifdef SHARED
ENTRY (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned_erms))
cmp %RDX_LP, %RCX_LP
jb HIDDEN_JUMPTARGET (__chk_fail)
END (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned_erms))
# endif
ENTRY_P2ALIGN (MEMMOVE_SYMBOL (__memmove, unaligned_erms), 6)
movq %rdi, %rax
L(start_erms):
# ifdef __ILP32__
/* Clear the upper 32 bits. */
movl %edx, %edx
# endif
cmp $VEC_SIZE, %RDX_LP
jb L(less_vec)
/* Load regardless. */
VMOVU (%rsi), %VEC(0)
cmp $(VEC_SIZE * 2), %RDX_LP
ja L(movsb_more_2x_vec)
/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE.
*/
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(1)
VMOVU %VEC(0), (%rdi)
VMOVU %VEC(1), -VEC_SIZE(%rdi, %rdx)
L(return):
# if VEC_SIZE > 16
ZERO_UPPER_VEC_REGISTERS_RETURN
# else
ret
# endif
#endif
#if LARGE_MOV_SIZE
/* If LARGE_MOV_SIZE this fits in the aligning bytes between the
ENTRY block and L(less_vec). */
.p2align 4,, 8
L(between_4_7):
/* From 4 to 7. No branch when size == 4. */
movl (%rsi), %ecx
movl (%rsi, %rdx), %esi
movl %ecx, (%rdi)
movl %esi, (%rdi, %rdx)
ret
#endif
.p2align 4
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
cmpl $32, %edx
jae L(between_32_63)
#endif
#if VEC_SIZE > 16
cmpl $16, %edx
jae L(between_16_31)
#endif
cmpl $8, %edx
jae L(between_8_15)
#if SMALL_MOV_SIZE
cmpl $4, %edx
#else
subq $4, %rdx
#endif
jae L(between_4_7)
cmpl $(1 - SMALL_SIZE_OFFSET), %edx
jl L(copy_0)
movb (%rsi), %cl
je L(copy_1)
movzwl (-2 + SMALL_SIZE_OFFSET)(%rsi, %rdx), %esi
movw %si, (-2 + SMALL_SIZE_OFFSET)(%rdi, %rdx)
L(copy_1):
movb %cl, (%rdi)
L(copy_0):
ret
#if SMALL_MOV_SIZE
.p2align 4,, 8
L(between_4_7):
/* From 4 to 7. No branch when size == 4. */
movl -4(%rsi, %rdx), %ecx
movl (%rsi), %esi
movl %ecx, -4(%rdi, %rdx)
movl %esi, (%rdi)
ret
#endif
#if VEC_SIZE > 16
/* From 16 to 31. No branch when size == 16. */
.p2align 4,, 8
L(between_16_31):
vmovdqu (%rsi), %xmm0
vmovdqu -16(%rsi, %rdx), %xmm1
vmovdqu %xmm0, (%rdi)
vmovdqu %xmm1, -16(%rdi, %rdx)
/* No ymm registers have been touched. */
ret
#endif
#if VEC_SIZE > 32
.p2align 4,, 10
L(between_32_63):
/* From 32 to 63. No branch when size == 32. */
VMOVU (%rsi), %YMM0
VMOVU -32(%rsi, %rdx), %YMM1
VMOVU %YMM0, (%rdi)
VMOVU %YMM1, -32(%rdi, %rdx)
VZEROUPPER_RETURN
#endif
.p2align 4,, 10
L(between_8_15):
/* From 8 to 15. No branch when size == 8. */
movq -8(%rsi, %rdx), %rcx
movq (%rsi), %rsi
movq %rsi, (%rdi)
movq %rcx, -8(%rdi, %rdx)
ret
.p2align 4,, 10
L(last_4x_vec):
/* Copy from 2 * VEC + 1 to 4 * VEC, inclusively. */
/* VEC(0) and VEC(1) have already been loaded. */
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(2)
VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(3)
VMOVU %VEC(0), (%rdi)
VMOVU %VEC(1), VEC_SIZE(%rdi)
VMOVU %VEC(2), -VEC_SIZE(%rdi, %rdx)
VMOVU %VEC(3), -(VEC_SIZE * 2)(%rdi, %rdx)
VZEROUPPER_RETURN
.p2align 4
#if defined USE_MULTIARCH && IS_IN (libc)
L(movsb_more_2x_vec):
cmp __x86_rep_movsb_threshold(%rip), %RDX_LP
ja L(movsb)
#endif
L(more_2x_vec):
/* More than 2 * VEC and there may be overlap between
destination and source. */
cmpq $(VEC_SIZE * 8), %rdx
ja L(more_8x_vec)
/* Load VEC(1) regardless. VEC(0) has already been loaded. */
VMOVU VEC_SIZE(%rsi), %VEC(1)
cmpq $(VEC_SIZE * 4), %rdx
jbe L(last_4x_vec)
/* Copy from 4 * VEC + 1 to 8 * VEC, inclusively. */
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2)
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3)
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(4)
VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(5)
VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(6)
VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(7)
VMOVU %VEC(0), (%rdi)
VMOVU %VEC(1), VEC_SIZE(%rdi)
VMOVU %VEC(2), (VEC_SIZE * 2)(%rdi)
VMOVU %VEC(3), (VEC_SIZE * 3)(%rdi)
VMOVU %VEC(4), -VEC_SIZE(%rdi, %rdx)
VMOVU %VEC(5), -(VEC_SIZE * 2)(%rdi, %rdx)
VMOVU %VEC(6), -(VEC_SIZE * 3)(%rdi, %rdx)
VMOVU %VEC(7), -(VEC_SIZE * 4)(%rdi, %rdx)
VZEROUPPER_RETURN
.p2align 4,, 4
L(more_8x_vec):
movq %rdi, %rcx
subq %rsi, %rcx
/* Go to backwards temporal copy if overlap no matter what as
backward REP MOVSB is slow and we don't want to use NT stores if
there is overlap. */
cmpq %rdx, %rcx
/* L(more_8x_vec_backward_check_nop) checks for src == dst. */
jb L(more_8x_vec_backward_check_nop)
/* Check if non-temporal move candidate. */
#if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc)
/* Check non-temporal store threshold. */
cmp __x86_shared_non_temporal_threshold(%rip), %RDX_LP
ja L(large_memcpy_2x)
#endif
/* To reach this point there cannot be overlap and dst > src. So
check for overlap and src > dst in which case correctness
requires forward copy. Otherwise decide between backward/forward
copy depending on address aliasing. */
/* Entry if rdx is greater than __x86_rep_movsb_stop_threshold
but less than __x86_shared_non_temporal_threshold. */
L(more_8x_vec_check):
/* rcx contains dst - src. Add back length (rdx). */
leaq (%rcx, %rdx), %r8
/* If r8 has different sign than rcx then there is overlap so we
must do forward copy. */
xorq %rcx, %r8
/* Isolate just sign bit of r8. */
shrq $63, %r8
/* Get 4k difference dst - src. */
andl $(PAGE_SIZE - 256), %ecx
/* If r8 is non-zero must do foward for correctness. Otherwise
if ecx is non-zero there is 4k False Alaising so do backward
copy. */
addl %r8d, %ecx
jz L(more_8x_vec_backward)
/* if rdx is greater than __x86_shared_non_temporal_threshold
but there is overlap, or from short distance movsb. */
L(more_8x_vec_forward):
/* Load first and last 4 * VEC to support overlapping addresses.
*/
/* First vec was already loaded into VEC(0). */
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(5)
VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(6)
/* Save begining of dst. */
movq %rdi, %rcx
/* Align dst to VEC_SIZE - 1. */
orq $(VEC_SIZE - 1), %rdi
VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(7)
VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(8)
/* Subtract dst from src. Add back after dst aligned. */
subq %rcx, %rsi
/* Finish aligning dst. */
incq %rdi
/* Restore src adjusted with new value for aligned dst. */
addq %rdi, %rsi
/* Store end of buffer minus tail in rdx. */
leaq (VEC_SIZE * -4)(%rcx, %rdx), %rdx
/* Dont use multi-byte nop to align. */
.p2align 4,, 11
L(loop_4x_vec_forward):
/* Copy 4 * VEC a time forward. */
VMOVU (%rsi), %VEC(1)
VMOVU VEC_SIZE(%rsi), %VEC(2)
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(3)
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(4)
subq $-(VEC_SIZE * 4), %rsi
VMOVA %VEC(1), (%rdi)
VMOVA %VEC(2), VEC_SIZE(%rdi)
VMOVA %VEC(3), (VEC_SIZE * 2)(%rdi)
VMOVA %VEC(4), (VEC_SIZE * 3)(%rdi)
subq $-(VEC_SIZE * 4), %rdi
cmpq %rdi, %rdx
ja L(loop_4x_vec_forward)
/* Store the last 4 * VEC. */
VMOVU %VEC(5), (VEC_SIZE * 3)(%rdx)
VMOVU %VEC(6), (VEC_SIZE * 2)(%rdx)
VMOVU %VEC(7), VEC_SIZE(%rdx)
VMOVU %VEC(8), (%rdx)
/* Store the first VEC. */
VMOVU %VEC(0), (%rcx)
/* Keep L(nop_backward) target close to jmp for 2-byte encoding.
*/
L(nop_backward):
VZEROUPPER_RETURN
.p2align 4,, 8
L(more_8x_vec_backward_check_nop):
/* rcx contains dst - src. Test for dst == src to skip all of
memmove. */
testq %rcx, %rcx
jz L(nop_backward)
L(more_8x_vec_backward):
/* Load the first 4 * VEC and last VEC to support overlapping
addresses. */
/* First vec was also loaded into VEC(0). */
VMOVU VEC_SIZE(%rsi), %VEC(5)
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(6)
/* Begining of region for 4x backward copy stored in rcx. */
leaq (VEC_SIZE * -4 + -1)(%rdi, %rdx), %rcx
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(7)
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(8)
/* Subtract dst from src. Add back after dst aligned. */
subq %rdi, %rsi
/* Align dst. */
andq $-(VEC_SIZE), %rcx
/* Restore src. */
addq %rcx, %rsi
/* Don't use multi-byte nop to align. */
.p2align 4,, 11
L(loop_4x_vec_backward):
/* Copy 4 * VEC a time backward. */
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(1)
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2)
VMOVU (VEC_SIZE * 1)(%rsi), %VEC(3)
VMOVU (VEC_SIZE * 0)(%rsi), %VEC(4)
addq $(VEC_SIZE * -4), %rsi
VMOVA %VEC(1), (VEC_SIZE * 3)(%rcx)
VMOVA %VEC(2), (VEC_SIZE * 2)(%rcx)
VMOVA %VEC(3), (VEC_SIZE * 1)(%rcx)
VMOVA %VEC(4), (VEC_SIZE * 0)(%rcx)
addq $(VEC_SIZE * -4), %rcx
cmpq %rcx, %rdi
jb L(loop_4x_vec_backward)
/* Store the first 4 * VEC. */
VMOVU %VEC(0), (%rdi)
VMOVU %VEC(5), VEC_SIZE(%rdi)
VMOVU %VEC(6), (VEC_SIZE * 2)(%rdi)
VMOVU %VEC(7), (VEC_SIZE * 3)(%rdi)
/* Store the last VEC. */
VMOVU %VEC(8), -VEC_SIZE(%rdx, %rdi)
VZEROUPPER_RETURN
#if defined USE_MULTIARCH && IS_IN (libc)
/* L(skip_short_movsb_check) is only used with ERMS. Not for
FSRM. */
.p2align 5,, 16
# if ALIGN_MOVSB
L(skip_short_movsb_check):
# if MOVSB_ALIGN_TO > VEC_SIZE
VMOVU VEC_SIZE(%rsi), %VEC(1)
# endif
# if MOVSB_ALIGN_TO > (VEC_SIZE * 2)
# error Unsupported MOVSB_ALIGN_TO
# endif
/* If CPU does not have FSRM two options for aligning. Align src
if dst and src 4k alias. Otherwise align dst. */
testl $(PAGE_SIZE - 512), %ecx
jnz L(movsb_align_dst)
/* Fall through. dst and src 4k alias. It's better to align src
here because the bottleneck will be loads dues to the false
dependency on dst. */
/* rcx already has dst - src. */
movq %rcx, %r9
/* Add src to len. Subtract back after src aligned. -1 because
src is initially aligned to MOVSB_ALIGN_TO - 1. */
leaq -1(%rsi, %rdx), %rcx
/* Inclusively align src to MOVSB_ALIGN_TO - 1. */
orq $(MOVSB_ALIGN_TO - 1), %rsi
/* Restore dst and len adjusted with new values for aligned dst.
*/
leaq 1(%rsi, %r9), %rdi
subq %rsi, %rcx
/* Finish aligning src. */
incq %rsi
rep movsb
VMOVU %VEC(0), (%r8)
# if MOVSB_ALIGN_TO > VEC_SIZE
VMOVU %VEC(1), VEC_SIZE(%r8)
# endif
VZEROUPPER_RETURN
# endif
.p2align 4,, 12
L(movsb):
movq %rdi, %rcx
subq %rsi, %rcx
/* Go to backwards temporal copy if overlap no matter what as
backward REP MOVSB is slow and we don't want to use NT stores if
there is overlap. */
cmpq %rdx, %rcx
/* L(more_8x_vec_backward_check_nop) checks for src == dst. */
jb L(more_8x_vec_backward_check_nop)
# if ALIGN_MOVSB
/* Save dest for storing aligning VECs later. */
movq %rdi, %r8
# endif
/* If above __x86_rep_movsb_stop_threshold most likely is
candidate for NT moves aswell. */
cmp __x86_rep_movsb_stop_threshold(%rip), %RDX_LP
jae L(large_memcpy_2x_check)
# if AVOID_SHORT_DISTANCE_REP_MOVSB || ALIGN_MOVSB
/* Only avoid short movsb if CPU has FSRM. */
testl $X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB, __x86_string_control(%rip)
jz L(skip_short_movsb_check)
# if AVOID_SHORT_DISTANCE_REP_MOVSB
/* Avoid "rep movsb" if RCX, the distance between source and
destination, is N*4GB + [1..63] with N >= 0. */
/* ecx contains dst - src. Early check for backward copy
conditions means only case of slow movsb with src = dst + [0,
63] is ecx in [-63, 0]. Use unsigned comparison with -64 check
for that case. */
cmpl $-64, %ecx
ja L(more_8x_vec_forward)
# endif
# endif
# if ALIGN_MOVSB
# if MOVSB_ALIGN_TO > VEC_SIZE
VMOVU VEC_SIZE(%rsi), %VEC(1)
# endif
# if MOVSB_ALIGN_TO > (VEC_SIZE * 2)
# error Unsupported MOVSB_ALIGN_TO
# endif
/* Fall through means cpu has FSRM. In that case exclusively
align destination. */
L(movsb_align_dst):
/* Subtract dst from src. Add back after dst aligned. */
subq %rdi, %rsi
/* Exclusively align dst to MOVSB_ALIGN_TO (64). */
addq $(MOVSB_ALIGN_TO - 1), %rdi
/* Add dst to len. Subtract back after dst aligned. */
leaq (%r8, %rdx), %rcx
/* Finish aligning dst. */
andq $-(MOVSB_ALIGN_TO), %rdi
/* Restore src and len adjusted with new values for aligned dst.
*/
addq %rdi, %rsi
subq %rdi, %rcx
rep movsb
/* Store VECs loaded for aligning. */
VMOVU %VEC(0), (%r8)
# if MOVSB_ALIGN_TO > VEC_SIZE
VMOVU %VEC(1), VEC_SIZE(%r8)
# endif
VZEROUPPER_RETURN
# else /* !ALIGN_MOVSB. */
L(skip_short_movsb_check):
mov %RDX_LP, %RCX_LP
rep movsb
ret
# endif
#endif
.p2align 4,, 10
#if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc)
L(large_memcpy_2x_check):
/* Entry from L(large_memcpy_2x) has a redundant load of
__x86_shared_non_temporal_threshold(%rip). L(large_memcpy_2x)
is only use for the non-erms memmove which is generally less
common. */
L(large_memcpy_2x):
mov __x86_shared_non_temporal_threshold(%rip), %R11_LP
cmp %R11_LP, %RDX_LP
jb L(more_8x_vec_check)
/* To reach this point it is impossible for dst > src and
overlap. Remaining to check is src > dst and overlap. rcx
already contains dst - src. Negate rcx to get src - dst. If
length > rcx then there is overlap and forward copy is best. */
negq %rcx
cmpq %rcx, %rdx
ja L(more_8x_vec_forward)
/* Cache align destination. First store the first 64 bytes then
adjust alignments. */
/* First vec was also loaded into VEC(0). */
# if VEC_SIZE < 64
VMOVU VEC_SIZE(%rsi), %VEC(1)
# if VEC_SIZE < 32
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2)
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3)
# endif
# endif
VMOVU %VEC(0), (%rdi)
# if VEC_SIZE < 64
VMOVU %VEC(1), VEC_SIZE(%rdi)
# if VEC_SIZE < 32
VMOVU %VEC(2), (VEC_SIZE * 2)(%rdi)
VMOVU %VEC(3), (VEC_SIZE * 3)(%rdi)
# endif
# endif
/* Adjust source, destination, and size. */
movq %rdi, %r8
andq $63, %r8
/* Get the negative of offset for alignment. */
subq $64, %r8
/* Adjust source. */
subq %r8, %rsi
/* Adjust destination which should be aligned now. */
subq %r8, %rdi
/* Adjust length. */
addq %r8, %rdx
/* Test if source and destination addresses will alias. If they
do the larger pipeline in large_memcpy_4x alleviated the
performance drop. */
/* ecx contains -(dst - src). not ecx will return dst - src - 1
which works for testing aliasing. */
notl %ecx
movq %rdx, %r10
testl $(PAGE_SIZE - VEC_SIZE * 8), %ecx
jz L(large_memcpy_4x)
/* r11 has __x86_shared_non_temporal_threshold. Shift it left
by LOG_4X_MEMCPY_THRESH to get L(large_memcpy_4x) threshold.
*/
shlq $LOG_4X_MEMCPY_THRESH, %r11
cmp %r11, %rdx
jae L(large_memcpy_4x)
/* edx will store remainder size for copying tail. */
andl $(PAGE_SIZE * 2 - 1), %edx
/* r10 stores outer loop counter. */
shrq $(LOG_PAGE_SIZE + 1), %r10
/* Copy 4x VEC at a time from 2 pages. */
.p2align 4
L(loop_large_memcpy_2x_outer):
/* ecx stores inner loop counter. */
movl $(PAGE_SIZE / LARGE_LOAD_SIZE), %ecx
L(loop_large_memcpy_2x_inner):
PREFETCH_ONE_SET(1, (%rsi), PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET(1, (%rsi), PREFETCHED_LOAD_SIZE * 2)
PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE + PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE + PREFETCHED_LOAD_SIZE * 2)
/* Load vectors from rsi. */
LOAD_ONE_SET((%rsi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
LOAD_ONE_SET((%rsi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
subq $-LARGE_LOAD_SIZE, %rsi
/* Non-temporal store vectors to rdi. */
STORE_ONE_SET((%rdi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
STORE_ONE_SET((%rdi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
subq $-LARGE_LOAD_SIZE, %rdi
decl %ecx
jnz L(loop_large_memcpy_2x_inner)
addq $PAGE_SIZE, %rdi
addq $PAGE_SIZE, %rsi
decq %r10
jne L(loop_large_memcpy_2x_outer)
sfence
/* Check if only last 4 loads are needed. */
cmpl $(VEC_SIZE * 4), %edx
jbe L(large_memcpy_2x_end)
/* Handle the last 2 * PAGE_SIZE bytes. */
L(loop_large_memcpy_2x_tail):
/* Copy 4 * VEC a time forward with non-temporal stores. */
PREFETCH_ONE_SET (1, (%rsi), PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET (1, (%rdi), PREFETCHED_LOAD_SIZE)
VMOVU (%rsi), %VEC(0)
VMOVU VEC_SIZE(%rsi), %VEC(1)
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2)
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3)
subq $-(VEC_SIZE * 4), %rsi
addl $-(VEC_SIZE * 4), %edx
VMOVA %VEC(0), (%rdi)
VMOVA %VEC(1), VEC_SIZE(%rdi)
VMOVA %VEC(2), (VEC_SIZE * 2)(%rdi)
VMOVA %VEC(3), (VEC_SIZE * 3)(%rdi)
subq $-(VEC_SIZE * 4), %rdi
cmpl $(VEC_SIZE * 4), %edx
ja L(loop_large_memcpy_2x_tail)
L(large_memcpy_2x_end):
/* Store the last 4 * VEC. */
VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(0)
VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(1)
VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(2)
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(3)
VMOVU %VEC(0), -(VEC_SIZE * 4)(%rdi, %rdx)
VMOVU %VEC(1), -(VEC_SIZE * 3)(%rdi, %rdx)
VMOVU %VEC(2), -(VEC_SIZE * 2)(%rdi, %rdx)
VMOVU %VEC(3), -VEC_SIZE(%rdi, %rdx)
VZEROUPPER_RETURN
.p2align 4
L(large_memcpy_4x):
/* edx will store remainder size for copying tail. */
andl $(PAGE_SIZE * 4 - 1), %edx
/* r10 stores outer loop counter. */
shrq $(LOG_PAGE_SIZE + 2), %r10
/* Copy 4x VEC at a time from 4 pages. */
.p2align 4
L(loop_large_memcpy_4x_outer):
/* ecx stores inner loop counter. */
movl $(PAGE_SIZE / LARGE_LOAD_SIZE), %ecx
L(loop_large_memcpy_4x_inner):
/* Only one prefetch set per page as doing 4 pages give more
time for prefetcher to keep up. */
PREFETCH_ONE_SET(1, (%rsi), PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE + PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE * 2 + PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE * 3 + PREFETCHED_LOAD_SIZE)
/* Load vectors from rsi. */
LOAD_ONE_SET((%rsi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
LOAD_ONE_SET((%rsi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
LOAD_ONE_SET((%rsi), PAGE_SIZE * 2, %VEC(8), %VEC(9), %VEC(10), %VEC(11))
LOAD_ONE_SET((%rsi), PAGE_SIZE * 3, %VEC(12), %VEC(13), %VEC(14), %VEC(15))
subq $-LARGE_LOAD_SIZE, %rsi
/* Non-temporal store vectors to rdi. */
STORE_ONE_SET((%rdi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
STORE_ONE_SET((%rdi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
STORE_ONE_SET((%rdi), PAGE_SIZE * 2, %VEC(8), %VEC(9), %VEC(10), %VEC(11))
STORE_ONE_SET((%rdi), PAGE_SIZE * 3, %VEC(12), %VEC(13), %VEC(14), %VEC(15))
subq $-LARGE_LOAD_SIZE, %rdi
decl %ecx
jnz L(loop_large_memcpy_4x_inner)
addq $(PAGE_SIZE * 3), %rdi
addq $(PAGE_SIZE * 3), %rsi
decq %r10
jne L(loop_large_memcpy_4x_outer)
sfence
/* Check if only last 4 loads are needed. */
cmpl $(VEC_SIZE * 4), %edx
jbe L(large_memcpy_4x_end)
/* Handle the last 4 * PAGE_SIZE bytes. */
L(loop_large_memcpy_4x_tail):
/* Copy 4 * VEC a time forward with non-temporal stores. */
PREFETCH_ONE_SET (1, (%rsi), PREFETCHED_LOAD_SIZE)
PREFETCH_ONE_SET (1, (%rdi), PREFETCHED_LOAD_SIZE)
VMOVU (%rsi), %VEC(0)
VMOVU VEC_SIZE(%rsi), %VEC(1)
VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2)
VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3)
subq $-(VEC_SIZE * 4), %rsi
addl $-(VEC_SIZE * 4), %edx
VMOVA %VEC(0), (%rdi)
VMOVA %VEC(1), VEC_SIZE(%rdi)
VMOVA %VEC(2), (VEC_SIZE * 2)(%rdi)
VMOVA %VEC(3), (VEC_SIZE * 3)(%rdi)
subq $-(VEC_SIZE * 4), %rdi
cmpl $(VEC_SIZE * 4), %edx
ja L(loop_large_memcpy_4x_tail)
L(large_memcpy_4x_end):
/* Store the last 4 * VEC. */
VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(0)
VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(1)
VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(2)
VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(3)
VMOVU %VEC(0), -(VEC_SIZE * 4)(%rdi, %rdx)
VMOVU %VEC(1), -(VEC_SIZE * 3)(%rdi, %rdx)
VMOVU %VEC(2), -(VEC_SIZE * 2)(%rdi, %rdx)
VMOVU %VEC(3), -VEC_SIZE(%rdi, %rdx)
VZEROUPPER_RETURN
#endif
END (MEMMOVE_SYMBOL (__memmove, unaligned_erms))
#if IS_IN (libc)
# ifdef USE_MULTIARCH
strong_alias (MEMMOVE_SYMBOL (__memmove, unaligned_erms),
MEMMOVE_SYMBOL (__memcpy, unaligned_erms))
# ifdef SHARED
strong_alias (MEMMOVE_SYMBOL (__memmove_chk, unaligned_erms),
MEMMOVE_SYMBOL (__memcpy_chk, unaligned_erms))
# endif
# endif
# ifdef SHARED
strong_alias (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned),
MEMMOVE_CHK_SYMBOL (__memcpy_chk, unaligned))
# endif
#endif
strong_alias (MEMMOVE_SYMBOL (__memmove, unaligned),
MEMCPY_SYMBOL (__memcpy, unaligned))
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