/* NEON/VFP/ARM version of memcpy optimized for Cortex-A15.
Copyright (C) 2013-2018 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/>.
This memcpy routine is optimised for Cortex-A15 cores and takes advantage
of VFP or NEON when built with the appropriate flags.
Assumptions:
ARMv6 (ARMv7-a if using Neon)
ARM state
Unaligned accesses
*/
/* Thumb cannot encode negative immediate offsets in memory operations. */
#ifndef NO_THUMB
#define NO_THUMB
#endif
#include <sysdep.h>
#include <arm-features.h>
.syntax unified
/* This implementation requires ARM state. */
.arm
#ifdef MEMCPY_NEON
.fpu neon
.arch armv7-a
# define FRAME_SIZE 4
# define USE_VFP
# define USE_NEON
#elif defined (MEMCPY_VFP)
.arch armv6
.fpu vfpv2
# define FRAME_SIZE 32
# define USE_VFP
#else
.arch armv6
# define FRAME_SIZE 32
#endif
#define ALIGN(addr, align) addr:align
#define INSN_SIZE 4
/* Call parameters. */
#define dstin r0
#define src r1
#define count r2
/* Locals. */
#define tmp1 r3
#define dst ip
#define tmp2 r8
/* These two macros both work by repeated invocation of the macro
dispatch_step (not defined here). That macro performs one "step",
doing one load instruction and one store instruction to copy one
"unit". On entry, TMP1 contains the number of bytes to be copied,
a multiple of the unit size. The macro clobbers TMP1 in the
process of doing a computed jump to the tail containing the
appropriate number of steps.
In dispatch_7_dword, dispatch_step is invoked seven times, with an
argument that is 7 for the first and 1 for the last. Units are
double-words (8 bytes). TMP1 is at most 56.
In dispatch_15_word, dispatch_step is invoked fifteen times,
with an argument that is 15 for the first and 1 for the last.
Units are words (4 bytes). TMP1 is at most 60. */
#ifndef ARM_ALWAYS_BX
# if ARM_BX_ALIGN_LOG2 != 2
# error case not handled
# endif
.macro dispatch_7_dword
rsb tmp1, tmp1, #((7 * 8) - PC_OFS + INSN_SIZE)
add pc, pc, tmp1
dispatch_step 7
dispatch_step 6
dispatch_step 5
dispatch_step 4
dispatch_step 3
dispatch_step 2
dispatch_step 1
.purgem dispatch_step
.endm
.macro dispatch_15_word
rsb tmp1, tmp1, #((15 * 4) - PC_OFS/2 + INSN_SIZE/2)
add pc, pc, tmp1, lsl #1
dispatch_step 15
dispatch_step 14
dispatch_step 13
dispatch_step 12
dispatch_step 11
dispatch_step 10
dispatch_step 9
dispatch_step 8
dispatch_step 7
dispatch_step 6
dispatch_step 5
dispatch_step 4
dispatch_step 3
dispatch_step 2
dispatch_step 1
.purgem dispatch_step
.endm
#else
# if ARM_BX_ALIGN_LOG2 < 3
# error case not handled
# endif
.macro dispatch_helper steps, log2_bytes_per_step
/* TMP1 gets (max_bytes - bytes_to_copy), where max_bytes is
(STEPS << LOG2_BYTES_PER_STEP).
So this is (steps_to_skip << LOG2_BYTES_PER_STEP).
Then it needs further adjustment to compensate for the
distance between the PC value taken below (0f + PC_OFS)
and the first step's instructions (1f). */
rsb tmp1, tmp1, #((\steps << \log2_bytes_per_step) \
+ ((1f - PC_OFS - 0f) \
>> (ARM_BX_ALIGN_LOG2 - \log2_bytes_per_step)))
/* Shifting down LOG2_BYTES_PER_STEP gives us the number of
steps to skip, then shifting up ARM_BX_ALIGN_LOG2 gives us
the (byte) distance to add to the PC. */
0: add tmp1, pc, tmp1, lsl #(ARM_BX_ALIGN_LOG2 - \log2_bytes_per_step)
bx tmp1
.p2align ARM_BX_ALIGN_LOG2
1:
.endm
.macro dispatch_7_dword
dispatch_helper 7, 3
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 7
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 6
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 5
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 4
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 3
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 2
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 1
.p2align ARM_BX_ALIGN_LOG2
.purgem dispatch_step
.endm
.macro dispatch_15_word
dispatch_helper 15, 2
dispatch_step 15
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 14
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 13
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 12
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 11
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 10
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 9
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 8
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 7
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 6
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 5
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 4
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 3
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 2
.p2align ARM_BX_ALIGN_LOG2
dispatch_step 1
.p2align ARM_BX_ALIGN_LOG2
.purgem dispatch_step
.endm
#endif
#ifndef USE_NEON
/* For bulk copies using GP registers. */
#define A_l r2 /* Call-clobbered. */
#define A_h r3 /* Call-clobbered. */
#define B_l r4
#define B_h r5
#define C_l r6
#define C_h r7
/* Don't use the pair r8,r9 because in some EABI variants r9 is reserved. */
#define D_l r10
#define D_h r11
#endif
/* Number of lines ahead to pre-fetch data. If you change this the code
below will need adjustment to compensate. */
#define prefetch_lines 5
#ifdef USE_VFP
.macro cpy_line_vfp vreg, base
vstr \vreg, [dst, #\base]
vldr \vreg, [src, #\base]
vstr d0, [dst, #\base + 8]
vldr d0, [src, #\base + 8]
vstr d1, [dst, #\base + 16]
vldr d1, [src, #\base + 16]
vstr d2, [dst, #\base + 24]
vldr d2, [src, #\base + 24]
vstr \vreg, [dst, #\base + 32]
vldr \vreg, [src, #\base + prefetch_lines * 64 - 32]
vstr d0, [dst, #\base + 40]
vldr d0, [src, #\base + 40]
vstr d1, [dst, #\base + 48]
vldr d1, [src, #\base + 48]
vstr d2, [dst, #\base + 56]
vldr d2, [src, #\base + 56]
.endm
.macro cpy_tail_vfp vreg, base
vstr \vreg, [dst, #\base]
vldr \vreg, [src, #\base]
vstr d0, [dst, #\base + 8]
vldr d0, [src, #\base + 8]
vstr d1, [dst, #\base + 16]
vldr d1, [src, #\base + 16]
vstr d2, [dst, #\base + 24]
vldr d2, [src, #\base + 24]
vstr \vreg, [dst, #\base + 32]
vstr d0, [dst, #\base + 40]
vldr d0, [src, #\base + 40]
vstr d1, [dst, #\base + 48]
vldr d1, [src, #\base + 48]
vstr d2, [dst, #\base + 56]
vldr d2, [src, #\base + 56]
.endm
#endif
.p2align 6
ENTRY(memcpy)
mov dst, dstin /* Preserve dstin, we need to return it. */
cmp count, #64
bge .Lcpy_not_short
/* Deal with small copies quickly by dropping straight into the
exit block. */
.Ltail63unaligned:
#ifdef USE_NEON
/* These need an extra layer of macro just to work around a
bug in the assembler's parser when an operand starts with
a {...}. https://sourceware.org/bugzilla/show_bug.cgi?id=15647
tracks that bug; it was not fixed as of binutils-2.23.2. */
.macro neon_load_d0 reg
vld1.8 {d0}, [\reg]!
.endm
.macro neon_store_d0 reg
vst1.8 {d0}, [\reg]!
.endm
and tmp1, count, #0x38
.macro dispatch_step i
neon_load_d0 src
neon_store_d0 dst
.endm
dispatch_7_dword
tst count, #4
ldrne tmp1, [src], #4
strne tmp1, [dst], #4
#else
/* Copy up to 15 full words of data. May not be aligned. */
/* Cannot use VFP for unaligned data. */
and tmp1, count, #0x3c
add dst, dst, tmp1
add src, src, tmp1
/* Jump directly into the sequence below at the correct offset. */
.macro dispatch_step i
ldr tmp1, [src, #-(\i * 4)]
str tmp1, [dst, #-(\i * 4)]
.endm
dispatch_15_word
#endif
lsls count, count, #31
ldrhcs tmp1, [src], #2
ldrbne src, [src] /* Src is dead, use as a scratch. */
strhcs tmp1, [dst], #2
strbne src, [dst]
bx lr
.Lcpy_not_short:
/* At least 64 bytes to copy, but don't know the alignment yet. */
str tmp2, [sp, #-FRAME_SIZE]!
cfi_adjust_cfa_offset (FRAME_SIZE)
cfi_rel_offset (tmp2, 0)
cfi_remember_state
and tmp2, src, #7
and tmp1, dst, #7
cmp tmp1, tmp2
bne .Lcpy_notaligned
#ifdef USE_VFP
/* Magic dust alert! Force VFP on Cortex-A9. Experiments show
that the FP pipeline is much better at streaming loads and
stores. This is outside the critical loop. */
vmov.f32 s0, s0
#endif
/* SRC and DST have the same mutual 64-bit alignment, but we may
still need to pre-copy some bytes to get to natural alignment.
We bring SRC and DST into full 64-bit alignment. */
lsls tmp2, dst, #29
beq 1f
rsbs tmp2, tmp2, #0
sub count, count, tmp2, lsr #29
ldrmi tmp1, [src], #4
strmi tmp1, [dst], #4
lsls tmp2, tmp2, #2
ldrhcs tmp1, [src], #2
ldrbne tmp2, [src], #1
strhcs tmp1, [dst], #2
strbne tmp2, [dst], #1
1:
subs tmp2, count, #64 /* Use tmp2 for count. */
blt .Ltail63aligned
cmp tmp2, #512
bge .Lcpy_body_long
.Lcpy_body_medium: /* Count in tmp2. */
#ifdef USE_VFP
1:
vldr d0, [src, #0]
subs tmp2, tmp2, #64
vldr d1, [src, #8]
vstr d0, [dst, #0]
vldr d0, [src, #16]
vstr d1, [dst, #8]
vldr d1, [src, #24]
vstr d0, [dst, #16]
vldr d0, [src, #32]
vstr d1, [dst, #24]
vldr d1, [src, #40]
vstr d0, [dst, #32]
vldr d0, [src, #48]
vstr d1, [dst, #40]
vldr d1, [src, #56]
vstr d0, [dst, #48]
add src, src, #64
vstr d1, [dst, #56]
add dst, dst, #64
bge 1b
tst tmp2, #0x3f
beq .Ldone
.Ltail63aligned: /* Count in tmp2. */
and tmp1, tmp2, #0x38
add dst, dst, tmp1
add src, src, tmp1
.macro dispatch_step i
vldr d0, [src, #-(\i * 8)]
vstr d0, [dst, #-(\i * 8)]
.endm
dispatch_7_dword
#else
sub src, src, #8
sub dst, dst, #8
1:
ldrd A_l, A_h, [src, #8]
strd A_l, A_h, [dst, #8]
ldrd A_l, A_h, [src, #16]
strd A_l, A_h, [dst, #16]
ldrd A_l, A_h, [src, #24]
strd A_l, A_h, [dst, #24]
ldrd A_l, A_h, [src, #32]
strd A_l, A_h, [dst, #32]
ldrd A_l, A_h, [src, #40]
strd A_l, A_h, [dst, #40]
ldrd A_l, A_h, [src, #48]
strd A_l, A_h, [dst, #48]
ldrd A_l, A_h, [src, #56]
strd A_l, A_h, [dst, #56]
ldrd A_l, A_h, [src, #64]!
strd A_l, A_h, [dst, #64]!
subs tmp2, tmp2, #64
bge 1b
tst tmp2, #0x3f
bne 1f
ldr tmp2,[sp], #FRAME_SIZE
cfi_adjust_cfa_offset (-FRAME_SIZE)
cfi_restore (tmp2)
bx lr
cfi_restore_state
cfi_remember_state
1:
add src, src, #8
add dst, dst, #8
.Ltail63aligned: /* Count in tmp2. */
/* Copy up to 7 d-words of data. Similar to Ltail63unaligned, but
we know that the src and dest are 64-bit aligned so we can use
LDRD/STRD to improve efficiency. */
/* TMP2 is now negative, but we don't care about that. The bottom
six bits still tell us how many bytes are left to copy. */
and tmp1, tmp2, #0x38
add dst, dst, tmp1
add src, src, tmp1
.macro dispatch_step i
ldrd A_l, A_h, [src, #-(\i * 8)]
strd A_l, A_h, [dst, #-(\i * 8)]
.endm
dispatch_7_dword
#endif
tst tmp2, #4
ldrne tmp1, [src], #4
strne tmp1, [dst], #4
lsls tmp2, tmp2, #31 /* Count (tmp2) now dead. */
ldrhcs tmp1, [src], #2
ldrbne tmp2, [src]
strhcs tmp1, [dst], #2
strbne tmp2, [dst]
.Ldone:
ldr tmp2, [sp], #FRAME_SIZE
cfi_adjust_cfa_offset (-FRAME_SIZE)
cfi_restore (tmp2)
bx lr
cfi_restore_state
cfi_remember_state
.Lcpy_body_long: /* Count in tmp2. */
/* Long copy. We know that there's at least (prefetch_lines * 64)
bytes to go. */
#ifdef USE_VFP
/* Don't use PLD. Instead, read some data in advance of the current
copy position into a register. This should act like a PLD
operation but we won't have to repeat the transfer. */
vldr d3, [src, #0]
vldr d4, [src, #64]
vldr d5, [src, #128]
vldr d6, [src, #192]
vldr d7, [src, #256]
vldr d0, [src, #8]
vldr d1, [src, #16]
vldr d2, [src, #24]
add src, src, #32
subs tmp2, tmp2, #prefetch_lines * 64 * 2
blt 2f
1:
cpy_line_vfp d3, 0
cpy_line_vfp d4, 64
cpy_line_vfp d5, 128
add dst, dst, #3 * 64
add src, src, #3 * 64
cpy_line_vfp d6, 0
cpy_line_vfp d7, 64
add dst, dst, #2 * 64
add src, src, #2 * 64
subs tmp2, tmp2, #prefetch_lines * 64
bge 1b
2:
cpy_tail_vfp d3, 0
cpy_tail_vfp d4, 64
cpy_tail_vfp d5, 128
add src, src, #3 * 64
add dst, dst, #3 * 64
cpy_tail_vfp d6, 0
vstr d7, [dst, #64]
vldr d7, [src, #64]
vstr d0, [dst, #64 + 8]
vldr d0, [src, #64 + 8]
vstr d1, [dst, #64 + 16]
vldr d1, [src, #64 + 16]
vstr d2, [dst, #64 + 24]
vldr d2, [src, #64 + 24]
vstr d7, [dst, #64 + 32]
add src, src, #96
vstr d0, [dst, #64 + 40]
vstr d1, [dst, #64 + 48]
vstr d2, [dst, #64 + 56]
add dst, dst, #128
add tmp2, tmp2, #prefetch_lines * 64
b .Lcpy_body_medium
#else
/* Long copy. Use an SMS style loop to maximize the I/O
bandwidth of the core. We don't have enough spare registers
to synthesise prefetching, so use PLD operations. */
/* Pre-bias src and dst. */
sub src, src, #8
sub dst, dst, #8
pld [src, #8]
pld [src, #72]
subs tmp2, tmp2, #64
pld [src, #136]
ldrd A_l, A_h, [src, #8]
strd B_l, B_h, [sp, #8]
cfi_rel_offset (B_l, 8)
cfi_rel_offset (B_h, 12)
ldrd B_l, B_h, [src, #16]
strd C_l, C_h, [sp, #16]
cfi_rel_offset (C_l, 16)
cfi_rel_offset (C_h, 20)
ldrd C_l, C_h, [src, #24]
strd D_l, D_h, [sp, #24]
cfi_rel_offset (D_l, 24)
cfi_rel_offset (D_h, 28)
pld [src, #200]
ldrd D_l, D_h, [src, #32]!
b 1f
.p2align 6
2:
pld [src, #232]
strd A_l, A_h, [dst, #40]
ldrd A_l, A_h, [src, #40]
strd B_l, B_h, [dst, #48]
ldrd B_l, B_h, [src, #48]
strd C_l, C_h, [dst, #56]
ldrd C_l, C_h, [src, #56]
strd D_l, D_h, [dst, #64]!
ldrd D_l, D_h, [src, #64]!
subs tmp2, tmp2, #64
1:
strd A_l, A_h, [dst, #8]
ldrd A_l, A_h, [src, #8]
strd B_l, B_h, [dst, #16]
ldrd B_l, B_h, [src, #16]
strd C_l, C_h, [dst, #24]
ldrd C_l, C_h, [src, #24]
strd D_l, D_h, [dst, #32]
ldrd D_l, D_h, [src, #32]
bcs 2b
/* Save the remaining bytes and restore the callee-saved regs. */
strd A_l, A_h, [dst, #40]
add src, src, #40
strd B_l, B_h, [dst, #48]
ldrd B_l, B_h, [sp, #8]
cfi_restore (B_l)
cfi_restore (B_h)
strd C_l, C_h, [dst, #56]
ldrd C_l, C_h, [sp, #16]
cfi_restore (C_l)
cfi_restore (C_h)
strd D_l, D_h, [dst, #64]
ldrd D_l, D_h, [sp, #24]
cfi_restore (D_l)
cfi_restore (D_h)
add dst, dst, #72
tst tmp2, #0x3f
bne .Ltail63aligned
ldr tmp2, [sp], #FRAME_SIZE
cfi_adjust_cfa_offset (-FRAME_SIZE)
cfi_restore (tmp2)
bx lr
#endif
cfi_restore_state
cfi_remember_state
.Lcpy_notaligned:
pld [src, #0]
pld [src, #64]
/* There's at least 64 bytes to copy, but there is no mutual
alignment. */
/* Bring DST to 64-bit alignment. */
lsls tmp2, dst, #29
pld [src, #(2 * 64)]
beq 1f
rsbs tmp2, tmp2, #0
sub count, count, tmp2, lsr #29
ldrmi tmp1, [src], #4
strmi tmp1, [dst], #4
lsls tmp2, tmp2, #2
ldrbne tmp1, [src], #1
ldrhcs tmp2, [src], #2
strbne tmp1, [dst], #1
strhcs tmp2, [dst], #2
1:
pld [src, #(3 * 64)]
subs count, count, #64
ldrmi tmp2, [sp], #FRAME_SIZE
bmi .Ltail63unaligned
pld [src, #(4 * 64)]
#ifdef USE_NEON
/* These need an extra layer of macro just to work around a
bug in the assembler's parser when an operand starts with
a {...}. */
.macro neon_load_multi reglist, basereg
vld1.8 {\reglist}, [\basereg]!
.endm
.macro neon_store_multi reglist, basereg
vst1.8 {\reglist}, [ALIGN (\basereg, 64)]!
.endm
neon_load_multi d0-d3, src
neon_load_multi d4-d7, src
subs count, count, #64
bmi 2f
1:
pld [src, #(4 * 64)]
neon_store_multi d0-d3, dst
neon_load_multi d0-d3, src
neon_store_multi d4-d7, dst
neon_load_multi d4-d7, src
subs count, count, #64
bpl 1b
2:
neon_store_multi d0-d3, dst
neon_store_multi d4-d7, dst
ands count, count, #0x3f
#else
/* Use an SMS style loop to maximize the I/O bandwidth. */
sub src, src, #4
sub dst, dst, #8
subs tmp2, count, #64 /* Use tmp2 for count. */
ldr A_l, [src, #4]
ldr A_h, [src, #8]
strd B_l, B_h, [sp, #8]
cfi_rel_offset (B_l, 8)
cfi_rel_offset (B_h, 12)
ldr B_l, [src, #12]
ldr B_h, [src, #16]
strd C_l, C_h, [sp, #16]
cfi_rel_offset (C_l, 16)
cfi_rel_offset (C_h, 20)
ldr C_l, [src, #20]
ldr C_h, [src, #24]
strd D_l, D_h, [sp, #24]
cfi_rel_offset (D_l, 24)
cfi_rel_offset (D_h, 28)
ldr D_l, [src, #28]
ldr D_h, [src, #32]!
b 1f
.p2align 6
2:
pld [src, #(5 * 64) - (32 - 4)]
strd A_l, A_h, [dst, #40]
ldr A_l, [src, #36]
ldr A_h, [src, #40]
strd B_l, B_h, [dst, #48]
ldr B_l, [src, #44]
ldr B_h, [src, #48]
strd C_l, C_h, [dst, #56]
ldr C_l, [src, #52]
ldr C_h, [src, #56]
strd D_l, D_h, [dst, #64]!
ldr D_l, [src, #60]
ldr D_h, [src, #64]!
subs tmp2, tmp2, #64
1:
strd A_l, A_h, [dst, #8]
ldr A_l, [src, #4]
ldr A_h, [src, #8]
strd B_l, B_h, [dst, #16]
ldr B_l, [src, #12]
ldr B_h, [src, #16]
strd C_l, C_h, [dst, #24]
ldr C_l, [src, #20]
ldr C_h, [src, #24]
strd D_l, D_h, [dst, #32]
ldr D_l, [src, #28]
ldr D_h, [src, #32]
bcs 2b
/* Save the remaining bytes and restore the callee-saved regs. */
strd A_l, A_h, [dst, #40]
add src, src, #36
strd B_l, B_h, [dst, #48]
ldrd B_l, B_h, [sp, #8]
cfi_restore (B_l)
cfi_restore (B_h)
strd C_l, C_h, [dst, #56]
ldrd C_l, C_h, [sp, #16]
cfi_restore (C_l)
cfi_restore (C_h)
strd D_l, D_h, [dst, #64]
ldrd D_l, D_h, [sp, #24]
cfi_restore (D_l)
cfi_restore (D_h)
add dst, dst, #72
ands count, tmp2, #0x3f
#endif
ldr tmp2, [sp], #FRAME_SIZE
cfi_adjust_cfa_offset (-FRAME_SIZE)
cfi_restore (tmp2)
bne .Ltail63unaligned
bx lr
END(memcpy)
libc_hidden_builtin_def (memcpy)