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platform_bionic/libc/arch-arm/bionic/memcpy.a9.S
Will Newton 2753e12af5 libc/arch-arm/bionic/memcpy.a9.S: memcpy from cortex-strings. 
This memcpy code uses NEON/VFP to achieve very good performance
on ARMv7-A processors. It is specifically tuned for A15 but should
provide good performance on A9 also. It is equivalent to the code
in cortex-strings rev 116.

This patch is a follow up the existing gerrit change:

I7f6f77995f3ca903ad9c66d14261441667a2a935

This version includes a tweak for performance on misaligned
buffers and splits the header comment into license and
documentation sections.

Change-Id: Ibd2e23c8d8e01357ba0247be1d05192de3ceba69
Signed-off-by: Will Newton <will.newton@linaro.org>
2013-07-03 10:20:43 -07:00

614 lines
15 KiB
ArmAsm
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/* Copyright (c) 2013, Linaro Limited
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Linaro Limited nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
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
LDRD/STRD support unaligned word accesses
*/
#include <machine/cpu-features.h>
#include <machine/asm.h>
.syntax unified
/* This implementation requires ARM state. */
.arm
#ifdef __ARM_NEON__
.fpu neon
.arch armv7-a
# define FRAME_SIZE 4
# define USE_VFP
# define USE_NEON
#elif !defined (__SOFTFP__)
.arch armv6
.fpu vfpv2
# define FRAME_SIZE 32
# define USE_VFP
#else
.arch armv6
# define FRAME_SIZE 32
#endif
/* Old versions of GAS incorrectly implement the NEON align semantics. */
#ifdef BROKEN_ASM_NEON_ALIGN
#define ALIGN(addr, align) addr,:align
#else
#define ALIGN(addr, align) addr:align
#endif
#define PC_OFFSET 8 /* PC pipeline compensation. */
#define INSN_SIZE 4
/* Call parameters. */
#define dstin r0
#define src r1
#define count r2
/* Locals. */
#define tmp1 r3
#define dst ip
#define tmp2 r10
#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
#define D_l r8
#define D_h r9
#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
and tmp1, count, #0x38
rsb tmp1, tmp1, #(56 - PC_OFFSET + INSN_SIZE)
add pc, pc, tmp1
vld1.8 {d0}, [src]! /* 14 words to go. */
vst1.8 {d0}, [dst]!
vld1.8 {d0}, [src]! /* 12 words to go. */
vst1.8 {d0}, [dst]!
vld1.8 {d0}, [src]! /* 10 words to go. */
vst1.8 {d0}, [dst]!
vld1.8 {d0}, [src]! /* 8 words to go. */
vst1.8 {d0}, [dst]!
vld1.8 {d0}, [src]! /* 6 words to go. */
vst1.8 {d0}, [dst]!
vld1.8 {d0}, [src]! /* 4 words to go. */
vst1.8 {d0}, [dst]!
vld1.8 {d0}, [src]! /* 2 words to go. */
vst1.8 {d0}, [dst]!
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
rsb tmp1, tmp1, #(60 - PC_OFFSET/2 + INSN_SIZE/2)
/* Jump directly into the sequence below at the correct offset. */
add pc, pc, tmp1, lsl #1
ldr tmp1, [src, #-60] /* 15 words to go. */
str tmp1, [dst, #-60]
ldr tmp1, [src, #-56] /* 14 words to go. */
str tmp1, [dst, #-56]
ldr tmp1, [src, #-52]
str tmp1, [dst, #-52]
ldr tmp1, [src, #-48] /* 12 words to go. */
str tmp1, [dst, #-48]
ldr tmp1, [src, #-44]
str tmp1, [dst, #-44]
ldr tmp1, [src, #-40] /* 10 words to go. */
str tmp1, [dst, #-40]
ldr tmp1, [src, #-36]
str tmp1, [dst, #-36]
ldr tmp1, [src, #-32] /* 8 words to go. */
str tmp1, [dst, #-32]
ldr tmp1, [src, #-28]
str tmp1, [dst, #-28]
ldr tmp1, [src, #-24] /* 6 words to go. */
str tmp1, [dst, #-24]
ldr tmp1, [src, #-20]
str tmp1, [dst, #-20]
ldr tmp1, [src, #-16] /* 4 words to go. */
str tmp1, [dst, #-16]
ldr tmp1, [src, #-12]
str tmp1, [dst, #-12]
ldr tmp1, [src, #-8] /* 2 words to go. */
str tmp1, [dst, #-8]
ldr tmp1, [src, #-4]
str tmp1, [dst, #-4]
#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]!
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 32-bit alignment, but we may
still need to pre-copy some bytes to get to natural alignment.
We bring 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
rsb tmp1, tmp1, #(56 - PC_OFFSET + INSN_SIZE)
add pc, pc, tmp1
vldr d0, [src, #-56] /* 14 words to go. */
vstr d0, [dst, #-56]
vldr d0, [src, #-48] /* 12 words to go. */
vstr d0, [dst, #-48]
vldr d0, [src, #-40] /* 10 words to go. */
vstr d0, [dst, #-40]
vldr d0, [src, #-32] /* 8 words to go. */
vstr d0, [dst, #-32]
vldr d0, [src, #-24] /* 6 words to go. */
vstr d0, [dst, #-24]
vldr d0, [src, #-16] /* 4 words to go. */
vstr d0, [dst, #-16]
vldr d0, [src, #-8] /* 2 words to go. */
vstr d0, [dst, #-8]
#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
bx lr
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 32-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
rsb tmp1, tmp1, #(56 - PC_OFFSET + INSN_SIZE)
add pc, pc, tmp1
ldrd A_l, A_h, [src, #-56] /* 14 words to go. */
strd A_l, A_h, [dst, #-56]
ldrd A_l, A_h, [src, #-48] /* 12 words to go. */
strd A_l, A_h, [dst, #-48]
ldrd A_l, A_h, [src, #-40] /* 10 words to go. */
strd A_l, A_h, [dst, #-40]
ldrd A_l, A_h, [src, #-32] /* 8 words to go. */
strd A_l, A_h, [dst, #-32]
ldrd A_l, A_h, [src, #-24] /* 6 words to go. */
strd A_l, A_h, [dst, #-24]
ldrd A_l, A_h, [src, #-16] /* 4 words to go. */
strd A_l, A_h, [dst, #-16]
ldrd A_l, A_h, [src, #-8] /* 2 words to go. */
strd A_l, A_h, [dst, #-8]
#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
bx lr
.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]
ldrd B_l, B_h, [src, #16]
strd C_l, C_h, [sp, #16]
ldrd C_l, C_h, [src, #24]
strd D_l, D_h, [sp, #24]
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]
strd C_l, C_h, [dst, #56]
ldrd C_l, C_h, [sp, #16]
strd D_l, D_h, [dst, #64]
ldrd D_l, D_h, [sp, #24]
add dst, dst, #72
tst tmp2, #0x3f
bne .Ltail63aligned
ldr tmp2, [sp], #FRAME_SIZE
bx lr
#endif
.Lcpy_notaligned:
pld [src]
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
vld1.8 {d0-d3}, [src]!
vld1.8 {d4-d7}, [src]!
subs count, count, #64
bmi 2f
1:
pld [src, #(4 * 64)]
vst1.8 {d0-d3}, [ALIGN (dst, 64)]!
vld1.8 {d0-d3}, [src]!
vst1.8 {d4-d7}, [ALIGN (dst, 64)]!
vld1.8 {d4-d7}, [src]!
subs count, count, #64
bpl 1b
2:
vst1.8 {d0-d3}, [ALIGN (dst, 64)]!
vst1.8 {d4-d7}, [ALIGN (dst, 64)]!
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]
ldr B_l, [src, #12]
ldr B_h, [src, #16]
strd C_l, C_h, [sp, #16]
ldr C_l, [src, #20]
ldr C_h, [src, #24]
strd D_l, D_h, [sp, #24]
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]
strd C_l, C_h, [dst, #56]
ldrd C_l, C_h, [sp, #16]
strd D_l, D_h, [dst, #64]
ldrd D_l, D_h, [sp, #24]
add dst, dst, #72
ands count, tmp2, #0x3f
#endif
ldr tmp2, [sp], #FRAME_SIZE
bne .Ltail63unaligned
bx lr
END(memcpy)
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