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/*
* Copyright (C) 2008 The Android Open Source Project
* 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.
*
* 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 OWNER 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.
*/
#if defined(__arm__)
#if defined(__ARM_NEON__)
.text
#ifndef __APPLE__
.fpu neon
.global fast_memcpy
.type fast_memcpy, %function
#else
.globl _fast_memcpy
#endif
.align 4
/* a prefetch distance of 4 cache-lines works best experimentally */
#define CACHE_LINE_SIZE 64
#define PREFETCH_DISTANCE (CACHE_LINE_SIZE*4)
#ifndef __APPLE__
.fnstart
.save {r0, lr}
fast_memcpy:
#else
_fast_memcpy:
#endif
stmfd sp!, {r0, lr}
/* start preloading as early as possible */
pld [r1, #(CACHE_LINE_SIZE*0)]
pld [r1, #(CACHE_LINE_SIZE*1)]
/* do we have at least 16-bytes to copy (needed for alignment below) */
cmp r2, #16
blo 5f
/* align destination to half cache-line for the write-buffer */
rsb r3, r0, #0
ands r3, r3, #0xF
beq 0f
/* copy up to 15-bytes (count in r3) */
sub r2, r2, r3
movs ip, r3, lsl #31
ldrmib lr, [r1], #1
strmib lr, [r0], #1
ldrcsb ip, [r1], #1
ldrcsb lr, [r1], #1
strcsb ip, [r0], #1
strcsb lr, [r0], #1
movs ip, r3, lsl #29
bge 1f
// copies 4 bytes, destination 32-bits aligned
vld4.8 {d0[0], d1[0], d2[0], d3[0]}, [r1]!
vst4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0, :32]!
1: bcc 2f
// copies 8 bytes, destination 64-bits aligned
vld1.8 {d0}, [r1]!
vst1.8 {d0}, [r0, :64]!
2:
0: /* preload immediately the next cache line, which we may need */
pld [r1, #(CACHE_LINE_SIZE*0)]
pld [r1, #(CACHE_LINE_SIZE*1)]
/* make sure we have at least 64 bytes to copy */
subs r2, r2, #64
blo 2f
/* preload all the cache lines we need.
* NOTE: the number of pld below depends on PREFETCH_DISTANCE,
* ideally would would increase the distance in the main loop to
* avoid the goofy code below. In practice this doesn't seem to make
* a big difference.
*/
pld [r1, #(CACHE_LINE_SIZE*2)]
pld [r1, #(CACHE_LINE_SIZE*3)]
pld [r1, #(PREFETCH_DISTANCE)]
1: /* The main loop copies 64 bytes at a time */
vld1.8 {d0 - d3}, [r1]!
vld1.8 {d4 - d7}, [r1]!
pld [r1, #(PREFETCH_DISTANCE)]
subs r2, r2, #64
vst1.8 {d0 - d3}, [r0, :128]!
vst1.8 {d4 - d7}, [r0, :128]!
bhs 1b
2: /* fix-up the remaining count and make sure we have >= 32 bytes left */
add r2, r2, #64
subs r2, r2, #32
blo 4f
3: /* 32 bytes at a time. These cache lines were already preloaded */
vld1.8 {d0 - d3}, [r1]!
subs r2, r2, #32
vst1.8 {d0 - d3}, [r0, :128]!
bhs 3b
4: /* less than 32 left */
add r2, r2, #32
tst r2, #0x10
beq 5f
// copies 16 bytes, 128-bits aligned
vld1.8 {d0, d1}, [r1]!
vst1.8 {d0, d1}, [r0, :128]!
5: /* copy up to 15-bytes (count in r2) */
movs ip, r2, lsl #29
bcc 1f
vld1.8 {d0}, [r1]!
vst1.8 {d0}, [r0]!
1: bge 2f
vld4.8 {d0[0], d1[0], d2[0], d3[0]}, [r1]!
vst4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]!
2: movs ip, r2, lsl #31
ldrmib r3, [r1], #1
ldrcsb ip, [r1], #1
ldrcsb lr, [r1], #1
strmib r3, [r0], #1
strcsb ip, [r0], #1
strcsb lr, [r0], #1
ldmfd sp!, {r0, lr}
bx lr
#ifndef __APPLE__
.fnend
#endif
#else /* __ARM_ARCH__ < 7 */
.text
#ifndef __APPLE__
.global fast_memcpy
.type fast_memcpy, %function
#else
.globl _fast_memcpy
#endif
.align 4
/*
* Optimized memcpy() for ARM.
*
* note that memcpy() always returns the destination pointer,
* so we have to preserve R0.
*/
#ifndef __APPLE__
fast_memcpy:
#else
_fast_memcpy:
#endif
/* The stack must always be 64-bits aligned to be compliant with the
* ARM ABI. Since we have to save R0, we might as well save R4
* which we can use for better pipelining of the reads below
*/
#ifndef __APPLE__
.fnstart
.save {r0, r4, lr}
#endif
stmfd sp!, {r0, r4, lr}
/* Making room for r5-r11 which will be spilled later */
.pad #28
sub sp, sp, #28
// preload the destination because we'll align it to a cache line
// with small writes. Also start the source "pump".
//PLD (r0, #0)
//PLD (r1, #0)
//PLD (r1, #32)
/* it simplifies things to take care of len<4 early */
cmp r2, #4
blo copy_last_3_and_return
/* compute the offset to align the source
* offset = (4-(src&3))&3 = -src & 3
*/
rsb r3, r1, #0
ands r3, r3, #3
beq src_aligned
/* align source to 32 bits. We need to insert 2 instructions between
* a ldr[b|h] and str[b|h] because byte and half-word instructions
* stall 2 cycles.
*/
movs r12, r3, lsl #31
sub r2, r2, r3 /* we know that r3 <= r2 because r2 >= 4 */
ldrmib r3, [r1], #1
ldrcsb r4, [r1], #1
ldrcsb r12,[r1], #1
strmib r3, [r0], #1
strcsb r4, [r0], #1
strcsb r12,[r0], #1
src_aligned:
/* see if src and dst are aligned together (congruent) */
eor r12, r0, r1
tst r12, #3
bne non_congruent
/* Use post-incriment mode for stm to spill r5-r11 to reserved stack
* frame. Don't update sp.
*/
stmea sp, {r5-r11}
/* align the destination to a cache-line */
rsb r3, r0, #0
ands r3, r3, #0x1C
beq congruent_aligned32
cmp r3, r2
andhi r3, r2, #0x1C
/* conditionnaly copies 0 to 7 words (length in r3) */
movs r12, r3, lsl #28
ldmcsia r1!, {r4, r5, r6, r7} /* 16 bytes */
ldmmiia r1!, {r8, r9} /* 8 bytes */
stmcsia r0!, {r4, r5, r6, r7}
stmmiia r0!, {r8, r9}
tst r3, #0x4
ldrne r10,[r1], #4 /* 4 bytes */
strne r10,[r0], #4
sub r2, r2, r3
congruent_aligned32:
/*
* here source is aligned to 32 bytes.
*/
cached_aligned32:
subs r2, r2, #32
blo less_than_32_left
/*
* We preload a cache-line up to 64 bytes ahead. On the 926, this will
* stall only until the requested world is fetched, but the linefill
* continues in the the background.
* While the linefill is going, we write our previous cache-line
* into the write-buffer (which should have some free space).
* When the linefill is done, the writebuffer will
* start dumping its content into memory
*
* While all this is going, we then load a full cache line into
* 8 registers, this cache line should be in the cache by now
* (or partly in the cache).
*
* This code should work well regardless of the source/dest alignment.
*
*/
// Align the preload register to a cache-line because the cpu does
// "critical word first" (the first word requested is loaded first).
bic r12, r1, #0x1F
add r12, r12, #64
1: ldmia r1!, { r4-r11 }
//PLD (r12, #64)
subs r2, r2, #32
// NOTE: if r12 is more than 64 ahead of r1, the following ldrhi
// for ARM9 preload will not be safely guarded by the preceding subs.
// When it is safely guarded the only possibility to have SIGSEGV here
// is because the caller overstates the length.
ldrhi r3, [r12], #32 /* cheap ARM9 preload */
stmia r0!, { r4-r11 }
bhs 1b
add r2, r2, #32
less_than_32_left:
/*
* less than 32 bytes left at this point (length in r2)
*/
/* skip all this if there is nothing to do, which should
* be a common case (if not executed the code below takes
* about 16 cycles)
*/
tst r2, #0x1F
beq 1f
/* conditionnaly copies 0 to 31 bytes */
movs r12, r2, lsl #28
ldmcsia r1!, {r4, r5, r6, r7} /* 16 bytes */
ldmmiia r1!, {r8, r9} /* 8 bytes */
stmcsia r0!, {r4, r5, r6, r7}
stmmiia r0!, {r8, r9}
movs r12, r2, lsl #30
ldrcs r3, [r1], #4 /* 4 bytes */
ldrmih r4, [r1], #2 /* 2 bytes */
strcs r3, [r0], #4
strmih r4, [r0], #2
tst r2, #0x1
ldrneb r3, [r1] /* last byte */
strneb r3, [r0]
/* we're done! restore everything and return */
1: ldmfd sp!, {r5-r11}
ldmfd sp!, {r0, r4, lr}
bx lr
/********************************************************************/
non_congruent:
/*
* here source is aligned to 4 bytes
* but destination is not.
*
* in the code below r2 is the number of bytes read
* (the number of bytes written is always smaller, because we have
* partial words in the shift queue)
*/
cmp r2, #4
blo copy_last_3_and_return
/* Use post-incriment mode for stm to spill r5-r11 to reserved stack
* frame. Don't update sp.
*/
stmea sp, {r5-r11}
/* compute shifts needed to align src to dest */
rsb r5, r0, #0
and r5, r5, #3 /* r5 = # bytes in partial words */
mov r12, r5, lsl #3 /* r12 = right */
rsb lr, r12, #32 /* lr = left */
/* read the first word */
ldr r3, [r1], #4
sub r2, r2, #4
/* write a partial word (0 to 3 bytes), such that destination
* becomes aligned to 32 bits (r5 = nb of words to copy for alignment)
*/
movs r5, r5, lsl #31
strmib r3, [r0], #1
movmi r3, r3, lsr #8
strcsb r3, [r0], #1
movcs r3, r3, lsr #8
strcsb r3, [r0], #1
movcs r3, r3, lsr #8
cmp r2, #4
blo partial_word_tail
/* Align destination to 32 bytes (cache line boundary) */
1: tst r0, #0x1c
beq 2f
ldr r5, [r1], #4
sub r2, r2, #4
orr r4, r3, r5, lsl lr
mov r3, r5, lsr r12
str r4, [r0], #4
cmp r2, #4
bhs 1b
blo partial_word_tail
/* copy 32 bytes at a time */
2: subs r2, r2, #32
blo less_than_thirtytwo
/* Use immediate mode for the shifts, because there is an extra cycle
* for register shifts, which could account for up to 50% of
* performance hit.
*/
cmp r12, #24
beq loop24
cmp r12, #8
beq loop8
loop16:
ldr r12, [r1], #4
1: mov r4, r12
ldmia r1!, { r5,r6,r7, r8,r9,r10,r11}
//PLD (r1, #64)
subs r2, r2, #32
ldrhs r12, [r1], #4
orr r3, r3, r4, lsl #16
mov r4, r4, lsr #16
orr r4, r4, r5, lsl #16
mov r5, r5, lsr #16
orr r5, r5, r6, lsl #16
mov r6, r6, lsr #16
orr r6, r6, r7, lsl #16
mov r7, r7, lsr #16
orr r7, r7, r8, lsl #16
mov r8, r8, lsr #16
orr r8, r8, r9, lsl #16
mov r9, r9, lsr #16
orr r9, r9, r10, lsl #16
mov r10, r10, lsr #16
orr r10, r10, r11, lsl #16
stmia r0!, {r3,r4,r5,r6, r7,r8,r9,r10}
mov r3, r11, lsr #16
bhs 1b
b less_than_thirtytwo
loop8:
ldr r12, [r1], #4
1: mov r4, r12
ldmia r1!, { r5,r6,r7, r8,r9,r10,r11}
//PLD (r1, #64)
subs r2, r2, #32
ldrhs r12, [r1], #4
orr r3, r3, r4, lsl #24
mov r4, r4, lsr #8
orr r4, r4, r5, lsl #24
mov r5, r5, lsr #8
orr r5, r5, r6, lsl #24
mov r6, r6, lsr #8
orr r6, r6, r7, lsl #24
mov r7, r7, lsr #8
orr r7, r7, r8, lsl #24
mov r8, r8, lsr #8
orr r8, r8, r9, lsl #24
mov r9, r9, lsr #8
orr r9, r9, r10, lsl #24
mov r10, r10, lsr #8
orr r10, r10, r11, lsl #24
stmia r0!, {r3,r4,r5,r6, r7,r8,r9,r10}
mov r3, r11, lsr #8
bhs 1b
b less_than_thirtytwo
loop24:
ldr r12, [r1], #4
1: mov r4, r12
ldmia r1!, { r5,r6,r7, r8,r9,r10,r11}
//PLD (r1, #64)
subs r2, r2, #32
ldrhs r12, [r1], #4
orr r3, r3, r4, lsl #8
mov r4, r4, lsr #24
orr r4, r4, r5, lsl #8
mov r5, r5, lsr #24
orr r5, r5, r6, lsl #8
mov r6, r6, lsr #24
orr r6, r6, r7, lsl #8
mov r7, r7, lsr #24
orr r7, r7, r8, lsl #8
mov r8, r8, lsr #24
orr r8, r8, r9, lsl #8
mov r9, r9, lsr #24
orr r9, r9, r10, lsl #8
mov r10, r10, lsr #24
orr r10, r10, r11, lsl #8
stmia r0!, {r3,r4,r5,r6, r7,r8,r9,r10}
mov r3, r11, lsr #24
bhs 1b
less_than_thirtytwo:
/* copy the last 0 to 31 bytes of the source */
rsb r12, lr, #32 /* we corrupted r12, recompute it */
add r2, r2, #32
cmp r2, #4
blo partial_word_tail
1: ldr r5, [r1], #4
sub r2, r2, #4
orr r4, r3, r5, lsl lr
mov r3, r5, lsr r12
str r4, [r0], #4
cmp r2, #4
bhs 1b
partial_word_tail:
/* we have a partial word in the input buffer */
movs r5, lr, lsl #(31-3)
strmib r3, [r0], #1
movmi r3, r3, lsr #8
strcsb r3, [r0], #1
movcs r3, r3, lsr #8
strcsb r3, [r0], #1
/* Refill spilled registers from the stack. Don't update sp. */
ldmfd sp, {r5-r11}
copy_last_3_and_return:
movs r2, r2, lsl #31 /* copy remaining 0, 1, 2 or 3 bytes */
ldrmib r2, [r1], #1
ldrcsb r3, [r1], #1
ldrcsb r12,[r1]
strmib r2, [r0], #1
strcsb r3, [r0], #1
strcsb r12,[r0]
/* we're done! restore sp and spilled registers and return */
add sp, sp, #28
ldmfd sp!, {r0, r4, lr}
bx lr
#ifndef __APPLE__
.fnend
#endif
#endif /* __ARM_ARCH__ < 7 */
#endif
#if defined(__linux__) && defined(__ELF__)
/* we don't need an executable stack */
.section .note.GNU-stack,"",%progbits
#endif
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