/* Optimized memcpy implementation for PowerPC32 on PowerPC64.
Copyright (C) 2003-2017 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
. */
#include
/* __ptr_t [r3] memcpy (__ptr_t dst [r3], __ptr_t src [r4], size_t len [r5]);
Returns 'dst'.
Memcpy handles short copies (< 32-bytes) using a binary move blocks
(no loops) of lwz/stw. The tail (remaining 1-3) bytes is handled
with the appropriate combination of byte and halfword load/stores.
There is minimal effort to optimize the alignment of short moves.
Longer moves (>= 32-bytes) justify the effort to get at least the
destination word (4-byte) aligned. Further optimization is
possible when both source and destination are word aligned.
Each case has an optimized unrolled loop. */
.machine power4
EALIGN (memcpy, 5, 0)
CALL_MCOUNT
stwu 1,-32(1)
cfi_adjust_cfa_offset(32)
stw 30,20(1)
cfi_offset(30,(20-32))
mr 30,3
cmplwi cr1,5,31
stw 31,24(1)
cfi_offset(31,(24-32))
neg 0,3
andi. 11,3,3 /* check alignment of dst. */
clrlwi 0,0,30 /* Number of bytes until the 1st word of dst. */
clrlwi 10,4,30 /* check alignment of src. */
cmplwi cr6,5,8
ble- cr1,.L2 /* If move < 32 bytes use short move code. */
cmplw cr6,10,11
mr 12,4
srwi 9,5,2 /* Number of full words remaining. */
mtcrf 0x01,0
mr 31,5
beq .L0
subf 31,0,5
/* Move 0-3 bytes as needed to get the destination word aligned. */
1: bf 31,2f
lbz 6,0(12)
addi 12,12,1
stb 6,0(3)
addi 3,3,1
2: bf 30,0f
lhz 6,0(12)
addi 12,12,2
sth 6,0(3)
addi 3,3,2
0:
clrlwi 10,12,30 /* check alignment of src again. */
srwi 9,31,2 /* Number of full words remaining. */
/* Copy words from source to destination, assuming the destination is
aligned on a word boundary.
At this point we know there are at least 25 bytes left (32-7) to copy.
The next step is to determine if the source is also word aligned.
If not branch to the unaligned move code at .L6. which uses
a load, shift, store strategy.
Otherwise source and destination are word aligned, and we can use
the optimized word copy loop. */
.L0:
clrlwi 11,31,30 /* calculate the number of tail bytes */
mtcrf 0x01,9
bne- cr6,.L6 /* If source is not word aligned. */
/* Move words where destination and source are word aligned.
Use an unrolled loop to copy 4 words (16-bytes) per iteration.
If the copy is not an exact multiple of 16 bytes, 1-3
words are copied as needed to set up the main loop. After
the main loop exits there may be a tail of 1-3 bytes. These bytes are
copied a halfword/byte at a time as needed to preserve alignment. */
srwi 8,31,4 /* calculate the 16 byte loop count */
cmplwi cr1,9,4
cmplwi cr6,11,0
mr 11,12
bf 30,1f
lwz 6,0(12)
lwz 7,4(12)
addi 11,12,8
mtctr 8
stw 6,0(3)
stw 7,4(3)
addi 10,3,8
bf 31,4f
lwz 0,8(12)
stw 0,8(3)
blt cr1,3f
addi 11,12,12
addi 10,3,12
b 4f
.align 4
1:
mr 10,3
mtctr 8
bf 31,4f
lwz 6,0(12)
addi 11,12,4
stw 6,0(3)
addi 10,3,4
.align 4
4:
lwz 6,0(11)
lwz 7,4(11)
lwz 8,8(11)
lwz 0,12(11)
stw 6,0(10)
stw 7,4(10)
stw 8,8(10)
stw 0,12(10)
addi 11,11,16
addi 10,10,16
bdnz 4b
3:
clrrwi 0,31,2
mtcrf 0x01,31
beq cr6,0f
.L9:
add 3,3,0
add 12,12,0
/* At this point we have a tail of 0-3 bytes and we know that the
destination is word aligned. */
2: bf 30,1f
lhz 6,0(12)
addi 12,12,2
sth 6,0(3)
addi 3,3,2
1: bf 31,0f
lbz 6,0(12)
stb 6,0(3)
0:
/* Return original dst pointer. */
mr 3,30
lwz 30,20(1)
lwz 31,24(1)
addi 1,1,32
blr
/* Copy up to 31 bytes. This is divided into two cases 0-8 bytes and
9-31 bytes. Each case is handled without loops, using binary
(1,2,4,8) tests.
In the short (0-8 byte) case no attempt is made to force alignment
of either source or destination. The hardware will handle the
unaligned load/stores with small delays for crossing 32- 64-byte, and
4096-byte boundaries. Since these short moves are unlikely to be
unaligned or cross these boundaries, the overhead to force
alignment is not justified.
The longer (9-31 byte) move is more likely to cross 32- or 64-byte
boundaries. Since only loads are sensitive to the 32-/64-byte
boundaries it is more important to align the source than the
destination. If the source is not already word aligned, we first
move 1-3 bytes as needed. While the destination and stores may
still be unaligned, this is only an issue for page (4096 byte
boundary) crossing, which should be rare for these short moves.
The hardware handles this case automatically with a small delay. */
.align 4
.L2:
mtcrf 0x01,5
neg 8,4
clrrwi 11,4,2
andi. 0,8,3
ble cr6,.LE8 /* Handle moves of 0-8 bytes. */
/* At least 9 bytes left. Get the source word aligned. */
cmplwi cr1,5,16
mr 10,5
mr 12,4
cmplwi cr6,0,2
beq .L3 /* If the source is already word aligned skip this. */
/* Copy 1-3 bytes to get source address word aligned. */
lwz 6,0(11)
subf 10,0,5
add 12,4,0
blt cr6,5f
srwi 7,6,16
bgt cr6,3f
#ifdef __LITTLE_ENDIAN__
sth 7,0(3)
#else
sth 6,0(3)
#endif
b 7f
.align 4
3:
#ifdef __LITTLE_ENDIAN__
rotlwi 6,6,24
stb 6,0(3)
sth 7,1(3)
#else
stb 7,0(3)
sth 6,1(3)
#endif
b 7f
.align 4
5:
#ifdef __LITTLE_ENDIAN__
rotlwi 6,6,8
#endif
stb 6,0(3)
7:
cmplwi cr1,10,16
add 3,3,0
mtcrf 0x01,10
.align 4
.L3:
/* At least 6 bytes left and the source is word aligned. */
blt cr1,8f
16: /* Move 16 bytes. */
lwz 6,0(12)
lwz 7,4(12)
stw 6,0(3)
lwz 6,8(12)
stw 7,4(3)
lwz 7,12(12)
addi 12,12,16
stw 6,8(3)
stw 7,12(3)
addi 3,3,16
8: /* Move 8 bytes. */
bf 28,4f
lwz 6,0(12)
lwz 7,4(12)
addi 12,12,8
stw 6,0(3)
stw 7,4(3)
addi 3,3,8
4: /* Move 4 bytes. */
bf 29,2f
lwz 6,0(12)
addi 12,12,4
stw 6,0(3)
addi 3,3,4
2: /* Move 2-3 bytes. */
bf 30,1f
lhz 6,0(12)
sth 6,0(3)
bf 31,0f
lbz 7,2(12)
stb 7,2(3)
mr 3,30
lwz 30,20(1)
addi 1,1,32
blr
1: /* Move 1 byte. */
bf 31,0f
lbz 6,0(12)
stb 6,0(3)
0:
/* Return original dst pointer. */
mr 3,30
lwz 30,20(1)
addi 1,1,32
blr
/* Special case to copy 0-8 bytes. */
.align 4
.LE8:
mr 12,4
bne cr6,4f
lwz 6,0(4)
lwz 7,4(4)
stw 6,0(3)
stw 7,4(3)
/* Return original dst pointer. */
mr 3,30
lwz 30,20(1)
addi 1,1,32
blr
.align 4
4: bf 29,2b
lwz 6,0(4)
stw 6,0(3)
6:
bf 30,5f
lhz 7,4(4)
sth 7,4(3)
bf 31,0f
lbz 8,6(4)
stb 8,6(3)
mr 3,30
lwz 30,20(1)
addi 1,1,32
blr
.align 4
5:
bf 31,0f
lbz 6,4(4)
stb 6,4(3)
.align 4
0:
/* Return original dst pointer. */
mr 3,30
lwz 30,20(1)
addi 1,1,32
blr
.align 4
.L6:
/* Copy words where the destination is aligned but the source is
not. Use aligned word loads from the source, shifted to realign
the data, to allow aligned destination stores.
Use an unrolled loop to copy 4 words (16-bytes) per iteration.
A single word is retained for storing at loop exit to avoid walking
off the end of a page within the loop.
If the copy is not an exact multiple of 16 bytes, 1-3
words are copied as needed to set up the main loop. After
the main loop exits there may be a tail of 1-3 bytes. These bytes are
copied a halfword/byte at a time as needed to preserve alignment. */
cmplwi cr6,11,0 /* are there tail bytes left ? */
subf 5,10,12 /* back up src pointer to prev word alignment */
slwi 10,10,3 /* calculate number of bits to shift 1st word left */
addi 11,9,-1 /* we move one word after the loop */
srwi 8,11,2 /* calculate the 16 byte loop count */
lwz 6,0(5) /* load 1st src word into R6 */
mr 4,3
lwz 7,4(5) /* load 2nd src word into R7 */
mtcrf 0x01,11
subfic 9,10,32 /* number of bits to shift 2nd word right */
mtctr 8
bf 30,1f
/* there are at least two words to copy, so copy them */
#ifdef __LITTLE_ENDIAN__
srw 0,6,10
slw 8,7,9
#else
slw 0,6,10 /* shift 1st src word to left align it in R0 */
srw 8,7,9 /* shift 2nd src word to right align it in R8 */
#endif
or 0,0,8 /* or them to get word to store */
lwz 6,8(5) /* load the 3rd src word */
stw 0,0(4) /* store the 1st dst word */
#ifdef __LITTLE_ENDIAN__
srw 0,7,10
slw 8,6,9
#else
slw 0,7,10 /* now left align 2nd src word into R0 */
srw 8,6,9 /* shift 3rd src word to right align it in R8 */
#endif
or 0,0,8 /* or them to get word to store */
lwz 7,12(5)
stw 0,4(4) /* store the 2nd dst word */
addi 4,4,8
addi 5,5,16
bf 31,4f
/* there is a third word to copy, so copy it */
#ifdef __LITTLE_ENDIAN__
srw 0,6,10
slw 8,7,9
#else
slw 0,6,10 /* shift 3rd src word to left align it in R0 */
srw 8,7,9 /* shift 4th src word to right align it in R8 */
#endif
or 0,0,8 /* or them to get word to store */
stw 0,0(4) /* store 3rd dst word */
mr 6,7
lwz 7,0(5)
addi 5,5,4
addi 4,4,4
b 4f
.align 4
1:
#ifdef __LITTLE_ENDIAN__
srw 0,6,10
slw 8,7,9
#else
slw 0,6,10 /* shift 1st src word to left align it in R0 */
srw 8,7,9 /* shift 2nd src word to right align it in R8 */
#endif
addi 5,5,8
or 0,0,8 /* or them to get word to store */
bf 31,4f
mr 6,7
lwz 7,0(5)
addi 5,5,4
stw 0,0(4) /* store the 1st dst word */
addi 4,4,4
.align 4
4:
/* copy 16 bytes at a time */
#ifdef __LITTLE_ENDIAN__
srw 0,6,10
slw 8,7,9
#else
slw 0,6,10
srw 8,7,9
#endif
or 0,0,8
lwz 6,0(5)
stw 0,0(4)
#ifdef __LITTLE_ENDIAN__
srw 0,7,10
slw 8,6,9
#else
slw 0,7,10
srw 8,6,9
#endif
or 0,0,8
lwz 7,4(5)
stw 0,4(4)
#ifdef __LITTLE_ENDIAN__
srw 0,6,10
slw 8,7,9
#else
slw 0,6,10
srw 8,7,9
#endif
or 0,0,8
lwz 6,8(5)
stw 0,8(4)
#ifdef __LITTLE_ENDIAN__
srw 0,7,10
slw 8,6,9
#else
slw 0,7,10
srw 8,6,9
#endif
or 0,0,8
lwz 7,12(5)
stw 0,12(4)
addi 5,5,16
addi 4,4,16
bdnz+ 4b
8:
/* calculate and store the final word */
#ifdef __LITTLE_ENDIAN__
srw 0,6,10
slw 8,7,9
#else
slw 0,6,10
srw 8,7,9
#endif
or 0,0,8
stw 0,0(4)
3:
clrrwi 0,31,2
mtcrf 0x01,31
bne cr6,.L9 /* If the tail is 0 bytes we are done! */
/* Return original dst pointer. */
mr 3,30
lwz 30,20(1)
lwz 31,24(1)
addi 1,1,32
blr
END (memcpy)
libc_hidden_builtin_def (memcpy)