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/* Optimized memset implementation for PowerPC.
Copyright (C) 1997-2019 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/>. */
#include <sysdep.h>
/* void * [r3] memset (void *s [r3], int c [r4], size_t n [r5]));
Returns 's'.
The memset is done in four sizes: byte (8 bits), word (32 bits),
32-byte blocks (256 bits) and __cache_line_size (128, 256, 1024 bits).
There is a special case for setting whole cache lines to 0, which
takes advantage of the dcbz instruction. */
.section ".text"
EALIGN (memset, 5, 1)
#define rTMP r0
#define rRTN r3 /* initial value of 1st argument */
#define rMEMP0 r3 /* original value of 1st arg */
#define rCHR r4 /* char to set in each byte */
#define rLEN r5 /* length of region to set */
#define rMEMP r6 /* address at which we are storing */
#define rALIGN r7 /* number of bytes we are setting now (when aligning) */
#define rMEMP2 r8
#define rPOS32 r7 /* constant +32 for clearing with dcbz */
#define rNEG64 r8 /* constant -64 for clearing with dcbz */
#define rNEG32 r9 /* constant -32 for clearing with dcbz */
#define rGOT r9 /* Address of the Global Offset Table. */
#define rCLS r8 /* Cache line size obtained from static. */
#define rCLM r9 /* Cache line size mask to check for cache alignment. */
/* take care of case for size <= 4 */
cmplwi cr1, rLEN, 4
andi. rALIGN, rMEMP0, 3
mr rMEMP, rMEMP0
ble- cr1, L(small)
/* align to word boundary */
cmplwi cr5, rLEN, 31
rlwimi rCHR, rCHR, 8, 16, 23
beq+ L(aligned) /* 8th instruction from .align */
mtcrf 0x01, rMEMP0
subfic rALIGN, rALIGN, 4
add rMEMP, rMEMP, rALIGN
sub rLEN, rLEN, rALIGN
bf+ 31, L(g0)
stb rCHR, 0(rMEMP0)
bt 30, L(aligned)
L(g0): sth rCHR, -2(rMEMP) /* 16th instruction from .align */
/* take care of case for size < 31 */
L(aligned):
mtcrf 0x01, rLEN
rlwimi rCHR, rCHR, 16, 0, 15
ble cr5, L(medium)
/* align to cache line boundary... */
andi. rALIGN, rMEMP, 0x1C
subfic rALIGN, rALIGN, 0x20
beq L(caligned)
mtcrf 0x01, rALIGN
add rMEMP, rMEMP, rALIGN
sub rLEN, rLEN, rALIGN
cmplwi cr1, rALIGN, 0x10
mr rMEMP2, rMEMP
bf 28, L(a1)
stw rCHR, -4(rMEMP2)
stwu rCHR, -8(rMEMP2)
L(a1): blt cr1, L(a2)
stw rCHR, -4(rMEMP2) /* 32nd instruction from .align */
stw rCHR, -8(rMEMP2)
stw rCHR, -12(rMEMP2)
stwu rCHR, -16(rMEMP2)
L(a2): bf 29, L(caligned)
stw rCHR, -4(rMEMP2)
/* now aligned to a cache line. */
L(caligned):
cmplwi cr1, rCHR, 0
clrrwi. rALIGN, rLEN, 5
mtcrf 0x01, rLEN /* 40th instruction from .align */
/* Check if we can use the special case for clearing memory using dcbz.
This requires that we know the correct cache line size for this
processor. Getting the __cache_line_size may require establishing GOT
addressability, so branch out of line to set this up. */
beq cr1, L(checklinesize)
/* Store blocks of 32-bytes (256-bits) starting on a 32-byte boundary.
Can't assume that rCHR is zero or that the cache line size is either
32-bytes or even known. */
L(nondcbz):
srwi rTMP, rALIGN, 5
mtctr rTMP
beq L(medium) /* we may not actually get to do a full line */
clrlwi. rLEN, rLEN, 27
add rMEMP, rMEMP, rALIGN
li rNEG64, -0x40
bdz L(cloopdone) /* 48th instruction from .align */
/* We can't use dcbz here as we don't know the cache line size. We can
use "data cache block touch for store", which is safe. */
L(c3): dcbtst rNEG64, rMEMP
stw rCHR, -4(rMEMP)
stw rCHR, -8(rMEMP)
stw rCHR, -12(rMEMP)
stw rCHR, -16(rMEMP)
nop /* let 601 fetch last 4 instructions of loop */
stw rCHR, -20(rMEMP)
stw rCHR, -24(rMEMP) /* 56th instruction from .align */
nop /* let 601 fetch first 8 instructions of loop */
stw rCHR, -28(rMEMP)
stwu rCHR, -32(rMEMP)
bdnz L(c3)
L(cloopdone):
stw rCHR, -4(rMEMP)
stw rCHR, -8(rMEMP)
stw rCHR, -12(rMEMP)
stw rCHR, -16(rMEMP) /* 64th instruction from .align */
stw rCHR, -20(rMEMP)
cmplwi cr1, rLEN, 16
stw rCHR, -24(rMEMP)
stw rCHR, -28(rMEMP)
stwu rCHR, -32(rMEMP)
beqlr
add rMEMP, rMEMP, rALIGN
b L(medium_tail2) /* 72nd instruction from .align */
.align 5
nop
/* Clear cache lines of memory in 128-byte chunks.
This code is optimized for processors with 32-byte cache lines.
It is further optimized for the 601 processor, which requires
some care in how the code is aligned in the i-cache. */
L(zloopstart):
clrlwi rLEN, rLEN, 27
mtcrf 0x02, rALIGN
srwi. rTMP, rALIGN, 7
mtctr rTMP
li rPOS32, 0x20
li rNEG64, -0x40
cmplwi cr1, rLEN, 16 /* 8 */
bf 26, L(z0)
dcbz 0, rMEMP
addi rMEMP, rMEMP, 0x20
L(z0): li rNEG32, -0x20
bf 25, L(z1)
dcbz 0, rMEMP
dcbz rPOS32, rMEMP
addi rMEMP, rMEMP, 0x40 /* 16 */
L(z1): cmplwi cr5, rLEN, 0
beq L(medium)
L(zloop):
dcbz 0, rMEMP
dcbz rPOS32, rMEMP
addi rMEMP, rMEMP, 0x80
dcbz rNEG64, rMEMP
dcbz rNEG32, rMEMP
bdnz L(zloop)
beqlr cr5
b L(medium_tail2)
.align 5
L(small):
/* Memset of 4 bytes or less. */
cmplwi cr5, rLEN, 1
cmplwi cr1, rLEN, 3
bltlr cr5
stb rCHR, 0(rMEMP)
beqlr cr5
nop
stb rCHR, 1(rMEMP)
bltlr cr1
stb rCHR, 2(rMEMP)
beqlr cr1
nop
stb rCHR, 3(rMEMP)
blr
/* Memset of 0-31 bytes. */
.align 5
L(medium):
cmplwi cr1, rLEN, 16
L(medium_tail2):
add rMEMP, rMEMP, rLEN
L(medium_tail):
bt- 31, L(medium_31t)
bt- 30, L(medium_30t)
L(medium_30f):
bt- 29, L(medium_29t)
L(medium_29f):
bge- cr1, L(medium_27t)
bflr- 28
stw rCHR, -4(rMEMP) /* 8th instruction from .align */
stw rCHR, -8(rMEMP)
blr
L(medium_31t):
stbu rCHR, -1(rMEMP)
bf- 30, L(medium_30f)
L(medium_30t):
sthu rCHR, -2(rMEMP)
bf- 29, L(medium_29f)
L(medium_29t):
stwu rCHR, -4(rMEMP)
blt- cr1, L(medium_27f) /* 16th instruction from .align */
L(medium_27t):
stw rCHR, -4(rMEMP)
stw rCHR, -8(rMEMP)
stw rCHR, -12(rMEMP)
stwu rCHR, -16(rMEMP)
L(medium_27f):
bflr- 28
L(medium_28t):
stw rCHR, -4(rMEMP)
stw rCHR, -8(rMEMP)
blr
L(checklinesize):
#ifdef SHARED
mflr rTMP
/* If the remaining length is less the 32 bytes then don't bother getting
the cache line size. */
beq L(medium)
/* Establishes GOT addressability so we can load __cache_line_size
from static. This value was set from the aux vector during startup. */
SETUP_GOT_ACCESS(rGOT,got_label)
addis rGOT,rGOT,__cache_line_size-got_label@ha
lwz rCLS,__cache_line_size-got_label@l(rGOT)
mtlr rTMP
#else
/* Load __cache_line_size from static. This value was set from the
aux vector during startup. */
lis rCLS,__cache_line_size@ha
/* If the remaining length is less the 32 bytes then don't bother getting
the cache line size. */
beq L(medium)
lwz rCLS,__cache_line_size@l(rCLS)
#endif
/* If the cache line size was not set then goto to L(nondcbz), which is
safe for any cache line size. */
cmplwi cr1,rCLS,0
beq cr1,L(nondcbz)
/* If the cache line size is 32 bytes then goto to L(zloopstart),
which is coded specifically for 32-byte lines (and 601). */
cmplwi cr1,rCLS,32
beq cr1,L(zloopstart)
/* Now we know the cache line size and it is not 32-bytes. However
we may not yet be aligned to the cache line and may have a partial
line to fill. Touch it 1st to fetch the cache line. */
dcbtst 0,rMEMP
addi rCLM,rCLS,-1
L(getCacheAligned):
cmplwi cr1,rLEN,32
and. rTMP,rCLM,rMEMP
blt cr1,L(handletail32)
beq L(cacheAligned)
/* We are not aligned to start of a cache line yet. Store 32-byte
of data and test again. */
addi rMEMP,rMEMP,32
addi rLEN,rLEN,-32
stw rCHR,-32(rMEMP)
stw rCHR,-28(rMEMP)
stw rCHR,-24(rMEMP)
stw rCHR,-20(rMEMP)
stw rCHR,-16(rMEMP)
stw rCHR,-12(rMEMP)
stw rCHR,-8(rMEMP)
stw rCHR,-4(rMEMP)
b L(getCacheAligned)
/* Now we are aligned to the cache line and can use dcbz. */
L(cacheAligned):
cmplw cr1,rLEN,rCLS
blt cr1,L(handletail32)
dcbz 0,rMEMP
subf rLEN,rCLS,rLEN
add rMEMP,rMEMP,rCLS
b L(cacheAligned)
/* We are here because; the cache line size was set, it was not
32-bytes, and the remainder (rLEN) is now less than the actual cache
line size. Set up the preconditions for L(nondcbz) and go there to
store the remaining bytes. */
L(handletail32):
clrrwi. rALIGN, rLEN, 5
b L(nondcbz)
END (memset)
libc_hidden_builtin_def (memset)
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