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/* Optimized memset implementation for PowerPC64.
Copyright (C) 1997-2025 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>
#include <rtld-global-offsets.h>
.section ".toc","aw"
__GLRO_DEF(dl_cache_line_size)
.section ".text"
.align 2
/* void * [r3] memset (void *s [r3], int c [r4], size_t n [r5]));
Returns 's'.
The memset is done in three sizes: byte (8 bits), word (32 bits),
cache line (256 bits). There is a special case for setting cache lines
to 0, to take advantage of the dcbz instruction. */
#ifndef MEMSET
# define MEMSET memset
#endif
ENTRY (MEMSET, 5)
CALL_MCOUNT 3
#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 rNEG64 r8 /* Constant -64 for clearing with dcbz. */
#define rCLS r8 /* Cache line size obtained from static. */
#define rCLM r9 /* Cache line size mask to check for cache alignment. */
L(_memset):
/* Take care of case for size <= 4. */
cmpldi cr1, rLEN, 8
andi. rALIGN, rMEMP0, 7
mr rMEMP, rMEMP0
ble- cr1, L(small)
/* Align to doubleword boundary. */
cmpldi cr5, rLEN, 31
insrdi rCHR, rCHR, 8, 48 /* Replicate byte to halfword. */
beq+ L(aligned2)
mtcrf 0x01, rMEMP0
subfic rALIGN, rALIGN, 8
cror 28,30,31 /* Detect odd word aligned. */
add rMEMP, rMEMP, rALIGN
sub rLEN, rLEN, rALIGN
insrdi rCHR, rCHR, 16, 32 /* Replicate halfword to word. */
bt 29, L(g4)
/* Process the even word of doubleword. */
bf+ 31, L(g2)
stb rCHR, 0(rMEMP0)
bt 30, L(g4x)
L(g2):
sth rCHR, -6(rMEMP)
L(g4x):
stw rCHR, -4(rMEMP)
b L(aligned)
/* Process the odd word of doubleword. */
L(g4):
bf 28, L(g4x) /* If false, word aligned on odd word. */
bf+ 31, L(g0)
stb rCHR, 0(rMEMP0)
bt 30, L(aligned)
L(g0):
sth rCHR, -2(rMEMP)
/* Handle the case of size < 31. */
L(aligned2):
insrdi rCHR, rCHR, 16, 32 /* Replicate halfword to word. */
L(aligned):
mtcrf 0x01, rLEN
ble cr5, L(medium)
/* Align to 32-byte boundary. */
andi. rALIGN, rMEMP, 0x18
subfic rALIGN, rALIGN, 0x20
insrdi rCHR, rCHR, 32, 0 /* Replicate word to double word. */
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)
stdu rCHR, -8(rMEMP2)
L(a1): blt cr1, L(a2)
std rCHR, -8(rMEMP2)
stdu rCHR, -16(rMEMP2)
L(a2):
/* Now aligned to a 32 byte boundary. */
L(caligned):
cmpldi cr1, rCHR, 0
clrrdi. rALIGN, rLEN, 5
mtcrf 0x01, rLEN
beq cr1, L(zloopstart) /* Special case for clearing memory using dcbz. */
L(nondcbz):
srdi rTMP, rALIGN, 5
mtctr rTMP
beq L(medium) /* We may not actually get to do a full line. */
clrldi. rLEN, rLEN, 59
add rMEMP, rMEMP, rALIGN
li rNEG64, -0x40
bdz L(cloopdone)
L(c3): dcbtst rNEG64, rMEMP
std rCHR, -8(rMEMP)
std rCHR, -16(rMEMP)
std rCHR, -24(rMEMP)
stdu rCHR, -32(rMEMP)
bdnz L(c3)
L(cloopdone):
std rCHR, -8(rMEMP)
std rCHR, -16(rMEMP)
cmpldi cr1, rLEN, 16
std rCHR, -24(rMEMP)
stdu rCHR, -32(rMEMP)
beqlr
add rMEMP, rMEMP, rALIGN
b L(medium_tail2)
.align 5
/* Clear lines of memory in 128-byte chunks. */
L(zloopstart):
/* If the remaining length is less the 32 bytes, don't bother getting
the cache line size. */
beq L(medium)
/* Read the cache line size. */
__GLRO (rCLS, dl_cache_line_size,
RTLD_GLOBAL_RO_DL_CACHE_LINE_SIZE_OFFSET)
/* If the cache line size was not set just goto to L(nondcbz) which is
safe for any cache line size. */
cmpldi cr1,rCLS,0
beq cr1,L(nondcbz)
/* Now we know the cache line size, and it is not 32-bytes, but
we may not yet be aligned to the cache line. May have a partial
line to fill, so touch it 1st. */
dcbt 0,rMEMP
addi rCLM,rCLS,-1
L(getCacheAligned):
cmpldi cr1,rLEN,32
and. rTMP,rCLM,rMEMP
blt cr1,L(handletail32)
beq L(cacheAligned)
addi rMEMP,rMEMP,32
addi rLEN,rLEN,-32
std rCHR,-32(rMEMP)
std rCHR,-24(rMEMP)
std rCHR,-16(rMEMP)
std rCHR,-8(rMEMP)
b L(getCacheAligned)
/* Now we are aligned to the cache line and can use dcbz. */
L(cacheAligned):
cmpld 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 and was not 32-bytes
and the remainder (rLEN) is less than the actual cache line size.
So set up the preconditions for L(nondcbz) and go there. */
L(handletail32):
clrrwi. rALIGN, rLEN, 5
b L(nondcbz)
.align 5
L(small):
/* Memset of 8 bytes or less. */
cmpldi cr6, rLEN, 4
cmpldi cr5, rLEN, 1
ble cr6,L(le4)
subi rLEN, rLEN, 4
stb rCHR,0(rMEMP)
stb rCHR,1(rMEMP)
stb rCHR,2(rMEMP)
stb rCHR,3(rMEMP)
addi rMEMP,rMEMP, 4
cmpldi cr5, rLEN, 1
L(le4):
cmpldi cr1, rLEN, 3
bltlr cr5
stb rCHR, 0(rMEMP)
beqlr cr5
stb rCHR, 1(rMEMP)
bltlr cr1
stb rCHR, 2(rMEMP)
beqlr cr1
stb rCHR, 3(rMEMP)
blr
/* Memset of 0-31 bytes. */
.align 5
L(medium):
insrdi rCHR, rCHR, 32, 0 /* Replicate word to double word. */
cmpldi 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
std 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)
L(medium_27t):
std rCHR, -8(rMEMP)
stdu rCHR, -16(rMEMP)
L(medium_27f):
bflr- 28
L(medium_28t):
std rCHR, -8(rMEMP)
blr
END_GEN_TB (MEMSET,TB_TOCLESS)
libc_hidden_builtin_def (memset)
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