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/* Optimized memcpy implementation for CELL BE PowerPC.
Copyright (C) 2010-2021 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>
#ifndef MEMCPY
# define MEMCPY memcpy
#endif
#define PREFETCH_AHEAD 6 /* no cache lines SRC prefetching ahead */
#define ZERO_AHEAD 4 /* no cache lines DST zeroing ahead */
/* memcpy routine optimized for CELL-BE-PPC v2.0
*
* The CELL PPC core has 1 integer unit and 1 load/store unit
* CELL:
* 1st level data cache = 32K
* 2nd level data cache = 512K
* 3rd level data cache = 0K
* With 3.2 GHz clockrate the latency to 2nd level cache is >36 clocks,
* latency to memory is >400 clocks
* To improve copy performance we need to prefetch source data
* far ahead to hide this latency
* For best performance instruction forms ending in "." like "andi."
* should be avoided as the are implemented in microcode on CELL.
* The below code is loop unrolled for the CELL cache line of 128 bytes
*/
.align 7
ENTRY_TOCLESS (MEMCPY, 5)
CALL_MCOUNT 3
dcbt 0,r4 /* Prefetch ONE SRC cacheline */
cmpldi cr1,r5,16 /* is size < 16 ? */
mr r6,r3
blt+ cr1,.Lshortcopy
.Lbigcopy:
neg r8,r3 /* LS 3 bits = # bytes to 8-byte dest bdry */
clrldi r8,r8,64-4 /* align to 16byte boundary */
sub r7,r4,r3
cmpldi cr0,r8,0
beq+ .Ldst_aligned
.Ldst_unaligned:
mtcrf 0x01,r8 /* put #bytes to boundary into cr7 */
subf r5,r8,r5
bf cr7*4+3,1f
lbzx r0,r7,r6 /* copy 1 byte */
stb r0,0(r6)
addi r6,r6,1
1: bf cr7*4+2,2f
lhzx r0,r7,r6 /* copy 2 byte */
sth r0,0(r6)
addi r6,r6,2
2: bf cr7*4+1,4f
lwzx r0,r7,r6 /* copy 4 byte */
stw r0,0(r6)
addi r6,r6,4
4: bf cr7*4+0,8f
ldx r0,r7,r6 /* copy 8 byte */
std r0,0(r6)
addi r6,r6,8
8:
add r4,r7,r6
.Ldst_aligned:
cmpdi cr5,r5,128-1
neg r7,r6
addi r6,r6,-8 /* prepare for stdu */
addi r4,r4,-8 /* prepare for ldu */
clrldi r7,r7,64-7 /* align to cacheline boundary */
ble+ cr5,.Llessthancacheline
cmpldi cr6,r7,0
subf r5,r7,r5
srdi r7,r7,4 /* divide size by 16 */
srdi r10,r5,7 /* number of cache lines to copy */
cmpldi r10,0
li r11,0 /* number cachelines to copy with prefetch */
beq .Lnocacheprefetch
cmpldi r10,PREFETCH_AHEAD
li r12,128+8 /* prefetch distance */
ble .Llessthanmaxprefetch
subi r11,r10,PREFETCH_AHEAD
li r10,PREFETCH_AHEAD
.Llessthanmaxprefetch:
mtctr r10
.LprefetchSRC:
dcbt r12,r4
addi r12,r12,128
bdnz .LprefetchSRC
.Lnocacheprefetch:
mtctr r7
cmpldi cr1,r5,128
clrldi r5,r5,64-7
beq cr6,.Lcachelinealigned
.Laligntocacheline:
ld r9,0x08(r4)
ldu r7,0x10(r4)
std r9,0x08(r6)
stdu r7,0x10(r6)
bdnz .Laligntocacheline
.Lcachelinealigned: /* copy while cache lines */
blt- cr1,.Llessthancacheline /* size <128 */
.Louterloop:
cmpdi r11,0
mtctr r11
beq- .Lendloop
li r11,128*ZERO_AHEAD +8 /* DCBZ dist */
.align 4
/* Copy whole cachelines, optimized by prefetching SRC cacheline */
.Lloop: /* Copy aligned body */
dcbt r12,r4 /* PREFETCH SOURCE some cache lines ahead */
ld r9, 0x08(r4)
dcbz r11,r6
ld r7, 0x10(r4) /* 4 register stride copy is optimal */
ld r8, 0x18(r4) /* to hide 1st level cache latency. */
ld r0, 0x20(r4)
std r9, 0x08(r6)
std r7, 0x10(r6)
std r8, 0x18(r6)
std r0, 0x20(r6)
ld r9, 0x28(r4)
ld r7, 0x30(r4)
ld r8, 0x38(r4)
ld r0, 0x40(r4)
std r9, 0x28(r6)
std r7, 0x30(r6)
std r8, 0x38(r6)
std r0, 0x40(r6)
ld r9, 0x48(r4)
ld r7, 0x50(r4)
ld r8, 0x58(r4)
ld r0, 0x60(r4)
std r9, 0x48(r6)
std r7, 0x50(r6)
std r8, 0x58(r6)
std r0, 0x60(r6)
ld r9, 0x68(r4)
ld r7, 0x70(r4)
ld r8, 0x78(r4)
ldu r0, 0x80(r4)
std r9, 0x68(r6)
std r7, 0x70(r6)
std r8, 0x78(r6)
stdu r0, 0x80(r6)
bdnz .Lloop
.Lendloop:
cmpdi r10,0
sldi r10,r10,2 /* adjust from 128 to 32 byte stride */
beq- .Lendloop2
mtctr r10
.Lloop2: /* Copy aligned body */
ld r9, 0x08(r4)
ld r7, 0x10(r4)
ld r8, 0x18(r4)
ldu r0, 0x20(r4)
std r9, 0x08(r6)
std r7, 0x10(r6)
std r8, 0x18(r6)
stdu r0, 0x20(r6)
bdnz .Lloop2
.Lendloop2:
.Llessthancacheline: /* less than cache to do ? */
cmpldi cr0,r5,16
srdi r7,r5,4 /* divide size by 16 */
blt- .Ldo_lt16
mtctr r7
.Lcopy_remaining:
ld r8,0x08(r4)
ldu r7,0x10(r4)
std r8,0x08(r6)
stdu r7,0x10(r6)
bdnz .Lcopy_remaining
.Ldo_lt16: /* less than 16 ? */
cmpldi cr0,r5,0 /* copy remaining bytes (0-15) */
beqlr+ /* no rest to copy */
addi r4,r4,8
addi r6,r6,8
.Lshortcopy: /* SIMPLE COPY to handle size =< 15 bytes */
mtcrf 0x01,r5
sub r7,r4,r6
bf- cr7*4+0,8f
ldx r0,r7,r6 /* copy 8 byte */
std r0,0(r6)
addi r6,r6,8
8:
bf cr7*4+1,4f
lwzx r0,r7,r6 /* copy 4 byte */
stw r0,0(r6)
addi r6,r6,4
4:
bf cr7*4+2,2f
lhzx r0,r7,r6 /* copy 2 byte */
sth r0,0(r6)
addi r6,r6,2
2:
bf cr7*4+3,1f
lbzx r0,r7,r6 /* copy 1 byte */
stb r0,0(r6)
1: blr
END_GEN_TB (MEMCPY,TB_TOCLESS)
libc_hidden_builtin_def (memcpy)
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