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/* Optimized memset for Fujitsu A64FX processor.
Copyright (C) 2021-2022 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 <sysdeps/aarch64/memset-reg.h>
/* Assumptions:
*
* ARMv8.2-a, AArch64, unaligned accesses, sve
*
*/
#define L1_SIZE (64*1024) // L1 64KB
#define L2_SIZE (8*1024*1024) // L2 8MB
#define CACHE_LINE_SIZE 256
#define PF_DIST_L1 (CACHE_LINE_SIZE * 16) // Prefetch distance L1
#define vector_length x9
#if HAVE_AARCH64_SVE_ASM
# if IS_IN (libc)
# define MEMSET __memset_a64fx
.arch armv8.2-a+sve
.macro st1b_unroll first=0, last=7
st1b z0.b, p0, [dst, \first, mul vl]
.if \last-\first
st1b_unroll "(\first+1)", \last
.endif
.endm
#undef BTI_C
#define BTI_C
ENTRY (MEMSET)
PTR_ARG (0)
SIZE_ARG (2)
cntb vector_length
dup z0.b, valw
whilelo p0.b, vector_length, count
b.last 1f
whilelo p1.b, xzr, count
st1b z0.b, p1, [dstin, 0, mul vl]
st1b z0.b, p0, [dstin, 1, mul vl]
ret
// count >= vector_length * 2
1: cmp count, vector_length, lsl 2
add dstend, dstin, count
b.hi 1f
st1b z0.b, p0, [dstin, 0, mul vl]
st1b z0.b, p0, [dstin, 1, mul vl]
st1b z0.b, p0, [dstend, -2, mul vl]
st1b z0.b, p0, [dstend, -1, mul vl]
ret
// count > vector_length * 4
1: lsl tmp1, vector_length, 3
cmp count, tmp1
b.hi L(vl_agnostic)
st1b z0.b, p0, [dstin, 0, mul vl]
st1b z0.b, p0, [dstin, 1, mul vl]
st1b z0.b, p0, [dstin, 2, mul vl]
st1b z0.b, p0, [dstin, 3, mul vl]
st1b z0.b, p0, [dstend, -4, mul vl]
st1b z0.b, p0, [dstend, -3, mul vl]
st1b z0.b, p0, [dstend, -2, mul vl]
st1b z0.b, p0, [dstend, -1, mul vl]
ret
.p2align 4
L(vl_agnostic): // VL Agnostic
mov dst, dstin
cmp count, L1_SIZE
b.hi L(L1_prefetch)
// count >= 8 * vector_length
L(unroll8):
sub count, count, tmp1
.p2align 4
// The 2 instructions at the beginning of the following loop,
// cmp and branch, are a workaround so as not to degrade at
// the peak performance 16KB.
// It is found heuristically and the branch condition, b.ne,
// is chosen intentionally never to jump.
1: cmp xzr, xzr
b.ne 1b
st1b_unroll 0, 7
add dst, dst, tmp1
subs count, count, tmp1
b.hi 1b
add count, count, tmp1
L(last):
cmp count, vector_length, lsl 1
b.ls 2f
add tmp2, vector_length, vector_length, lsl 2
cmp count, tmp2
b.ls 5f
st1b z0.b, p0, [dstend, -8, mul vl]
st1b z0.b, p0, [dstend, -7, mul vl]
st1b z0.b, p0, [dstend, -6, mul vl]
5: st1b z0.b, p0, [dstend, -5, mul vl]
st1b z0.b, p0, [dstend, -4, mul vl]
st1b z0.b, p0, [dstend, -3, mul vl]
2: st1b z0.b, p0, [dstend, -2, mul vl]
st1b z0.b, p0, [dstend, -1, mul vl]
ret
// count >= L1_SIZE
.p2align 3
L(L1_prefetch):
cmp count, L2_SIZE
b.hs L(L2)
cmp vector_length, 64
b.ne L(unroll8)
1: st1b_unroll 0, 3
prfm pstl1keep, [dst, PF_DIST_L1]
st1b_unroll 4, 7
prfm pstl1keep, [dst, PF_DIST_L1 + CACHE_LINE_SIZE]
add dst, dst, CACHE_LINE_SIZE * 2
sub count, count, CACHE_LINE_SIZE * 2
cmp count, PF_DIST_L1
b.hs 1b
b L(unroll8)
// count >= L2_SIZE
.p2align 3
L(L2):
tst valw, 255
b.ne L(unroll8)
// align dst to CACHE_LINE_SIZE byte boundary
and tmp2, dst, CACHE_LINE_SIZE - 1
st1b z0.b, p0, [dst, 0, mul vl]
st1b z0.b, p0, [dst, 1, mul vl]
st1b z0.b, p0, [dst, 2, mul vl]
st1b z0.b, p0, [dst, 3, mul vl]
sub dst, dst, tmp2
add count, count, tmp2
// clear cachelines using DC ZVA
sub count, count, CACHE_LINE_SIZE * 2
.p2align 4
1: add dst, dst, CACHE_LINE_SIZE
dc zva, dst
subs count, count, CACHE_LINE_SIZE
b.hi 1b
add count, count, CACHE_LINE_SIZE
b L(last)
END (MEMSET)
libc_hidden_builtin_def (MEMSET)
#endif /* IS_IN (libc) */
#endif /* HAVE_AARCH64_SVE_ASM */
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