178 lines
4.0 KiB
ArmAsm
178 lines
4.0 KiB
ArmAsm
/*
|
|
* memcpy - copy memory area
|
|
*
|
|
* Copyright (c) 2019-2023, Arm Limited.
|
|
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
|
|
*/
|
|
|
|
/* Assumptions:
|
|
*
|
|
* ARMv8-a, AArch64, Advanced SIMD, SVE, unaligned accesses.
|
|
*
|
|
*/
|
|
|
|
#include "asmdefs.h"
|
|
|
|
#ifdef HAVE_SVE
|
|
|
|
.arch armv8-a+sve
|
|
|
|
#define dstin x0
|
|
#define src x1
|
|
#define count x2
|
|
#define dst x3
|
|
#define srcend x4
|
|
#define dstend x5
|
|
#define tmp1 x6
|
|
#define vlen x6
|
|
|
|
#define A_q q0
|
|
#define B_q q1
|
|
#define C_q q2
|
|
#define D_q q3
|
|
#define E_q q4
|
|
#define F_q q5
|
|
#define G_q q6
|
|
#define H_q q7
|
|
|
|
/* This implementation handles overlaps and supports both memcpy and memmove
|
|
from a single entry point. It uses unaligned accesses and branchless
|
|
sequences to keep the code small, simple and improve performance.
|
|
SVE vectors are used to speedup small copies.
|
|
|
|
Copies are split into 3 main cases: small copies of up to 32 bytes, medium
|
|
copies of up to 128 bytes, and large copies. The overhead of the overlap
|
|
check is negligible since it is only required for large copies.
|
|
|
|
Large copies use a software pipelined loop processing 64 bytes per iteration.
|
|
The source pointer is 16-byte aligned to minimize unaligned accesses.
|
|
The loop tail is handled by always copying 64 bytes from the end.
|
|
*/
|
|
|
|
ENTRY_ALIAS (__memmove_aarch64_sve)
|
|
ENTRY (__memcpy_aarch64_sve)
|
|
PTR_ARG (0)
|
|
PTR_ARG (1)
|
|
SIZE_ARG (2)
|
|
|
|
cmp count, 128
|
|
b.hi L(copy_long)
|
|
cntb vlen
|
|
cmp count, vlen, lsl 1
|
|
b.hi L(copy32_128)
|
|
|
|
whilelo p0.b, xzr, count
|
|
whilelo p1.b, vlen, count
|
|
ld1b z0.b, p0/z, [src, 0, mul vl]
|
|
ld1b z1.b, p1/z, [src, 1, mul vl]
|
|
st1b z0.b, p0, [dstin, 0, mul vl]
|
|
st1b z1.b, p1, [dstin, 1, mul vl]
|
|
ret
|
|
|
|
/* Medium copies: 33..128 bytes. */
|
|
L(copy32_128):
|
|
add srcend, src, count
|
|
add dstend, dstin, count
|
|
ldp A_q, B_q, [src]
|
|
ldp C_q, D_q, [srcend, -32]
|
|
cmp count, 64
|
|
b.hi L(copy128)
|
|
stp A_q, B_q, [dstin]
|
|
stp C_q, D_q, [dstend, -32]
|
|
ret
|
|
|
|
/* Copy 65..128 bytes. */
|
|
L(copy128):
|
|
ldp E_q, F_q, [src, 32]
|
|
cmp count, 96
|
|
b.ls L(copy96)
|
|
ldp G_q, H_q, [srcend, -64]
|
|
stp G_q, H_q, [dstend, -64]
|
|
L(copy96):
|
|
stp A_q, B_q, [dstin]
|
|
stp E_q, F_q, [dstin, 32]
|
|
stp C_q, D_q, [dstend, -32]
|
|
ret
|
|
|
|
/* Copy more than 128 bytes. */
|
|
L(copy_long):
|
|
add srcend, src, count
|
|
add dstend, dstin, count
|
|
|
|
/* Use backwards copy if there is an overlap. */
|
|
sub tmp1, dstin, src
|
|
cmp tmp1, count
|
|
b.lo L(copy_long_backwards)
|
|
|
|
/* Copy 16 bytes and then align src to 16-byte alignment. */
|
|
ldr D_q, [src]
|
|
and tmp1, src, 15
|
|
bic src, src, 15
|
|
sub dst, dstin, tmp1
|
|
add count, count, tmp1 /* Count is now 16 too large. */
|
|
ldp A_q, B_q, [src, 16]
|
|
str D_q, [dstin]
|
|
ldp C_q, D_q, [src, 48]
|
|
subs count, count, 128 + 16 /* Test and readjust count. */
|
|
b.ls L(copy64_from_end)
|
|
L(loop64):
|
|
stp A_q, B_q, [dst, 16]
|
|
ldp A_q, B_q, [src, 80]
|
|
stp C_q, D_q, [dst, 48]
|
|
ldp C_q, D_q, [src, 112]
|
|
add src, src, 64
|
|
add dst, dst, 64
|
|
subs count, count, 64
|
|
b.hi L(loop64)
|
|
|
|
/* Write the last iteration and copy 64 bytes from the end. */
|
|
L(copy64_from_end):
|
|
ldp E_q, F_q, [srcend, -64]
|
|
stp A_q, B_q, [dst, 16]
|
|
ldp A_q, B_q, [srcend, -32]
|
|
stp C_q, D_q, [dst, 48]
|
|
stp E_q, F_q, [dstend, -64]
|
|
stp A_q, B_q, [dstend, -32]
|
|
ret
|
|
|
|
/* Large backwards copy for overlapping copies.
|
|
Copy 16 bytes and then align srcend to 16-byte alignment. */
|
|
L(copy_long_backwards):
|
|
cbz tmp1, L(return)
|
|
ldr D_q, [srcend, -16]
|
|
and tmp1, srcend, 15
|
|
bic srcend, srcend, 15
|
|
sub count, count, tmp1
|
|
ldp A_q, B_q, [srcend, -32]
|
|
str D_q, [dstend, -16]
|
|
ldp C_q, D_q, [srcend, -64]
|
|
sub dstend, dstend, tmp1
|
|
subs count, count, 128
|
|
b.ls L(copy64_from_start)
|
|
|
|
L(loop64_backwards):
|
|
str B_q, [dstend, -16]
|
|
str A_q, [dstend, -32]
|
|
ldp A_q, B_q, [srcend, -96]
|
|
str D_q, [dstend, -48]
|
|
str C_q, [dstend, -64]!
|
|
ldp C_q, D_q, [srcend, -128]
|
|
sub srcend, srcend, 64
|
|
subs count, count, 64
|
|
b.hi L(loop64_backwards)
|
|
|
|
/* Write the last iteration and copy 64 bytes from the start. */
|
|
L(copy64_from_start):
|
|
ldp E_q, F_q, [src, 32]
|
|
stp A_q, B_q, [dstend, -32]
|
|
ldp A_q, B_q, [src]
|
|
stp C_q, D_q, [dstend, -64]
|
|
stp E_q, F_q, [dstin, 32]
|
|
stp A_q, B_q, [dstin]
|
|
L(return):
|
|
ret
|
|
|
|
END (__memcpy_aarch64_sve)
|
|
|
|
#endif
|