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ARCv2: lib: introduce memcpy optimized for unaligned access 

Optimise code to use efficient unaligned memory access which is
available on ARCv2. This allows us to really simplify memcpy code
and speed up the code one and a half times (in case of unaligned
source or destination).

Don't wire it up yet !

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Eugeniy Paltsev 2019-01-30 19:32:43 +03:00 committed by Vineet Gupta
parent 5d4ab8d096
commit 4d1e7918aa
1 changed files with 47 additions and 0 deletions
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arch/arc/lib/memcpy-archs-unaligned.S Normal file
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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* ARCv2 memcpy implementation optimized for unaligned memory access using.
*
* Copyright (C) 2019 Synopsys
* Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
*/
#include <linux/linkage.h>
#ifdef CONFIG_ARC_HAS_LL64
# define LOADX(DST,RX) ldd.ab DST, [RX, 8]
# define STOREX(SRC,RX) std.ab SRC, [RX, 8]
# define ZOLSHFT 5
# define ZOLAND 0x1F
#else
# define LOADX(DST,RX) ld.ab DST, [RX, 4]
# define STOREX(SRC,RX) st.ab SRC, [RX, 4]
# define ZOLSHFT 4
# define ZOLAND 0xF
#endif
ENTRY_CFI(memcpy)
mov r3, r0 ; don;t clobber ret val
lsr.f lp_count, r2, ZOLSHFT
lpnz @.Lcopy32_64bytes
;; LOOP START
LOADX (r6, r1)
LOADX (r8, r1)
LOADX (r10, r1)
LOADX (r4, r1)
STOREX (r6, r3)
STOREX (r8, r3)
STOREX (r10, r3)
STOREX (r4, r3)
.Lcopy32_64bytes:
and.f lp_count, r2, ZOLAND ;Last remaining 31 bytes
lpnz @.Lcopyremainingbytes
;; LOOP START
ldb.ab r5, [r1, 1]
stb.ab r5, [r3, 1]
.Lcopyremainingbytes:
j [blink]
END_CFI(memcpy)