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SubjectRe: [PATCH 5/5] ARCv2: LIB: MEMCPY: fixed and optimised routine
Date
On 1/29/19 2:49 AM, Eugeniy Paltsev wrote:
> 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).
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
> arch/arc/Kconfig | 4 +++
> arch/arc/lib/Makefile | 5 +++-
> arch/arc/lib/memcpy-archs-unaligned.S | 46 +++++++++++++++++++++++++++++++++++
> 3 files changed, 54 insertions(+), 1 deletion(-)
> create mode 100644 arch/arc/lib/memcpy-archs-unaligned.S
>
> diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
> index a1d976c612a6..88f1a3205b8f 100644
> --- a/arch/arc/Kconfig
> +++ b/arch/arc/Kconfig
> @@ -396,6 +396,10 @@ config ARC_USE_UNALIGNED_MEM_ACCESS
> which is disabled by default. Enable unaligned access in
> hardware and use it in software.
>
> +#dummy symbol for using in makefile
> +config ARC_NO_UNALIGNED_MEM_ACCESS
> + def_bool !ARC_USE_UNALIGNED_MEM_ACCESS
> +

Not needed - you can use the kconfig symbols in Makefile.
See arch/arc/kernel/Makefile

> config ARC_HAS_LL64
> bool "Insn: 64bit LDD/STD"
> help
> diff --git a/arch/arc/lib/Makefile b/arch/arc/lib/Makefile
> index b1656d156097..59cc8b61342e 100644
> --- a/arch/arc/lib/Makefile
> +++ b/arch/arc/lib/Makefile
> @@ -8,4 +8,7 @@
> lib-y := strchr-700.o strcpy-700.o strlen.o memcmp.o
>
> lib-$(CONFIG_ISA_ARCOMPACT) += memcpy-700.o memset.o strcmp.o
> -lib-$(CONFIG_ISA_ARCV2) += memcpy-archs.o memset-archs.o strcmp-archs.o
> +lib-$(CONFIG_ISA_ARCV2) += memset-archs.o strcmp-archs.o
> +
> +lib-$(CONFIG_ARC_NO_UNALIGNED_MEM_ACCESS) += memcpy-archs.o
> +lib-$(CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS) += memcpy-archs-unaligned.o

ifdef CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS
lib-$(CONFIG_ISA_ARCV2) +=memcpy-archs-unaligned.o
else
lib-$(CONFIG_ISA_ARCV2) +=memcpy-archs.o
endif

> diff --git a/arch/arc/lib/memcpy-archs-unaligned.S b/arch/arc/lib/memcpy-archs-unaligned.S
> new file mode 100644
> index 000000000000..e09b51d4de70
> --- /dev/null
> +++ b/arch/arc/lib/memcpy-archs-unaligned.S
> @@ -0,0 +1,46 @@
> +/* 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)


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