linux-kernel - [PATCH v2 4/5] ARCv2: LIB: MEMCPY: fixed and optimised routine

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Date:   Wed, 30 Jan 2019 19:32:43 +0300
From:   Eugeniy Paltsev <eugeniy.paltsev@...opsys.com>
To:     linux-snps-arc@...ts.infradead.org,
        Vineet Gupta <vineet.gupta1@...opsys.com>
Cc:     linux-kernel@...r.kernel.org,
        Alexey Brodkin <alexey.brodkin@...opsys.com>,
        Eugeniy Paltsev <eugeniy.paltsev@...opsys.com>
Subject: [PATCH v2 4/5] ARCv2: LIB: MEMCPY: fixed and optimised routine

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@...opsys.com>
---
 arch/arc/lib/Makefile                 |  8 +++++-
 arch/arc/lib/memcpy-archs-unaligned.S | 47 +++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 arch/arc/lib/memcpy-archs-unaligned.S

diff --git a/arch/arc/lib/Makefile b/arch/arc/lib/Makefile
index b1656d156097..f7537b466b23 100644
--- a/arch/arc/lib/Makefile
+++ b/arch/arc/lib/Makefile
@@ -8,4 +8,10 @@
 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-$(CONFIG_ISA_ARCV2)		+= memset-archs.o strcmp-archs.o
+
+ifdef CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS
+lib-$(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..28993a73fdde
--- /dev/null
+++ b/arch/arc/lib/memcpy-archs-unaligned.S
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * ARCv2 memcpy implementation optimized for unaligned memory access using.
+ *
+ * Copyright (C) 2019 Synopsys
+ * Author: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.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)
-- 
2.14.5