aarch64: Added optimized memcpy and memmove for A64FX

This patch optimizes the performance of memcpy/memmove for A64FX [1]
which implements ARMv8-A SVE and has L1 64KB cache per core and L2 8MB
cache per NUMA node.

The performance optimization makes use of Scalable Vector Register
with several techniques such as loop unrolling, memory access
alignment, cache zero fill, and software pipelining.

SVE assembler code for memcpy/memmove is implemented as Vector Length
Agnostic code so theoretically it can be run on any SOC which supports
ARMv8-A SVE standard.

We confirmed that all testcases have been passed by running 'make
check' and 'make xcheck' not only on A64FX but also on ThunderX2.

And also we confirmed that the SVE 512 bit vector register performance
is roughly 4 times better than Advanced SIMD 128 bit register and 8
times better than scalar 64 bit register by running 'make bench'.

[1] https://github.com/fujitsu/A64FX

Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Reviewed-by: Szabolcs Nagy <Szabolcs.Nagy@arm.com>

6 files changed, 443 insertions, 13 deletions

diff --git a/sysdeps/aarch64/multiarch/Makefile b/sysdeps/aarch64/multiarch/Makefile
index dc3efff..04c3f17 100644
--- a/sysdeps/aarch64/multiarch/Makefile
+++ b/sysdeps/aarch64/multiarch/Makefile
@@ -1,6 +1,6 @@
 ifeq ($(subdir),string)
 sysdep_routines += memcpy_generic memcpy_advsimd memcpy_thunderx memcpy_thunderx2 \
-		   memcpy_falkor \
+		   memcpy_falkor memcpy_a64fx \
 		   memset_generic memset_falkor memset_emag memset_kunpeng \
 		   memchr_generic memchr_nosimd \
 		   strlen_mte strlen_asimd
diff --git a/sysdeps/aarch64/multiarch/ifunc-impl-list.c b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
index 99a8c68..9113935 100644
--- a/sysdeps/aarch64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
@@ -25,7 +25,7 @@
 #include <stdio.h>
 
 /* Maximum number of IFUNC implementations.  */
-#define MAX_IFUNC	4
+#define MAX_IFUNC	7
 
 size_t
 __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
@@ -43,12 +43,18 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 	      IFUNC_IMPL_ADD (array, i, memcpy, !bti, __memcpy_thunderx2)
 	      IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_falkor)
 	      IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_simd)
+#if HAVE_AARCH64_SVE_ASM
+	      IFUNC_IMPL_ADD (array, i, memcpy, sve, __memcpy_a64fx)
+#endif
 	      IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))
   IFUNC_IMPL (i, name, memmove,
 	      IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_thunderx)
 	      IFUNC_IMPL_ADD (array, i, memmove, !bti, __memmove_thunderx2)
 	      IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_falkor)
 	      IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_simd)
+#if HAVE_AARCH64_SVE_ASM
+	      IFUNC_IMPL_ADD (array, i, memmove, sve, __memmove_a64fx)
+#endif
 	      IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_generic))
   IFUNC_IMPL (i, name, memset,
 	      /* Enable this on non-falkor processors too so that other cores
diff --git a/sysdeps/aarch64/multiarch/init-arch.h b/sysdeps/aarch64/multiarch/init-arch.h
index a167699..6d92c1b 100644
--- a/sysdeps/aarch64/multiarch/init-arch.h
+++ b/sysdeps/aarch64/multiarch/init-arch.h
@@ -33,4 +33,6 @@
   bool __attribute__((unused)) bti =					      \
     HAVE_AARCH64_BTI && GLRO(dl_aarch64_cpu_features).bti;		      \
   bool __attribute__((unused)) mte =					      \
-    MTE_ENABLED ();
+    MTE_ENABLED ();							      \
+  bool __attribute__((unused)) sve =					      \
+    GLRO(dl_aarch64_cpu_features).sve;
diff --git a/sysdeps/aarch64/multiarch/memcpy.c b/sysdeps/aarch64/multiarch/memcpy.c
index 0e0a5cb..25e0081 100644
--- a/sysdeps/aarch64/multiarch/memcpy.c
+++ b/sysdeps/aarch64/multiarch/memcpy.c
@@ -33,6 +33,9 @@ extern __typeof (__redirect_memcpy) __memcpy_simd attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_thunderx attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_thunderx2 attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_falkor attribute_hidden;
+# if HAVE_AARCH64_SVE_ASM
+extern __typeof (__redirect_memcpy) __memcpy_a64fx attribute_hidden;
+# endif
 
 libc_ifunc (__libc_memcpy,
             (IS_THUNDERX (midr)
@@ -40,12 +43,17 @@ libc_ifunc (__libc_memcpy,
 	     : (IS_FALKOR (midr) || IS_PHECDA (midr)
 		? __memcpy_falkor
 		: (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr)
-		  ? __memcpy_thunderx2
-		  : (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
-		     || IS_NEOVERSE_V1 (midr)
-		     ? __memcpy_simd
+		   ? __memcpy_thunderx2
+		   : (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
+		      || IS_NEOVERSE_V1 (midr)
+		      ? __memcpy_simd
+# if HAVE_AARCH64_SVE_ASM
+		     : (IS_A64FX (midr)
+			? __memcpy_a64fx
+			: __memcpy_generic))))));
+# else
 		     : __memcpy_generic)))));
-
+# endif
 # undef memcpy
 strong_alias (__libc_memcpy, memcpy);
 #endif
diff --git a/sysdeps/aarch64/multiarch/memcpy_a64fx.S b/sysdeps/aarch64/multiarch/memcpy_a64fx.S
new file mode 100644
index 0000000..6552840
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/memcpy_a64fx.S
@@ -0,0 +1,406 @@
+/* Optimized memcpy for Fujitsu A64FX processor.
+   Copyright (C) 2021 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>
+
+/* Assumptions:
+ *
+ * ARMv8.2-a, AArch64, unaligned accesses, sve
+ *
+ */
+
+#define L2_SIZE		(8*1024*1024)/2	// L2 8MB/2
+#define CACHE_LINE_SIZE	256
+#define ZF_DIST		(CACHE_LINE_SIZE * 21)	// Zerofill distance
+#define dest		x0
+#define src		x1
+#define n		x2	// size
+#define tmp1		x3
+#define tmp2		x4
+#define tmp3		x5
+#define rest		x6
+#define dest_ptr	x7
+#define src_ptr		x8
+#define vector_length	x9
+#define cl_remainder	x10	// CACHE_LINE_SIZE remainder
+
+#if HAVE_AARCH64_SVE_ASM
+# if IS_IN (libc)
+#  define MEMCPY __memcpy_a64fx
+#  define MEMMOVE __memmove_a64fx
+
+	.arch armv8.2-a+sve
+
+	.macro dc_zva times
+	dc	zva, tmp1
+	add	tmp1, tmp1, CACHE_LINE_SIZE
+	.if \times-1
+	dc_zva "(\times-1)"
+	.endif
+	.endm
+
+	.macro ld1b_unroll8
+	ld1b	z0.b, p0/z, [src_ptr, #0, mul vl]
+	ld1b	z1.b, p0/z, [src_ptr, #1, mul vl]
+	ld1b	z2.b, p0/z, [src_ptr, #2, mul vl]
+	ld1b	z3.b, p0/z, [src_ptr, #3, mul vl]
+	ld1b	z4.b, p0/z, [src_ptr, #4, mul vl]
+	ld1b	z5.b, p0/z, [src_ptr, #5, mul vl]
+	ld1b	z6.b, p0/z, [src_ptr, #6, mul vl]
+	ld1b	z7.b, p0/z, [src_ptr, #7, mul vl]
+	.endm
+
+	.macro stld1b_unroll4a
+	st1b	z0.b, p0,   [dest_ptr, #0, mul vl]
+	st1b	z1.b, p0,   [dest_ptr, #1, mul vl]
+	ld1b	z0.b, p0/z, [src_ptr,  #0, mul vl]
+	ld1b	z1.b, p0/z, [src_ptr,  #1, mul vl]
+	st1b	z2.b, p0,   [dest_ptr, #2, mul vl]
+	st1b	z3.b, p0,   [dest_ptr, #3, mul vl]
+	ld1b	z2.b, p0/z, [src_ptr,  #2, mul vl]
+	ld1b	z3.b, p0/z, [src_ptr,  #3, mul vl]
+	.endm
+
+	.macro stld1b_unroll4b
+	st1b	z4.b, p0,   [dest_ptr, #4, mul vl]
+	st1b	z5.b, p0,   [dest_ptr, #5, mul vl]
+	ld1b	z4.b, p0/z, [src_ptr,  #4, mul vl]
+	ld1b	z5.b, p0/z, [src_ptr,  #5, mul vl]
+	st1b	z6.b, p0,   [dest_ptr, #6, mul vl]
+	st1b	z7.b, p0,   [dest_ptr, #7, mul vl]
+	ld1b	z6.b, p0/z, [src_ptr,  #6, mul vl]
+	ld1b	z7.b, p0/z, [src_ptr,  #7, mul vl]
+	.endm
+
+	.macro stld1b_unroll8
+	stld1b_unroll4a
+	stld1b_unroll4b
+	.endm
+
+	.macro st1b_unroll8
+	st1b	z0.b, p0, [dest_ptr, #0, mul vl]
+	st1b	z1.b, p0, [dest_ptr, #1, mul vl]
+	st1b	z2.b, p0, [dest_ptr, #2, mul vl]
+	st1b	z3.b, p0, [dest_ptr, #3, mul vl]
+	st1b	z4.b, p0, [dest_ptr, #4, mul vl]
+	st1b	z5.b, p0, [dest_ptr, #5, mul vl]
+	st1b	z6.b, p0, [dest_ptr, #6, mul vl]
+	st1b	z7.b, p0, [dest_ptr, #7, mul vl]
+	.endm
+
+	.macro shortcut_for_small_size exit
+	// if rest <= vector_length * 2
+	whilelo	p0.b, xzr, n
+	whilelo	p1.b, vector_length, n
+	b.last	1f
+	ld1b	z0.b, p0/z, [src, #0, mul vl]
+	ld1b	z1.b, p1/z, [src, #1, mul vl]
+	st1b	z0.b, p0, [dest, #0, mul vl]
+	st1b	z1.b, p1, [dest, #1, mul vl]
+	ret
+1:	// if rest > vector_length * 8
+	cmp	n, vector_length, lsl 3 // vector_length * 8
+	b.hi	\exit
+	// if rest <= vector_length * 4
+	lsl	tmp1, vector_length, 1  // vector_length * 2
+	whilelo	p2.b, tmp1, n
+	incb	tmp1
+	whilelo	p3.b, tmp1, n
+	b.last	1f
+	ld1b	z0.b, p0/z, [src, #0, mul vl]
+	ld1b	z1.b, p1/z, [src, #1, mul vl]
+	ld1b	z2.b, p2/z, [src, #2, mul vl]
+	ld1b	z3.b, p3/z, [src, #3, mul vl]
+	st1b	z0.b, p0, [dest, #0, mul vl]
+	st1b	z1.b, p1, [dest, #1, mul vl]
+	st1b	z2.b, p2, [dest, #2, mul vl]
+	st1b	z3.b, p3, [dest, #3, mul vl]
+	ret
+1:	// if rest <= vector_length * 8
+	lsl	tmp1, vector_length, 2  // vector_length * 4
+	whilelo	p4.b, tmp1, n
+	incb	tmp1
+	whilelo	p5.b, tmp1, n
+	b.last	1f
+	ld1b	z0.b, p0/z, [src, #0, mul vl]
+	ld1b	z1.b, p1/z, [src, #1, mul vl]
+	ld1b	z2.b, p2/z, [src, #2, mul vl]
+	ld1b	z3.b, p3/z, [src, #3, mul vl]
+	ld1b	z4.b, p4/z, [src, #4, mul vl]
+	ld1b	z5.b, p5/z, [src, #5, mul vl]
+	st1b	z0.b, p0, [dest, #0, mul vl]
+	st1b	z1.b, p1, [dest, #1, mul vl]
+	st1b	z2.b, p2, [dest, #2, mul vl]
+	st1b	z3.b, p3, [dest, #3, mul vl]
+	st1b	z4.b, p4, [dest, #4, mul vl]
+	st1b	z5.b, p5, [dest, #5, mul vl]
+	ret
+1:	lsl	tmp1, vector_length, 2	// vector_length * 4
+	incb	tmp1			// vector_length * 5
+	incb	tmp1			// vector_length * 6
+	whilelo	p6.b, tmp1, n
+	incb	tmp1
+	whilelo	p7.b, tmp1, n
+	ld1b	z0.b, p0/z, [src, #0, mul vl]
+	ld1b	z1.b, p1/z, [src, #1, mul vl]
+	ld1b	z2.b, p2/z, [src, #2, mul vl]
+	ld1b	z3.b, p3/z, [src, #3, mul vl]
+	ld1b	z4.b, p4/z, [src, #4, mul vl]
+	ld1b	z5.b, p5/z, [src, #5, mul vl]
+	ld1b	z6.b, p6/z, [src, #6, mul vl]
+	ld1b	z7.b, p7/z, [src, #7, mul vl]
+	st1b	z0.b, p0, [dest, #0, mul vl]
+	st1b	z1.b, p1, [dest, #1, mul vl]
+	st1b	z2.b, p2, [dest, #2, mul vl]
+	st1b	z3.b, p3, [dest, #3, mul vl]
+	st1b	z4.b, p4, [dest, #4, mul vl]
+	st1b	z5.b, p5, [dest, #5, mul vl]
+	st1b	z6.b, p6, [dest, #6, mul vl]
+	st1b	z7.b, p7, [dest, #7, mul vl]
+	ret
+	.endm
+
+ENTRY (MEMCPY)
+
+	PTR_ARG (0)
+	PTR_ARG (1)
+	SIZE_ARG (2)
+
+L(memcpy):
+	cntb	vector_length
+	// shortcut for less than vector_length * 8
+	// gives a free ptrue to p0.b for n >= vector_length
+	shortcut_for_small_size L(vl_agnostic)
+	// end of shortcut
+
+L(vl_agnostic): // VL Agnostic
+	mov	rest, n
+	mov	dest_ptr, dest
+	mov	src_ptr, src
+	// if rest >= L2_SIZE && vector_length == 64 then L(L2)
+	mov	tmp1, 64
+	cmp	rest, L2_SIZE
+	ccmp	vector_length, tmp1, 0, cs
+	b.eq	L(L2)
+
+L(unroll8): // unrolling and software pipeline
+	lsl	tmp1, vector_length, 3	// vector_length * 8
+	.p2align 3
+	cmp	 rest, tmp1
+	b.cc	L(last)
+	ld1b_unroll8
+	add	src_ptr, src_ptr, tmp1
+	sub	rest, rest, tmp1
+	cmp	rest, tmp1
+	b.cc	2f
+	.p2align 3
+1:	stld1b_unroll8
+	add	dest_ptr, dest_ptr, tmp1
+	add	src_ptr, src_ptr, tmp1
+	sub	rest, rest, tmp1
+	cmp	rest, tmp1
+	b.ge	1b
+2:	st1b_unroll8
+	add	dest_ptr, dest_ptr, tmp1
+
+	.p2align 3
+L(last):
+	whilelo	p0.b, xzr, rest
+	whilelo	p1.b, vector_length, rest
+	b.last	1f
+	ld1b	z0.b, p0/z, [src_ptr, #0, mul vl]
+	ld1b	z1.b, p1/z, [src_ptr, #1, mul vl]
+	st1b	z0.b, p0, [dest_ptr, #0, mul vl]
+	st1b	z1.b, p1, [dest_ptr, #1, mul vl]
+	ret
+1:	lsl	tmp1, vector_length, 1	// vector_length * 2
+	whilelo	p2.b, tmp1, rest
+	incb	tmp1
+	whilelo	p3.b, tmp1, rest
+	b.last	1f
+	ld1b	z0.b, p0/z, [src_ptr, #0, mul vl]
+	ld1b	z1.b, p1/z, [src_ptr, #1, mul vl]
+	ld1b	z2.b, p2/z, [src_ptr, #2, mul vl]
+	ld1b	z3.b, p3/z, [src_ptr, #3, mul vl]
+	st1b	z0.b, p0, [dest_ptr, #0, mul vl]
+	st1b	z1.b, p1, [dest_ptr, #1, mul vl]
+	st1b	z2.b, p2, [dest_ptr, #2, mul vl]
+	st1b	z3.b, p3, [dest_ptr, #3, mul vl]
+	ret
+1:	lsl	tmp1, vector_length, 2	// vector_length * 4
+	whilelo	p4.b, tmp1, rest
+	incb	tmp1
+	whilelo	p5.b, tmp1, rest
+	incb	tmp1
+	whilelo	p6.b, tmp1, rest
+	incb	tmp1
+	whilelo	p7.b, tmp1, rest
+	ld1b	z0.b, p0/z, [src_ptr, #0, mul vl]
+	ld1b	z1.b, p1/z, [src_ptr, #1, mul vl]
+	ld1b	z2.b, p2/z, [src_ptr, #2, mul vl]
+	ld1b	z3.b, p3/z, [src_ptr, #3, mul vl]
+	ld1b	z4.b, p4/z, [src_ptr, #4, mul vl]
+	ld1b	z5.b, p5/z, [src_ptr, #5, mul vl]
+	ld1b	z6.b, p6/z, [src_ptr, #6, mul vl]
+	ld1b	z7.b, p7/z, [src_ptr, #7, mul vl]
+	st1b	z0.b, p0, [dest_ptr, #0, mul vl]
+	st1b	z1.b, p1, [dest_ptr, #1, mul vl]
+	st1b	z2.b, p2, [dest_ptr, #2, mul vl]
+	st1b	z3.b, p3, [dest_ptr, #3, mul vl]
+	st1b	z4.b, p4, [dest_ptr, #4, mul vl]
+	st1b	z5.b, p5, [dest_ptr, #5, mul vl]
+	st1b	z6.b, p6, [dest_ptr, #6, mul vl]
+	st1b	z7.b, p7, [dest_ptr, #7, mul vl]
+	ret
+
+L(L2):
+	// align dest address at CACHE_LINE_SIZE byte boundary
+	mov	tmp1, CACHE_LINE_SIZE
+	ands	tmp2, dest_ptr, CACHE_LINE_SIZE - 1
+	// if cl_remainder == 0
+	b.eq	L(L2_dc_zva)
+	sub	cl_remainder, tmp1, tmp2
+	// process remainder until the first CACHE_LINE_SIZE boundary
+	whilelo	p1.b, xzr, cl_remainder	// keep p0.b all true
+	whilelo	p2.b, vector_length, cl_remainder
+	b.last	1f
+	ld1b	z1.b, p1/z, [src_ptr, #0, mul vl]
+	ld1b	z2.b, p2/z, [src_ptr, #1, mul vl]
+	st1b	z1.b, p1, [dest_ptr, #0, mul vl]
+	st1b	z2.b, p2, [dest_ptr, #1, mul vl]
+	b	2f
+1:	lsl	tmp1, vector_length, 1	// vector_length * 2
+	whilelo	p3.b, tmp1, cl_remainder
+	incb	tmp1
+	whilelo	p4.b, tmp1, cl_remainder
+	ld1b	z1.b, p1/z, [src_ptr, #0, mul vl]
+	ld1b	z2.b, p2/z, [src_ptr, #1, mul vl]
+	ld1b	z3.b, p3/z, [src_ptr, #2, mul vl]
+	ld1b	z4.b, p4/z, [src_ptr, #3, mul vl]
+	st1b	z1.b, p1, [dest_ptr, #0, mul vl]
+	st1b	z2.b, p2, [dest_ptr, #1, mul vl]
+	st1b	z3.b, p3, [dest_ptr, #2, mul vl]
+	st1b	z4.b, p4, [dest_ptr, #3, mul vl]
+2:	add	dest_ptr, dest_ptr, cl_remainder
+	add	src_ptr, src_ptr, cl_remainder
+	sub	rest, rest, cl_remainder
+
+L(L2_dc_zva):
+	// zero fill
+	and	tmp1, dest, 0xffffffffffffff
+	and	tmp2, src, 0xffffffffffffff
+	subs	tmp1, tmp1, tmp2	// diff
+	b.ge	1f
+	neg	tmp1, tmp1
+1:	mov	tmp3, ZF_DIST + CACHE_LINE_SIZE * 2
+	cmp	tmp1, tmp3
+	b.lo	L(unroll8)
+	mov	tmp1, dest_ptr
+	dc_zva	(ZF_DIST / CACHE_LINE_SIZE) - 1
+	// unroll
+	ld1b_unroll8	// this line has to be after "b.lo L(unroll8)"
+	add	 src_ptr, src_ptr, CACHE_LINE_SIZE * 2
+	sub	 rest, rest, CACHE_LINE_SIZE * 2
+	mov	 tmp1, ZF_DIST
+	.p2align 3
+1:	stld1b_unroll4a
+	add	tmp2, dest_ptr, tmp1	// dest_ptr + ZF_DIST
+	dc	zva, tmp2
+	stld1b_unroll4b
+	add	tmp2, tmp2, CACHE_LINE_SIZE
+	dc	zva, tmp2
+	add	dest_ptr, dest_ptr, CACHE_LINE_SIZE * 2
+	add	src_ptr, src_ptr, CACHE_LINE_SIZE * 2
+	sub	rest, rest, CACHE_LINE_SIZE * 2
+	cmp	rest, tmp3	// ZF_DIST + CACHE_LINE_SIZE * 2
+	b.ge	1b
+	st1b_unroll8
+	add	dest_ptr, dest_ptr, CACHE_LINE_SIZE * 2
+	b	L(unroll8)
+
+END (MEMCPY)
+libc_hidden_builtin_def (MEMCPY)
+
+
+ENTRY (MEMMOVE)
+
+	PTR_ARG (0)
+	PTR_ARG (1)
+	SIZE_ARG (2)
+
+	// remove tag address
+	// dest has to be immutable because it is the return value
+	// src has to be immutable because it is used in L(bwd_last)
+	and	tmp2, dest, 0xffffffffffffff	// save dest_notag into tmp2
+	and	tmp3, src, 0xffffffffffffff	// save src_notag intp tmp3
+	cmp	n, 0
+	ccmp	tmp2, tmp3, 4, ne
+	b.ne	1f
+	ret
+1:	cntb	vector_length
+	// shortcut for less than vector_length * 8
+	// gives a free ptrue to p0.b for n >= vector_length
+	// tmp2 and tmp3 should not be used in this macro to keep
+	// notag addresses
+	shortcut_for_small_size L(dispatch)
+	// end of shortcut
+
+L(dispatch):
+	// tmp2 = dest_notag, tmp3 = src_notag
+	// diff = dest_notag - src_notag
+	sub	tmp1, tmp2, tmp3
+	// if diff <= 0 || diff >= n then memcpy
+	cmp	tmp1, 0
+	ccmp	tmp1, n, 2, gt
+	b.cs	L(vl_agnostic)
+
+L(bwd_start):
+	mov	rest, n
+	add	dest_ptr, dest, n	// dest_end
+	add	src_ptr, src, n		// src_end
+
+L(bwd_unroll8): // unrolling and software pipeline
+	lsl	tmp1, vector_length, 3	// vector_length * 8
+	.p2align 3
+	cmp	rest, tmp1
+	b.cc	L(bwd_last)
+	sub	src_ptr, src_ptr, tmp1
+	ld1b_unroll8
+	sub	rest, rest, tmp1
+	cmp	rest, tmp1
+	b.cc	2f
+	.p2align 3
+1:	sub	src_ptr, src_ptr, tmp1
+	sub	dest_ptr, dest_ptr, tmp1
+	stld1b_unroll8
+	sub	rest, rest, tmp1
+	cmp	rest, tmp1
+	b.ge	1b
+2:	sub	dest_ptr, dest_ptr, tmp1
+	st1b_unroll8
+
+L(bwd_last):
+	mov	dest_ptr, dest
+	mov	src_ptr, src
+	b	L(last)
+
+END (MEMMOVE)
+libc_hidden_builtin_def (MEMMOVE)
+# endif /* IS_IN (libc) */
+#endif /* HAVE_AARCH64_SVE_ASM */
diff --git a/sysdeps/aarch64/multiarch/memmove.c b/sysdeps/aarch64/multiarch/memmove.c
index 12d7781..d0adefc 100644
--- a/sysdeps/aarch64/multiarch/memmove.c
+++ b/sysdeps/aarch64/multiarch/memmove.c
@@ -33,6 +33,9 @@ extern __typeof (__redirect_memmove) __memmove_simd attribute_hidden;
 extern __typeof (__redirect_memmove) __memmove_thunderx attribute_hidden;
 extern __typeof (__redirect_memmove) __memmove_thunderx2 attribute_hidden;
 extern __typeof (__redirect_memmove) __memmove_falkor attribute_hidden;
+# if HAVE_AARCH64_SVE_ASM
+extern __typeof (__redirect_memmove) __memmove_a64fx attribute_hidden;
+# endif
 
 libc_ifunc (__libc_memmove,
             (IS_THUNDERX (midr)
@@ -40,12 +43,17 @@ libc_ifunc (__libc_memmove,
 	     : (IS_FALKOR (midr) || IS_PHECDA (midr)
 		? __memmove_falkor
 		: (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr)
-		  ? __memmove_thunderx2
-		  : (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
-		     || IS_NEOVERSE_V1 (midr)
-		     ? __memmove_simd
+		   ? __memmove_thunderx2
+		   : (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
+		      || IS_NEOVERSE_V1 (midr)
+		      ? __memmove_simd
+# if HAVE_AARCH64_SVE_ASM
+		     : (IS_A64FX (midr)
+			? __memmove_a64fx
+			: __memmove_generic))))));
+# else
 		     : __memmove_generic)))));
-
+# endif
 # undef memmove
 strong_alias (__libc_memmove, memmove);
 #endif