[PATCH v6 3/3] RISC-V: add riscv vector support for memcpy

[daichengrong@iscas.ac.cn]

From: daichengrong <daichengrong@iscas.ac.cn>

Change in v6:
  Optimize the RVV memcpy for small lengths less than VLEN/8 bytes

Changes in v5:
   fix Indentation in memcpy.c
   check ifunc-impl-list memcpy vector support with by dl_hwcap

Changes in v4:
  update rvv memcpy support by compiler 
  check whether rvv enabled by dl_hwcap

Changes in v3:
  Remove unnecessary whitespace

Changes in v2:
  delete size-0 branch

---
 sysdeps/riscv/multiarch/memcpy_vector.S       | 43 +++++++++++++++++++
 .../unix/sysv/linux/riscv/multiarch/Makefile  |  8 ++++
 .../linux/riscv/multiarch/ifunc-impl-list.c   | 13 ++++++
 .../unix/sysv/linux/riscv/multiarch/memcpy.c  |  7 +++
 4 files changed, 71 insertions(+)
 create mode 100644 sysdeps/riscv/multiarch/memcpy_vector.S

diff --git a/sysdeps/riscv/multiarch/memcpy_vector.S b/sysdeps/riscv/multiarch/memcpy_vector.S
new file mode 100644
index 0000000000..4783640776
--- /dev/null
+++ b/sysdeps/riscv/multiarch/memcpy_vector.S
@@ -0,0 +1,43 @@
+/* memcpy for RISC-V Vector.
+   Copyright (C) 2024-2025 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>
+#include <sys/asm.h>
+
+ENTRY (__memcpy_vector) 
+    beq	a2, zero, L(ret)
+    mv	    a6, a0
+
+    /* if LEN > VLMAX jump to block_copy handling.  */   
+    vsetvli a4,zero,e8,m1,ta,ma
+    bgt a2,a4,L(block_copy)
+    vle8.v  v8,(a1)
+    vse8.v  v8,(a6)
+    ret
+L(block_copy):
+    vsetvli a3,a2,e8,m8,ta,ma
+    vle8.v  v8,(a1)
+    vse8.v  v8,(a6)
+    add     a1,a1,a3
+    add     a6,a6,a3 
+    sub     a2,a2,a3 
+    bnez    a2,L(block_copy)
+L(ret):    
+    ret
+END (__memcpy_vector)
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index fcef5659d4..394033e077 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -5,5 +5,13 @@ sysdep_routines += \
   memcpy_noalignment \
   # sysdep_routines
 
+ifeq ($(have-gcc-riscv-rvv),yes)
+sysdep_routines += \
+  memcpy_vector \
+  # rvv sysdep_routines
+  
+ASFLAGS-memcpy_vector.S += -march=rv64gcv
+endif
+
 CFLAGS-memcpy_noalignment.c += -mno-strict-align
 endif
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
index 1c1deca8f6..2088097558 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -19,6 +19,7 @@
 #include <ifunc-impl-list.h>
 #include <string.h>
 #include <sys/hwprobe.h>
+#include <ldsodefs.h>
 
 size_t
 __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
@@ -27,6 +28,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   size_t i = max;
 
   bool fast_unaligned = false;
+#if defined(HAVE_RISCV_ASM_VECTOR_SUPPORT) 
+  bool rvv_ext = false;
+#endif
 
   struct riscv_hwprobe pair = { .key = RISCV_HWPROBE_KEY_CPUPERF_0 };
   if (__riscv_hwprobe (&pair, 1, 0, NULL, 0) == 0
@@ -34,7 +38,16 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
           == RISCV_HWPROBE_MISALIGNED_FAST)
     fast_unaligned = true;
 
+#if defined(HAVE_RISCV_ASM_VECTOR_SUPPORT) 
+  if (GLRO(dl_hwcap) & COMPAT_HWCAP_ISA_V) 
+    rvv_ext = true;
+#endif
+
   IFUNC_IMPL (i, name, memcpy,
+#if defined(HAVE_RISCV_ASM_VECTOR_SUPPORT) 
+	      IFUNC_IMPL_ADD (array, i, memcpy, rvv_ext,
+			      __memcpy_vector)
+#endif
 	      IFUNC_IMPL_ADD (array, i, memcpy, fast_unaligned,
 			      __memcpy_noalignment)
 	      IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c b/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
index 8544f5402a..1982e4ab65 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
@@ -32,11 +32,18 @@ extern __typeof (__redirect_memcpy) __libc_memcpy;
 
 extern __typeof (__redirect_memcpy) __memcpy_generic attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_noalignment attribute_hidden;
+extern __typeof (__redirect_memcpy) __memcpy_vector attribute_hidden;
 
 static inline __typeof (__redirect_memcpy) *
 select_memcpy_ifunc (uint64_t dl_hwcap, __riscv_hwprobe_t hwprobe_func)
 {
   unsigned long long int v;
+
+#if defined(HAVE_RISCV_ASM_VECTOR_SUPPORT) 
+  if (dl_hwcap & COMPAT_HWCAP_ISA_V) 
+    return __memcpy_vector;
+#endif
+
   if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_CPUPERF_0, &v) == 0
       && (v & RISCV_HWPROBE_MISALIGNED_MASK) == RISCV_HWPROBE_MISALIGNED_FAST)
     return __memcpy_noalignment;
-- 
2.25.1