[PATCH v4 16/18] riscv: Add RVV strncpy for multiarch and non-multiarch
Yao Zihong
zihong.plct@isrc.iscas.ac.cn
Mon Jan 19 07:03:23 GMT 2026
Signed-off-by: Yao Zihong <zihong.plct@isrc.iscas.ac.cn>
---
sysdeps/riscv/multiarch/strncpy-generic.c | 26 +++++++++
sysdeps/riscv/multiarch/strncpy-vector.S | 24 ++++++++
sysdeps/riscv/rvv/stpncpy.S | 27 +++++++--
sysdeps/riscv/rvv/strncpy.S | 20 +++++++
.../unix/sysv/linux/riscv/multiarch/Makefile | 3 +
.../linux/riscv/multiarch/ifunc-impl-list.c | 5 ++
.../unix/sysv/linux/riscv/multiarch/stpncpy.c | 15 ++---
.../unix/sysv/linux/riscv/multiarch/strncpy.c | 56 +++++++++++++++++++
8 files changed, 164 insertions(+), 12 deletions(-)
create mode 100644 sysdeps/riscv/multiarch/strncpy-generic.c
create mode 100644 sysdeps/riscv/multiarch/strncpy-vector.S
create mode 100644 sysdeps/riscv/rvv/strncpy.S
create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/strncpy.c
diff --git a/sysdeps/riscv/multiarch/strncpy-generic.c b/sysdeps/riscv/multiarch/strncpy-generic.c
new file mode 100644
index 0000000000..ab0eb9af42
--- /dev/null
+++ b/sysdeps/riscv/multiarch/strncpy-generic.c
@@ -0,0 +1,26 @@
+/* Re-include the default strncpy implementation.
+ Copyright (C) 2026 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 <string.h>
+
+#if IS_IN(libc)
+# define STRNCPY __strncpy_generic
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+#endif
+#include <string/strncpy.c>
diff --git a/sysdeps/riscv/multiarch/strncpy-vector.S b/sysdeps/riscv/multiarch/strncpy-vector.S
new file mode 100644
index 0000000000..32256f7695
--- /dev/null
+++ b/sysdeps/riscv/multiarch/strncpy-vector.S
@@ -0,0 +1,24 @@
+/* Re-include the RISC-V RVV based strncpy implementation.
+ Copyright (C) 2026 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/>. */
+
+#if IS_IN(libc)
+# define STRNCPY __strncpy_vector
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+# include <sysdeps/riscv/rvv/strncpy.S>
+#endif
diff --git a/sysdeps/riscv/rvv/stpncpy.S b/sysdeps/riscv/rvv/stpncpy.S
index 57406685b0..d9004f2fba 100644
--- a/sysdeps/riscv/rvv/stpncpy.S
+++ b/sysdeps/riscv/rvv/stpncpy.S
@@ -19,12 +19,20 @@
#include <sysdep.h>
#include <sys/asm.h>
-#ifndef STPNCPY
-# ifdef weak_alias
-# define STPNCPY __stpncpy
+#ifndef USE_AS_STRNCPY
+# ifndef STPNCPY
+# ifdef weak_alias
+# define STPNCPY __stpncpy
weak_alias (__stpncpy, stpncpy)
+# else
+# define STPNCPY stpncpy
+# endif
+# endif
+#else
+# ifndef STRNCPY
+# define STPNCPY strncpy
# else
-# define STPNCPY stpncpy
+# define STPNCPY STRNCPY
# endif
#endif
@@ -62,7 +70,9 @@ L(stpcpy_loop):
add dst_ptr, dst_ptr, cur_vl
bgez active_elem_pos, L(fill_zero)
bnez length, L(stpcpy_loop)
+#ifndef USE_AS_STRNCPY
mv dst, dst_ptr
+#endif
ret
/* Fill the tail zero. */
@@ -72,8 +82,10 @@ L(fill_zero):
to get the correct remaining length for zero filling. */
sub temp, cur_vl, active_elem_pos
addi temp, temp, -1
+#ifndef USE_AS_STRNCPY
sub dst, dst_ptr, cur_vl
add dst, dst, active_elem_pos
+#endif
add length, length, temp
/* Have an earily return for `strlen(src) + 1 == count` case. */
bnez length, L(do_fill_zero)
@@ -92,6 +104,11 @@ L(fill_zero_loop):
ret
.option pop
END (STPNCPY)
-#ifdef weak_alias
+
+#ifndef USE_AS_STRNCPY
+# ifdef weak_alias
libc_hidden_def (__stpncpy)
+# endif
+#else
+libc_hidden_builtin_def (strncpy)
#endif
diff --git a/sysdeps/riscv/rvv/strncpy.S b/sysdeps/riscv/rvv/strncpy.S
new file mode 100644
index 0000000000..961c16416e
--- /dev/null
+++ b/sysdeps/riscv/rvv/strncpy.S
@@ -0,0 +1,20 @@
+/* RISC-V RVV based strncpy.
+ Copyright (C) 2026 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/>. */
+
+#define USE_AS_STRNCPY
+#include <sysdeps/riscv/rvv/stpncpy.S>
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index bb3488e849..df33147de9 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -49,6 +49,9 @@ sysdep_routines += \
strncmp \
strncmp-generic \
strncmp-vector \
+ strncpy \
+ strncpy-generic \
+ strncpy-vector \
# sysdep_routines
CFLAGS-memcpy_noalignment.c += -mno-strict-align
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 025b026cf3..26444cc99d 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -125,5 +125,10 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
__strncmp_vector)
IFUNC_IMPL_ADD (array, i, strncmp, 1, __strncmp_generic))
+ IFUNC_IMPL (i, name, strncpy,
+ IFUNC_IMPL_ADD (array, i, strncpy, rvv_enabled,
+ __strncpy_vector)
+ IFUNC_IMPL_ADD (array, i, strncpy, 1, __strncpy_generic))
+
return 0;
}
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c b/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c
index e451391f1a..190b479a1b 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c
@@ -22,14 +22,15 @@
mismatch with the IFUNC selector in strong_alias, below. */
# undef stpncpy
# define stpncpy __redirect_stpncpy
+# define __stpncpy __redirect___stpncpy
# include <stdint.h>
# include <string.h>
+# undef stpncpy
+# undef __stpncpy
# include <ifunc-init.h>
# include <riscv-ifunc.h>
# include <sys/hwprobe.h>
-extern __typeof (__redirect_stpncpy) __libc_stpncpy;
-
extern __typeof (__redirect_stpncpy) __stpncpy_generic attribute_hidden;
extern __typeof (__redirect_stpncpy) __stpncpy_vector attribute_hidden;
@@ -43,14 +44,14 @@ select_stpncpy_ifunc (uint64_t dl_hwcap, __riscv_hwprobe_t hwprobe_func)
return __stpncpy_generic;
}
-riscv_libc_ifunc (__libc_stpncpy, select_stpncpy_ifunc);
+riscv_libc_ifunc_redirected (__redirect___stpncpy, __stpncpy,
+ select_stpncpy_ifunc);
# undef stpncpy
-weak_alias (__libc_stpncpy, stpncpy);
-libc_hidden_def (__stpncpy);
+weak_alias (__stpncpy, stpncpy);
# ifdef SHARED
-__hidden_ver1 (stpncpy, __GI_stpncpy, __redirect_stpncpy)
- __attribute__ ((visibility ("hidden"))) __attribute_copy__ (stpncpy);
+__hidden_ver1 (__stpncpy, __GI___stpncpy, __redirect___stpncpy)
+ __attribute__ ((visibility ("hidden"))) __attribute_copy__ (__stpncpy);
# endif
#else
# include <string/stpncpy.c>
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/strncpy.c b/sysdeps/unix/sysv/linux/riscv/multiarch/strncpy.c
new file mode 100644
index 0000000000..459032312f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/strncpy.c
@@ -0,0 +1,56 @@
+/* Multiple versions of strncpy.
+ All versions must be listed in ifunc-impl-list.c.
+ Copyright (C) 2026 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/>. */
+
+#if IS_IN (libc)
+/* Redefine strncpy so that the compiler won't complain about the type
+ mismatch with the IFUNC selector in strong_alias, below. */
+# undef strncpy
+# define strncpy __redirect_strncpy
+# include <stdint.h>
+# include <string.h>
+# include <ifunc-init.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (__redirect_strncpy) __libc_strncpy;
+
+extern __typeof (__redirect_strncpy) __strncpy_generic attribute_hidden;
+extern __typeof (__redirect_strncpy) __strncpy_vector attribute_hidden;
+
+static inline __typeof (__redirect_strncpy) *
+select_strncpy_ifunc (uint64_t dl_hwcap, __riscv_hwprobe_t hwprobe_func)
+{
+ unsigned long long int v;
+ if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_IMA_EXT_0, &v) == 0
+ && (v & RISCV_HWPROBE_IMA_V) == RISCV_HWPROBE_IMA_V)
+ return __strncpy_vector;
+ return __strncpy_generic;
+}
+
+riscv_libc_ifunc (__libc_strncpy, select_strncpy_ifunc);
+
+# undef strncpy
+strong_alias (__libc_strncpy, strncpy);
+# ifdef SHARED
+__hidden_ver1 (strncpy, __GI_strncpy, __redirect_strncpy)
+ __attribute__ ((visibility ("hidden"))) __attribute_copy__ (strncpy);
+# endif
+#else
+# include <string/strncpy.c>
+#endif
--
2.47.2
More information about the Libc-alpha
mailing list