Re: [PATCH v5 06/18] riscv: Add RVV memmove for multiarch and non-multiarch
Peter Bergner <[email protected]>
| Newsgroups | gmane.comp.lib.glibc.alpha |
|---|---|
| Message-ID | <[email protected]> |
On 6/9/26 2:56 PM, Peter Bergner wrote:
> I'll note I see the following with the v5 stpncpy patch doing a normal
> glibc build with -march=rv64gc (ie, no vector):
>
>
> ./../include/libc-symbols.h:475:33: error: '__EI___stpncpy' aliased to undefined symbol '__GI___stpncpy'
> 475 | extern thread __typeof (name) __EI_##name \
> | ^~~~~
> ./../include/libc-symbols.h:471:3: note: in expansion of macro '__hidden_ver2'
> 471 | __hidden_ver2 (, local, internal, name)
> | ^~~~~~~~~~~~~
> ./../include/libc-symbols.h:479:41: note: in expansion of macro '__hidden_ver1'
> 479 | # define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
> | ^~~~~~~~~~~~~
> ./../include/libc-symbols.h:560:32: note: in expansion of macro 'hidden_def'
> 560 | # define libc_hidden_def(name) hidden_def (name)
> | ^~~~~~~~~~
> ../sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c:50:1: note: in expansion of macro 'libc_hidden_def'
> 50 | libc_hidden_def (__stpncpy);
> | ^~~~~~~~~~~~~~~
Given the freeze is coming this weekend, I spent some time fixing this issue, as well as a few others
once this issue is fixed. Basically, I needed the following patch to fix the compile and
make chack-abi errors:
@@ -19,9 +19,11 @@
#if IS_IN (libc)
/* Redefine stpncpy so that the compiler won't complain about the type
- mismatch with the IFUNC selector in strong_alias, below. */
+ mismatch with the IFUNC selector in weak_alias, below. */
# undef stpncpy
+# undef __stpncpy
# define stpncpy __redirect_stpncpy
+# define __stpncpy __redirect___stpncpy
# include <stdint.h>
# include <string.h>
# include <ifunc-init.h>
@@ -46,10 +48,11 @@
riscv_libc_ifunc (__libc_stpncpy, select_stpncpy_ifunc);
# undef stpncpy
+# undef __stpncpy
weak_alias (__libc_stpncpy, stpncpy);
-libc_hidden_def (__stpncpy);
+weak_alias (__libc_stpncpy, __stpncpy);
# ifdef SHARED
-__hidden_ver1 (stpncpy, __GI_stpncpy, __redirect_stpncpy)
+__hidden_ver1 (stpncpy, __GI___stpncpy, __redirect_stpncpy)
__attribute__ ((visibility ("hidden"))) __attribute_copy__ (stpncpy);
# endif
#else
That said, I went a little further and made a couple more changes to stpncpy.c to make our
implementation use the macros defined in ifunc-init.h similar to x86_64's. I'm including
the full updated patch below which includes some comment fixes in the stpncpy.S file too.
I plan on pushing this commit tomorrow unless someone notices a problem with it.
Peter
riscv: Add RVV stpncpy for both multiarch and non-multiarch builds
This patch adds an RVV-optimized implementation of stpncpy for RISC-V and
enables it for both multiarch (IFUNC) and non-multiarch builds.
The implementation integrates Hau Hsu's 2023 RVV work under a unified
ifunc-based framework. A vectorized version (__stpncpy_vector) is added
alongside the generic fallback (__stpncpy_generic). The runtime resolver
selects the RVV variant when RISCV_HWPROBE_KEY_IMA_EXT_0 reports vector
support (RVV).
Currently, the resolver still selects the RVV variant even when the RVV
extension is disabled via prctl(). As a consequence, any process that
has RVV disabled via prctl() will receive SIGILL when calling stpncpy().
Co-authored-by: Hau Hsu <[email protected]>
Co-authored-by: Jerry Shih <[email protected]>
Signed-off-by: Yao Zihong <[email protected]>
Reviewed-by: Peter Bergner <[email protected]>
---
sysdeps/riscv/multiarch/stpncpy-generic.c | 28 ++++++
sysdeps/riscv/multiarch/stpncpy-vector.S | 28 ++++++
sysdeps/riscv/rvv/stpncpy.S | 97 +++++++++++++++++++
.../unix/sysv/linux/riscv/multiarch/Makefile | 3 +
.../linux/riscv/multiarch/ifunc-impl-list.c | 5 +
.../unix/sysv/linux/riscv/multiarch/stpncpy.c | 62 ++++++++++++
6 files changed, 223 insertions(+)
create mode 100644 sysdeps/riscv/multiarch/stpncpy-generic.c
create mode 100644 sysdeps/riscv/multiarch/stpncpy-vector.S
create mode 100644 sysdeps/riscv/rvv/stpncpy.S
create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c
diff --git a/sysdeps/riscv/multiarch/stpncpy-generic.c b/sysdeps/riscv/multiarch/stpncpy-generic.c
new file mode 100644
index 0000000000..4be8080d88
--- /dev/null
+++ b/sysdeps/riscv/multiarch/stpncpy-generic.c
@@ -0,0 +1,28 @@
+/* Re-include the default stpncpy 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 STPNCPY __stpncpy_generic
+# undef libc_hidden_def
+# define libc_hidden_def(name)
+# undef weak_alias
+# define weak_alias(x, x2)
+# include <string/stpncpy.c>
+#endif
diff --git a/sysdeps/riscv/multiarch/stpncpy-vector.S b/sysdeps/riscv/multiarch/stpncpy-vector.S
new file mode 100644
index 0000000000..e84d28a1e4
--- /dev/null
+++ b/sysdeps/riscv/multiarch/stpncpy-vector.S
@@ -0,0 +1,28 @@
+/* Re-include the RISC-V RVV based stpncpy 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 STPNCPY __stpncpy_vector
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(name)
+# undef libc_hidden_def
+# define libc_hidden_def(name)
+# undef weak_alias
+# define weak_alias(name, alias)
+# include <sysdeps/riscv/rvv/stpncpy.S>
+#endif
diff --git a/sysdeps/riscv/rvv/stpncpy.S b/sysdeps/riscv/rvv/stpncpy.S
new file mode 100644
index 0000000000..7cfc2f76cc
--- /dev/null
+++ b/sysdeps/riscv/rvv/stpncpy.S
@@ -0,0 +1,97 @@
+/* RISC-V RVV based stpncpy.
+ 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 <sysdep.h>
+#include <sys/asm.h>
+
+#ifndef STPNCPY
+# ifdef weak_alias
+# define STPNCPY __stpncpy
+weak_alias (__stpncpy, stpncpy)
+# else
+# define STPNCPY stpncpy
+# endif
+#endif
+
+#define dst a0
+#define src a1
+#define length a2
+#define dst_ptr a3
+#define active_elem_pos a4
+#define cur_vl a5
+#define ivl a6
+#define temp a1
+
+#define ELEM_LMUL_SETTING m1
+#define vmask1 v0
+#define vmask2 v1
+#define ZERO_FILL_ELEM_LMUL_SETTING m8
+#define vstr1 v8
+#define vstr2 v16
+
+ENTRY (STPNCPY)
+.option push
+.option arch, +v
+ mv dst_ptr, dst
+ /* Copy src to dst_ptr. */
+L(stpcpy_loop):
+ vsetvli zero, length, e8, ELEM_LMUL_SETTING, ta, ma
+ vle8ff.v vstr1, (src)
+ vmseq.vx vmask2, vstr1, zero
+ csrr cur_vl, vl
+ vfirst.m active_elem_pos, vmask2
+ vmsif.m vmask1, vmask2
+ add src, src, cur_vl
+ sub length, length, cur_vl
+ vse8.v vstr1, (dst_ptr), vmask1.t
+ add dst_ptr, dst_ptr, cur_vl
+ bgez active_elem_pos, L(fill_zero)
+ bnez length, L(stpcpy_loop)
+ mv dst, dst_ptr
+ ret
+
+ /* Fill the tail zero. */
+L(fill_zero):
+ /* We already copied the `\0` to dst, but we use `vfirst.m` to
+ get the `index` of the `\0` position. We need to adjust by `-1`
+ to get the correct remaining length for zero filling. */
+ sub temp, cur_vl, active_elem_pos
+ addi temp, temp, -1
+ sub dst, dst_ptr, cur_vl
+ add dst, dst, active_elem_pos
+ add length, length, temp
+ /* Return early for the `strlen(src) + 1 == count` case. */
+ bnez length, L(do_fill_zero)
+ ret
+
+L(do_fill_zero):
+ sub dst_ptr, dst_ptr, temp
+ vsetvli zero, length, e8, ZERO_FILL_ELEM_LMUL_SETTING, ta, ma
+ vmv.v.x vstr2, zero
+L(fill_zero_loop):
+ vsetvli ivl, length, e8, ZERO_FILL_ELEM_LMUL_SETTING, ta, ma
+ vse8.v vstr2, (dst_ptr)
+ sub length, length, ivl
+ add dst_ptr, dst_ptr, ivl
+ bnez length, L(fill_zero_loop)
+ ret
+.option pop
+END (STPNCPY)
+#ifdef weak_alias
+libc_hidden_def (__stpncpy)
+#endif
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index 929df14a6f..25d8216d2e 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -19,6 +19,9 @@ sysdep_routines += \
memset \
memset-generic \
memset-vector \
+ stpncpy \
+ stpncpy-generic \
+ stpncpy-vector \
strcat \
strcat-generic \
strcat-vector \
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 4c28e22606..755ba9d637 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -110,5 +110,10 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
__memmove_vector)
IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_generic))
+ IFUNC_IMPL (i, name, stpncpy,
+ IFUNC_IMPL_ADD (array, i, stpncpy, rvv_enabled,
+ __stpncpy_vector)
+ IFUNC_IMPL_ADD (array, i, stpncpy, 1, __stpncpy_generic))
+
return 0;
}
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c b/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c
new file mode 100644
index 0000000000..989003f081
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/stpncpy.c
@@ -0,0 +1,62 @@
+/* Multiple versions of stpncpy.
+ 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)
+#define SYMBOL_NAME stpncpy
+# include <ifunc-init.h>
+
+/* Redefine stpncpy so that the compiler won't complain about the type
+ mismatch with the IFUNC selector in weak_alias, below. */
+# undef stpncpy
+# undef __stpncpy
+# define stpncpy REDIRECT_NAME
+# define __stpncpy __redirect___stpncpy
+# include <string.h>
+# undef stpncpy
+# undef __stpncpy
+
+# include <stdint.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (REDIRECT_NAME) __stpncpy;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (generic) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (vector) attribute_hidden;
+
+static inline __typeof (REDIRECT_NAME) *
+select_stpncpy_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 OPTIMIZE (vector);
+ return OPTIMIZE (generic);
+}
+
+riscv_libc_ifunc (__stpncpy, select_stpncpy_ifunc);
+
+weak_alias (__stpncpy, stpncpy);
+
+# ifdef SHARED
+__hidden_ver1 (__stpncpy, __GI___stpncpy, __redirect___stpncpy)
+ __attribute__ ((visibility ("hidden")));
+# endif
+#else
+# include <string/stpncpy.c>
+#endif
--
2.43.0