When building with Zbb enabled, strlen benefits from using orc.b in
find_zero_all(). This patch changes the build system such, that a
non-Zbb version as well as a Zbb version of this routine is built.
Further, a ifunc resolver is provided that selects the right routine
based on the outcome of extension probing via hwprobe().
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
---
sysdeps/riscv/multiarch/strlen-generic.c | 24 ++++++++
sysdeps/riscv/multiarch/strlen-zbb.c | 23 ++++++++
.../unix/sysv/linux/riscv/multiarch/Makefile | 3 +
.../linux/riscv/multiarch/ifunc-impl-list.c | 6 ++
.../unix/sysv/linux/riscv/multiarch/strlen.c | 59 +++++++++++++++++++
5 files changed, 115 insertions(+)
create mode 100644 sysdeps/riscv/multiarch/strlen-generic.c
create mode 100644 sysdeps/riscv/multiarch/strlen-zbb.c
create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/strlen.c
new file mode 100644
@@ -0,0 +1,24 @@
+/* Re-include the default strlen implementation.
+ Copyright (C) 2024 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 STRLEN __strlen_generic
+#endif
+#include <string/strlen.c>
new file mode 100644
@@ -0,0 +1,23 @@
+/* Re-include the default strlen implementation for Zbb.
+ Copyright (C) 2024 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/>. */
+
+/* Build with Zbb enabled. */
+#define __CODEGEN_ATTRIBUTES __attribute__((target("arch=+zbb")))
+#define USE_ZBB_ORCB 1
+#define STRLEN __strlen_zbb
+#include <string/strlen.c>
@@ -11,6 +11,8 @@ sysdep_routines += \
strchrnul-generic \
strcmp \
strcmp-generic \
+ strlen \
+ strlen-generic \
# sysdep_routines
ifeq ($(have-fattribute-zbb-support),yes)
@@ -19,6 +21,7 @@ sysdep_routines += \
memrchr-zbb \
strchrnul-zbb \
strcmp-zbb \
+ strlen-zbb \
# Zbb sysdep_routines
endif
@@ -84,5 +84,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
#endif
IFUNC_IMPL_ADD (array, i, strcmp, 1, __strcmp_generic))
+ IFUNC_IMPL (i, name, strlen,
+#if HAVE_RISCV_FATTRIBUTE_ZBB
+ IFUNC_IMPL_ADD (array, i, strlen, has_zbb, __strlen_zbb)
+#endif
+ IFUNC_IMPL_ADD (array, i, strlen, 1, __strlen_generic))
+
return 0;
}
new file mode 100644
@@ -0,0 +1,59 @@
+/* Multiple versions of strlen.
+ All versions must be listed in ifunc-impl-list.c.
+ Copyright (C) 2017-2024 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 strlen so that the compiler won't complain about the type
+ mismatch with the IFUNC selector in strong_alias, below. */
+# undef strlen
+# define strlen __redirect_strlen
+# include <stdint.h>
+# include <string.h>
+# include <ifunc-init.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (__redirect_strlen) __libc_strlen;
+
+extern __typeof (__redirect_strlen) __strlen_generic attribute_hidden;
+extern __typeof (__redirect_strlen) __strlen_zbb attribute_hidden;
+
+static inline __typeof (__redirect_strlen) *
+select_strlen_ifunc (uint64_t dl_hwcap, __riscv_hwprobe_t hwprobe_func)
+{
+#if HAVE_RISCV_FATTRIBUTE_ZBB
+ unsigned long long int v;
+ if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_IMA_EXT_0, &v) == 0
+ && (v & RISCV_HWPROBE_EXT_ZBB))
+ return __strlen_zbb;
+#endif
+
+ return __strlen_generic;
+}
+
+riscv_libc_ifunc (__libc_strlen, select_strlen_ifunc);
+
+# undef strlen
+strong_alias (__libc_strlen, strlen);
+# ifdef SHARED
+__hidden_ver1 (strlen, __GI_strlen, __redirect_strlen)
+ __attribute__ ((visibility ("hidden"))) __attribute_copy__ (strlen);
+# endif
+#else
+# include <string/strlen.c>
+#endif