When building with Zbb enabled, memrchr 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/memrchr-generic.c | 26 ++++++++
sysdeps/riscv/multiarch/memrchr-zbb.c | 30 +++++++++
.../unix/sysv/linux/riscv/multiarch/Makefile | 3 +
.../linux/riscv/multiarch/ifunc-impl-list.c | 4 ++
.../unix/sysv/linux/riscv/multiarch/memrchr.c | 61 +++++++++++++++++++
5 files changed, 124 insertions(+)
create mode 100644 sysdeps/riscv/multiarch/memrchr-generic.c
create mode 100644 sysdeps/riscv/multiarch/memrchr-zbb.c
create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/memrchr.c
new file mode 100644
@@ -0,0 +1,26 @@
+/* Re-include the default memrchr 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 MEMRCHR __memrchr_generic
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+#endif
+#include <string/memrchr.c>
new file mode 100644
@@ -0,0 +1,30 @@
+/* Re-include the default memrchr 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/>. */
+
+#include <string.h>
+
+#if IS_IN(libc)
+# define MEMRCHR __memrchr_zbb
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+#endif
+/* Convince preprocessor to have Zbb instructions. */
+#ifndef __riscv_zbb
+# define __riscv_zbb
+#endif
+#include <string/memrchr.c>
@@ -6,6 +6,9 @@ sysdep_routines += \
memcpy \
memcpy-generic \
memcpy_noalignment \
+ memrchr \
+ memrchr-generic \
+ memrchr-zbb \
# sysdep_routines
CFLAGS-memcpy_noalignment.c += -mno-strict-align
@@ -60,5 +60,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
__memcpy_noalignment)
IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))
+ IFUNC_IMPL (i, name, memrchr,
+ IFUNC_IMPL_ADD (array, i, memrchr, has_zbb, __memrchr_zbb)
+ IFUNC_IMPL_ADD (array, i, memrchr, 1, __memrchr_generic))
+
return 0;
}
new file mode 100644
@@ -0,0 +1,61 @@
+/* Multiple versions of memrchr.
+ 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 memrchr so that the compiler won't complain about the type
+ mismatch with the IFUNC selector in strong_alias, below. */
+# undef memrchr
+# undef __memrchr
+# define memrchr __redirect_memrchr
+# define __memrchr __redirect___memrchr
+# include <stdint.h>
+# include <string.h>
+# include <ifunc-init.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (__redirect_memrchr) __libc_memrchr;
+
+extern __typeof (__redirect_memrchr) __memrchr_generic attribute_hidden;
+extern __typeof (__redirect_memrchr) __memrchr_zbb attribute_hidden;
+
+static inline __typeof (__redirect_memrchr) *
+select_memrchr_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_EXT_ZBB))
+ return __memrchr_zbb;
+
+ return __memrchr_generic;
+}
+
+riscv_libc_ifunc (__libc_memrchr, select_memrchr_ifunc);
+
+# undef memrchr
+# undef __memrchr
+strong_alias (__libc_memrchr, __memrchr);
+weak_alias (__memrchr, memrchr)
+# ifdef SHARED
+__hidden_ver1 (memrchr, __GI___memrchr, __redirect_memrchr)
+ __attribute__ ((visibility ("hidden"))) __attribute_copy__ (memrchr);
+# endif
+#else
+# include <string/memrchr.c>
+#endif