[PATCH 2/7] RISC-V: Add Zbb optimized memchr as ifunc
Christoph Müllner
christoph.muellner@vrull.eu
Mon Apr 22 07:43:58 GMT 2024
When building with Zbb enabled, memchr 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/memchr-generic.c | 26 +++++++++
sysdeps/riscv/multiarch/memchr-zbb.c | 30 ++++++++++
.../unix/sysv/linux/riscv/multiarch/Makefile | 3 +
.../linux/riscv/multiarch/ifunc-impl-list.c | 31 ++++++++--
.../unix/sysv/linux/riscv/multiarch/memchr.c | 57 +++++++++++++++++++
5 files changed, 142 insertions(+), 5 deletions(-)
create mode 100644 sysdeps/riscv/multiarch/memchr-generic.c
create mode 100644 sysdeps/riscv/multiarch/memchr-zbb.c
create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/memchr.c
diff --git a/sysdeps/riscv/multiarch/memchr-generic.c b/sysdeps/riscv/multiarch/memchr-generic.c
new file mode 100644
index 0000000000..a96c36398b
--- /dev/null
+++ b/sysdeps/riscv/multiarch/memchr-generic.c
@@ -0,0 +1,26 @@
+/* Re-include the default memchr 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 MEMCHR __memchr_generic
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+#endif
+#include <string/memchr.c>
diff --git a/sysdeps/riscv/multiarch/memchr-zbb.c b/sysdeps/riscv/multiarch/memchr-zbb.c
new file mode 100644
index 0000000000..bead0335ae
--- /dev/null
+++ b/sysdeps/riscv/multiarch/memchr-zbb.c
@@ -0,0 +1,30 @@
+/* Re-include the default memchr 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 MEMCHR __memchr_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/memchr.c>
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index fcef5659d4..5586d11c89 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -1,5 +1,8 @@
ifeq ($(subdir),string)
sysdep_routines += \
+ memchr \
+ memchr-generic \
+ memchr-zbb \
memcpy \
memcpy-generic \
memcpy_noalignment \
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 9f806d7a9e..7321144a32 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -20,19 +20,40 @@
#include <string.h>
#include <sys/hwprobe.h>
+#define ARRAY_SIZE(A) (sizeof (A) / sizeof ((A)[0]))
+
size_t
__libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
size_t max)
{
size_t i = max;
+ struct riscv_hwprobe pairs[] = {
+ { .key = RISCV_HWPROBE_KEY_IMA_EXT_0 },
+ { .key = RISCV_HWPROBE_KEY_CPUPERF_0 },
+ };
+ bool has_zbb = false;
bool fast_unaligned = false;
- struct riscv_hwprobe pair = { .key = RISCV_HWPROBE_KEY_CPUPERF_0 };
- if (__riscv_hwprobe (&pair, 1, 0, NULL, 0) == 0
- && (pair.value & RISCV_HWPROBE_MISALIGNED_MASK)
- == RISCV_HWPROBE_MISALIGNED_FAST)
- fast_unaligned = true;
+ if (__riscv_hwprobe (pairs, ARRAY_SIZE (pairs), 0, NULL, 0) == 0)
+ {
+ struct riscv_hwprobe *pair;
+
+ /* RISCV_HWPROBE_KEY_IMA_EXT_0 */
+ pair = &pairs[0];
+ if (pair->value & RISCV_HWPROBE_EXT_ZBB)
+ has_zbb = true;
+
+ /* RISCV_HWPROBE_KEY_CPUPERF_0 */
+ pair = &pairs[1];
+ if ((pair->value & RISCV_HWPROBE_MISALIGNED_MASK)
+ == RISCV_HWPROBE_MISALIGNED_FAST)
+ fast_unaligned = true;
+ }
+
+ IFUNC_IMPL (i, name, memchr,
+ IFUNC_IMPL_ADD (array, i, memchr, has_zbb, __memchr_zbb)
+ IFUNC_IMPL_ADD (array, i, memchr, 1, __memchr_generic))
IFUNC_IMPL (i, name, memcpy,
IFUNC_IMPL_ADD (array, i, memcpy, fast_unaligned,
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/memchr.c b/sysdeps/unix/sysv/linux/riscv/multiarch/memchr.c
new file mode 100644
index 0000000000..bc076cbf24
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/memchr.c
@@ -0,0 +1,57 @@
+/* Multiple versions of memchr.
+ 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 memchr so that the compiler won't complain about the type
+ mismatch with the IFUNC selector in strong_alias, below. */
+# undef memchr
+# define memchr __redirect_memchr
+# include <stdint.h>
+# include <string.h>
+# include <ifunc-init.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (__redirect_memchr) __libc_memchr;
+
+extern __typeof (__redirect_memchr) __memchr_generic attribute_hidden;
+extern __typeof (__redirect_memchr) __memchr_zbb attribute_hidden;
+
+static inline __typeof (__redirect_memchr) *
+select_memchr_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 __memchr_zbb;
+
+ return __memchr_generic;
+}
+
+riscv_libc_ifunc (__libc_memchr, select_memchr_ifunc);
+
+# undef memchr
+strong_alias (__libc_memchr, memchr);
+# ifdef SHARED
+__hidden_ver1 (memchr, __GI_memchr, __redirect_memchr)
+ __attribute__ ((visibility ("hidden"))) __attribute_copy__ (memchr);
+# endif
+#else
+# include <string/memchr.c>
+#endif
--
2.44.0
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