[7/7] RISC-V: Add Zbb optimized strncmp as ifunc

Message ID 20240422074403.2399529-8-christoph.muellner@vrull.eu
State Superseded
Delegated to: Carlos O'Donell
Headers
Series Add ifunc support for existing Zbb optimizations |

Checks

Context Check Description
redhat-pt-bot/TryBot-apply_patch success Patch applied to master at the time it was sent
redhat-pt-bot/TryBot-32bit success Build for i686
linaro-tcwg-bot/tcwg_glibc_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_glibc_check--master-arm success Testing passed
linaro-tcwg-bot/tcwg_glibc_build--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_glibc_check--master-aarch64 success Testing passed

Commit Message

Christoph Müllner April 22, 2024, 7:44 a.m. UTC
  When building with Zbb enabled, strncmp 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/strncmp-generic.c     | 26 +++++++++
 sysdeps/riscv/multiarch/strncmp-zbb.c         | 30 ++++++++++
 .../unix/sysv/linux/riscv/multiarch/Makefile  |  3 +
 .../linux/riscv/multiarch/ifunc-impl-list.c   |  4 ++
 .../unix/sysv/linux/riscv/multiarch/strncmp.c | 57 +++++++++++++++++++
 5 files changed, 120 insertions(+)
 create mode 100644 sysdeps/riscv/multiarch/strncmp-generic.c
 create mode 100644 sysdeps/riscv/multiarch/strncmp-zbb.c
 create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/strncmp.c
  

Patch

diff --git a/sysdeps/riscv/multiarch/strncmp-generic.c b/sysdeps/riscv/multiarch/strncmp-generic.c
new file mode 100644
index 0000000000..67eb89e62e
--- /dev/null
+++ b/sysdeps/riscv/multiarch/strncmp-generic.c
@@ -0,0 +1,26 @@ 
+/* Re-include the default strncmp 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 STRNCMP __strncmp_generic
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+#endif
+#include <string/strncmp.c>
diff --git a/sysdeps/riscv/multiarch/strncmp-zbb.c b/sysdeps/riscv/multiarch/strncmp-zbb.c
new file mode 100644
index 0000000000..993b494d8b
--- /dev/null
+++ b/sysdeps/riscv/multiarch/strncmp-zbb.c
@@ -0,0 +1,30 @@ 
+/* Re-include the default strncmp 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 STRNCMP __strncmp_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/strncmp.c>
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index daf5af9608..4a34eab00c 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -18,6 +18,9 @@  sysdep_routines += \
   strlen \
   strlen-generic \
   strlen-zbb \
+  strncmp \
+  strncmp-generic \
+  strncmp-zbb \
   # 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 f5f34818ed..583c77934e 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -76,5 +76,9 @@  __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 	      IFUNC_IMPL_ADD (array, i, strlen, has_zbb, __strlen_zbb)
 	      IFUNC_IMPL_ADD (array, i, strlen, 1, __strlen_generic))
 
+  IFUNC_IMPL (i, name, strncmp,
+	      IFUNC_IMPL_ADD (array, i, strncmp, has_zbb, __strncmp_zbb)
+	      IFUNC_IMPL_ADD (array, i, strncmp, 1, __strncmp_generic))
+
   return 0;
 }
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/strncmp.c b/sysdeps/unix/sysv/linux/riscv/multiarch/strncmp.c
new file mode 100644
index 0000000000..9bc026681f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/strncmp.c
@@ -0,0 +1,57 @@ 
+/* Multiple versions of strncmp.
+   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 strncmp so that the compiler won't complain about the type
+   mismatch with the IFUNC selector in strong_alias, below.  */
+# undef strncmp
+# define strncmp __redirect_strncmp
+# include <stdint.h>
+# include <string.h>
+# include <ifunc-init.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (__redirect_strncmp) __libc_strncmp;
+
+extern __typeof (__redirect_strncmp) __strncmp_generic attribute_hidden;
+extern __typeof (__redirect_strncmp) __strncmp_zbb attribute_hidden;
+
+static inline __typeof (__redirect_strncmp) *
+select_strncmp_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 __strncmp_zbb;
+
+  return __strncmp_generic;
+}
+
+riscv_libc_ifunc (__libc_strncmp, select_strncmp_ifunc);
+
+# undef strncmp
+strong_alias (__libc_strncmp, strncmp);
+# ifdef SHARED
+__hidden_ver1 (strncmp, __GI_strncmp, __redirect_strncmp)
+  __attribute__ ((visibility ("hidden"))) __attribute_copy__ (strncmp);
+# endif
+#else
+# include <string/strncmp.c>
+#endif