Loongarch: Add ifunc support for strchr{aligned, lsx, lasx} and strchrnul{aligned, lsx, lasx}

These implementations improve the time to run strchr{nul}
microbenchmark in glibc as below:
strchr-lasx       reduces the runtime about 50%-83%
strchr-lsx        reduces the runtime about 30%-67%
strchr-aligned    reduces the runtime about 10%-20%
strchrnul-lasx    reduces the runtime about 50%-83%
strchrnul-lsx     reduces the runtime about 36%-65%
strchrnul-aligned reduces the runtime about 6%-10%

1 files changed, 39 insertions, 0 deletions

diff --git a/sysdeps/loongarch/lp64/multiarch/strchrnul.c b/sysdeps/loongarch/lp64/multiarch/strchrnul.c
new file mode 100644
index 0000000000..f3b8296ee8
--- /dev/null
+++ b/sysdeps/loongarch/lp64/multiarch/strchrnul.c
@@ -0,0 +1,39 @@
+/* Multiple versions of strchrnul.
+   All versions must be listed in ifunc-impl-list.c.
+   Copyright (C) 2023 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
+   <http://www.gnu.org/licenses/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+
+#if IS_IN (libc)
+# define strchrnul __redirect_strchrnul
+# define __strchrnul __redirect___strchrnul
+# include <string.h>
+# undef __strchrnul
+# undef strchrnul
+
+# define SYMBOL_NAME strchrnul
+# include "ifunc-strchrnul.h"
+
+libc_ifunc_redirected (__redirect_strchrnul, __strchrnul,
+                       IFUNC_SELECTOR ());
+weak_alias (__strchrnul, strchrnul)
+# ifdef SHARED
+__hidden_ver1 (__strchrnul, __GI___strchrnul, __redirect_strchrnul)
+  __attribute__((visibility ("hidden"))) __attribute_copy__ (strchrnul);
+# endif
+#endif