x86: Add evex optimized functions for the wchar_t strcpy family

Implemented:
    wcscat-evex  (+ 905 bytes)
    wcscpy-evex  (+ 674 bytes)
    wcpcpy-evex  (+ 709 bytes)
    wcsncpy-evex (+1358 bytes)
    wcpncpy-evex (+1467 bytes)
    wcsncat-evex (+1213 bytes)

Performance Changes:
    Times are from N = 10 runs of the benchmark suite and are reported
    as geometric mean of all ratios of New Implementation / Best Old
    Implementation. Best Old Implementation was determined with the
    highest ISA implementation.

    wcscat-evex     -> 0.991
    wcscpy-evex     -> 0.587
    wcpcpy-evex     -> 0.695
    wcsncpy-evex    -> 0.719
    wcpncpy-evex    -> 0.694
    wcsncat-evex    -> 0.979

Code Size Changes:
    This change  increase the size of libc.so by ~6.3kb bytes. For
    reference the patch optimizing the normal strcpy family functions
    decreases libc.so by ~5.7kb.

Full check passes on x86-64 and build succeeds for all ISA levels w/
and w/o multiarch.

1 files changed, 34 insertions, 0 deletions

diff --git a/sysdeps/x86_64/multiarch/wcsncat.c b/sysdeps/x86_64/multiarch/wcsncat.c
new file mode 100644
index 0000000000..49c46aef08
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/wcsncat.c
@@ -0,0 +1,34 @@
+/* Multiple versions of wcsncat.
+   All versions must be listed in ifunc-impl-list.c.
+   Copyright (C) 2022 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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define wcsncat __redirect_wcsncat
+# include <wchar.h>
+# undef wcsncat
+
+# define SYMBOL_NAME wcsncat
+# include "ifunc-wcs.h"
+
+libc_ifunc_redirected (__redirect_wcsncat, wcsncat, IFUNC_SELECTOR ());
+# ifdef SHARED
+__hidden_ver1 (wcsncat, __GI_wcsncat, __redirect_wcsncat)
+  __attribute__((visibility ("hidden"))) __attribute_copy__ (wcsncat);
+# endif
+#endif