x86-64: Test strlen and wcslen with 0 in the RSI register [BZ #28064]

commit 6f573a27b6
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Wed Jun 23 01:19:34 2021 -0400

    x86-64: Add wcslen optimize for sse4.1

added wcsnlen-sse4.1 to the wcslen ifunc implementation list.  Since the
random value in the the RSI register is larger than the wide-character
string length in the existing wcslen test, it didn't trigger the wcslen
test failure.  Add a test to force 0 into the RSI register before calling
wcslen.

(cherry picked from commit a6e7c3745d)

sysdeps/x86_64/Makefile

@@ -20,6 +20,8 @@ endif
 ifeq ($(subdir),string)
 sysdep_routines += cacheinfo strcasecmp_l-nonascii strncase_l-nonascii
 gen-as-const-headers += locale-defines.sym
+tests += \
+  tst-rsi-strlen
 endif
 
 ifeq ($(subdir),elf)
@@ -150,6 +152,11 @@ ifeq ($(subdir),csu)
 gen-as-const-headers += tlsdesc.sym rtld-offsets.sym
 endif
 
+ifeq ($(subdir),wcsmbs)
+tests += \
+  tst-rsi-wcslen
+endif
+
 $(objpfx)x86_64/tst-x86_64mod-1.os: $(objpfx)tst-x86_64mod-1.os
 	$(make-target-directory)
 	rm -f $@

sysdeps/x86_64/tst-rsi-strlen.c

@@ -0,0 +1,81 @@
+/* Test strlen with 0 in the RSI register.
+   Copyright (C) 2021 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/>.  */
+
+#ifdef WIDE
+# define TEST_NAME "wcslen"
+#else
+# define TEST_NAME "strlen"
+#endif /* WIDE */
+
+#define TEST_MAIN
+#include <string/test-string.h>
+
+#ifdef WIDE
+# include <wchar.h>
+# define STRLEN wcslen
+# define CHAR wchar_t
+#else
+# define STRLEN strlen
+# define CHAR char
+#endif /* WIDE */
+
+IMPL (STRLEN, 1)
+
+typedef size_t (*proto_t) (const CHAR *);
+
+typedef struct
+{
+  void (*fn) (void);
+} parameter_t;
+
+size_t
+__attribute__ ((weak, noinline, noclone))
+do_strlen (parameter_t *a, int zero, const CHAR *str)
+{
+  return CALL (a, str);
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+
+  size_t size = page_size / sizeof (CHAR) - 1;
+  CHAR *buf = (CHAR *) buf2;
+  buf[size] = 0;
+
+  parameter_t a;
+
+  int ret = 0;
+  FOR_EACH_IMPL (impl, 0)
+    {
+      a.fn = impl->fn;
+      /* NB: Pass 0 in RSI.  */
+      size_t res = do_strlen (&a, 0, buf);
+      if (res != size)
+	{
+	  error (0, 0, "Wrong result in function %s: %zu != %zu",
+		 impl->name, res, size);
+	  ret = 1;
+	}
+    }
+
+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>

sysdeps/x86_64/tst-rsi-wcslen.c

@@ -0,0 +1,20 @@
+/* Test wcslen with 0 in the RSI register.
+   Copyright (C) 2021 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 WIDE 1
+#include "tst-rsi-strlen.c"