[PATCH v2 08/10] x86: Add string/memory function tests in RTM region

["H.J. Lu" <hjl.tools@gmail.com>]

At function exit, AVX optimized string/memory functions have VZEROUPPER
which triggers RTM abort.   When such functions are called inside a
transactionally executing RTM region, RTM abort causes severe performance
degradation.  Add tests to verify that string/memory functions won't
cause RTM abort in RTM region.
---
 sysdeps/x86/Makefile          | 23 +++++++++++
 sysdeps/x86/tst-memchr-rtm.c  | 54 ++++++++++++++++++++++++++
 sysdeps/x86/tst-memcmp-rtm.c  | 52 +++++++++++++++++++++++++
 sysdeps/x86/tst-memmove-rtm.c | 53 ++++++++++++++++++++++++++
 sysdeps/x86/tst-memrchr-rtm.c | 54 ++++++++++++++++++++++++++
 sysdeps/x86/tst-memset-rtm.c  | 45 ++++++++++++++++++++++
 sysdeps/x86/tst-strchr-rtm.c  | 54 ++++++++++++++++++++++++++
 sysdeps/x86/tst-strcpy-rtm.c  | 53 ++++++++++++++++++++++++++
 sysdeps/x86/tst-string-rtm.h  | 72 +++++++++++++++++++++++++++++++++++
 sysdeps/x86/tst-strlen-rtm.c  | 53 ++++++++++++++++++++++++++
 sysdeps/x86/tst-strncmp-rtm.c | 52 +++++++++++++++++++++++++
 sysdeps/x86/tst-strrchr-rtm.c | 53 ++++++++++++++++++++++++++
 12 files changed, 618 insertions(+)
 create mode 100644 sysdeps/x86/tst-memchr-rtm.c
 create mode 100644 sysdeps/x86/tst-memcmp-rtm.c
 create mode 100644 sysdeps/x86/tst-memmove-rtm.c
 create mode 100644 sysdeps/x86/tst-memrchr-rtm.c
 create mode 100644 sysdeps/x86/tst-memset-rtm.c
 create mode 100644 sysdeps/x86/tst-strchr-rtm.c
 create mode 100644 sysdeps/x86/tst-strcpy-rtm.c
 create mode 100644 sysdeps/x86/tst-string-rtm.h
 create mode 100644 sysdeps/x86/tst-strlen-rtm.c
 create mode 100644 sysdeps/x86/tst-strncmp-rtm.c
 create mode 100644 sysdeps/x86/tst-strrchr-rtm.c

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index 06c9f84f51..0a5fbebeb5 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -76,6 +76,29 @@ endif
 
 ifeq ($(subdir),string)
 sysdep_routines += cacheinfo
+
+tests += \
+  tst-memchr-rtm \
+  tst-memcmp-rtm \
+  tst-memmove-rtm \
+  tst-memrchr-rtm \
+  tst-memset-rtm \
+  tst-strchr-rtm \
+  tst-strcpy-rtm \
+  tst-strlen-rtm \
+  tst-strncmp-rtm \
+  tst-strrchr-rtm
+
+CFLAGS-tst-memchr-rtm.c += -mrtm
+CFLAGS-tst-memcmp-rtm.c += -mrtm
+CFLAGS-tst-memmove-rtm.c += -mrtm
+CFLAGS-tst-memrchr-rtm.c += -mrtm
+CFLAGS-tst-memset-rtm.c += -mrtm
+CFLAGS-tst-strchr-rtm.c += -mrtm
+CFLAGS-tst-strcpy-rtm.c += -mrtm
+CFLAGS-tst-strlen-rtm.c += -mrtm
+CFLAGS-tst-strncmp-rtm.c += -mrtm
+CFLAGS-tst-strrchr-rtm.c += -mrtm
 endif
 
 ifneq ($(enable-cet),no)
diff --git a/sysdeps/x86/tst-memchr-rtm.c b/sysdeps/x86/tst-memchr-rtm.c
new file mode 100644
index 0000000000..e47494011e
--- /dev/null
+++ b/sysdeps/x86/tst-memchr-rtm.c
@@ -0,0 +1,54 @@
+/* Test case for memchr inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE);
+  string1[100] = 'c';
+  string1[STRING_SIZE - 100] = 'c';
+  char *p = memchr (string1, 'c', STRING_SIZE);
+  if (p == &string1[100])
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  char *p = memchr (string1, 'c', STRING_SIZE);
+  if (p == &string1[100])
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("memchr", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-memcmp-rtm.c b/sysdeps/x86/tst-memcmp-rtm.c
new file mode 100644
index 0000000000..e4c8a623bb
--- /dev/null
+++ b/sysdeps/x86/tst-memcmp-rtm.c
@@ -0,0 +1,52 @@
+/* Test case for memcmp inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+char string2[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE);
+  memset (string2, 'a', STRING_SIZE);
+  if (memcmp (string1, string2, STRING_SIZE) == 0)
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  if (memcmp (string1, string2, STRING_SIZE) == 0)
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("memcmp", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-memmove-rtm.c b/sysdeps/x86/tst-memmove-rtm.c
new file mode 100644
index 0000000000..4bf97ef1e3
--- /dev/null
+++ b/sysdeps/x86/tst-memmove-rtm.c
@@ -0,0 +1,53 @@
+/* Test case for memmove inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+char string2[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE);
+  if (memmove (string2, string1, STRING_SIZE) == string2
+      && memcmp (string2, string1, STRING_SIZE) == 0)
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  if (memmove (string2, string1, STRING_SIZE) == string2
+      && memcmp (string2, string1, STRING_SIZE) == 0)
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("memmove", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-memrchr-rtm.c b/sysdeps/x86/tst-memrchr-rtm.c
new file mode 100644
index 0000000000..a57a5a8eb9
--- /dev/null
+++ b/sysdeps/x86/tst-memrchr-rtm.c
@@ -0,0 +1,54 @@
+/* Test case for memrchr inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE);
+  string1[100] = 'c';
+  string1[STRING_SIZE - 100] = 'c';
+  char *p = memrchr (string1, 'c', STRING_SIZE);
+  if (p == &string1[STRING_SIZE - 100])
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  char *p = memrchr (string1, 'c', STRING_SIZE);
+  if (p == &string1[STRING_SIZE - 100])
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("memrchr", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-memset-rtm.c b/sysdeps/x86/tst-memset-rtm.c
new file mode 100644
index 0000000000..bf343a4dad
--- /dev/null
+++ b/sysdeps/x86/tst-memset-rtm.c
@@ -0,0 +1,45 @@
+/* Test case for memset inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE);
+  return EXIT_SUCCESS;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  memset (string1, 'a', STRING_SIZE);
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("memset", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-strchr-rtm.c b/sysdeps/x86/tst-strchr-rtm.c
new file mode 100644
index 0000000000..a82e29c072
--- /dev/null
+++ b/sysdeps/x86/tst-strchr-rtm.c
@@ -0,0 +1,54 @@
+/* Test case for strchr inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE - 1);
+  string1[100] = 'c';
+  string1[STRING_SIZE - 100] = 'c';
+  char *p = strchr (string1, 'c');
+  if (p == &string1[100])
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  char *p = strchr (string1, 'c');
+  if (p == &string1[100])
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("strchr", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-strcpy-rtm.c b/sysdeps/x86/tst-strcpy-rtm.c
new file mode 100644
index 0000000000..2b2a583fb4
--- /dev/null
+++ b/sysdeps/x86/tst-strcpy-rtm.c
@@ -0,0 +1,53 @@
+/* Test case for strcpy inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+char string2[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE - 1);
+  if (strcpy (string2, string1) == string2
+      && strcmp (string2, string1) == 0)
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  if (strcpy (string2, string1) == string2
+      && strcmp (string2, string1) == 0)
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("strcpy", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-string-rtm.h b/sysdeps/x86/tst-string-rtm.h
new file mode 100644
index 0000000000..c81ba4b422
--- /dev/null
+++ b/sysdeps/x86/tst-string-rtm.h
@@ -0,0 +1,72 @@
+/* Test string function in a transactionally executing RTM region.
+   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/>.  */
+
+#include <string.h> 
+#include <x86intrin.h>
+#include <sys/platform/x86.h>
+#include <support/check.h>
+#include <support/test-driver.h>
+
+static int
+do_test_1 (const char *name, unsigned int loop, int (*prepare) (void),
+	   int (*function) (void))
+{
+  if (!CPU_FEATURE_USABLE (RTM))
+    return EXIT_UNSUPPORTED;
+
+  int status = prepare ();
+  if (status != EXIT_SUCCESS)
+    return status;
+
+  unsigned int i;
+  unsigned int naborts = 0;
+  unsigned int failed = 0;
+  for (i = 0; i < loop; i++)
+    {
+      failed |= function ();
+      if (_xbegin() == _XBEGIN_STARTED)
+	{
+	  failed |= function ();
+	  _xend();
+	}
+      else
+	{
+	  failed |= function ();
+	  ++naborts;
+	}
+    }
+
+  if (failed)
+    FAIL_EXIT1 ("%s() failed", name);
+
+  if (naborts)
+    {
+      /* NB: Low single digit (<= 5%) noise-level aborts are normal for
+	 TSX.  */
+      double rate = 100 * ((double) naborts) / ((double) loop);
+      if (rate > 5)
+	FAIL_EXIT1 ("TSX abort rate: %.2f%% (%d out of %d)",
+		    rate, naborts, loop);
+    }
+
+  return EXIT_SUCCESS;
+}
+
+static int do_test (void);
+
+#include <support/test-driver.c>
diff --git a/sysdeps/x86/tst-strlen-rtm.c b/sysdeps/x86/tst-strlen-rtm.c
new file mode 100644
index 0000000000..0dcf14db87
--- /dev/null
+++ b/sysdeps/x86/tst-strlen-rtm.c
@@ -0,0 +1,53 @@
+/* Test case for strlen inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE - 1);
+  string1[STRING_SIZE - 100] = '\0';
+  size_t len = strlen (string1);
+  if (len == STRING_SIZE - 100)
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  size_t len = strlen (string1);
+  if (len == STRING_SIZE - 100)
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("strlen", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-strncmp-rtm.c b/sysdeps/x86/tst-strncmp-rtm.c
new file mode 100644
index 0000000000..236ad951b5
--- /dev/null
+++ b/sysdeps/x86/tst-strncmp-rtm.c
@@ -0,0 +1,52 @@
+/* Test case for strncmp inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+char string2[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE - 1);
+  memset (string2, 'a', STRING_SIZE - 1);
+  if (strncmp (string1, string2, STRING_SIZE) == 0)
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  if (strncmp (string1, string2, STRING_SIZE) == 0)
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("strncmp", LOOP, prepare, function);
+}
diff --git a/sysdeps/x86/tst-strrchr-rtm.c b/sysdeps/x86/tst-strrchr-rtm.c
new file mode 100644
index 0000000000..e32bfaf5f5
--- /dev/null
+++ b/sysdeps/x86/tst-strrchr-rtm.c
@@ -0,0 +1,53 @@
+/* Test case for strrchr inside a transactionally executing RTM region.
+   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/>.  */
+
+#include <tst-string-rtm.h>
+
+#define LOOP 3000
+#define STRING_SIZE 1024
+char string1[STRING_SIZE];
+
+__attribute__ ((noinline, noclone))
+static int
+prepare (void)
+{
+  memset (string1, 'a', STRING_SIZE - 1);
+  string1[STRING_SIZE - 100] = 'c';
+  char *p = strrchr (string1, 'c');
+  if (p == &string1[STRING_SIZE - 100])
+    return EXIT_SUCCESS;
+  else
+    return EXIT_FAILURE;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function (void)
+{
+  char *p = strrchr (string1, 'c');
+  if (p == &string1[STRING_SIZE - 100])
+    return 0;
+  else
+    return 1;
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ("strrchr", LOOP, prepare, function);
+}
-- 
2.30.2