other/7814: incorrect scheduling for glibc-2.2.92 stpcpy test

[Glen Nakamura]

Hmm, I intended to file this under optimization, but I must have selected
other by mistake... *grr*  Anyway, here is the C source for the uploaded
testcase.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7814
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#define _GNU_SOURCE

#include <stdio.h>
#include <string.h>

const char *it = "<UNSET>";	/* Routine name for message routines. */
size_t errors = 0;

/* Complain if condition is not true.  */
static void
check (int thing, int number)
{
  if (!thing)
    {
      printf("%s flunked test %d\n", it, number);
      ++errors;
    }
}

/* Complain if first two args don't strcmp as equal.  */
static void
equal (const char *a, const char *b, int number)
{
  check(a != NULL && b != NULL && (strcmp (a, b) == 0), number);
}

char one[50];
char two[50];
char *cp;

#undef __stpcpy
#    define __stpcpy(dest, src) \
  (__extension__ (__builtin_constant_p (src)                                  \
                  ? (__string2_1bptr_p (src) && strlen (src) + 1 <= 8         \
                     ? __builtin_strcpy (dest, src) + strlen (src)            \
                     : ((char *) (__mempcpy) (dest, src, strlen (src) + 1)    \
                        - 1))                                                 \
                  : __stpcpy (dest, src)))

static void
test_stpcpy (void)
{
  it = "stpcpy";
  check ((stpcpy (one, "a") - one) == 1, 1);
  equal (one, "a", 2);

  check ((stpcpy (one, "ab") - one) == 2, 3);
  equal (one, "ab", 4);

  check ((stpcpy (one, "abc") - one) == 3, 5);
  equal (one, "abc", 6);

  check ((stpcpy (one, "abcd") - one) == 4, 7);
  equal (one, "abcd", 8);

  check ((stpcpy (one, "abcde") - one) == 5, 9);
  equal (one, "abcde", 10);

  check ((stpcpy (one, "abcdef") - one) == 6, 11);
  equal (one, "abcdef", 12);

  check ((stpcpy (one, "abcdefg") - one) == 7, 13);
  equal (one, "abcdefg", 14);

  check ((stpcpy (one, "abcdefgh") - one) == 8, 15);
  equal (one, "abcdefgh", 16);

  check ((stpcpy (one, "abcdefghi") - one) == 9, 17);
  equal (one, "abcdefghi", 18);

  check ((stpcpy (one, "x") - one) == 1, 19);
  equal (one, "x", 20);			/* Writeover. */
  equal (one+2, "cdefghi", 21);		/* Wrote too much? */

  check ((stpcpy (one, "xx") - one) == 2, 22);
  equal (one, "xx", 23);		/* Writeover. */
  equal (one+3, "defghi", 24);		/* Wrote too much? */

  check ((stpcpy (one, "xxx") - one) == 3, 25);
  equal (one, "xxx", 26);		/* Writeover. */
  equal (one+4, "efghi", 27);		/* Wrote too much? */

  check ((stpcpy (one, "xxxx") - one) == 4, 28);
  equal (one, "xxxx", 29);		/* Writeover. */
  equal (one+5, "fghi", 30);		/* Wrote too much? */

  check ((stpcpy (one, "xxxxx") - one) == 5, 31);
  equal (one, "xxxxx", 32);		/* Writeover. */
  equal (one+6, "ghi", 33);		/* Wrote too much? */

  check ((stpcpy (one, "xxxxxx") - one) == 6, 34);
  equal (one, "xxxxxx", 35);		/* Writeover. */
  equal (one+7, "hi", 36);		/* Wrote too much? */

  check ((stpcpy (one, "xxxxxxx") - one) == 7, 37);
  equal (one, "xxxxxxx", 38);		/* Writeover. */
  equal (one+8, "i", 39);		/* Wrote too much? */

  check ((stpcpy (stpcpy (stpcpy (one, "a"), "b"), "c") - one) == 3, 40);
  equal (one, "abc", 41);
  equal (one + 4, "xxx", 42);
}

int
main (void)
{
  int status;

  /* A closely related function is stpcpy.  */
  test_stpcpy ();

  if (errors == 0)
    {
      status = 0;
      puts("No errors.");
    }
  else
    {
      status = 1;
      printf("%Zd errors.\n", errors);
    }

  return status;
}