gcc/testsuite/gcc.c-torture/execute/pr15262-1.c

   1 /* PR 15262.
   2    The alias analyzer only considers relations between pointers and
   3    symbols.  If two pointers P and Q point to the same symbol S, then
   4    their respective memory tags will either be the same or they will
   5    have S in their alias set.
   6
   7    However, if there are no common symbols between P and Q, TBAA will
   8    currently miss their alias relationship altogether.  */
   9 struct A
  10 {
  11   int t;
  12   int i;
  13 };
  14
  15 int foo () { return 3; }
  16
  17 main ()
  18 {
  19   struct A loc, *locp;
  20   float f, g, *p;
  21   int T355, *T356;
  22
  23   /* Avoid the partial hack in TBAA that would consider memory tags if
  24      the program had no addressable symbols.  */
  25   f = 3;
  26   g = 2;
  27   p = foo () ? &g : &f;
  28   if (*p > 0.0)
  29     g = 1;
  30
  31   /* Store into *locp and cache its current value.  */
  32   locp = malloc (sizeof (*locp));
  33   locp->i = 10;
  34   T355 = locp->i;
  35
  36   /* Take the address of one of locp's fields and write to it.  */
  37   T356 = &locp->i;
  38   *T356 = 1;
  39
  40   /* Read the recently stored value.  If TBAA fails, this will appear
  41      as a redundant load that will be replaced with '10'.  */
  42   T355 = locp->i;
  43   if (T355 != 1)
  44     abort ();
  45
  46   return 0;
  47 }