gcc/testsuite/gcc.dg/pr33136-2.c

   1 /* PR tree-optimization/33136 */
   2 /* { dg-do run } */
   3 /* { dg-options "-O2" } */
   4
   5 extern void abort (void);
   6
   7 struct S
   8 {
   9   void *a;
  10   int b;
  11   int *c;
  12 };
  13 static int d, e;
  14
  15 static struct S s;
  16
  17 static int *
  18 __attribute__((noinline, const))
  19 foo (void)
  20 {
  21   return &s.b;
  22 }
  23
  24 int *
  25 __attribute__((noinline))
  26 bar (int **f)
  27 {
  28   s.c = &d;
  29   *f = &e;
  30   /* As nothing ever takes the address of any int * field in struct S,
  31      the write to *f can't alias with the s.c field.  */
  32   return s.c;
  33 }
  34
  35 int
  36 __attribute__((noinline))
  37 baz (int *x)
  38 {
  39   s.b = 1;
  40   *x = 4;
  41   /* Function foo takes address of an int field in struct S,
  42      so *x can alias with the s.b field (and it does in this testcase).  */
  43   return s.b;
  44 }
  45
  46 int
  47 __attribute__((noinline))
  48 t (void)
  49 {
  50   int *f = (int *) 0;
  51   return 10 * (bar (&f) != &d) + baz (foo ());
  52 }
  53
  54 int
  55 main (void)
  56 {
  57   if (t () != 4)
  58     abort ();
  59   return 0;
  60 }