gcc/testsuite/gcc.dg/tree-ssa/pr22591.c

   1 /* { dg-do run } */
   2 /* { dg-options "-O2" } */
   3
   4 void abort ();
   5
   6 typedef struct _Node
   7 {
   8   struct _Node *next, *prev;
   9 } Node;
  10
  11 void __attribute__ ((noinline)) append (Node * q, Node * p)
  12 {
  13   p->next = q;
  14   p->prev = q;
  15   q->next = p;
  16   q->prev = p;
  17 }
  18
  19 inline void
  20 swap (Node ** a, Node ** b)
  21 {
  22   Node *tmp = *a;
  23   *a = *b;
  24   *b = tmp;
  25 }
  26
  27 /* Miscompilation seems to happen here. If one removes the if condition
  28    (which should be true) the program works fine.  */
  29 void
  30 ListSwap (Node * x, Node * y)
  31 {
  32   Node *tmp;
  33   if (x->next)
  34     {
  35       swap (&x->next, &y->next);
  36       swap (&x->prev, &y->prev);
  37       x->next->prev = x->prev->next = x;
  38       y->next->prev = y->prev->next = y;
  39     }
  40 }
  41
  42 int
  43 main ()
  44 {
  45   Node A, A1, B, B1;
  46
  47   append (&A, &A1);
  48   append (&B, &B1);
  49
  50   ListSwap (&A, &B);
  51
  52   if (&A != A.next->prev)
  53     abort ();
  54
  55   return 0;
  56 }