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  }