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/* { dg-do run } */

/* { dg-options "-O2" } */

void abort ();

typedef struct _Node

{

  struct _Node *next, *prev;

} Node;

void __attribute__ ((noinline)) append (Node * q, Node * p)

{

  p->next = q;

  p->prev = q;

  q->next = p;

  q->prev = p;

}

inline void

swap (Node ** a, Node ** b)

{

  Node *tmp = *a;

  *a = *b;

  *b = tmp;

}

/* Miscompilation seems to happen here. If one removes the if condition

   (which should be true) the program works fine.  */

void

ListSwap (Node * x, Node * y)

{

  Node *tmp;

  if (x->next)

    {

      swap (&x->next, &y->next);

      swap (&x->prev, &y->prev);

      x->next->prev = x->prev->next = x;

      y->next->prev = y->prev->next = y;

    }

}

int

main ()

{

  Node A, A1, B, B1;

  append (&A, &A1);

  append (&B, &B1);

  ListSwap (&A, &B);

  if (&A != A.next->prev)

    abort ();

  return 0;

}