1  /* { dg-do compile } */
       2  /* { dg-options "-O2 -ftree-tail-merge -fdump-tree-pre" } */
       3  
       4  struct node
       5  {
       6    struct node *next;
       7    struct node *prev;
       8  };
       9  
      10  struct node node;
      11  
      12  struct head
      13  {
      14    struct node *first;
      15  };
      16  
      17  struct head heads[5];
      18  
      19  int k = 2;
      20  
      21  struct head *head = &heads[2];
      22  
      23  int
      24  main ()
      25  {
      26    struct node *p;
      27  
      28    node.next = (void*)0;
      29  
      30    node.prev = (void *)head;
      31  
      32    asm("":"=m"(node.prev));
      33  
      34    head->first = &node;
      35  
      36    struct node *n = head->first;
      37  
      38    struct head *h = &heads[k];
      39  
      40    heads[2].first = n->next;
      41  
      42    if ((void*)n->prev == (void *)h)
      43      p = h->first;
      44    else
      45      /* Dead tbaa-unsafe load from ((struct node *)&heads[2])->next.  */
      46      p = n->prev->next;
      47  
      48    return !(p == (void*)0);
      49  }
      50  
      51  /* { dg-final { scan-tree-dump-not "Removing basic block" "pre"} } */