gcc/testsuite/gcc.dg/pr62167.c

   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"} } */