gcc/testsuite/gcc.dg/tree-ssa/20041122-1.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O1 -fstrict-aliasing -fdump-tree-fre1" } */
   3
   4 __extension__ typedef __SIZE_TYPE__ size_t;
   5 extern void *xmalloc (size_t) __attribute__ ((__malloc__));
   6 struct edge_def
   7 {
   8   struct basic_block_def *dest;
   9   int flags;
  10 };
  11 typedef struct edge_def *edge;
  12 struct basic_block_def
  13 {
  14   int flags;
  15 };
  16 typedef struct basic_block_def *basic_block;
  17 extern int n_basic_blocks;
  18 extern edge frob ();
  19 basic_block *
  20 find_unreachable_blocks (void)
  21 {
  22   basic_block *tos, *worklist;
  23   tos = worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
  24   edge e = frob();
  25   if (!(e->dest->flags & 4))
  26     {
  27       e->dest->flags |= 4;
  28       *tos++ = e->dest;
  29     }
  30   return worklist;
  31 }
  32
  33 /* If the aliasing code does its job properly, then we should be
  34    able to determine that modifying e->dest->flags does not
  35    modify e or e->dest if we can assert strict-aliasing rules.
  36    The net result is that we only need one load of e->dest.  */
  37 /* { dg-final { scan-tree-dump-times "->dest" 1 "fre1" } } */
  38 /* { dg-final { cleanup-tree-dump "fre1" } } */