gcc/testsuite/gcc.dg/tree-ssa/pr21559.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -fdump-tree-vrp1-details" } */
   3
   4 static int blocksize = 4096;
   5
   6 int bar (int);
   7
   8 void foo (void)
   9 {
  10   int toread;
  11   int bytes;
  12   __attribute__ ((used))
  13   static char eof_reached = 0;
  14
  15   toread = blocksize;
  16   bytes = 1;
  17
  18   while (toread != 0)
  19     {
  20       bytes = bar (toread);
  21       if (bytes <= 0)
  22         {
  23           if (bytes < 0)
  24             continue;
  25           break;
  26         }
  27       toread -= bytes;
  28     }
  29
  30   if (bytes == 0)
  31     eof_reached = 1;
  32 }
  33
  34
  35 /* First, we should simplify the bits < 0 test within the loop.  */
  36 /* { dg-final { scan-tree-dump-times "Simplified relational" 1 "vrp1" } } */
  37
  38 /* Second, we should thread the edge out of the loop via the break
  39    statement.  We also realize that the final bytes == 0 test is useless,
  40    and thread over it.  We also know that toread != 0 is useless when
  41    entering while loop and thread over it.  */
  42 /* { dg-final { scan-tree-dump-times "Threaded jump" 3 "vrp1" } } */
  43
  44