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

   1 /* { dg-do compile } */
   2 /* { dg-do run } */
   3 /* { dg-options "-O2 -funroll-loops --param max-unroll-times=8 -fpredictive-commoning -fdump-tree-pcom-details" } */
   4
   5 void abort (void);
   6
   7 unsigned fib[1000];
   8
   9 __attribute__ ((noinline))
  10 void count_fib(void)
  11 {
  12   int i;
  13
  14   fib[0] = 0;
  15   fib[1] = 1;
  16   for (i = 2; i < 1000; i++)
  17     fib[i] = (fib[i-1] + fib[i - 2]) & 0xffff;
  18 }
  19
  20 unsigned avg[1000];
  21
  22 __attribute__ ((noinline))
  23 void count_averages(int n)
  24 {
  25   int i;
  26
  27   for (i = 1; i < n; i++)
  28     avg[i] = (((unsigned long) fib[i - 1] + fib[i] + fib[i + 1]) / 3) & 0xffff;
  29 }
  30
  31 int main(void)
  32 {
  33   count_fib ();
  34   count_averages (999);
  35
  36   if (fib[19] != 4181 || avg[19] != 4510)
  37     abort ();
  38
  39   if (fib[999] != 162 || avg[998] != 21953)
  40     abort ();
  41
  42   return 0;
  43 }
  44
  45 /* Verify that both loops were transformed and unrolled.  */
  46 /* { dg-final { scan-tree-dump-times "Unrolling 2 times." 2 "pcom"} } */
  47
  48 /* Also check that we undid the transformation previously made by PRE.  */
  49 /* { dg-final { scan-tree-dump-times "looparound ref" 1 "pcom"} } */
  50
  51 /* { dg-final { cleanup-tree-dump "pcom" } } */