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

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -ftree-loop-distribution -fdump-tree-ldist-all" } */
   3
   4 void foo (int * __restrict__ ia,
   5           int * __restrict__ ib,
   6           int * __restrict__ oxa,
   7           int * __restrict__ oxb,
   8           int * __restrict__ oya,
   9           int * __restrict__ oyb)
  10 {
  11   int i;
  12   long int mya[52];
  13   long int myb[52];
  14
  15   for (i=0; i < 52; i++)
  16     {
  17       mya[i] = ia[i] * oxa[i] + ib[i] * oxb[i];
  18       myb[i] = -ia[i] * oxb[i] + ib[i] * oxa[i];
  19       oya[i] = mya[i] >> 10;
  20       oyb[i] = myb[i] >> 10;
  21     }
  22
  23   /* This loop was distributed, but it is not anymore due to the cost
  24      model changes: the result of a distribution would look like this:
  25
  26      |  for (i=0; i < 52; i++)
  27      |    oya[i] = ia[i] * oxa[i] + ib[i] * oxb[i] >> 10;
  28      |
  29      |  for (i=0; i < 52; i++)
  30      |    oyb[i] = -ia[i] * oxb[i] + ib[i] * oxa[i] >> 10;
  31
  32      and in this the array IA is read in both tasks.  For maximizing
  33      the cache reuse, ldist does not distributes this loop anymore.
  34   */
  35 }
  36
  37 /* { dg-final { scan-tree-dump-times "distributed: split to 2 loops" 0 "ldist" } } */