gcc/testsuite/gcc.dg/autopar/pr49960-1.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -ftree-parallelize-loops=4 -fdump-tree-parloops2-details -fdump-tree-optimized" } */
   3
   4 #include <stdlib.h>
   5 #include <stdio.h>
   6
   7 int main()
   8 {
   9   unsigned int x, y, idx, H = 1024, W = 1024;
  10
  11   int * tmps = (int *)malloc(H*W*sizeof(int));
  12
  13   /* This loop gets parallelized even though output dependences exist
  14      between writes to 'tmps' that prevent parallelization.
  15      For example: tmps[1] = 1, ..., tmps[1] = 17.  */
  16
  17   for(x = 1; x < H; x++)
  18     {
  19       for(y = 1; y < W; y++)
  20         {
  21           idx = x*W+y;
  22           tmps[idx % 4096] = idx;
  23         }
  24     }
  25
  26   for(x = 1; x < 8; x++)
  27     printf("tmps[%d]=%d\n", x, tmps[x]);
  28
  29   return 0;
  30 }
  31 /* Check that no loop gets parallelized.  */
  32
  33 /* { dg-final { scan-tree-dump-times "SUCCESS: may be parallelized" 0 "parloops2" } } */
  34 /* { dg-final { scan-tree-dump-times "loopfn" 0 "optimized" } } */