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

/* { dg-do compile } */
/* { dg-options "-O2 -ftree-parallelize-loops=4 -fdump-tree-parloops-details -fdump-tree-optimized" } */

#include <stdio.h>
#define MB 100
#define NA 450
#define MA 400

int T[MA][MB],A[MA][NA],B[MB][NA];
void MRTRBR(int MA_1, int NA_1, int MB_1)
{
  int i,j, t,k;

  /* At the moment we are not able to hoist the loop headers out of the loop
     nest.  */
  if (MA_1 < 4 || NA_1 < 4 || MB_1 < 4)
    return;

  /* The outer most loop is not parallel because for different k's there
     is write-write dependency for T[i][j].  */
  
  /* The two inner loops don't get parallelized due to low number of 
     iterations.  */

  for (k = 3; k < NA_1; k++)
    for (i = 3; i < MA_1; i++)
      for (j = 3; j < MB_1; j++)
	{
	  t = T[i][j];
	  T[i][j] = t+2+A[i][k]*B[j][k];
	}
}
void main ()
{
  int j,i;
  
  for (i = 3; i < MA; i++)
    for (j = 3; j < MB; j++)
      T[i][j] = (i>j?i:j);
  
  MRTRBR (MA,NA,MB);
  
  for (i = MA-1; i < MA; i++)
    for (j = MB-10; j < MB; j++)
      printf ("i %d j %d T[i][j] = %d\n",i,j,T[i][j]);
}


/* Check that the outer most loop doesn't get parallelized (thus no loop gets parallelized)  */

/* { dg-final { scan-tree-dump-times "SUCCESS: may be parallelized" 0 "parloops" } } */
/* { dg-final { scan-tree-dump-times "loopfn" 0 "optimized" } } */
/* { dg-final { cleanup-tree-dump "parloops" } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */