gcc/testsuite/gcc.dg/tree-ssa/loop-interchange-10.c

   1 /* { dg-do run } */
   2 /* { dg-options "-O2 -floop-interchange -fdump-tree-linterchange-details" } */
   3
   4 #define M 256
   5 int a[M][M], b[M][M];
   6 int __attribute__((noinline))
   7 double_reduc (int n)
   8 {
   9   int sum = 0;
  10   for (int j = 0; j < n; j++)
  11     {
  12       for (int i = 0; i < n; i++)
  13         sum = sum + a[i][j]*b[i][j];
  14     }
  15   return sum;
  16 }
  17
  18 extern void abort ();
  19
  20 static void __attribute__((noinline))
  21 init (int i)
  22 {
  23   for (int j = 0; j < M; j++)
  24     {
  25       a[i][j] = i;
  26       b[i][j] = j;
  27     }
  28 }
  29
  30 int main (void)
  31 {
  32   for (int i = 0; i < M; ++i)
  33     init (i);
  34
  35   int sum = double_reduc (M);
  36
  37   if (sum != 1065369600)
  38     abort ();
  39
  40   return 0;
  41 }
  42
  43 /* { dg-final { scan-tree-dump-times "Loop_pair<outer:., inner:.> is interchanged" 1 "linterchange" } } */