gcc/testsuite/gcc.dg/tree-ssa/prefetch-5.c

   1 /* { dg-do compile { target { i?86-*-* x86_64-*-* } } } */
   2 /* { dg-options "-O2 -fprefetch-loop-arrays -march=amdfam10 --param min-insn-to-prefetch-ratio=5 -fdump-tree-aprefetch-details" } */
   3
   4 /* These are common idioms for writing variable-length arrays at the end
   5    of structures.  We should not deduce anything about the number of iterations
   6    of the loops from them.  */
   7
   8 struct tail0
   9 {
  10   int xxx;
  11   int yyy[0];
  12 };
  13
  14 int loop0 (int n, struct tail0 *x)
  15 {
  16   int i, s = 0;
  17
  18   for (i = 0; i < n; i++)
  19     s += x->yyy[i];
  20
  21   return s;
  22 }
  23
  24 struct tail1
  25 {
  26   int xxx;
  27   int yyy[1];
  28 };
  29 int loop1 (int n, struct tail1 *x)
  30 {
  31   int i, s = 0;
  32
  33   for (i = 0; i < n; i++)
  34     s += x->yyy[i];
  35
  36   return s;
  37 }
  38
  39 /* It is unlikely that this should be a tail array.  We may deduce that most
  40    likely, the loop iterates about 5 times, and the array is not worth prefetching.  */
  41
  42 struct tail5
  43 {
  44   int xxx;
  45   int yyy[5];
  46 };
  47 int loop5 (int n, struct tail5 *x)
  48 {
  49   int i, s = 0;
  50
  51   for (i = 0; i < n; i++)
  52     s += x->yyy[i];
  53
  54   return s;
  55 }
  56
  57 /* Until we are able to track likely upper bounds, we can't really work out that
  58    small trailing arrays should not be prefetched.  */
  59 /* { dg-final { scan-tree-dump-times "Issued prefetch" 2 "aprefetch"  } } */
  60 /* { dg-final { scan-tree-dump-times "Not prefetching" 1 "aprefetch"  } } */