gcc/testsuite/gcc.dg/tree-ssa/loop-4.c

   1 /* A test for strength reduction and induction variable elimination.  */
   2
   3 /* { dg-do compile } */
   4 /* { dg-options "-O1 -fdump-tree-vars" } */
   5
   6 /* Size of this structure should be sufficiently weird so that no memory
   7    addressing mode applies.  */
   8
   9 struct bla
  10 {
  11   char x[187];
  12   int y;
  13   char z[253];
  14 } arr_base[100];
  15
  16 int foo(void);
  17
  18 void xxx(void)
  19 {
  20   int iter;
  21
  22   for (iter = 0; iter < 100; iter++)
  23     arr_base[iter].y = foo ();
  24 }
  25
  26 /* Access to arr_base[iter].y should be strength reduced.  Depending on
  27    whether we have an addressing mode of type [base + offset], one of the
  28    following forms might get chosen:
  29
  30    -- induction variable with base &arr_base[0].y, the memory access of
  31       form *iv = ...
  32    -- induction variable with base 0, the memory access of form
  33       *(iv + &arr_base[0].y) = ...
  34
  35    In any case, we should not have 'arr_base.[^0].* ='  */
  36
  37 /* { dg-final { scan-tree-dump-times "arr_base.\[^0\]\[^\\n\\r\]*=" 0 "vars" } } */
  38
  39 /* And the original induction variable should be eliminated.  */
  40
  41 /* { dg-final { scan-tree-dump-times "iter" 0 "vars" } } */