[Bug tree-optimization/66873] fortran variant of outer-1.c not parallelized by autopar

["vries at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66873

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization

--- Comment #1 from vries at gcc dot gnu.org ---
Once noticeable difference with outer-1.c, is that pass_iv_canon make the inner
and outer loop ivs run downwards (from 500 to 0).

Removing pass_iv_canon from the pass list fixes that, but doesn't change
anything about the dependency analysis in parloops:
...
(Data Dep:
#(Data Ref:
#  bb: 4
#  stmt: x[_12] = _14;
#  ref: x[_12];
#  base_object: x;
#  Access function 0: {{0, +, 1}_3, +, 500}_4
#)
#(Data Ref:
#  bb: 4
#  stmt: x[_12] = _14;
#  ref: x[_12];
#  base_object: x;
#  Access function 0: {{0, +, 1}_3, +, 500}_4
#)
  access_fn_A: {{0, +, 1}_3, +, 500}_4
  access_fn_B: {{0, +, 1}_3, +, 500}_4

 (subscript
  iterations_that_access_an_element_twice_in_A: [0]
  last_conflict: scev_not_known
  iterations_that_access_an_element_twice_in_B: [0]
  last_conflict: scev_not_known
  (Subscript distance: 0 ))
  inner loop index: 0
  loop nest: (3 4 )
  distance_vector:   0   0
  distance_vector: 500  -1
  direction_vector:     =    =
  direction_vector:     +    -
)
  FAILED: data dependencies exist across iterations
...