[Bug tree-optimization/46194] [4.5/4.6 Regression] gcc.dg/graphite/block-0.c FAILs with -ftree-parallelize-loops

[Sebastian Pop]

Here is the loop kernel from block-0.c

  for (i = 0; i < N; i++)
    for (j = 0; j < N; j++)
      a[j] = a[i] + 1;

On Fri, Dec 31, 2010 at 06:01, jakub at gcc dot gnu.org
<gcc-bugzilla@gcc.gnu.org> wrote:
>  access_fn_A: {0, +, 1}_1
>  access_fn_B: {0, +, 1}_2
>
>  (subscript
>  iterations_that_access_an_element_twice_in_A: [0 + 1 * x_1]
>  last_conflict: 1000
>  iterations_that_access_an_element_twice_in_B: [0 + 1 * x_1]

I think that this representation of affine functions is wrong:
the access in B should read [0 + 0 * x_1 + 1 * x_2] and that
would not lead to a wrong conclusion like the following...

>  last_conflict: 1000
>  (Subscript distance: 0
>  )
>  )
>  inner loop index: 0
>  loop nest: (1 2 )
>  distance_vector:   0   0
>  direction_vector:     =    =
> )