reorder() before indexing produces incorrect results

[0xjc]

For inp1, I create a 2x3x2 array, reorder it to 2x2x3, and index it along dimension 1.

For inp2, I prepare the reordering beforehand, and index it along dimension 1.

int idx_host[2] = {1, 1};
float inp1_host[12] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
float inp2_host[12] = {0, 1, 6, 7, 2, 3, 8, 9, 4, 5, 10, 11};
array idx(2, idx_host);
array inp1 = reorder(array(2, 3, 2, inp1_host), 0, 2, 1);
array inp2(2, 2, 3, inp2_host);
array res1 = inp1(span, idx, span);
array res2 = inp2(span, idx, span);
af::print("idx", idx);
af::print("inp1", inp1);
af::print("inp2", inp2);
af::print("res1", res1);
af::print("res2", res2);

Output:

idx
[2 1 1 1]
         1 
         1 

inp1
[2 2 3 1]
    0.0000     6.0000 
    1.0000     7.0000 

    2.0000     8.0000 
    3.0000     9.0000 

    4.0000    10.0000 
    5.0000    11.0000 


inp2
[2 2 3 1]
    0.0000     6.0000 
    1.0000     7.0000 

    2.0000     8.0000 
    3.0000     9.0000 

    4.0000    10.0000 
    5.0000    11.0000 


res1
[2 2 3 1]
    2.0000     2.0000 
    3.0000     3.0000 

    8.0000     8.0000 
    9.0000     9.0000 

    0.0000     0.0000 
    0.0000     0.0000 


res2
[2 2 3 1]
    6.0000     6.0000 
    7.0000     7.0000 

    8.0000     8.0000 
    9.0000     9.0000 

   10.0000    10.0000 
   11.0000    11.0000 

We get inp1 and inp2 the same, as expected, but res1 and res2 differ. res2 is what I would expect.

[0xjc]

It seems that setting the reorder() result's dimensions to itself works:

array my_reorder(
    const array& in,
    const unsigned x,
    const unsigned y = 1,
    const unsigned z = 2,
    const unsigned w = 3) {
  const array& result = reorder(in, x, y, z, w);
  return moddims(result, result.dims());
}

[umar456]

That is very odd. I have been able to confirm this behavior. I will look into it later today.

[umar456]

Fixed in v3.6