[flang-commits] [flang] [flang][OpenMP] Implement collapse for imperfectly nested loops (PR #202435)

[Tom Eccles via flang-commits]

https://github.com/tblah commented:

Thanks for the patch.

There's a crash if there is a collapsed nest containing a loop-transforming tile construct. I think you need a not yet implemented message to catch this.
Reproducer (from codex):
```
subroutine tile_collapse(n, x)
  integer, intent(in) :: n
  integer, intent(inout) :: x
  integer :: i, j

  !$omp do collapse(4)
  !$omp tile sizes(2, 2)
  do i = 1, n
    do j = 1, n
      x = x + i + j
    end do
  end do
end subroutine
```

https://github.com/llvm/llvm-project/pull/202435