lowering of loop ranges with start/step

[ehsantn]

Commit be51d48 in phdf5 branch adds support for start and step in parfor loops. However, we need lowering support in gufunc backend.

[ninegua]

Is there any sample program to run in this branch?

[ehsantn]

This branch needs a bit of set up at the moment but you can cherry-pick be51d48 and 20209a4, then run any data-parallel program to see initial errors. Below is an example. For testing start and step fields, we can set them manually in parfor pass to different values.

import numba
import numpy as np

@numba.njit(parallel=True)
def ff(n):
    A = np.ones(n)
    return np.sum(A)

n = 128
print(ff(n))

[ninegua]

Supporting step size other than 1 is tricky, I'm putting this off for now.

Branch parfor-range should have working code supporting start/stop in LoopNest.

[DrTodd13]

I believe the scheduling part of this is done.