isl-remap.py

import islpy as isl
dt = isl.dim_type


def mat_to_map(mat: isl.Mat, input_space: isl.Space) -> isl.Map:
    if input_space.dim(dt.set) != mat.cols() - 1:
        raise ValueError("number of columns must match input space")
    map_space = (input_space
            .move_dims(dt.in_, 0, dt.out, 0, input_space.dim(dt.set))
            .insert_dims(dt.out, 0, mat.rows() - 1))

    for j in range(1, mat.cols()):
        assert mat.get_element_val(0, j) == 0

    result = isl.BasicMap.universe(map_space)

    for i in range(mat.rows() - 1):
        cns = (
                isl.Constraint.equality_alloc(map_space)
                .set_coefficient_val(dt.out, i, -1)
                .set_constant_val(
                    mat.get_element_val(i+1, 0))
                )
        for j in range(mat.cols() - 1):
            cns = cns.set_coefficient_val(dt.in_, j,
                    mat.get_element_val(i+1, j+1))

        result = result.add_constraint(cns)

    return result


def remap(s: isl.BasicSet) -> isl.BasicMap:
    s_lifted = s.lift()
    print(s_lifted)
    s_no_eq, t1, t2 = s_lifted.remove_equalities()
    print(s_no_eq)

    t1.dump()
    t2.dump()
    # FIXME could assert t2.product(t1) is an identity
    t2.product(t1).dump()

    mat_to_map(t1, s.space))

    1/0



def main():
     s = isl.BasicSet("{ [i, j] : (2i + j) mod 8 = 0 "
             "and 0<= i < 10 and 0<=j<80"
             "}") 
     remap(s)

main()