Summary:
This diff tries to make less imprecise division by constants results.
For example, the results of the division `[l, u] / c`, where `c` is a positive constant, are:
1. If `l/c` or `u/c` is representable in the bound domain, it uses the precise bounds, i.e., `[l/c, u/c]`.
2. If it is not representable, it tries to make conservative results:
if `0<=l<=u`, it returns `[0, u]` because `0 <= [l/c, u/c] <= u`
if `l<=u<=0`, it returns `[l, 0]` because `l <= [l/c, u/c] <= 0`
if `l<=0<=u`, it returns `[l, u]` because `l <= [l/c, u/c] <= u`
3. otherwise, it returns top, `[-oo, +oo]`
Reviewed By: ezgicicek
Differential Revision: D18270380
fbshipit-source-id: 8fb14c0e4
Sungkeun Cho
88813fdaa7