* Extract "value" functionality of `FlatAffineConstraints` into a new derived `FlatAffineValueConstraints` class. Current users of `FlatAffineConstraints` can use `FlatAffineValueConstraints` without additional code changes, thus NFC.
* `FlatAffineConstraints` no longer associates dimensions with SSA Values. All functionality that requires this, is moved to `FlatAffineValueConstraints`.
* `FlatAffineConstraints` no longer makes assumptions about where Values associated with dimensions are coming from.
Differential Revision: https://reviews.llvm.org/D107725
test/lib/Transforms/ has bitrot and become somewhat of a dumping grounds for testing pretty much any part of the project. This revision cleans this up, and moves the files within to a directory that reflects what is actually being tested.
Differential Revision: https://reviews.llvm.org/D102456