Note that PointerUnion::{is,get} have been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
I'm not touching PointerUnion::dyn_cast for now because it's a bit
complicated; we could blindly migrate it to dyn_cast_if_present, but
we should probably use dyn_cast when the operand is known to be
non-null.
This commit generalizes and cleans up the `ValueBoundsConstraintSet`
API. The API used to provide function overloads for comparing/computing
bounds of:
- index-typed SSA value
- dimension of shaped value
- affine map + operands
This commit removes all overloads. There is now a single entry point for
each `compare` variant and each `computeBound` variant. These functions
now take a `Variable`, which is internally represented as an affine map
and map operands.
This commit also adds support for computing bounds for an affine map +
operands. There was previously no public API for that.