This commit adds the visitNonControlFlowArguments method to
DataFlowAnalysis, allowing analyses to provide lattice values for the
arguments to a RegionSuccessor block that aren't directly tied to an
op's inputs. For example, integer range interface can use this method
to infer bounds for the step values in loops.
This method has a default implementation that keeps the old behavior
of assigning a pessimistic fixedpoint state to all such arguments.
Reviewed By: Mogball, rriddle
Differential Revision: https://reviews.llvm.org/D124021
d35f7f254f