Add a customizable `visitBlockTransfer` method to dense forward and
backward dataflow analyses, allowing subclasses to customize lattice
propagation behavior along control flow edges between blocks. Default
implementation preserves existing join/meet semantics.
This change mirrors the exiting structure of both dense dataflow
classes, where `RegionBranchOpInterface` and callables are allowed to be
customized by subclasses.
The use case motivating this change is dense liveness analysis.
Currently, without the customization hook the block transfer function
produces incorrect results. The issue is the current logic doesn't
remove the successor block arguments from the live set, as it only meets
the successor state with the predecessor state (ie. set union).
With this change is now possible to compute the correct result by
specifying the correct logic in `visitBlockTransfer`.
Signed-off-by: Fabian Mora <fabian.mora-cordero@amd.com>
389aa46a99