Andrei Elovikov 0215f6b6cf [DominanceFrontier] Support post-dominators on graphs with single root (#179336) ...

I plan to use that to optimize mask creation in VPlan predicator by
`or`ing edge masks from the post-dominance frontier instead of all
predecessors in a subsequent patch. Note that it would require to use
the same unmodified post-dom tree for *all* the basic blocks in a VPlan
that is already limited to a particular loopnest so the algorithmic
complexity concerns behind the "deprecation" notice in the beggining of
`DominanceFrontier.h` (and also discussion in the
https://discourse.llvm.org/t/dominance-frontiers/21755 thread) don't
apply for my use case (at least to the best of my understanding).

The change here is to properly use graph-traits for children traversal
plus inline `ForwardDominanceFrontierBase` into `DominanceFrontierBase` now 
that it's used for post-dom-frontier.

Since the only planned use-case is in the vectorizer, I'm adding a
VPlan-base unittest along with this change.

Support for multiple root nodes via using virtual root node to seed the
worklist is left to a subsequent PR.

2026-02-11 20:49:41 +00:00

2.5 KiB

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