[PATCH] D77417: [BFI][CGP] Add limited support for detecting missed BFI updates and fix one in CodeGenPrepare.

[Hiroshi Yamauchi via Phabricator via llvm-commits]

yamauchi added a comment.

Noting that the "updatedness" of BFI *during a pass* is currently only on a best effort basis, what this patch is intended to provide is to have a way to check how well BFI is updated during CGP. It's sort of a middle ground between teaching CGP to preserve BFI (which is hard) and having no way to assess how well it can preserve BFI.  Because its updatedness could still have performance consequences.

As I see it, this is a bit different from -verify/-verify-dom-info in that unlike -verify, it cannot be a separate pass as it needs to look at the state of BFI right before it gets erased at the end of CGP (as CGP isn't declared to preserve BFI), and unlike -verify-dom-info, Pass:verifyAnalysis isn't a good place to check it in as Pass:verifyAnalysis is called on preserved analyses only. Though we might be able to extend the pass manager interface to have a place for it (maybe checkNotPreservedAnalysis?) if it's really a good idea. I'm not sure if it's mature enough at this point to be generalized.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77417/new/

https://reviews.llvm.org/D77417