[PATCH] D136827: [JT] Preserve exisiting BPI/BFI during JumpThreading

[Evgeniy via Phabricator via llvm-commits]

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Currently, JT creates and updates local instances of BPI\BFI. As a result global ones have to be invalidated if JT made any changes.
In fact, JT doesn't use any information from BPI/BFI for the sake of the transformation itself. It only creates BPI/BFI to keep them up to date. But since it updates local copies (besides cases when it updates profile metadata) it just waste of time.

Current patch is a rework of D124439 <https://reviews.llvm.org/D124439>. D124439 <https://reviews.llvm.org/D124439> makes one step and replaces local copies with global ones retrieved through AnalysisPassManager. Here we do one more step and don't create BPI/BFI if the only reason of creation is to keep BPI/BFI up to date. Overall logic is the following. If there is cached BPI/BFI then update it along the transformations. If there is no existing BPI/BFI, then create it only if it is required to update profile metadata.

Please note if BPI/BFI exists on exit from JT (either cached or created) it is always up to date and no reason to invalidate it.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D136827

Files:
  llvm/include/llvm/Transforms/Scalar/JumpThreading.h
  llvm/lib/Transforms/Scalar/JumpThreading.cpp
  llvm/test/Transforms/JumpThreading/thread-prob-2.ll
  llvm/test/Transforms/JumpThreading/thread-prob-3.ll
  llvm/test/Transforms/JumpThreading/thread-prob-4.ll
  llvm/test/Transforms/JumpThreading/thread-prob-5.ll
  llvm/test/Transforms/JumpThreading/thread-prob-6.ll
  llvm/test/Transforms/JumpThreading/threading_prof1.ll
  llvm/test/Transforms/JumpThreading/threading_prof2.ll
  llvm/test/Transforms/JumpThreading/threading_prof3.ll

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