[PATCH] D11651: [LVI] Improve LazyValueInfo compile time performance

[Bruno Cardoso Lopes]

bruno created this revision.
bruno added reviewers: resistor, hfinkel, reames.
bruno added subscribers: llvm-commits, dexonsmith.

Changes in LoopUnroll in the past six months exposed scalability
issues in LazyValueInfo when used from JumpThreading. One internal test
that used to take 20s under -O2 now takes 6min.
    
This patch makes a couple of changes to speed-up LazyValueInfo and
reduces compile time to 1m20s.
    
- Change the OverDefinedCache from
DenseSet<std::pair<AssertingVH<BasicBlock>, Value*>>
to
DenseMap<AssertingVH<BasicBlock>, SmallPtrSet<Value *, 4>>

- Use DenseMap instead of std::map for ValueCacheEntryTy. Historically
there seems to be some resistance regarding the change to DenseMap
(r147980), but I couldn't find cases of iterator invalidation for
ValueCacheEntryTy (only for ValueCache, but this one is left unchanged
- still using std::map).


http://reviews.llvm.org/D11651

Files:
  lib/Analysis/LazyValueInfo.cpp

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