[PATCH] D110234: [LoopFlatten] Updating Phi nodes after IV widening

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added a comment.

@dmgreen : I propose to keep this revision. The extra bit of state for `NarrowInnerInductionPHI` and `NarrowOuterInductionPHI` is needed anyway, to checks on the phi nodes (and skip these ones). That's why e.g. just this is not enough:

  diff --git a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
  index 931bcc2aada6..f81eb07b5425 100644                                                             
  --- a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp                                                    
  +++ b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp                                                    
  @@ -711,7 +711,7 @@ static bool CanWidenIV(FlattenInfo &FI, DominatorTree *DT, LoopInfo *LI,        
     // If the inner Phi node cannot be trivially deleted, we need to at least                        
     // bring it in a consistent state.                                                               
     if (!Deleted)                                                                                    
  -    FI.InnerInductionPHI->removeIncomingValue(FI.InnerLoop->getLoopLatch());                       
  +    FI.InnerPHIsToTransform.insert(FI.InnerInductionPHI);                                          
     if (!CreateWideIV({FI.OuterInductionPHI, MaxLegalType, false }, Deleted))                        
       return false;

And I think it is clearer to keep these narrow phi separate from InnerPHIsToTransform. Let me know what you think.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110234/new/

https://reviews.llvm.org/D110234