[PATCH] D106593: [WIP][SimplifyCFG] Replace FoldTwoEntryPHINode i1 hack with a different hack.

Roman Lebedev via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Jul 22 14:37:58 PDT 2021


lebedev.ri added a comment.

In D106593#2898008 <https://reviews.llvm.org/D106593#2898008>, @efriedma wrote:

> As far as I can tell, there's nothing specifically wrong with flattening i1 values.  Maybe we're slightly underestimating the cost of some of these i1 logic ops on x86? The more general issue is some combination of flattening the CFG too aggressively, and not unflattening aggressively enough before SelectionDAG, I think.  Unfortunately, that's a delicate area to mess with; any change will inevitably break something.

I agree with everything said above.


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https://reviews.llvm.org/D106593



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