[PATCH] D92247: [IR][LoopRotate] avoid leaving phi with no operands (PR48296)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


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Comment at: llvm/lib/IR/BasicBlock.cpp:335-337
+/// If \p KeepOneInputPHIs is true, then don't remove PHIs that are left with
+/// one incoming value, and don't simplify PHIs with all incoming values that
+/// are the same constant.
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There's also a comment at the declaration of the function


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Comment at: llvm/lib/IR/BasicBlock.cpp:338-366
 void BasicBlock::removePredecessor(BasicBlock *Pred,
                                    bool KeepOneInputPHIs) {
   // Use hasNUsesOrMore to bound the cost of this assertion for complex CFGs.
   assert((hasNUsesOrMore(16) || llvm::is_contained(predecessors(this), Pred)) &&
          "Pred is not a predecessor!");
 
   // Return early if there are no PHI nodes to update.
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Ok, but i think this is rather akward.
It should be more like this.
Note that `removeIncomingValue()` *only* removes PHI's if they had a single pred,
so it doesn't make sense to pass anything related to `KeepOneInputPHIs` to it.


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  https://reviews.llvm.org/D92247/new/

https://reviews.llvm.org/D92247