[llvm] [InstCombinePHI] Enhance PHI CSE to remove redundant phis (PR #163453)

[via llvm-commits]

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@@ -4866,6 +4866,89 @@ static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F,
   return nullptr;
 }
 
+/// Look for the following pattern and simplify %1 to %identicalPhi.
+/// Here %phi, %1 and %phi.next perform the same functionality as
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CongzheUalberta wrote:

I've changed `%1` to  `%to_fold`.

https://github.com/llvm/llvm-project/pull/163453