[PATCH] D132542: [InstCombine] Use dyn_cast instead of cast in visitPHINode

[Liao Chunyu via Phabricator via llvm-commits]

liaolucy created this revision.
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Fix crash https://github.com/llvm/llvm-project/issues/57329


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132542

Files:
  llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp


Index: llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -1505,8 +1505,8 @@
   // the blocks in the same order. This will help identical PHIs be eliminated
   // by other passes. Other passes shouldn't depend on this for correctness
   // however.
-  PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
-  if (&PN != FirstPN)
+  PHINode *FirstPN = dyn_cast<PHINode>(PN.getParent()->begin());
+  if (FirstPN && &PN != FirstPN)
     for (unsigned I = 0, E = FirstPN->getNumIncomingValues(); I != E; ++I) {
       BasicBlock *BBA = PN.getIncomingBlock(I);
       BasicBlock *BBB = FirstPN->getIncomingBlock(I);


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