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

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D132542#3747321 <https://reviews.llvm.org/D132542#3747321>, @hiraditya wrote:

> My understanding is that a basic block with a PHI node should have first instruction as PHI

That understanding matches the IR verifier

  void Verifier::visitPHINode(PHINode &PN) {                                       
    // Ensure that the PHI nodes are all grouped together at the top of the block. 
    // This can be tested by checking whether the instruction before this is       
    // either nonexistent (because this is begin()) or is a PHI node.  If not,     
    // then there is some other instruction before a PHI.                          
    Check(&PN == &PN.getParent()->front() ||                                       
              isa<PHINode>(--BasicBlock::iterator(&PN)),                           
          "PHI nodes not grouped at top of basic block!", &PN, PN.getParent()); 


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  https://reviews.llvm.org/D132542/new/

https://reviews.llvm.org/D132542