[PATCH] D150039: [InstCombine] Update instcombine for vectorOps to use new shufflevector semantics

[Manuel Brito via Phabricator via llvm-commits]

ManuelJBrito added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp:1262
+  if (!match(FirstIE->getOperand(0), m_Undef()) ||
+      match(FirstIE->getOperand(0), m_Poison()))
+    for (unsigned i = 0; i != NumElements; ++i)
----------------
nikic wrote:
> I don't understand what is going on in this conditional. Why do we need the undef check here? We already checked above that either the base operand is poison or all elements are present.
Yes you are correct. It's redundant. Thanks !


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  https://reviews.llvm.org/D150039/new/

https://reviews.llvm.org/D150039