[llvm-branch-commits] [llvm] [SelectionDAG] Deal with POISON for INSERT_VECTOR_ELT/INSERT_SUBVECTOR (part 3) (PR #143105)

[Matt Arsenault via llvm-branch-commits]

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@@ -953,8 +953,17 @@ class SelectionDAG {
   }
 
   /// Insert \p SubVec at the \p Idx element of \p Vec.
+  /// If \p SkipUndef is true and \p SubVec is UNDEF/POISON, then \p Vec is
+  /// returned.
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arsenm wrote:

This is a strange pattern that I feel like should be avoided. I don't understand why this would need semantic treatment. These get* functions should just return with the node with the requested operands 

https://github.com/llvm/llvm-project/pull/143105