[llvm] [SDag] Notify listeners when deleting a node (PR #66991)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> > SelectionDAG::DeleteNode does not notify listeners about node deletion. As a result, SelectionDAG::Legalize may skip legalization of some nodes resulting in "Legalized selection DAG" containing illegal nodes.
> 
> Is this because a new node gets allocated in the same memory that `LegalizedNodes` is still pointing at?

Yes, exactly.


https://github.com/llvm/llvm-project/pull/66991