9b1b93766d
This reverts commit eeb43806eb1b40e690aeeba496ee974172202df9. Recommit with with a fix for MSan failure ( https://lab.llvm.org/buildbot/#/builders/169/builds/14799), by adding a set to track deleted values. Using the InsertedInstructions set is not sufficient, as it use asserting value handles as keys, which may dereference the value at construction. Original message: Add new helper to erase dead instructions inserted during SCEV expansion but not being used due to InstSimplifyFolder simplifications. Together with https://github.com/llvm/llvm-project/pull/157307 this also allows removing some specialized folds, e.g. https://github.com/llvm/llvm-project/blob/main/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp#L2205 PR: https://github.com/llvm/llvm-project/pull/157308