Only passes that preserve MemorySSA must mark it as preserved.
The method getLoopPassPreservedAnalyses should not mark MemorySSA as
preserved, because it's being called in a lot of passes that do not
Instead, mark the MemorySSA analysis as preserved by each pass that does
These changes only affect the new pass mananger.
Subscribers: mehdi_amini, jlebar, Prazek, george.burgess.iv, llvm-commits
Differential Revision: https://reviews.llvm.org/D62536