[PATCH] D45299: API to update MemorySSA for cloned blocks.

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea added a comment.

Thanks a lot of the comments, working to address them.

A couple of quick clarifications. 
Yes, enabling memoryssa is guarded by a flag, see dependent patches (unswitch, simple loop unswitch; the tests for those passes enable the flag so we do check correctness) and a couple of additional patches already landed to update memoryssa, again guarded and currently disabled, but the tests for those passes also enable the flag (the landed patches don't use any of the apis in this patch, hence no dependency).

comments-related:
Currently it does do CalculateFromScratch; it's creating a new DT based on a snapshot CFG where the "Delete" edges are undone. It updates MSSA only for "Inserts" added, then doing the "Deletes". 
I have additional work I need to do to cleanup DT to use a GraphDiff internally as part of its update process (replace BatchUpdateInfo), and then I should be able to have this be an incremental update of doing the deletes in reverse (i.e. re-insert edges).
As for the IDF accessing succ/pred, it does! I taught it to use a snapshot graph too (GraphDiff passed as arg) in https://reviews.llvm.org/D50675.
Using a GraphDiff and the GraphTraits defined in CFGDiff.h should be the common interface for all.
Long-story short, there's a lot more work to be done before this is enabled :)


Repository:
  rL LLVM

https://reviews.llvm.org/D45299