[PATCH] D109068: Fix a missing memoryssa update in breakLoopBackedge

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/LoopUtils.cpp:751
+        if (MSSA)
+          MSSAU->applyUpdates({{DominatorTree::Delete, Latch, Header}}, DT);
         return;
----------------
I think there may be a preference to let MSSAU also update DT for performance reasons, along the lines of:
```
if (MSSA)
  MSSAU->applyUpdates({{DominatorTree::Delete, Latch, Header}}, DT, /*UpdateDT*/true);
else
  DT.applyUpdates({{DominatorTree::Delete, Latch, Header}});
```
But I'm not sure how important this is. @asbirlea will know...


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D109068/new/

https://reviews.llvm.org/D109068