[PATCH] D48974: [DomTreeUpdater] Ignore updates when both DT and PDT are nullptrs

[Jakub Kuderski via Phabricator via llvm-commits]

kuhar added a comment.

Have you considered detecting that both trees are null and overriding the update strategy to Eager in that case? I think that should functionally be equivalent, although more confusing when the strategy you get can be different from what someone just set :P I'm just wondering what pros/cons there are.



================
Comment at: lib/IR/DomTreeUpdater.cpp:343
 
+  if (!DT && !PDT)
+    return true;
----------------
Same as below.


================
Comment at: lib/IR/DomTreeUpdater.cpp:390
 
+  if (!DT && !PDT)
+    return true;
----------------
Can you save some work by moving it at the top of the function such that it doesn't have to validate updates if both trees are null?

Or is it intentional to validate them and catch some logic errors in this case as well?


Repository:
  rL LLVM

https://reviews.llvm.org/D48974