[PATCH] D23843: GVN-hoist: fix hoistingFromAllPaths for loops (PR29034)

[Daniel Berlin via llvm-commits]

dberlin added inline comments.

================
Comment at: llvm/lib/Transforms/Scalar/GVNHoist.cpp:315
@@ -303,1 +314,3 @@
+        return false;
+
       // Increment DFS traversal when not skipping children.
----------------
How is this different than just checking whether one of the successors is a loop backedge?
(and if so, why not just compute and store that set once :P)

If it's different, how is this not basically a dominance frontier check?

dominance frontier of BB = blocks where BB's dominance ends. 

So this is a check if any of the blocks are in the dominance frontier of BB, no?




https://reviews.llvm.org/D23843