[PATCH] D35918: [GVNHoist] Factor out reachability to search for anticipable instructions quickly

[Daniel Berlin via Phabricator via llvm-commits]

dberlin added a comment.

This looks reasonable at a glance, note it is likely to be subtly broken in some cases until https://reviews.llvm.org/D35381 goes in.
I've added a few coments, i'll take a deeper look in a little bit.



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Comment at: lib/Transforms/Scalar/GVNHoist.cpp:751
+        DEBUG(for (auto B : IDFBlocks) dbgs() << "\nPDF: " << B->getName(););
+        // continue; // Cannot find a unique common-dom-frontier for set of VNs.
+      }
----------------
What are you really trying to do here? (IE why is the continue commented out)


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Comment at: lib/Transforms/Scalar/GVNHoist.cpp:954
           MemoryAccess *Def = OldMemAcc->getDefiningAccess();
-          NewMemAcc =
-            MSSAUpdater->createMemoryAccessInBB(Repl, Def, HoistPt, MemorySSA::End);
+          NewMemAcc = MSSAUpdater->createMemoryAccessInBB(Repl, Def, HoistPt,
+                                                          MemorySSA::End);
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I think since you wrote this we added moving functions you could use here.



https://reviews.llvm.org/D35918