[PATCH] D67995: [MemorySSA] Avoid adding Phis in the presence of unreachable blocks.

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea marked 2 inline comments as done.
asbirlea added inline comments.


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Comment at: lib/Analysis/MemorySSAUpdater.cpp:82
+        else if (IncomingAccess != SingleAccess)
+          UniqueIncomingAccess = false;
+        PhiOps.push_back(IncomingAccess);
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george.burgess.iv wrote:
> nit: would it be simpler to keep a count of the unreachable blocks we saw (not adding anything to PhiOps), then if PhiOps.size() > 1, just adding `NumUnreachablePreds` LiveOnEntryDefs?
I think having the `SingleAccess` is important to not end up adding Phis when multiple reachable blocks provide the same incoming access. Given this, we can't really model everything with a single counter. Yes, we can use a counter and add the LiveOnEntryDefs after the loop, but it's roughly the same amount of code/same complexity.


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  rL LLVM

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  https://reviews.llvm.org/D67995/new/

https://reviews.llvm.org/D67995