[PATCH] D102615: [LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration

[Philip Reames via Phabricator via llvm-commits]

reames accepted this revision.
reames added a comment.
This revision is now accepted and ready to land.

LGTM w/minor comments.



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Comment at: llvm/lib/Transforms/Scalar/LoopDeletion.cpp:204
+  auto GetOnlyLivePred = [&](BasicBlock * BB)->BasicBlock * {
+    if (BB == Header)
+      return L->getLoopPredecessor();
----------------
This check should probably be lifted to caller, and assert !Header here.  It confuses the interface of this lambda.

You could also consider renaming the lambda to getSolePredecessorOnFirstIteration.  


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Comment at: llvm/lib/Transforms/Scalar/LoopDeletion.cpp:210
+        // 2 live preds.
+        if (OnlyPred)
+          return nullptr;
----------------
Note that predecessors can be listed multiple times due to switches.  You should check that OnlyPred is non-null and not equal to this block.


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https://reviews.llvm.org/D102615