[PATCH] D101142: [SimplifyCFG/JumpThreading] Do not simplify empty blocks with unconditional branches if this causes loop metadata confusion.

[Jeroen Dobbelaere via Phabricator via llvm-commits]

jeroen.dobbelaere added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/Local.cpp:1090
+    MDNode *PredMD = PredTI ? PredTI->getMetadata(LoopMDKind) : nullptr;
+    if (LoopMD != PredMD && BBIsLatch && IsLoopLatch(PredBB))
+      return false;
----------------
Is (LoopMD != PredMD) a sufficient rule ?

Assume you have two nested loops with both a 'loop unroll 4' annotation. Can we get in a situation where both latches would be merged ? If so, is it valid then to still merge the latches ?



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  https://reviews.llvm.org/D101142/new/

https://reviews.llvm.org/D101142