[PATCH] D155420: [PostDom] add findNearestCommonDominator for instructions

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

I think I would prefer to add this as a local helper to MemCpyOpt until we have a second use case.



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Comment at: llvm/include/llvm/Analysis/PostDominators.h:49
+  /// Find the nearest instruction I that post-dominates both I1 and I2, in the
+  /// sense that a result produced after I will be available at both I1 and I2.
+  Instruction *findNearestCommonDominator(Instruction *I1,
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The "in the sense" part isn't correct for post-dominators.


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Comment at: llvm/lib/Analysis/PostDominators.cpp:90
+    return I1;
+  return PDomBB->getFirstNonPHI();
+}
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I wasn't able to come up with an example where the nearest common post-dom would be an exception pad, so I think getFirstNonPHI() is fine.


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  https://reviews.llvm.org/D155420/new/

https://reviews.llvm.org/D155420