[PATCH] D47475: [Local] Make KDominatesJ required for combineMetadata.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: lib/Transforms/Utils/Local.cpp:2086
       LLVMContext::MD_dereferenceable_or_null};
-  combineMetadata(K, J, KnownIDs);
+  combineMetadata(K, J, KnownIDs, KDominatesJ);
 }
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Is it actually correct to use the same metadata list if KDominatesJ is false?

It's undefined behavior if a nonnull load actually produces null.  So preserving nonnull metadata on a hoisted load requires proving that the hoisted load never produces null (separately from proving the load is safe to hoist).


https://reviews.llvm.org/D47475