[PATCH] D112312: [DSE] Add OR_None (not for commit)

[Evgeniy via Phabricator via llvm-commits]

ebrevnov added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp:1012
+      if (AAR == AliasResult::NoAlias)
+        return OW_None;
       return OW_Unknown;
----------------
fhahn wrote:
> ebrevnov wrote:
> > fhahn wrote:
> > > nikic wrote:
> > > > Maybe move this check to the start?
> > > I originally had the check just after getting `AAR`, but `isOverwrite` considers out-of-bounds writes killing other writes to the same underlying object, which would be missed by the early exit.
> > Could you clarify which particular piece of code handles "out-of-bounds" case?
> It is not handled explicitly and is a consequence of the code just below (lines 1017-1020). If the underlying object size matches the size of the out-of-bounds store, the out of bounds store is considered killing other stores to the same object. Note that this logic does not kick in, if the out-of-bounds store is smaller than the underlying object. I added such a test case in 9c00afe926e9
Got it, thanks. Will update D105098 and add related comment.


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https://reviews.llvm.org/D112312