[PATCH] D16986: [LICM] Don't assert on volatile accesses

Philip Reames via llvm-commits llvm-commits at lists.llvm.org
Mon Feb 22 15:16:58 PST 2016

reames added a comment.

In http://reviews.llvm.org/D16986#359180, @nlopes wrote:

> But then store forwarding happens and LICM realizes (or doesn't) that two of the alias sets that were said to be disjoint by TBAA in fact alias.

Can you clarify this point?  AFAIK, LICM does not do store forwarding.  How did store forwarding come into the picture at all?

Also, if we ever discover two pointers mustalias, then by definition they must be the same alias set.  If not, we have constructed *invalid, and incorrect* alias sets.  Oh, I think I see the problem.  You're saying that they're both noalias and mustalias discovered through two different mechanism.  Ouch, ouch, ouch.


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