[PATCH] D107605: [MemCpyOpt] Teach memcpyopt to handle loads from the constant memory.

[Eli Friedman via Phabricator via llvm-commits]

efriedma accepted this revision.
efriedma added a comment.
This revision is now accepted and ready to land.

LGTM



================
Comment at: llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp:1173
   // operands cannot partially overlap, exact equality is allowed.
-  if (!AA->isNoAlias(MemoryLocation(MemCpy->getSource(),
-                                    LocationSize::precise(1)),
-                     MemoryLocation(MemCpy->getDest(),
-                                    LocationSize::precise(1))))
+  if (isModSet(AA->getModRefInfo(MemCpy, MemoryLocation::getForSource(MemCpy))))
     return false;
----------------
I think the original code was trying to do something slightly different... but I guess there isn't any test coverage? Not completely sure how the difference could matter, anyway; maybe we could do something funny with pointer alignment in certain edge cases.


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https://reviews.llvm.org/D107605