Revert "MemorySSA: Add support for caching clobbering access in stores"

This reverts revision r299322.

llvm-svn: 299485
diff --git a/llvm/lib/Transforms/Utils/MemorySSAUpdater.cpp b/llvm/lib/Transforms/Utils/MemorySSAUpdater.cpp
index c396bd7..7e04395 100644
--- a/llvm/lib/Transforms/Utils/MemorySSAUpdater.cpp
+++ b/llvm/lib/Transforms/Utils/MemorySSAUpdater.cpp
@@ -451,8 +451,8 @@
 
     while (!MA->use_empty()) {
       Use &U = *MA->use_begin();
-      if (auto *MUD = dyn_cast<MemoryUseOrDef>(U.getUser()))
-        MUD->resetOptimized();
+      if (MemoryUse *MU = dyn_cast<MemoryUse>(U.getUser()))
+        MU->resetOptimized();
       U.set(NewDefTarget);
     }
   }