getEntryFor() may invalidate DenseMap iterator.
Walking an invalidated iterator is not a good idea.

llvm-svn: 68047
diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index a386a49..18c2b66 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -520,6 +520,7 @@
   if (Entry.hasAliasSet()) return;    // Already in the tracker!
 
   // Add it to the alias set it aliases...
+  I = PointerMap.find(From);
   AliasSet *AS = I->second->getAliasSet(*this);
   AS->addPointer(*this, Entry, I->second->getSize(), true);
 }