[Attributor] Further cut down on non-determinism

llvm-svn: 369936
diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index a2ea006..ebe4fba 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -689,7 +689,7 @@
 
   /// Mapping of values potentially returned by the associated function to the
   /// return instructions that might return them.
-  DenseMap<Value *, SmallSetVector<ReturnInst *, 4>> ReturnedValues;
+  MapVector<Value *, SmallSetVector<ReturnInst *, 4>> ReturnedValues;
 
   /// Mapping to remember the number of returned values for a call site such
   /// that we can avoid updates if nothing changed.