Improve comments in alias analysis

Author: trentxintong

include/swift/SILAnalysis/AliasAnalysis.h

@@ -70,7 +70,9 @@ class AliasAnalysis : public SILAnalysis {
 
   SideEffectAnalysis *getSideEffectAnalysis() const { return SEA; }
 
-  /// Perform alias analysis on SILValues with multiple underlying objects.
+  /// Perform alias queries to see if \p V1, \p V2 can refer to the same value.
+  /// \p V1 and \p V2 may be SILValues with multiple underlying objects. e.g.
+  /// SILArgument. \returns MayAlias or NoAlias.
   AliasResult handleMultiUnderlyingObjectAlias(SILValue V1, SILValue V2);
 
   /// Perform an alias query to see if V1, V2 refer to the same values.