diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 665639128ec8..67f04b6a0cf9 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -250,6 +250,10 @@ public:
   /// folded, but discard the result.
   bool isEvaluatable(ASTContext &Ctx) const;
 
+  /// HasSideEffects - This routine returns true for all those expressions
+  /// which must be evaluated each time and must not be optimization away 
+  /// or evaluated at compile time. Example is a function call, volatile
+  /// variable read.
   bool HasSideEffects(ASTContext &Ctx) const;
   
   /// EvaluateAsInt - Call Evaluate and return the folded integer. This