-In addition to the @samp{-pg} and @samp{-g} options,
-you may also wish to specify the @samp{-a} option when compiling.
-This will instrument
-the program to perform basic-block counting. As the program runs,
+In addition to the @samp{-pg} and @samp{-g} options, older versions of
+GCC required you to specify the @samp{-a} option when compiling in
+order to instrument it to perform basic-block counting. Newer
+versions do not require this option and will not accept it;
+basic-block counting is always enabled when @samp{-pg} is on.
+
+When basic-block counting is enabled, as the program runs