[PATCH] clarify documentation of -Q --help=optimizers

[Sandra Loosemore]

On 11/04/2015 04:52 PM, Martin Sebor wrote:

> gcc/ChangeLog:
> 2015-11-04  Martin Sebor  <msebor@redhat.com>
>
> 	* opts.c (print_filtered_help): Indicate when an optimization option
> 	is disabled as a result of -O0.
> 	* doc/invoke.texi: Further clarify the effect of -O options
> 	on individual optimization options.

invoke.texi is a huge file.  In ChangeLogs, please use (node name) to 
indicate which sections have been changed unless the changes really do 
apply throughout the whole file.

> @@ -1509,6 +1509,14 @@
>  disabled or set to a specific value (assuming that the compiler
>  knows this at the point where the @option{--help=} option is used).
>
> +It's important to remember that when a given optimization option is
> +enabled, either explicitly on the command line or implicitly, whether
> +or not the optimization it controls will be performed during an

s/will be performed/is performed/

> +Finally, the following example shows the difference in output for
> +an option that, while technically enabled, is disabled as a consequence
> +of the implicit @option{-O0} option, and for one that is disabled by
> +default.  This distinction is typically only of interest to GCC developers.

If the distinction is only interesting to developers, why does it need 
an example in GCC's user documentation?  :-S

I don't have any other comments on the writing aspects of the patch, but 
others may want to comment on technical accuracy, etc.

-Sandra