Re: [wwwdocs] gcc-4.9/changes.html: Mention that LTO now generates slim objects

[Jan Hubicka <hubicka at ucw dot cz>]

> This patch mentions that -flto now generates slim objects. That's especially
> relevant for static libraries as one can there run into surprises, if one
> does not know about gcc-ar.
> 
> OK - or do you have a better suggestion?
> 
> Tobias
> 
> 
> --- changes.html        8 Mar 2014 20:45:54 -0000       1.63
> +++ changes.html        21 Mar 2014 09:10:32 -0000
> @@ -65,6 +65,13 @@
>        <li>Function bodies are now loaded on-demand and released early improving
>           overall memory usage at link time.</li>
>        <li>C++ hidden keyed methods can now be optimized out.</li>
> +      <li>By default, compiling with the <code>-flto</code> option now generates
> +         slim objects files (<code>.o</code>) which only contain intermediate
> +         language representation for LTO. Use <code>-ffat-lto-objects</code> to
> +         create files which contain additionally the object code.  To generate
> +         static libraries suitable for LTO processing, use <code>gcc-ar</code>
> +         and <code>gcc-ranlib</code> (requires that <code>ar</code> and
> +         <code>ranlib</code> have been compiled with plugin support).</li>

Ah,
seems I forgot some of wwwdocs updates, since I wrote one already. But yours is better.
I would perhaps mention that with slim objects the LTO build times are often better (you
can reffer i.e. to SPEC2k6 compilation time) and also mention gcc-nm.

Honza
>      </ul>
>      Memory usage building Firefox with debug enabled was reduced from 15GB to
>      3.5GB; link time from 1700 seconds to 350 seconds.