On Fri, 21 Mar 2014, Tobias Burnus wrote: > On Fri, Mar 21, 2014 at 10:40:26AM +0100, Richard Biener wrote: > > On Fri, 21 Mar 2014, Tobias Burnus wrote: > > > 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. > > > > Please adjust slightly to "When using a linker-plugin, > > compiling with the <code>-flto</code> option now generates slim > > object files by default ..." as the change doesn't affect _all_ > > configurations but only those with HAVE_LTO_PLUGIN set (thus > > -fno-use-linker-plugin overrides the default as well). > > > > I'd also mention gcc-nm which needs to be used to inspect archives > > with thin LTO files. > > Thanks for the suggestions - updated patch below.
Ok. Thanks, Richard. > > Tobias > > --- changes.html 8 Mar 2014 20:45:54 -0000 1.63 > +++ changes.html 21 Mar 2014 12:43:44 -0000 > @@ -65,6 +65,16 @@ > <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>When using a linker plugin, 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>; to list symbols from a slim object file use > + <code>gcc-nm</code>. (Requires that <code>ar</code>, > + <code>ranlib</code> and <code>nm</code> have been compiled with > + plugin support.)</li> > </ul> > Memory usage building Firefox with debug enabled was reduced from 15GB to > 3.5GB; link time from 1700 seconds to 350 seconds. > > -- Richard Biener <rguent...@suse.de> SUSE / SUSE Labs SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746 GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer
