On Nov 16, 2011 2:26 PM, "Michael Mol" <mike...@gmail.com> wrote: > > On Wed, Nov 16, 2011 at 2:11 AM, Stéphane Guedon <steph...@22decembre.eu> wrote: > > On Wednesday 16 November 2011 02:07:12 Pandu Poluan wrote: > >> And if you're adventurous, add USE "graphite", reemerge gcc, and reemerge > >> world :) > > > > what does "graphite" add ? > > Thanks for reminding me; I meant to look it up when I got home. > > shortcircuit:1@serenity~ > Wed Nov 16 02:16 AM > !501 #1 j0 ?0 $ euse -i graphite > global use flags (searching: graphite) > ************************************************************ > no matching entries found > > local use flags (searching: graphite) > ************************************************************ > > [snip] > > [- ] graphite > sys-devel/gcc: Add support for the framework for loop optimizations > based on a polyhedral intermediate representation > > So, a new, experimental optimization model and framework inside your > compiler. If it's specifically for optimizing on loops, I'll venture a > guess it's going to be mostly effective for graphics libraries and > apps. I've got some slightly riskier educated guesses on how it works > and what some numeric side effects and consequences might be, but they > scare me, so I think I'll leave it to someone who actually knows more > about it... >
I've been using USE "graphite" since gcc-4.5.3-r1 appeared. Upstream says that graphite is stable, feature-complete, and production-ready since 4.5.3. To fully taste the effect of graphite, I even went the torturous route of emerging gcc + libtool + binutils (in that order) twice, followed by a wholesale-rebuild of everything (emerge --emptytree), then tarballed the result to my own "stage3.1" tarball to spare me the *huge* amount of time required. I've deployed 3 systems with USE "graphite", and they *felt* snappier. emerge's *felt* slower, though. (no objective tests, I know). I use Gentoo as a gatewall, and there I did a wholesale-rebuild one more time, this time specifying CFLAGS "-march=native"... and I just couldn't be happier with the resulting performance :-) Rgds, Rgds,
