> Hi Diego, > > Thanks for the summary, it's great to see the progress of the project. Do > you have any compile time numbers for LTO so far? If you pick a mid-sided > program from spec or even a bootstrap, how much slower is LTO than compiling > at -O3?
We haven't tried a bootstrap with LTO enabled yet (needs some changes to the build system to find the gold plugin during bootstrap). We should probably try -flto-single one day... Some initial testing with internal apps showed that the streamer is normally a problem and in some cases the performance is IO bound! This is very true if the streamer debug is enabled, since that adds some fairly large synchronization strings to the output. Cary wrote a patch to gold to ignore IL sections if not using the plugin, and it had a noticeable impact.. Diego, you tested SPEC a bit, do you know what the slowdown was? > -Chris > Cheers, -- Rafael Avila de Espindola Google | Gordon House | Barrow Street | Dublin 4 | Ireland Registered in Dublin, Ireland | Registration Number: 368047
