On Fri, 2020-07-24 at 22:24 +0200, Igor Raits wrote: > On Fri, 2020-07-24 at 13:29 -0600, Jeff Law wrote: > > On Fri, 2020-07-24 at 19:12 +0000, Artem Tim wrote: > > > Hi. In rare cases building packages with LTO producing binaries or > > > libraries which have bigger size then if they have built without > > > LTO. For example 'kitty' package: > > > > > > * with LTO: > > > - koji task > > > https://koji.fedoraproject.org/koji/taskinfo?taskID=47762998 > > > 1.79 MB glfw-wayland.so > > > 1.99 MB glfw-x11.so > > > 4.78 MB fast_data_types.so > > > 8.56 MB total > > > > > > * no LTO > > > - koji > > > https://koji.fedoraproject.org/koji/taskinfo?taskID=47769854 > > > 1.65 MB glfw-wayland.so > > > 1.84 MB glfw-x11.so > > > 4.51 MB fast_data_types.so > > > 8.00 MB total > > > > > > Difference is 7%. What we should do in such case? Should we disable > > > LTO for such packages? Or there is still could be gains from faster > > > code execution speed? > > I'd tend to leave LTO on, but it's totally your call. Without > > looking at the > > binaries, sources and compiler dumps I'd hazard a guess you're > > getting a lot of > > cross module inlining, but very little identical code folding. THe > > former tends > > to make things bigger, but faster. The latter tends to shrink code > > with little > > impact on runtime performance. > > From what I see in this case, -ffat-lto-objects generates code that is > bigger than without -flto. -flto alone generates smaller code than > without -flto. The fat-lto-objects bits are not used during an LTO link. They exist solely to cover the case where there's a .o/.a that ends up installed.
jeff > _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org
