> On May 2, 2012, 11:30 a.m., Ali Saidi wrote: > > i don't think this is really a problem, but you mention it could work with > > debug and don't include the lto flags in the debug binary.
Well spotted! It seems I spoke to soon. For some reason, when adding the link flags to the debug target, some regressions fail with rather mysterious aborts, segfaults etc. Not many...but e.g. memtest for ALPHA, realview-timing for ARM. It works absolutely fine for fast opt and prof though. - Andreas ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://reviews.gem5.org/r/1171/#review2625 ----------------------------------------------------------- On May 2, 2012, 11:25 a.m., Andreas Hansson wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > http://reviews.gem5.org/r/1171/ > ----------------------------------------------------------- > > (Updated May 2, 2012, 11:25 a.m.) > > > Review request for Default. > > > Description > ------- > > gcc: Enable Link-Time Optimization for gcc >= 4.6 > > This patch adds a scons flag to indicate that compilation and linking > should be done using LTO. No check is used to guarantee that the > linked supports LTO, so the user has to ensure that binutils GNU ld >= > 2.21 or the gold linker is available. > > The same number of jobs is used for the parallel phase of LTO as the > jobs specified on the scons command line, using the -flto=n flag that > was introduced with gcc 4.6. > > Currently the LTO option is only useful for gcc >= 4.6, due to the > limited support on clang and earlier versions of gcc. The intention is > to also add support for clang once the LTO integration matures. The > use of LTO is independent of the target, i.e. debug, opt, fast and > pro, although opt and fast are the most likely candidates. > > The compilation and linking (wall) time is increased by almost 50% for > the observed cases, and simulation performance improves by roughly > 15%, i.e. for long regression runs it really helps. > > > Diffs > ----- > > SConstruct 7f36d4436074 > src/SConscript 7f36d4436074 > > Diff: http://reviews.gem5.org/r/1171/diff/ > > > Testing > ------- > > util/regress all passing (disregarding t1000 and eio) > > > Thanks, > > Andreas Hansson > > _______________________________________________ gem5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/gem5-dev
