Il 19/11/2013 11:05, Markus Trippelsdorf ha scritto: > On 2013.11.19 at 09:44 +0100, Paolo Bonzini wrote: >> Il 18/11/2013 20:09, Jan Hubicka ha scritto: >>>>>>> this patch switches the default for fat-lto-objects as was documented >>>>>>> for a while. >>>>>>> -ffat-lto-objects doubles compilation time and often makes users to not >>>>>>> notice that >>>>>>> LTO was not used at all (because they forgot to use gcc-ar/gcc-nm >>>>>>> plugins). >>>>>>> >>>>>>> Sadly I had to add -ffat-lto-objects to bootstrap. This is because I do >>>>>>> not know >>>>>>> how to convince our build machinery to use gcc-ar/gcc-nm during the >>>>>>> stage2+ >>>>> >>>>> I've posted a minimal patch set for slim-lto-bootstrap last year, see: >>>>> http://thread.gmane.org/gmane.comp.gcc.patches/270842 >>>>> >>>>> If there's interest I could repost it. >>> It would be really nice to have it in indeed. I think we do not really need >>> lto-bootstrap.mk and slim-lto-bootstrap.mk, but otherwise the patch seems >>> easy >>> enough and would save quite some of lto bootstrap testing time... >> >> Patches 1 and 2 should go upstream first. > > OK, but where is upstream? > Please note that a general libtool update would fix this issue, too.
Ah, so they're already upstream. > So, maybe it is just time to upgrade libtool everywhere in gnu-land? Yes, that would be better but no need to do that now. >> Patch 3 in the series is wrong because Makefile.in is a generated file. >> The message does not explain why it is necessary, and it is probably >> working around a bug elsewhere. >> For patch 4, I agree with Jan that we do not need a separate configuration. > > The problem is that fixincl links with libiberty.a: > > /var/tmp/gcc_build_dir/./gcc/xgcc -B/var/tmp/gcc_build_dir/./gcc/ > -B/usr/x86_64-pc-linux-gnu/bin/ -B/usr/x86_64-pc-linux-gnu/lib/ -isystem > /usr/x86_64-pc-linux-gnu/include -isystem > /usr/x86_64-pc-linux-gnu/sys-include -O2 -pipe -static-libstdc++ > -static-libgcc -o fixincl fixincl.o fixtests.o fixfixes.o server.o > procopen.o fixlib.o fixopts.o ../libiberty/libiberty.a > > And this archive consists of object files with LTO sections only. So we > need to find a way to pass -fuse-linker-plugin to the invocation above. Then -fuse-linker-plugin should be added to the LDFLAGS (not CFLAGS) for all host modules, as in "LDFLAGS += -fuse-linker-plugin". Other host modules than fixincludes could also use libiberty or another bootstrapped host library (libbfd is one, I think), and would require the same fix. Paolo
