* Török Edwin wrote on Fri, Mar 26, 2010 at 08:45:44PM CET: > There's also a caveat (or rather compiler bug): using one -O level when > compiling, and another when linking doesn't really work: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42402
Yes. > >> So if I call gcc -O2 -flto x.o y.o, libtool will need to pass both -O2 > >> and -flto. And of course any -f* -m* flags that affect code generation. > > > > -m* is passed through by libtool. > > Ok, but I think -f* should be passed too, they affect code generation as > well, especially -fPIC. Well, we simply cannot pass all of -f* through. -fPIC should be added by libtool itself. > Apparently even if you compile ALL the individual files with -fPIC, > you need to pass -fPIC on the link command-line too, otherwise you get a > failure when building shared libs (that relocation error message that > tells you to use -fPIC). > I consider this rather a gcc bug (it should know that -shared needs > -fPIC for -flto), see here #575451. > > Or do you think libtool should handle this? Yes. > >> Also -fuser-linker-plugin needs to be passed on by libtool. > > > > Yes, I gues libtool should support -fuse-linker-plugin too. > > Ok. > BTW I'm using a simple hack for now, I set > new_inherited_linker_flags="-flto -O2", and that allows me to test LTO. You should be able to use ./configure CC='gcc -flto -O2' too. Cheers, Ralf -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
