Hi, On Fri, 12 Jul 2013, Ian Lance Taylor wrote:
> >> It was probably a mistake to have a linker -O option at all. > > > > > > Doesn't the linker produce something that is faster to link and/or smaller, > > with this flag? > > For gold I think it has two effects. If you use compressed debug > sections, it will compress them with zlib level 9 rather than 1. If > you use -O2 or greater it will optimize string tables (e.g., the table > holding the names of symbols) such that if the table stores two > strings S1 and S2, and S2 is a suffix of S1, it will store only S1, > and change pointers to S2 to point to the suffix of S1. So you are > correct that the result will be smaller, but not faster to link. For bfd ld it has only one effect (except for alpha), namely to try to use shorter chains for the ELF hash buckets (string table optimization will be done unconditionally). The resulting objects are a slight bit faster to link (I don't think I could ever actually measure any improvement, though), and since the introduction of .gnu.hash the whole dance is useless. So, I'd also argue against calling the linker with -O or -O2 except if any interesting speedup can be demonstrated. Ciao, Michael.
