> > On Mar 13, 2011, at 8:38 AM, Jack Howarth wrote: > > > On Sun, Mar 13, 2011 at 12:39:26PM +0100, Jan Hubicka wrote: > >>> With release of Xcode 3.2.6/4.0 this week, an unfortunate change was > >>> made to > >>> the darwin assembler which effectively breaks LTO support for darwin. The > >>> design > >>> of LTO on darwin was based on the fact that mach-o object files tolerated > >>> additional > >>> sections as long as they didin't contain symbols. With Xcode 3.2.6/4.0, > >>> the assembler > >>> appears to be strictly counting sections and objecting when these exceed > >>> 255. This > >>> breaks huge sections of the lto testsuite and prevents larger projects > >>> like xplor-nih > >>> to compile if Xcode 3.2.6/4.0 is installed. I am afraid that unless Apple > >>> reverts this > >>> change, our only recourse would be to resort to an elf object container > >>> for the lto > >>> sections within the mach-o files (introducing an undesired dependency on > >>> libelf for > >>> FSF gcc on darwin). My understanding was that the lto design did not > >>> allow the number > >>> of sections required in the lto files to be reduced. > >> > >> If the problem is not fixed, we could always pack all the LTO sections > >> into one section containing > >> our own subsections. > >> > >> Honza > > > > Jan, > > If this could be done without resorting to other container types (like > > elf), it might be > > the wisest approach for the long run. I've read through the mach-o > > documentation and it > > seems rather vague on the section limits. Even if Apple fixes Xcode (which > > likley won't > > happen for 6-9 months at best), we always we have to worry that they will > > break this > > 'feature' somewhere else in their tool chain. Better to follow the > > strictest possible reading > > of mach-o object format to protect ourselves from overzealous Apple interns. > > Yes, I agree that this is a better solution. This error was put into the > linker to detect some overflow conditions for part of the code that expected > the section number to only be a byte. It is likely that "things worked" only > out of luck before.
Interesting, so there is no -ffunction-section type tricks at darwin? Pickling everything into single section seems indeed like easiest approach here. The question is who will volunteer to implement it ;) Honza > > -Chris
