On Tue, 18 May 2010, Jon Beniston wrote: > Hi, > > Is it possible to update the multilib combinations supported by GCC after it > has been built? (I would like to build some libraries optimised for > different CPUs variants, that aren't built by default). > > I tried doing this via a specs file, but something like the following fails:
Even if you get modifications of specs to work (and some pieces such as --with-arch configuration are handled in different ways that may not be configurable that way), GCC's own libraries are nontrivial to build outside of building GCC itself - especially libgcc (libstdc++ is easier). The libgcc configuration uses information passed from the gcc/ directory because the toplevel libgcc transition is incomplete, including target macros from tm.h which is mainly a host header but also used for some things on the target. I certainly encourage cleaning up these things so that the libgcc build configuration can be properly contained within the libgcc/ directory and not depend on host tm.h headers. http://gcc.gnu.org/wiki/Top-Level_Libgcc_Migration If you only want to optimize some libraries but not others, GCC doesn't effectively support different multilibs having different sets of libraries either. My proposal <http://gcc.gnu.org/ml/gcc/2010-01/msg00063.html> would have the effect of making it much easier to have different sets of libraries for each multilib. -- Joseph S. Myers jos...@codesourcery.com
