> My reading of bfd/plugin.c is that it basically walks the directory and looks > for first plugin that returns OK for onload. (that is always the case for > GCC/LLVM plugins). So if I instlal GCC and llvm plugin there it will > depend who will end up being first and only that plugin will be used. > > We need multiple plugin support as suggested by the directory name ;) > > Also it sems that currently plugin is not used if file is ELF for ar/nm/ranlib > (as mentioned by Markus) and also GNU-ld seems to choke on LLVM object files > even if it has plugin. > > This probably needs ot be sanitized.
CCing Hal Finkel. He got this to work some time ago. Not sure if he ever ported the patches to bfd trunk. >> For OS X the situation is a bit different. There instead of a plugin >> the linker loads a library: libLTO.dylib. When doing LTO with a newer >> llvm, one needs to set DYLD_LIBRARY_PATH. I think I proposed setting >> that from clang some time ago, but I don't remember the outcome. >> >> In theory GCC could implement a libLTO.dylib and set >> DYLD_LIBRARY_PATH. The gold/bfd plugin that LLVM uses is basically a >> API mapping the other way, so the job would be inverting it. The LTO >> model ld64 is a bit more strict about knowing all symbol definitions >> and uses (including inline asm), so there would be work to be done to >> cover that, but the simple cases shouldn't be too hard. > > I would not care that much about symbols in asm definitions to start with. > Even if we will force users to non-LTO those object files, it would be an > improvement over what we have now. > > One problem is that we need a volunteer to implement the reverse glue > (libLTO->plugin API), since I do not have an OS X box (well, have an old G5, > but even that is quite far from me right now) > > Why complete symbol tables are required? Can't ld64 be changed to ignore > unresolved symbols in the first stage just like gold/gnu-ld does? I am not sure about this. My *guess* is that it does dead stripping computation before asking libLTO for the object file. I noticed the issue while trying to LTO firefox some time ago. Cheers, Rafael
