On Mon, May 11, 2015 at 8:48 AM, Michael Matz <m...@suse.de> wrote: > Hi, > > On Mon, 11 May 2015, H.J. Lu wrote: > >> To remove one direct branch to PLT for external function calls: >> >> https://gcc.gnu.org/ml/gcc-patches/2015-05/msg00001.html >> >> I am proposing to add 2 new relocations, R_X86_64_RELAX_PC32 >> and R_X86_64_RELAX_PLT32: >> >> 1. They can only be used on 32-bit PC relative call/jmp instructions. >> 2. call/jmp instructions must have a 0x48 prefix. >> 3. Linker can treat them as R_X86_64_PC32 and R_X86_64_PLT32, >> respectively. >> 4. Optionally, linker can convert >> >> 0x48 call/jmp foo[@PLT] >> >> to >> >> call/jmp *foo@GOTPCREL(%rip) > > Perhaps it should be clarified that the intention here is, that the > respective GOT slot will be relocated with the PLT slot address+6, not > with the final address of symbol foo (that will be done when actually > jumping/calling through that got slot); at least when RELAX_PLT32 is used. >
I will clarify in the spec language. Yes, that is the intention for both R_X86_64_RELAX_PC32 and R_X86_64_RELAX_PLT32. That is what is implemented on users/hjl/relax branch. -- H.J.
