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) when function foo is undefined. R_X86_64_RELAX_PC32 is defined as 39, which was the deprecated R_X86_64_PC32_BND for bnd call/jmp foo R_X86_64_RELAX_PLT32 is defined as 40, which was the deprecated R_X86_64_PLT32_BND for bnd call/jmp foo@PLT Since the current linkers treat R_X86_64_PC32_BND and R_X86_64_PLT32_BND as _X86_64_PC32 and R_X86_64_PLT32, respectively, they can handle the new ones correctly. Comments, suggestions? Thanks. -- H.J.
