This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [x86-64-psABI] RFC: Add R_X86_64_RELAX_PC32 and R_X86_64_RELAX_PLT32


>>> On 12.05.15 at 20:42, <hjl.tools@gmail.com> wrote:
> Here is the updated proposal.  I changed nop prefix from 0x48
> to 0x67 and clarified how foo@GOTPCREL(%rip) should be
> resolved.

Mind clarifying how 67 is better than 48?

> 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 direct call/jmp instructions.
> 2. call/jmp instructions must have a 0x67 prefix, which is the address
> size prefix and is ignored by 32-bit direct call/jmp instructions.

The same could have been said several years ago about segment
overrides used with conditional branches, yet they obtained a
meaning (even if only affecting performance, not correctness). Is
it anywhere publicly stated that the address size override will
continue to be ignored?

Jan


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]