[PATCH] D19995: Optimize access to global variable references in PIE mode when linker supports copy relocations for PIE

[Joerg Sonnenberger via llvm-commits]

On Mon, May 09, 2016 at 08:08:28AM -0700, H.J. Lu wrote:
> On Mon, May 9, 2016 at 7:53 AM, Joerg Sonnenberger via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
> > On Mon, May 09, 2016 at 07:30:20AM -0700, H.J. Lu wrote:
> >> > The original ABI design was static linking and dynamic linking of the
> >> > main program from exactly the same object files. Using GOT-style
> >> > relocations is prohibitive on all platforms without cheap PC-relative
> >> > addressing. This includes for example i386. I don't know why amd64
> >>
> >> You can use the new R_386_GOT32X relocation to access the
> >> GOT in executable with the base register, like
> >>
> >> movl $foo at GOT, %eax
> >> movl foo at GOT, %eax
> >>
> >> But not all linkers can relocate it properly.
> >
> > But that still requires the base register to be set up?
> 
> The same as x86-64.

Huh? AMD64 can address data explicitly via (%rip). i386 has no such
index register, so normally uses %ebx for that?

Joerg