Re: RFC: TLS improvements for IA32 and AMD64/EM64T

[Alexandre Oliva <aoliva@redhat.com>]

On Oct  9, 2006, "Menezes, Evandro" <evandro.menezes@amd.com> wrote:

> Would you consider adding the calculations for the new relocations
> in order to improve their clarity?

I can try, although relaxations make it much trickier than it might
seem.

> I remember some examples in your paper at the GCC Summit and adding
> them to section 3.5 would be swell too.

So we're talking *really* self-contained, eh?  Fair enough, I'll take
a shot.

> From your paper at the GCC Summit it's quite clear that such
> additions to the psABI would be a fine idea.  Perhaps HJ would like
> to consider the corresponding additions for the i386 psABI
> extension.

H.J., do you have the i386 psABI in source form somewhere I could get
it, to make the corresponding changes?

> So, there's no question about the technical part of your proposal.
> But, as you can infer from my comments above, I'd like to improve
> the clarity of the psABI so that one wouldn't have to go to specific
> implementations to figure out the details.  What do you think?

Sounds like a reasonable goal.

> -+referenced symbol binds locally, the \texttt{DTPOFF} may be omitted.
> ++referenced symbol binds locally, the relocations \texttt{R_X86_64_64} and \texttt{R_X86_64_32} may be used instead.

No, in such cases the linker omits the relocation entirely, and fills
the corresponding stop with the value it can compute itself.

>  +Otherwise, such relocations are always in pairs, such that the
> -+\texttt{DTPOFF64} relocation applies to the word64 right past the
> -+corresponding \texttt{DTPMOD} relocation.
> ++\texttt{R_X86_64_DTPOFF64} relocation applies to the word64 right past the
> ++corresponding \texttt{R_X86_64_DTPMOD64} relocation.

Ok, I've added R_X86_64_ everywhere I'd omitted it.

Please expect an updated patch soon.

If you'd rather install a patch with these minor modifications and
keep the more detailed patch separate, let me know and I'll send you
what I have right away.

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
Secretary for FSF Latin America        http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}