On Fri, Nov 21, 2008 at 11:19:32AM +0100, Joel Porquet wrote:
> I agree that wether the code is pic or not and the tls model are quite
> independent.
> According to the manual, the default policy for TLS is affected by the
> pic model though:
>
> -ftls-model=model
> ...
> The default without -fpic is "initial-exec"; with -fpic the
> default is "global-dynamic".
Which is exactly what happens. Using -fpie does not cound as "with
-fpic".
> > It's a difference between linking an executable versus linking a
> > shared library; this is one of the distinctions between -fpie and
> > -fpic.
>
> Yes for the linking stage but for the object compilation, -fpie should
> be almost the same.
No, it shouldn't.
`-fpie'
`-fPIE'
These options are similar to `-fpic' and `-fPIC', but generated
position independent code can be only linked into executables.
This is one of the reasons that the generated code can only be used
in executables.
> It could be but firstly when the global-dynamic model is specified one
> should expect to get global-dynamic and not local-dynamic, and anyway
> it is not local-dynamic.
I don't remember what the deal is with the command line option, but
I've run into that before. The answer was, I think, that it is
behaving as designed - but not intuitively.
As for the model, you're right, it's not local dynamic. It's global
dynamic linked into an executable. The linker has performed some
optimization on your output file because it can determine the symbol
binding at static link time. There's no need for a dynamic relocation
to calculate DTPREL when it's a link-time constant.
This is all very interesting, but you didn't answer my question: is
this causing some problem, or just confusing? These are all intended
optimizations.
--
Daniel Jacobowitz
CodeSourcery
