[LLVMdev] [PATCH] Add support for accessing the FS segment register on X86

[Zoltan Varga]

 Hi,

  If I'm writing a JIT, and want to access the TLS variables of the app
containing the JIT, I can't
use thread_local since that only works for variables declared in LLVM IL
and/or managed by
the ExecutionEngine. While this patch allows a JIT to generate the TLS
accesses itself, if
it knows the tls offset of the variable in question.

                  Zoltan

On Tue, May 5, 2009 at 12:16 AM, Dan Gohman <gohman at apple.com> wrote:

> Hello,
>
> The preferred way to do TLS is to use the thread_local keyword.
> There is x86-64 support for thread_local on ELF; if you need
> it for other targets, I recommend looking at adapting it.
>
> Dan
>
> On May 4, 2009, at 2:59 PM, Zoltan Varga wrote:
>
> > Hi,
> >
> >   Here is an updated version of the patch using address space 257.
> >
> >                 Zoltan
> >
> > On Mon, May 4, 2009 at 11:36 PM, Shantonu Sen <ssen at apple.com> wrote:
> > Maybe 257 would be better (or other unused), because of r70197,
> > which gives special behavior for <256
> >
> > Shantonu Sen
> > ssen at apple.com
> >
> > Sent from my Mac Pro
> >
> >
> > On May 4, 2009, at 2:28 PM, Zoltan Varga wrote:
> >
> > Hi,
> >
> >  The attached patch adds support for accessing the FS segment
> > register using address space 255, similarly to the way the GS
> > segment register can be accessed. This is useful for generating TLS
> > access code on amd64 for example.
> >
> >              Zoltan
> >
> >
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