On Thu, May 23, 2013 at 12:06:01PM -0700, Richard Henderson wrote:
> > struct foo_c_state
> > {
> > some_type bar;
> > };
> > # define bar ctxt->x_foo_c_bar;
> > /* there's a "context *ctxt;" variable somewhere, possibly
> > using TLS */
>
> I've an idea that this will perform very badly. With ctxt being a global (if
> tls) variable, it's call clobbered. Thus we'll wind up reloading it all the
> time, which for pic involves another call to the __get_tlsaddr runtime
> function.
If all of gcc just has one __thread pointer in it, then we can just use
tls_model ("initial-exec") for it and lower that overhead down a lot.
Jakub
