Purpose of attribute_tls_model_ie

[Joseph Myers]

On Fri, 16 Oct 2015, Florian Weimer wrote:

> On 10/16/2015 03:31 PM, Joseph Myers wrote:
> > On Fri, 16 Oct 2015, Florian Weimer wrote:
> > 
> >> Why are some thread-local variables marked with attribute_tls_model_ie?
> > 
> > Maybe to indicate variables located in initial modules that are accessed 
> > from other modules (i.e. for use when those other modules are being built, 
> > without -ftls-model=initial-exec)?
> 
> But this would not apply to the arena pointer in malloc/arena.c, right?
>  (It's a static TLS variable, after all.)  So we could drop it there and
> get better code for statically linked glibc.

Indeed.  If it's being built as part of libc then the command-line option 
should suffice.  The attribute should help for cases such as the 
GLIBC_PRIVATE TLS errno, however (subject to fixing the attribute to use 
local-exec in static libraries (but not *_nonshared)).

-- 
Joseph S. Myers
joseph@codesourcery.com