Purpose of attribute_tls_model_ie

[Alexander Monakov]

On Fri, 16 Oct 2015, Florian Weimer wrote:

> Why are some thread-local variables marked with attribute_tls_model_ie?
> 
> As far as I can tell, the default for PIC is set by
> -ftls-model=initial-exec, and for non-PIC, it's the compiler default.
> The latter is more efficient (no GOT indirection), but
> attribute_tls_model_ie overrides this.

Can you please clarify, what does it override?  I see: 

include/libc-symbols.h:
#define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))

So the macro requests IE model, same as the command line flag.  Did you mean
that the attribute was redundant?

A problem with the attribute is that it disallows the compiler to optimize
initial-exec to local-exec for accesses to locally-defined variables.  Is that
what you meant?

Alexander