split stack on darwin

[IainS]

On 28 Sep 2010, at 17:29, Ian Lance Taylor wrote:

> Jack Howarth <howarth@bromo.med.uc.edu> writes:
>
>>  Does the new split stack feature in gcc trunk absolutely require  
>> additional
>> libc support to function or can it be made to work on other targets  
>> like
>> darwin with just changes to libgcc? Thanks in advance for any
>> clarifications.
>
> The additional support that it needs is a thread local place to store
> the stack bound which can be accessed efficiently.  On GNU/Linux I'm
> using a word in the thread block--I've actually stolen a word which  
> was
> reserved for transactional memory but which RTH says he doesn't need.
> This can be accessed as an offset from %fs or %gs.  To make this
> functionality work on Darwin, you need something similar.  I don't  
> know
> how thread local storage works on Darwin, so I don't know if you can  
> do
> something similar.

We have emulated TLS (Richard's new code) .

> I list some other options at http://gcc.gnu.org/wiki/SplitStacks under
> "Possible strategies.


I sincerely doubt something this involved can be accommodated in the  
remaining time of stage 1
(unless we magic some additional Darwin devs from somewhere ;-))

Iain