OK, from today till the end of the week I'm going to be sitting
down and thinking through this, as I'd really like the emitting
of _tlsstart and _tlsend out of the compiler by hook or by crook.
Phase one - start:
We have rt/tls.S. Have added this to the libdruntime builds, and
I see no immediate problems running this through the testsuite
(though - that is never really a good indicator of anything).
Drawbacks, this is only available for linux at the moment. But
that's fine if we keep this temporary for the week.
Phase two - plan:
The GC has a hook gc_addRoot used for the purpose of tracking GC
allocated memory in C-land. The idea I've got turning over in my
head at the moment is that any thread local decls that are
'new-able' (classes, pointers, d arrays) are added as a root upon
'new' declaration, this is safe-guarded by a thread-local static
to prevent multiple calls to gc_addRoot.
eg:
---
var = new Object();
---
if (!var.guard)
{
++var.guard;
gc_addRoot (&var);
}
var = _d_new_class (&Object_Class);
---
Then in the destruction of the thread (eg: atexit, or through a
destructor called in .fini section)
---
if (var.guard)
gc_removeRoot (&var);
---
Though this should not be required if we have a proper TLS GC in
place.
Does this seem like a reasonable job? Or have I completely lost
the plot at half past 2 in the morning? :o)
Regards
Iain.
