[cxx-abi-dev] thread_local summary

[Dennis Handly]

>From: Jason Merrill <jason at redhat.com>
>I'm currently mangling the init and wrapper functions as normal 
>functions with a function name of _TH <object name> or _TW <object 
>name>, respectively.  I've thought about dropping the function type from 
>the mangling, but don't have a strong opinion.

So is this going to be added to the mangling specs?

>The destructors for the current thread are also run on std::exit.

And we don't care about other threads?

>Dennis suggested that we still include the DSO handle in the parameters 
>to this function.  Since there's really no way to run destructors in all 
>threads on dlclose, I don't really see the need; instead, an 
>implementation can use internal mechanisms to improve semantics and/or 
>diagnostics for dlclosing a shared object with pending thread_local 
>destructors.
Jason

I don't see any easy way to diagnose it without the DSO handle.
For static variables, you can look at the address ranges for text and data
for each shlib that you unload and make a guess on that.  But thread local
data is in the heap somewhere, with no idea who owns it.

I.e. I don't think you want the C++ runtime to get in bed with the threads
lib at that low level.  For something that can be easily solved by passing
that extra handle.