On Tue, Oct 26, 2021 at 08:10:16AM -0700, Richard Henderson wrote:
> On 10/26/21 6:22 AM, Stefan Hajnoczi wrote:
> > If "safe" TLS variables are opt-in then we'll likely have obscure bugs
> > when code changes to access a TLS variable that was previously never
> > accessed from a coroutine. There is no compiler error and no way to
> > detect this. When it happens debugging it is painful.
> 
> Co-routines are never used in user-only builds.

If developers have the choice of using __thread then bugs can slip
through.

Your assembly get_addr() approach reduces the performance overhead of
TLS getters/setters.

Are you concerned about performance, the awkwardness of calling
getters/setters, or something else for qemu-user?

Stefan