* Richard Biener: > On Wed, 19 Dec 2018, Florian Weimer wrote: > >> * Richard Biener: >> >> > The cost is probably target dependent - on x86 it's simply a $fs based >> > load/store. >> >> Do you need to reserve something in the TCB for this? > > No idea. But I figured using TLS with the patch only works when > optimizing and not with -O0. Huh. Anyway, it should be equivalent > to what presence of > > __thread void *_SV1MASK = (void *)-1l; > > requires (plus I make that symbol GNU_UNIQUE). I see this > allocates -1 in the .tdata section marked TLS.
Oh. That's going to be substantially worse for PIC, even with the initial-exec model, especially on architectures which do not have arbitrary PC-relative loads. Which is why I'm asking about the TCB reservation. Thanks, Florian
