On Tue, 12 Dec 2017 15:08:00 +0800 Alan Kao <noner...@gmail.com> wrote:
> > It's not a big deal, though -- we can fix these later. The more interesting > > thing here is that this code means our `-pg` stuff is now part of the GCC > > ABI, which is something I'd never though of before. I've added Jim, our GCC > > guy. > > > > Jim: do you mind checking to make sure the GCC profiling support is sane? > > Specifically, I'm thinking: > > > > * Are there any profiling features we don't support that would require an > > ABI break? > > * Is there a way to add future ISA extensions without breaking the ABI? > > * Should we document this as part of the ELF psABI specification? > > > > Even though this isn't user-visible as far an Linux is concerned, it'd be a > > bit of a pain to have to break this ABI because we did something brain-dead. > > Since there's a bit of time before 7.3.0, I think it'd be OK to consider > > breaking the profiling ABI if there's a good reason. > > > > As far as I can tell, the `-pg` flag only inserts the _mcount call after > every > valid function prologue and seems breaking no existing ABI. But indeed > it would be good if compiler guys can take a look at the gcc profiling > features. This is an interesting discussion, although I'm a bit confused. What ABI are you worried about breaking? -- Steve
