Invalid program counters and unwinding

[Florian Weimer]

On 07/02/2018 06:14 PM, Michael Matz wrote:
> There is no such language in the psABI, no (at least I haven't found
> anything; you had me worried for a moment :) ).  But there's stronger one:
> all functions through which unwinding is expected must provide CFI.  So,
> yes, such code isn't strictly conforming.  But there we are, there's much
> code that isn't and we still have to sensibly deal with it (if we can).
> IMHO making guesses is better than to stop unwinding.  And IMHO guessing
> that it's FP-using is better than guessing that it's leaf, especially if
> the PC in question was the result of a prior unwinding step (making it
> clear that it certainly was_not_  leaf).

Well, the previous frame could have been a signal handler frame, but I 
see your point.

Anyway, I've proposed a BoF for these topics for the next Cauldron.

Thanks,
Florian