[LLVMdev] Proposal: Loads/stores with deterministic trap/unwind behavior

[Joerg Sonnenberger]

On Tue, Apr 01, 2014 at 09:03:10PM +0100, David Chisnall wrote:
> On 1 Apr 2014, at 19:38, Peter Collingbourne <peter at pcc.me.uk> wrote:
> 
> > I'm pretty sure that it is possible to unwind through signal handlers. This
> > is, for example, how gccgo implements some run-time panics.
> 
> It' highly OS dependent and not something to rely on for any
> vaguely-portable code.

libc++abi's unwind doesn't really support unwinding through signal
handlers, at least it wouldn't do anything special for them. I don't
have the faintest idea what the correct semantic would even be. Does it
restore the saved signal mask? Can you even unwind past the frame? In
general you won't as unwind instructions are not precise/

Joerg