On 06/26/2018 07:21 AM, Florian Weimer wrote:
GCC doesn't do this AFAIK, but it's theoretically possible not to
preserve the return address for a noreturn function. But that would
be very bad for exception handling, so let's hope compilers don't do
this.
I'd forgotten about noreturn. Such functions may terminate by throwing
an exception (and for our purposes I think pthread_cancel implementatio
is sufficiently exception-like):
from C++ std: [dcl.attr.noreturn]/2 [ Note: The function may terminate
by throwing an exception. — end note ]
and from doc/extend.texi:
The @code{noreturn} keyword does not affect the exceptional path
when that applies: a @code{noreturn}-marked function may still
return to the caller by throwing an exception or calling
@code{longjmp}.
IIRC, in gcc-land you have to give both noreturn and nothrow attributes
to make it non-unwindable.