From: Florian Weimer <fweimer@redhat.com>
To: Nathan Sidwell <nathan@acm.org>, GCC <gcc@gcc.gnu.org>,
GNU C Library <libc-alpha@sourceware.org>,
Binutils <binutils@sourceware.org>,
gnu-gabi@sourceware.org
Subject: Re: Invalid program counters and unwinding
Date: Tue, 26 Jun 2018 11:39:00 -0000 [thread overview]
Message-ID: <d1d58d83-cf2a-c91d-385b-07afbed26593@redhat.com> (raw)
In-Reply-To: <f0e5d83d-7de4-5e24-cbce-9bc4db44dea3@acm.org>
On 06/26/2018 01:35 PM, Nathan Sidwell wrote:
> 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:Â [dcl.attr.noreturn]/2 [ Note: The function may terminate
> by throwing an exception. â 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.
Are you sure? I was under the impression that GCC did not do this
because it interferes too much with debugging.
Furthermore, glibc marks abort as nothrow and noreturn, which is a bit
dubious, considering that it is perfectly fine to throw exception from
synchronously delivered signals.
Thanks,
Florian
next prev parent reply other threads:[~2018-06-26 11:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-26 9:26 Florian Weimer
2018-06-26 10:56 ` Nathan Sidwell
2018-06-26 11:01 ` Florian Weimer
2018-06-26 11:15 ` Nathan Sidwell
2018-06-26 11:21 ` Florian Weimer
2018-06-26 11:35 ` Nathan Sidwell
2018-06-26 11:39 ` Florian Weimer [this message]
2018-06-26 11:46 ` Jakub Jelinek
2018-06-26 11:46 ` Nathan Sidwell
2018-06-26 11:25 ` Jakub Jelinek
2018-06-26 11:31 ` Florian Weimer
2018-06-28 2:16 ` Jeff Law
2018-06-28 12:31 ` Florian Weimer
2018-06-28 14:18 ` Jeff Law
2018-06-28 14:49 ` Florian Weimer
2018-07-02 15:48 ` Michael Matz
2018-07-02 15:54 ` Jakub Jelinek
2018-07-02 16:14 ` Michael Matz
2018-07-05 19:31 ` Florian Weimer
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