From: Paul Koning <paulkoning@comcast.net>
To: Florian Weimer <fweimer@redhat.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>, gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] middle-end/81035: Mention that noreturn suppresses tail call optimization
Date: Fri, 21 Sep 2018 18:36:00 -0000 [thread overview]
Message-ID: <386B7752-2567-4601-AE2C-89C359B3C432@comcast.net> (raw)
In-Reply-To: <87y3bu90ky.fsf@oldenburg.str.redhat.com>
> On Sep 21, 2018, at 2:17 PM, Florian Weimer <fweimer@redhat.com> wrote:
>
> * Segher Boessenkool:
>
>> On Fri, Sep 21, 2018 at 12:59:27PM +0200, Florian Weimer wrote:
>>> 2018-09-21 Florian Weimer <fweimer@redhat.com>
>>>
>>> PR middle-end/81035
>>> * doc/extend.texi (Common Function Attributes): Mention that
>>> noreturn suppresses tail call optimization.
>>
>>> +In order to preserve backtraces, GCC will never turn calls to
>>> +@code{noreturn} functions into tail calls.
>>
>> Should we document this? Shouldn't we fix it, instead?
>
> Fix how? What is currently broken?
>
> For things like assertion failures, we do not want to replace the
> current stack frame with that of __assert_fail, I think.
I agree. Also, tailcalls are optimizations. Speed optimizing noreturn calls is obviously not interesting. Calls to noreturn functions are short, and turning them into a jump probably makes no difference in size, or if it does, not enough to matter.
paul
next prev parent reply other threads:[~2018-09-21 18:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 11:10 Florian Weimer
2018-09-21 18:16 ` Segher Boessenkool
2018-09-21 18:29 ` Florian Weimer
2018-09-21 18:36 ` Paul Koning [this message]
2018-09-21 18:40 ` Florian Weimer
2018-09-21 22:32 ` Segher Boessenkool
2018-09-21 19:44 ` Jeff Law
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