From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Jonathan Wakely via Gcc <gcc@gcc.gnu.org>,
Jakub Jelinek <jakub@redhat.com>,
Theodore Papadopoulo <Theodore.Papadopoulo@inria.fr>
Subject: Re: Enquiry
Date: Mon, 31 Jan 2022 10:33:50 +0000 [thread overview]
Message-ID: <CAH6eHdQu1aSamPyqs485TtfywOB0CVhUrrW2YRBCOLbpgNVWbw@mail.gmail.com> (raw)
In-Reply-To: <87czk86w2l.fsf@igel.home>
On Mon, 31 Jan 2022 at 10:25, Andreas Schwab wrote:
>
> On Jan 30 2022, Jonathan Wakely via Gcc wrote:
>
> > On Sun, 30 Jan 2022, 10:58 Jakub Jelinek, <jakub@redhat.com> wrote:
> >
> >> On Sun, Jan 30, 2022 at 10:50:56AM +0000, Jonathan Wakely wrote:
> >> > We could put a trap instruction at the end of the function though, which
> >> > would make the result a bit less arbitrary.
> >> >
> >> > I've come around to thinking that's preferable for cases like this.
> >>
> >> Depends on which exact cases.
> >> Because for
> >> int foo (int s) { if (s == 123) return 1; }
> >> we want to optimize it into
> >> return 1;
> >> rather than if (s == 123) return 1; else __builtin_trap ();
> >> For debugging we have -fsanitize=undefined
> >
> >
> > What if we inserted the trap for -O0?
>
> Note that in C it is not an error to fall through the end of a non-void
> function if the caller does not use the return value.
Indeed. Theo's program is undefined in C++ and valid in C.
I would love to see the trap inserted for C++ though.
next prev parent reply other threads:[~2022-01-31 10:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-30 9:47 Enquiry Theodore Papadopoulo
2022-01-30 10:41 ` Enquiry Jakub Jelinek
2022-01-30 10:50 ` Enquiry Jonathan Wakely
2022-01-30 10:58 ` Enquiry Jakub Jelinek
2022-01-30 11:11 ` Enquiry Jonathan Wakely
2022-01-31 9:42 ` Enquiry Jakub Jelinek
2022-01-31 10:25 ` Enquiry Andreas Schwab
2022-01-31 10:33 ` Jonathan Wakely [this message]
2022-01-31 10:16 ` Enquiry Theodore Papadopoulo
2022-01-31 10:23 ` Enquiry Jonathan Wakely
2022-01-30 11:17 ` Enquiry Jonathan Wakely
2022-01-31 9:26 ` Enquiry Theodore Papadopoulo
-- strict thread matches above, loose matches on Subject: below --
2020-09-12 23:44 Enquiry Paul
2009-06-02 13:52 Enquiry Vijay Holimath
[not found] ` <dfa53ad0906021048t7e1c1fc7pf019d1229f529592@mail.gmail.com>
[not found] ` <dfa53ad0906021050p7aa605f2m4a1b6459b7f1f89e@mail.gmail.com>
2009-06-03 10:33 ` Enquiry Vijay
2009-06-02 13:00 Enquiry Vijay Holimath
2006-09-29 13:00 ENQUIRY Dr.Richard Lovward
2000-09-21 20:26 enquiry Adarsh MP
2000-09-22 2:15 ` enquiry Erik Mouw
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