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From: Jakub Jelinek <jakub@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>,
	linux-toolchains@vger.kernel.org, Michael Matz <matz@suse.de>,
	Richard Biener <rguenther@suse.de>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: older gccs and case labels producing integer constants
Date: Wed, 6 Apr 2022 12:13:27 +0200	[thread overview]
Message-ID: <Yk1nx2dwh6e3YFHu@tucnak> (raw)
In-Reply-To: <Ykw0wzdab0ICUFvy@hirez.programming.kicks-ass.net>

On Tue, Apr 05, 2022 at 02:23:31PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 05, 2022 at 11:50:35AM +0200, Borislav Petkov wrote:
> > Hi folks,
> > 
> > I'm starting to see failures like this on allmodconfig builds:
> > 
> > sound/usb/midi.c: In function ‘snd_usbmidi_out_endpoint_create’:
> > sound/usb/midi.c:1389:2: error: case label does not reduce to an integer constant
> >   case (((0xfc08) << 16) | (0x0101)):
> >   ^~~~
> > 
> > (The case statement is a macro but it evaluates to what I have there)
> > 
> > and that thing fails with
> > 
> > $ gcc --version
> > gcc (SUSE Linux) 7.5.0
> > 
> > although it doesn't have any problems building with newer compilers.
> > 
> > I'm presuming older gccs consider those case statements signed ints and
> > the following fixes it:
> > 
> >   case ((((unsigned int)0xfc08) << 16) | (0x0101)):
> > 
> > and I guess we can whack the couple of occurrences but what I'm
> > wondering is why does this work with newer gccs?
> 
> IIRC GCC-8 fixed a bunch of -wrapv issues. Could be this is one of them
> I suppose.

If we are talking about -fsanitize=shift -fwrapv, then that is
https://gcc.gnu.org/PR68418 , i.e. it was fixed already for GCC 6.

	Jakub


      parent reply	other threads:[~2022-04-06 14:22 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-05  9:50 older gccs and case labels producing integer constants Borislav Petkov
2022-04-05  9:58 ` Richard Biener
2022-04-05 10:04   ` Borislav Petkov
2022-04-05 10:06   ` Richard Biener
2022-04-05 10:36     ` Borislav Petkov
2022-04-05 10:45       ` Borislav Petkov
2022-04-05 11:41         ` Richard Biener
2022-04-07 15:16           ` Borislav Petkov
2022-04-05 11:37       ` Richard Biener
2022-04-06  9:53       ` Jakub Jelinek
2022-04-06 10:04         ` Jakub Jelinek
2022-04-05 12:23 ` Peter Zijlstra
2022-04-05 12:39   ` Michael Matz
2022-04-05 12:53     ` Richard Biener
2022-04-05 13:04       ` Borislav Petkov
2022-04-06 10:13   ` Jakub Jelinek [this message]

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