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From: Peter Maydell <peter.maydell@linaro.org>
To: Markus Armbruster <armbru@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Frank Blaschka <frank.blaschka@de.ibm.com>,
	Frank Blaschka <blaschka@linux.vnet.ibm.com>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 2/3 V3] s390: implement pci instructions
Date: Wed, 21 Jan 2015 14:41:28 +0000	[thread overview]
Message-ID: <CAFEAcA_5rJdwUWeHZdReALWMwwfzheUatFwhyxmtu-=8KuonOA@mail.gmail.com> (raw)
In-Reply-To: <87mw5cfdyy.fsf@blackfin.pond.sub.org>

On 21 January 2015 at 13:41, Markus Armbruster <armbru@redhat.com> wrote:
> I suspect we shift signed values all over the place, without regard for
> signed overflow.  Machines are fine with that, but some day some
> compiler wiseguy may find a way to save a femtosecond or two for some
> program that never does that, breaking programs that do it, and then
> we'll be in trouble.

clang with its undefined behaviour sanitizers will warn at runtime
when we do this. I've sent out some patches to fix instances of
this in the past. Coverity will also warn in some cases I think.

> We should follow the kernel's lead and compile with
> -fno-strict-overflow.

I don't believe that option affects signed shifts, only signed
addition, subtraction and multiplication.

-- PMM

  reply	other threads:[~2015-01-21 14:41 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-09  8:04 [Qemu-devel] [PATCH 0/3 V3] add PCI support for the s390 platform Frank Blaschka
2015-01-09  8:04 ` [Qemu-devel] [PATCH 1/3 V3] s390: Add PCI bus support Frank Blaschka
2015-01-09 11:54   ` Cornelia Huck
2015-01-09  8:04 ` [Qemu-devel] [PATCH 2/3 V3] s390: implement pci instructions Frank Blaschka
2015-01-20  9:45   ` Markus Armbruster
2015-01-20 10:03     ` Cornelia Huck
2015-01-20 12:33       ` Markus Armbruster
2015-01-20 12:56         ` Markus Armbruster
2015-01-20 14:20           ` Frank Blaschka
2015-01-20 20:24             ` Markus Armbruster
2015-01-21 11:54               ` Markus Armbruster
2015-01-21 13:12                 ` Peter Maydell
2015-01-21 13:41                   ` Markus Armbruster
2015-01-21 14:41                     ` Peter Maydell [this message]
2015-01-21 15:32                     ` Paolo Bonzini
2015-01-21  9:49         ` Cornelia Huck
2015-01-09  8:04 ` [Qemu-devel] [PATCH 3/3 V3] kvm: extend kvm_irqchip_add_msi_route to work on s390 Frank Blaschka
2015-01-09 11:59 ` [Qemu-devel] [PATCH 0/3 V3] add PCI support for the s390 platform Cornelia Huck

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