From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, ehabkost@redhat.com
Subject: Re: [Qemu-devel] [PATCH 3/3] disas/arm: avoid clang shifting negative signed warning
Date: Tue, 10 Nov 2015 18:33:36 +0100 [thread overview]
Message-ID: <56422A70.8040306@redhat.com> (raw)
In-Reply-To: <1447171055-29567-4-git-send-email-stefanha@redhat.com>
On 10/11/2015 16:57, Stefan Hajnoczi wrote:
> clang 3.7.0 on x86_64 warns about the following:
>
> disas/arm.c:1782:17: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
> imm |= (-1 << 7);
> ~~ ^
>
> Note that this patch preserves the tab indent in this source file
> because the surrounding code still uses tabs.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
I would like to know a case where (except with ubsan) clang actually
uses the optimization.
If not, this is just error message theatre (which is not news for clang)
and shouldn't have been part of -Wall.
Paolo
next prev parent reply other threads:[~2015-11-10 17:33 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-10 15:57 [Qemu-devel] [PATCH 0/3] fix clang negative signed bit shift warning Stefan Hajnoczi
2015-11-10 15:57 ` [Qemu-devel] [PATCH 1/3] monitor: avoid clang shifting negative signed warning Stefan Hajnoczi
2015-11-13 15:37 ` Eduardo Habkost
2015-11-10 15:57 ` [Qemu-devel] [PATCH 2/3] tpm: " Stefan Hajnoczi
2015-11-10 15:57 ` [Qemu-devel] [PATCH 3/3] disas/arm: " Stefan Hajnoczi
2015-11-10 17:33 ` Paolo Bonzini [this message]
2015-11-10 17:48 ` Peter Maydell
2015-11-10 17:59 ` Paolo Bonzini
2015-11-10 18:52 ` Markus Armbruster
2015-11-10 19:51 ` Steven Noonan
2015-11-10 20:06 ` Markus Armbruster
2015-11-10 20:17 ` Steven Noonan
2015-11-10 20:18 ` Paolo Bonzini
2015-11-10 16:04 ` [Qemu-devel] [PATCH 0/3] fix clang negative signed bit shift warning Peter Maydell
2015-11-16 14:23 ` Peter Maydell
2015-11-16 15:20 ` Peter Maydell
2015-11-17 3:50 ` Stefan Hajnoczi
2015-11-17 3:53 ` Stefan Hajnoczi
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