From: Stefan Hajnoczi <stefanha@gmail.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@redhat.com>,
Markus Armbruster <armbru@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 2/7] Convert (ffs(val) - 1) to ctz32(val)
Date: Tue, 17 Mar 2015 14:54:38 +0000 [thread overview]
Message-ID: <CAJSP0QU9BUv1ss=DvUVoXmCovA=kKeX3L3HDna2oMHxOURaexA@mail.gmail.com> (raw)
In-Reply-To: <CAFEAcA_WRN7U2ryRnyT6XVp8a9VtbHNVD6XXX3b8QaTkSo0++w@mail.gmail.com>
On Tue, Mar 17, 2015 at 12:09 PM, Peter Maydell
<peter.maydell@linaro.org> wrote:
> On 17 March 2015 at 11:56, Stefan Hajnoczi <stefanha@redhat.com> wrote:
>> This commit was generated mechanically by coccinelle from the following
>> semantic patch:
>>
>> @@
>> expression val;
>> @@
>> - (ffs(val) - 1)
>> + ctz32(val)
>
> Did you check all these callsites to make sure that the value
> passed in can never be zero? (ffs(0) - 1) is -1 whereas
> ctz32(0) is 32...
I have done that now and found 2 cases where it's possible. They will
be moved to separate patches in v2.
Stefan
next prev parent reply other threads:[~2015-03-17 14:54 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-17 11:56 [Qemu-devel] [PATCH 0/7] Convert ffs(3) to ctz32() Stefan Hajnoczi
2015-03-17 11:56 ` [Qemu-devel] [PATCH 1/7] bt-sdp: fix broken uuids power-of-2 calculation Stefan Hajnoczi
2015-03-17 14:37 ` Eric Blake
2015-03-17 11:56 ` [Qemu-devel] [PATCH 2/7] Convert (ffs(val) - 1) to ctz32(val) Stefan Hajnoczi
2015-03-17 12:09 ` Peter Maydell
2015-03-17 14:54 ` Stefan Hajnoczi [this message]
2015-03-17 11:56 ` [Qemu-devel] [PATCH 3/7] Convert ffs() != 0 callers to ctz32() Stefan Hajnoczi
2015-03-30 15:42 ` Richard Henderson
2015-03-17 11:56 ` [Qemu-devel] [PATCH 4/7] sd: convert sd_normal_command() ffs(3) call " Stefan Hajnoczi
2015-03-17 11:56 ` [Qemu-devel] [PATCH 5/7] omap_intc: convert ffs(3) to ctz32() in omap_inth_sir_update() Stefan Hajnoczi
2015-03-17 14:58 ` Paolo Bonzini
2015-03-30 15:44 ` Richard Henderson
2015-03-17 11:56 ` [Qemu-devel] [PATCH 6/7] os-win32: drop ffs(3) prototype Stefan Hajnoczi
2015-03-17 11:56 ` [Qemu-devel] [PATCH 7/7] checkpatch: complain about ffs(3) calls Stefan Hajnoczi
2015-03-17 12:02 ` [Qemu-devel] [PATCH 0/7] Convert ffs(3) to ctz32() Stefan Hajnoczi
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