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Date: Tue, 17 Mar 2015 14:54:38 +0000
Message-ID: <CAJSP0QU9BUv1ss=DvUVoXmCovA=kKeX3L3HDna2oMHxOURaexA@mail.gmail.com>
From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 2/7] Convert (ffs(val) - 1) to ctz32(val)
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>, Markus Armbruster <armbru@redhat.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