linux-kernel - Re: [PATCH] TRACING: Fix a copmile warning

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Message-ID: <CACqU3MXysWUYNnNQniR5LB4x1UGhJqwoYnTFmj=U8do-qRghow@mail.gmail.com>
Date:	Mon, 25 Jul 2011 21:19:57 -0400
From:	Arnaud Lacombe <lacombar@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Ian Lance Taylor <iant@...gle.com>, gcc-help@....gnu.org,
	stufever@...il.com, linux-kernel@...r.kernel.org,
	Wang Shaoyan <wangshaoyan.pt@...bao.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] TRACING: Fix a copmile warning

Hi,

On Mon, Jul 25, 2011 at 9:12 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
> On Mon, 2011-07-25 at 21:08 -0400, Arnaud Lacombe wrote:
>> Hi,
>>
>
>> but the code generated seem to test %esi (`b', potentially
>> uninitialized) before %ebx (`a'). Am I still missing something ?
>
> But it tests 'a' again afterward. If 'a' is 0, it doesn't matter what
> 'b' was. So the uninitialized test is a wash. No harm done, except for
> some wasted CPU cycles.
>
I see, even if `b' is junk, the final logic does not change.

 - Arnaud
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