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DateMon, 14 Jun 2010 10:51:03 -0400
FromBill Davidsen <>
SubjectRe: warning from gcc version 4.6.0 20100416
Andi Kleen wrote:
> On Sun, Jun 13, 2010 at 09:17:41PM -0400, Bill Davidsen wrote:
>
>> Justin P. Mattock wrote:
>>
>>> o.k. andi,
>>>
>>> here is the rest of the warnings that
>>> I see when compiling the kernel
>>>
>>> I can try and create some patches for
>>> this(hopefully!!)
>>>
>>>
>> There is no great solution to this, in a fair number of cases the fix would
>> slow the code or make it harder to read, so some of these probably don't
>>
>
> Sorry that's wrong: the optimizer will generate the same
> code anyways as if the unused variable was not there
> because it eliminates unused variables.
>
>
If one puts an 'if' around the variable set (I've seen it) the test may
well take longer than the assign, assuming that there's a case where the
assign is done.
> So fixing this cannot make code slower.
>
> I also don't see how unused variables make the code easier
> to read.
>
>
No, my point was that putting a bunch of ifdef statements in to avoid
the warning will make the code harder to read.

> The only difficult case sometimes is with #ifdef code,
> that has to be handled case by case. One elegant solution
> is to replace the ifdef code with an inline.
>
>
>> want a fix. Of course some clearly are errors, so you are doing something
>>
>
> All warnings should be fixed, I only left those in that
> are real code bugs if I couldn't fix the code.
>
> Kernel builds are expected to be relatively warning free
> so that you can easily spot new warnings.
>
> But eventually someone who knows the code better has to
> fix that bug.
>
> --Andi
>
>


--
Bill Davidsen <davidsen@tmr.com>
"We can't solve today's problems by using the same thinking we
used in creating them." - Einstein



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