2015-12-10 12:29 GMT-03:00 Geyslan G. Bem <geyslan@xxxxxxxxx>:
> 2015-12-10 12:17 GMT-03:00 David Laight <David.Laight@xxxxxxxxxx>:
>> From: Felipe Balbi
>>> Sent: 10 December 2015 15:14
>>> "Geyslan G. Bem" <geyslan@xxxxxxxxx> writes:
>>>
>>> > This patch removes redundant conditions.
>>> >
>>> > - (!A || (A && B)) is the same as (!A || B).
>>> > - (length && length > 5) can be reduced to a single evaluation.
>>> >
>>> > Caught by: cppcheck
>>> >
>>> > Signed-off-by: Geyslan G. Bem <geyslan@xxxxxxxxx>
>>> > ---
>>>
>>> I guess you didn't get previous comment in time; let's split this per
>>> driver so different maintainers can pick their parts.
>>
>> I also suspect that gcc will optimise out the redundant checks as well.
> Yes, David. it will.
>
> Let's see.
>
> void f(int f, int s)
> {
> if (!f || (f && s))
> printf("branch\n");
> }
>
> Generates without optimization three comparisons:
>
> cmpl $0, -4(%rbp)
> je .L2
> cmpl $0, -4(%rbp)
> je .L4
> cmpl $0, -8(%rbp)
> je .L4
>
> But with -O2 it generates only two:
>
> testl %edi, %edi
> je .L2
> testl %esi, %esi
> je .L1
>
> Despite that, I think that the patches are welcome since they silence
> checkpatch and make code clearer. Don't you think?
Sorry, silence "cppcheck". I'm mistaking the tool name.
>
>>
>> David
>>
>
>
>
> --
> Regards,
>
> Geyslan G. Bem
> hackingbits.com
--
Regards,
Geyslan G. Bem
hackingbits.com
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