Re: [PATCH] usb: remove redundant conditions
Hi, "Geyslan G. Bem" writes: > 2015-12-10 12:13 GMT-03:00 Felipe Balbi : >> "Geyslan G. Bem" 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 >>> --- >> >> I guess you didn't get previous comment in time; let's split this per >> driver so different maintainers can pick their parts. > > Okeydokey. :) thanks :-) -- balbi signature.asc Description: PGP signature
Re: [PATCH] usb: remove redundant conditions
2015-12-10 12:29 GMT-03:00 Geyslan G. Bem :
> 2015-12-10 12:17 GMT-03:00 David Laight :
>> From: Felipe Balbi
>>> Sent: 10 December 2015 15:14
>>> "Geyslan G. Bem" 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
>>> > ---
>>>
>>> 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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Re: [PATCH] usb: remove redundant conditions
2015-12-10 12:17 GMT-03:00 David Laight :
> From: Felipe Balbi
>> Sent: 10 December 2015 15:14
>> "Geyslan G. Bem" 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
>> > ---
>>
>> 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?
>
> David
>
--
Regards,
Geyslan G. Bem
hackingbits.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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RE: [PATCH] usb: remove redundant conditions
From: Felipe Balbi > Sent: 10 December 2015 15:14 > "Geyslan G. Bem" 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 > > --- > > 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. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] usb: remove redundant conditions
2015-12-10 12:13 GMT-03:00 Felipe Balbi : > "Geyslan G. Bem" 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 >> --- > > I guess you didn't get previous comment in time; let's split this per > driver so different maintainers can pick their parts. Okeydokey. :) > > -- > balbi -- Regards, Geyslan G. Bem hackingbits.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] usb: remove redundant conditions
"Geyslan G. Bem" 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 > --- I guess you didn't get previous comment in time; let's split this per driver so different maintainers can pick their parts. -- balbi signature.asc Description: PGP signature
Re: [PATCH] usb: remove redundant conditions
2015-12-10 11:50 GMT-03:00 Felipe Balbi : > > Hi, > > "Geyslan G. Bem" 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 > > Can you split this into one patch per driver, that way it's easier to > apply by different maintainers. Balbi, sure, I can. Tks. > > -- > balbi -- Regards, Geyslan G. Bem hackingbits.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] usb: remove redundant conditions
Hi, "Geyslan G. Bem" 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 Can you split this into one patch per driver, that way it's easier to apply by different maintainers. -- balbi signature.asc Description: PGP signature
Re: [PATCH] usb: remove redundant conditions
2015-12-10 7:44 GMT-03:00 Johan Hovold : > On Wed, Dec 09, 2015 at 10:52:42PM -0300, Geyslan G. Bem wrote: >> 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 >> --- >> drivers/usb/gadget/udc/s3c-hsudc.c | 2 +- >> drivers/usb/host/fhci-sched.c | 2 +- >> drivers/usb/musb/musb_gadget.c | 5 ++--- >> drivers/usb/serial/io_edgeport.c | 35 ++- >> drivers/usb/serial/mos7840.c | 2 +- >> 5 files changed, 19 insertions(+), 27 deletions(-) > > Please split out (at least) the usb-serial changes into two patches. Ok, I'll send v2 later. > > Johan -- Regards, Geyslan G. Bem hackingbits.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] usb: remove redundant conditions
On Wed, Dec 09, 2015 at 10:52:42PM -0300, Geyslan G. Bem wrote: > 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 > --- > drivers/usb/gadget/udc/s3c-hsudc.c | 2 +- > drivers/usb/host/fhci-sched.c | 2 +- > drivers/usb/musb/musb_gadget.c | 5 ++--- > drivers/usb/serial/io_edgeport.c | 35 ++- > drivers/usb/serial/mos7840.c | 2 +- > 5 files changed, 19 insertions(+), 27 deletions(-) Please split out (at least) the usb-serial changes into two patches. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
