linux-kernel - Re: [PATCH V2 06/15] genirq: Generic chip: Optimize for fixed-endian systems

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Date:	Thu, 30 Oct 2014 10:04:24 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Brian Norris <computersforpeace@...il.com>
Cc:	Kevin Cernekee <cernekee@...il.com>, f.fainelli@...il.com,
	tglx@...utronix.de, jason@...edaemon.net, ralf@...ux-mips.org,
	lethal@...ux-sh.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, mbizon@...ebox.fr, jogo@...nwrt.org,
	linux-mips@...ux-mips.org
Subject: Re: [PATCH V2 06/15] genirq: Generic chip: Optimize for fixed-endian systems

On Wednesday 29 October 2014 21:16:58 Brian Norris wrote:
> >  static int is_big_endian(struct irq_chip_generic *gc)
> >  {
> > -     return !!(gc->domain->gc->gc_flags & IRQ_GC_BE_IO);
> > +     if (IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP) &&
> > +         !IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP_BE))
> > +             return 0;
> > +     else if (IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP_BE) &&
> > +              !IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP))
> > +             return 1;
> 
> Would XOR make this any easier to read? e.g.:
> 
>         if (IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP) ^
>             IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP_BE))
>                 return IS_ENABLED(CONFIG_GENERIC_IRQ_CHIP_BE);
>         else
>                 ...
> 

I think that would only be easier to read for the compiler, not for
for a human. ;-)

	Arnd
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