linux-kernel - Re: [PATCH 2/3 V2] time: allow gcc to fold constants when using

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Message-ID: <20150422151214.GA3464@opentech.at>
Date:	Wed, 22 Apr 2015 17:12:14 +0200
From:	Nicholas Mc Guire <der.herr@...r.at>
To:	Joe Perches <joe@...ches.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Nicholas Mc Guire <hofrat@...dl.org>,
	Michal Marek <mmarek@...e.cz>,
	Masahiro Yamada <yamada.m@...panasonic.com>,
	Sam Ravnborg <sam@...nborg.org>,
	"H. Peter Alvin" <hpa@...or.com>,
	John Stultz <john.stultz@...aro.org>,
	Andrew Hunter <ahh@...gle.com>, Paul Turner <pjt@...gle.com>,
	Aaron Sierra <asierra@...-inc.com>,
	Brian Norris <computersforpeace@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3 V2] time: allow gcc to fold constants when using

On Wed, 22 Apr 2015, Joe Perches wrote:

> On Wed, 2015-04-22 at 14:00 +0200, Thomas Gleixner wrote:
> > On Sun, 12 Apr 2015, Nicholas Mc Guire wrote:
> > > +extern unsigned long __msecs_to_jiffies(const unsigned int m);
> > > +#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
> > > +static inline unsigned long _msecs_to_jiffies(const unsigned int m)
> > > +{
> > 
> > This should move the comments explaining the logic for each variant as
> > well.
> []
> > It'd be nice to have this as two patches:
> > 
> > 1) Factor out the code into inline helpers w/o adding anything
> 
> It also might be nice to use a single static inline
> with #ifdef blocks inside that inline rather than
> have 3 separate static inline msecs_to_jiffies.

That was actually intentional to make it more readable - atleast
I thought its more readable this way than it
was before.

> 
> > 2) Add the __builtin_constant_p() check
> 
> And please add the usecs_to_jiffies variants in a
> similar patch set.
>
yup - as soon as its clean for msecs_to_jiffies applying
the same refactoring for usecs_to_jiffies is streight forward
so basically just waiting for the feedback on the 
first one before pushing the usecs_to_jiffies case out.

thx!
hofrat 
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