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

[Nicholas Mc Guire]

On Wed, 22 Apr 2015, 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.

should be covered by [PATCH 3/3 V2] time: update msecs_to_jiffies doc and move to kernel-doc

> 
> > +		return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
> > +}
> > +#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
> > +static inline unsigned long _msecs_to_jiffies(const unsigned int m)
> > +{
> > +		if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
> > +			return MAX_JIFFY_OFFSET;
> > +		return m * (HZ / MSEC_PER_SEC);
> > +}
> > +#else
> > +static inline unsigned long _msecs_to_jiffies(const unsigned int m)
> > +{
> > +		if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
> > +			return MAX_JIFFY_OFFSET;
> > +
> > +		return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)
> > +			>> MSEC_TO_HZ_SHR32;
> > +}
> > +#endif
> > +static inline unsigned long msecs_to_jiffies(const unsigned int m)
> > +{
> > +	if (__builtin_constant_p(m)) {
> > +		if ((int)m < 0)
> > +			return MAX_JIFFY_OFFSET;
> > +		return _msecs_to_jiffies(m);
> > +	} else
> > +		return __msecs_to_jiffies(m);
> 
> It'd be nice to have this as two patches:
> 
> 1) Factor out the code into inline helpers w/o adding anything
> 
> 2) Add the __builtin_constant_p() check
>

so basically 1) is refactoring only and 2) is the actual
change keept at a minimum or what is the intent of this split ?

will cleanup and resubmit - just waiting for some feedback on
the Kbuild change.

thx!
hofrat 
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