linux-kernel - Re: [tip:perf/core] bitops: Provide compile time HWEIGHT{8,16,32,64}

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Date:	Fri, 29 Jan 2010 14:50:46 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>, mingo@...hat.com,
	eranian@...gle.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, tglx@...utronix.de, mingo@...e.hu,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] bitops: Provide compile time HWEIGHT{8,16,32,64}

On 01/29/2010 03:03 AM, Peter Zijlstra wrote:
> 
> *sigh* and here I though it being placed right next to hweight_long()
> which uses the arch hweightN() would be clue enough.
> 
> If people are so clueless, who says they'll read a comment.. but sure I
> guess I can add one.
> 

I would personally say that the Right Way[TM] to do this is to call
these __constant_hweightX() -- so the name reflects the function -- and
then have

#define hweight(x) (__builtin_constant_p(x) ? __constant_hweight(x) :
__arch_hweight(x))

[example does not reflect actual naming]

	-hpa
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