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To: dphillips@sistina.com
Cc: Linus Torvalds <torvalds@transmeta.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] Faster generic_fls
References: <200304300446.24330.dphillips@sistina.com>
	<87isswxmn0.fsf@student.uni-tuebingen.de>
	<200304301503.38650.dphillips@sistina.com>
From: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
Date: 30 Apr 2003 15:17:13 +0200
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Daniel Phillips <dphillips@sistina.com> writes:

> It's somewhat annoying that __builtin_clz leaves the all-ones case
> dangling instead of returning -1.

I assume you mean all-zero... Well, the semantics of the corresponding
instructions simply differ too much. clz(0) is 31 on some, 32 on some
others, and undefined on some more architectures. So nailing it down
would incur some performance penalty.

-- 
	Falk