Messages in this thread |  | | | Subject | Re: [RFC][PATCH] Faster generic_fls | | From | Falk Hueffner <> | | 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.
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