Re: [PATCH] speed up on find_first_bit for i386 (let compiler dothe work)

From: Maciej W. Rozycki
Date: Fri Jul 29 2005 - 10:12:39 EST

On Thu, 28 Jul 2005, Linus Torvalds wrote:

> > Since you're considering GCC-generated code for ffs(), ffz() and friends,
> > how about trying __builtin_ffs(), __builtin_clz() and __builtin_ctz() as
> > apropriate?
> Please don't. Try again in three years when everybody has them.

Well, __builtin_ffs() has been there since at least gcc 2.95. The two
others are quite recent, indeed -- apparently only since GCC 3.4. They
may still be considered to be used conditionally if there is justified

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at