Messages in this thread | | | Subject | Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions | From | "민찬호" <> | Date | Thu, 2 May 2013 09:58:02 +0900 |
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>No, the link errors are for __ctzdi2, not __clzdi2. >__ctzdi2 can be implemented using __ffs(). >> How's about we stop using __builtin_ctz[ll]() altogether? Use N-fls()? > >That was my first suggestion ;-) > Do we remove existing __builtin_ct[l]z? Some architecture's __builtin_clz will be more optimized than N-fls IMHO, This is not only about __builtin- but also supporting another libgcc functions in kernel. Some future user may need __clz[t]s[d]i2 symbol also.
>> btw, this: >> >> int __weak __clzsi2(int val) >> { >> return BITS_PER_LONG - fls(val); >> } >> >> looks wrong. It will give a different result for 32- and 64-bit. > >Indeed. It should be hardcoded 32. > I will re-work this for 64-bit, and ctz also.
Thanks Chanho Min
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