Messages in this thread | | | Date | Tue, 30 Apr 2013 14:46:05 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions |
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On Mon, 29 Apr 2013 09:20:25 +0200 Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Mon, Apr 29, 2013 at 7:40 AM, Chanho Min <chanho.min@lge.com> wrote: > > Some architectures need __clzsi2() or __clzdi2() for __builtin_clz and > > It causes build failure. They can be implemented using the fls() and > > overridden by linking arch-specific versions may not be implemented yet. > > > > Reference: https://lkml.org/lkml/2013/4/18/603 > > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> > > Signed-off-by: Chanho Min <chanho.min@lge.com> > > Thanks, this fixes the link error on m68k, so > > Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
It doesn't work for alpha (gcc-4.4.4):
ERROR: "__ctzdi2" [lib/lz4/lz4hc_compress.ko] undefined! ERROR: "__ctzdi2" [lib/lz4/lz4_compress.ko] undefined!
akpm3:/usr/src/25> nm vmlinux|grep ctzd akpm3:/usr/src/25>
I assume the linker threw the code away.
How's about we stop using __builtin_ctz[ll]() altogether? Use N-fls()?
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.
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