From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions Date: Wed, 1 May 2013 09:35:35 +0200 Message-ID: References: <1367214005-14302-1-git-send-email-chanho.min@lge.com> <20130430144605.1a99a7397702b332ee818fc8@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20130430144605.1a99a7397702b332ee818fc8@linux-foundation.org> Sender: sparclinux-owner@vger.kernel.org To: Andrew Morton Cc: Chanho Min , Kyungsik Lee , Yann Collet , Bob Pearson , Richard Weinberger , "linux-kernel@vger.kernel.org" , sparclinux , Linux/m68k , Linux-Next List-Id: linux-next.vger.kernel.org On Tue, Apr 30, 2013 at 11:46 PM, Andrew Morton wrote: > On Mon, 29 Apr 2013 09:20:25 +0200 Geert Uytterhoeven wrote: >> On Mon, Apr 29, 2013 at 7:40 AM, Chanho Min 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 >> > Signed-off-by: Chanho Min >> >> Thanks, this fixes the link error on m68k, so >> >> Acked-by: Geert Uytterhoeven > > 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. 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 ;-) > 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. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds