Date: Thu, 29 Apr 2010 08:45:41 +0300 From: Andriy Gapon <avg@freebsd.org> To: Jung-uk Kim <jkim@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Roman Divacky <rdivacky@freebsd.org> Subject: Re: svn commit: r207330 - head/sys/dev/sound/pcm Message-ID: <4BD91D05.3090806@freebsd.org> In-Reply-To: <201004281726.o3SHQ6xN095645@svn.freebsd.org> References: <201004281726.o3SHQ6xN095645@svn.freebsd.org>
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on 28/04/2010 20:26 Jung-uk Kim said the following: > Author: jkim > Date: Wed Apr 28 17:26:05 2010 > New Revision: 207330 > URL: http://svn.freebsd.org/changeset/base/207330 > > Log: > Remove dead code. Calculated greatest common divisor was not used at all. > On top of that, LLVM+Clang mis-compiles this code because of its register > allocator bug. > > Analyzed by: Andrew Reilly (areilly at bigpond dot net dot au) > Reviewed by: ariff, rdivacky > MFC after: 3 days I think that we also owe an attribution to Alexander Best <alexbestms@wwu.de>, who discovered the problem, reported it and did an immense job of narrowing it down to a single function. > Modified: > head/sys/dev/sound/pcm/buffer.c > > Modified: head/sys/dev/sound/pcm/buffer.c > ============================================================================== > --- head/sys/dev/sound/pcm/buffer.c Wed Apr 28 15:38:01 2010 (r207329) > +++ head/sys/dev/sound/pcm/buffer.c Wed Apr 28 17:26:05 2010 (r207330) > @@ -568,7 +568,6 @@ sndbuf_updateprevtotal(struct snd_dbuf * > unsigned int > snd_xbytes(unsigned int v, unsigned int from, unsigned int to) > { > - unsigned int w, x, y; > > if (from == to) > return v; > @@ -576,16 +575,6 @@ snd_xbytes(unsigned int v, unsigned int > if (from == 0 || to == 0 || v == 0) > return 0; > > - x = from; > - y = to; > - while (y != 0) { > - w = x % y; > - x = y; > - y = w; > - } > - from /= x; > - to /= x; > - > return (unsigned int)(((u_int64_t)v * to) / from); > } > -- Andriy Gapon
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