Date: Fri, 2 Jul 2010 18:16:38 -0400 From: David Schultz <das@FreeBSD.ORG> To: Marcel Moolenaar <xcllnt@mac.com> Cc: svn-src-head@FreeBSD.ORG, svn-src-all@FreeBSD.ORG, Marcel Moolenaar <marcel@FreeBSD.ORG>, src-committers@FreeBSD.ORG, Bruce Evans <brde@optusnet.com.au> Subject: Re: svn commit: r209604 - head/lib/libc/gmon Message-ID: <20100702221638.GA31280@zim.MIT.EDU> In-Reply-To: <79DD181D-3885-45F5-9E9D-753553D19891@mac.com> References: <201006300140.o5U1eQVG097566@svn.freebsd.org> <20100630184517.B51465@delplex.bde.org> <79DD181D-3885-45F5-9E9D-753553D19891@mac.com>
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On Wed, Jun 30, 2010, Marcel Moolenaar wrote: > >> s_scale = ((float)p->kcountsize / o ) * SCALE_1_TO_1; > > > > I can't see any bugs in this expression. p->kcountsize is < o, and the > > scale factor is only 65536, so there should be no problems with overflow. > > This leaves GCC a the problem. What does the generated assembly look like, and what are the inputs that screw up? PowerPC doesn't have an instruction to convert integer types to floats, so that's done in software. The hardest/most esoteric is the conversion from a 64-bit int to a float (as above with kcountsize), so it wouldn't be surprising if that's buggy.
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