Date: Tue, 11 Sep 2012 11:13:17 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Roman Divacky <rdivacky@freebsd.org> Cc: toolchain@freebsd.org, Tijl Coosemans <tijl@coosemans.org>, Dimitry Andric <dim@freebsd.org>, current@freebsd.org Subject: Re: Clang as default compiler November 4th Message-ID: <20120911181317.GB96512@troutmask.apl.washington.edu> In-Reply-To: <20120911171948.GA81334@freebsd.org> References: <20120910211207.GC64920@lor.one-eyed-alien.net> <20120911104518.GF37286@deviant.kiev.zoral.com.ua> <20120911120649.GA52235@freebsd.org> <20120911132410.GA87126@troutmask.apl.washington.edu> <504F4645.4070900@FreeBSD.org> <504F4A6B.4010001@coosemans.org> <20120911151230.GB87526@troutmask.apl.washington.edu> <20120911171948.GA81334@freebsd.org>
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On Tue, Sep 11, 2012 at 07:19:48PM +0200, Roman Divacky wrote: > On Tue, Sep 11, 2012 at 08:12:30AM -0700, Steve Kargl wrote: > > > > I'm not sure if anyone has done any extensive testing. > > I've started to run some of my test codes to compare > > certain functions in a clang-compiled libm, gcc-compiled > > libm, and reference solutions generated from math/mpfr. > > For a locally patched j0f, I found that clang gave > > much worse accuracy. If I revert the local patch, > > clang and gcc are to give the same results. Unfortnately, > > an unpatched j0f gives 500000 ULP errors. > > Steve, > > Can you please provide a small self contained test case that shows > that clang is doing worse on accuracy than gcc? > > So that we can analyze it and decide if it's a bug in the code or > in the compiler. So far we know absolutely nothing. > > Thank you, Roman Unfortunately, supplying a test is going to be problematic. I thought I had a diff in one of my development trees, so I reverted the working copy of msun/e_j0f.c to stock source. gcc and clang give consistent results with stock e_j0f.c. When I went to re-apply my local changes, I discovered that I no longer had a diff. I think I can recreate the problematic code, but it will need to wait until the weekend. -- Steve
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