Clang as default compiler November 4th
Steve Kargl
sgk at troutmask.apl.washington.edu
Tue Sep 11 18:13:21 UTC 2012
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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