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Re: [PATCH] Update x86_64 ULPs
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: OndÅej BÃlka <neleai at seznam dot cz>, Andreas Jaeger <aj at suse dot com>, Markus Trippelsdorf <markus at trippelsdorf dot de>, libc-alpha at sourceware dot org
- Date: Thu, 02 May 2013 14:55:20 -0400
- Subject: Re: [PATCH] Update x86_64 ULPs
- References: <20130426055835 dot GA644 at x4> <517A2CF9 dot 20504 at suse dot com> <20130502160937 dot GA8564 at domone dot kolej dot mff dot cuni dot cz> <Pine dot LNX dot 4 dot 64 dot 1305021847100 dot 12072 at digraph dot polyomino dot org dot uk>
On 05/02/2013 02:49 PM, Joseph S. Myers wrote:
> On Thu, 2 May 2013, Ondrej Bilka wrote:
>
>> Could we compute ulp directly with mpfr or I am missing some roadblock?
>
> The whole point of ulps baselines is to record the errors produced by the
> actual glibc implementation, compared to an exact expected result (which
> quite likely was computed with MPFR). Those baselines can, on x86 and
> x86_64, depend on the processor implementation of the x87 instructions for
> transcendental operations (so on whether an Intel or AMD processor is in
> use, for example), as well as, on 32-bit x86, on the details of where the
> compiler uses excess precision.
>
> I've been thinking lately about how to better automate computation of the
> *expected results* with MPFR and MPC, but that won't remove the need for
> ulps values for the glibc implementations used on different platforms.
+1
Automating expected result computation would be great.
Cheers,
Carlos.