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Re: [PATCH][BZ #14412] Define __sincos_finite as a fast version of sincos
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: Siddhesh Poyarekar <siddhesh at redhat dot com>, libc-alpha at sourceware dot org, libc-ports at sourceware dot org
- Date: Mon, 29 Apr 2013 16:15:53 +0200
- Subject: Re: [PATCH][BZ #14412] Define __sincos_finite as a fast version of sincos
- References: <20130429102739 dot GE1330 at spoyarek dot pnq dot redhat dot com> <Pine dot LNX dot 4 dot 64 dot 1304291332320 dot 10827 at digraph dot polyomino dot org dot uk>
On Mon, Apr 29, 2013 at 01:34:42PM +0000, Joseph S. Myers wrote:
> On Mon, 29 Apr 2013, Siddhesh Poyarekar wrote:
>
> > This patch brings back the assembly implementation of sincos (with
> > some changes) to give a fast alternative to the default sincos
> > implementation. This is defined as __sincos_finite and is used if the
> > implementing program is compiled with the -ffinite-math-only gcc flag.
>
> The changes don't seem to include accurate range reduction. Without that,
> I think this is inappropriate, as it will result in wildly inaccurate
> results for large but finite inputs.
>
These inputs contain zero significant digits. You cannot expect any
accuracty from them.
> (I've stated before that all libm tests with finite inputs and outputs
> should be run with -ffinite-math-only - and I consider that they should
> pass when they pass without that option, and should not need different
> ulps for the different ways of running them.)
>
> --
> Joseph S. Myers
> joseph@codesourcery.com