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Re: The state of glibc libm

From: Jeff Law <law at redhat dot com>
To: "Joseph S. Myers" <joseph at codesourcery dot com>
Cc: libc-alpha at sourceware dot org, gcc at gcc dot gnu dot org, Geert Bosch <bosch at adacore dot com>, Christoph Lauter <christoph dot lauter at lip6 dot fr>
Date: Wed, 14 Mar 2012 10:41:27 -0600
Subject: Re: The state of glibc libm
References: <Pine.LNX.4.64.1202291655580.7156@digraph.polyomino.org.uk> <20120314143045.GG3804@xvii.vinc17.org> <4F60B64D.1020606@redhat.com> <Pine.LNX.4.64.1203141627170.22094@digraph.polyomino.org.uk>

On 03/14/2012 10:30 AM, Joseph S. Myers wrote:


I'd say that "better performance with the potential loss of accuracy"
should be covered by -ffast-math - that GCC should generate direct use of
fsin/fcos instructions for sin/cos for -O2 -funsafe-math-optimizations on
x86_64, as it does on x86, unless there is some reason to think they would
perform worse than the out-of-line implementation.

The better performance with potential loss of accuracy is an across the board request, it's not just a sin/cos issue. All the trig, exp, pow, log, etc, which I don't think are necessarily covered by using the old x87 fp unit.

Jeff

Follow-Ups:
- Re: The state of glibc libm
  - From: Andi Kleen
- Re: The state of glibc libm
  - From: David Miller

References:
- Re: The state of glibc libm
  - From: Vincent Lefevre
- Re: The state of glibc libm
  - From: Jeff Law
- Re: The state of glibc libm
  - From: Joseph S. Myers

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