From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: Joseph Myers <joseph@codesourcery.com>
Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>,
Paul E Murphy <murphyp@linux.ibm.com>,
libc-alpha@sourceware.org
Subject: Re: faster expf128
Date: Fri, 26 Jun 2020 11:09:16 +0100 [thread overview]
Message-ID: <20200626100915.GN16726@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2006241736480.28946@digraph.polyomino.org.uk>
The 06/24/2020 17:39, Joseph Myers wrote:
> On Wed, 24 Jun 2020, Paul Zimmermann wrote:
>
> > I forgot to say my code is intended mainly for machines that do not provide
> > hardware float128 support. However I did compare with the glibc
> > expf128 on gcc135.fsffrance.org (ppc64le GNU/Linux) and below are the
> > results. You can reproduce them with the code from [1]. We see that
> > my implementation is about 27% faster, but slightly less accurate
> > (999585 instead of 999999 correct rounding over 1000000). One caveat
> > though: I did not find how to efficiently set the inexact flag, thus
> > it is not set in my code.
>
> There is no expectation that most libm functions (other than those such as
> fma and sqrt that are fully defined by the corresponding IEEE operations)
> set inexact correctly. (It is necessary to set other exceptions
> correctly, and the glibc testsuite verifies that; for expf128, that's
> invalid (for signaling NaNs), overflow and underflow.)
and presumably target specific exceptions are not considered.
(e.g. input denormal on x86)
next prev parent reply other threads:[~2020-06-26 10:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 11:02 Paul Zimmermann
2020-06-22 13:59 ` Paul E Murphy
2020-06-22 21:18 ` Joseph Myers
2020-06-24 6:22 ` Paul Zimmermann
2020-06-24 17:39 ` Joseph Myers
2020-06-26 10:09 ` Szabolcs Nagy [this message]
2020-06-29 22:39 ` Joseph Myers
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