From: "Joseph S. Myers" <joseph@codesourcery.com>
To: rth@twiddle.net
Cc: libc-ports@sourceware.org
Subject: fma ulps
Date: Wed, 30 May 2012 23:51:00 -0000 [thread overview]
Message-ID: <Pine.LNX.4.64.1205302347520.8161@digraph.polyomino.org.uk> (raw)
In-Reply-To: <20120530233749.16824.qmail@sourceware.org>
On Wed, 30 May 2012, rth@sourceware.org wrote:
> +# fma
> +Test "fma (-0x1.19cab66d73e17p-959, 0x1.c7108a8c5ff51p-107, -0x0.80b0ad65d9b64p-1022) == -0x0.80b0ad65d9d59p-1022":
> +double: 1
> +idouble: 1
> +Test "fma (0x1.0000002p+0, 0x1.ffffffcp-1, -0x1p-300) == 0x1.fffffffffffffp-1":
> +double: 1
> +idouble: 1
> +Test "fma (0x1.153d650bb9f06p-907, 0x1.2d01230d48407p-125, -0x0.b278d5acfc3cp-1022) == -0x0.b22757123bbe9p-1022":
> +double: 1
> +idouble: 1
> +Test "fma (0x1.4000004p-967, 0x1p-106, 0x0.000001p-1022) == 0x0.0000010000003p-1022":
> +double: 1
> +idouble: 1
fma isn't meant to have ulps. You previously mentioned that special
options are needed to get "inexact" exceptions on alpha, and the fma code
relies on testing those exceptions to get correct results, so maybe you
need to make appropriate arrangements for it (for all floating-point
types) to be compiled with the right options to get such exceptions?
(I cut out fma ulps from my ARM results, pending testing on hardware to
see if they were a QEMU bug or something needing further investigation.)
--
Joseph S. Myers
joseph@codesourcery.com
next parent reply other threads:[~2012-05-30 23:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120530233749.16824.qmail@sourceware.org>
2012-05-30 23:51 ` Joseph S. Myers [this message]
2012-05-31 0:25 ` Chris Metcalf
2012-05-31 0:30 ` Joseph S. Myers
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