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Sender: Richard Henderson <rth7680@gmail.com>
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Date: Tue, 31 Dec 2013 07:17:41 -0800
From: Richard Henderson <rth@twiddle.net>
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Subject: Re: [Qemu-devel] [PATCH 17/22] target-arm: Ignore most exceptions
 from scalbn when doing fixpoint conversion
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To: Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org
Cc: Tom Musta <tommusta@gmail.com>, Peter Crosthwaite <peter.crosthwaite@xilinx.com>, patches@linaro.org, Aurelien Jarno <aurelien@aurel32.net>, Michael Matz <matz@suse.de>, Alexander Graf <agraf@suse.de>, Claudio Fontana <claudio.fontana@linaro.org>, Dirk Mueller <dmueller@suse.de>, Will Newton <will.newton@linaro.org>, Laurent Desnogues <laurent.desnogues@gmail.com>, =?ISO-8859-1?Q?Alex_Benn=E9e?= <alex.bennee@linaro.org>, kvmarm@lists.cs.columbia.edu, Christoffer Dall <christoffer.dall@linaro.org>

On 12/31/2013 05:35 AM, Peter Maydell wrote:
> The VFP fixed point conversion helpers first call float_scalbn and
> then convert the result to an integer. This scalbn operation may
> set floating point exception flags for:
>  * overflow & inexact (if it overflows to infinity)
>  * input denormal squashed to zero
>  * output denormal squashed to zero
> Of these, we only care about the input-denormal flag, since
> the output of the whole scale-and-convert operation will be
> an integer (so squashed-output-denormal and overflow don't
> apply). Suppress the others by saving the pre-scalb exception
> flags and only copying across a potential input-denormal flag.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target-arm/helper.c | 9 +++++++++
>  1 file changed, 9 insertions(+)

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~