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Re: [Qemu-ppc] [Qemu-devel] [V4 PATCH 12/14] target-ppc: VSX Stage 4: Ad

From: Richard Henderson
Subject: Re: [Qemu-ppc] [Qemu-devel] [V4 PATCH 12/14] target-ppc: VSX Stage 4: Add Scalar SP Fused Multiply-Adds
Date: Fri, 06 Dec 2013 10:15:54 +1300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0

On 12/06/2013 04:45 AM, Tom Musta wrote:
> This patch adds the Single Precision VSX Scalar Fused Multiply-Add
> instructions: xsmaddasp, xsmaddmsp, xssubasp, xssubmsp, xsnmaddasp,
> xsnmaddmsp, xsnmsubasp, xsnmsubmsp.
> The existing VSX_MADD() macro is modified to support rounding of the
> intermediate double precision result to single precision.
> V2: Re-implemented per feedback from Richard Henderson.  In order to
> avoid double rounding and incorrect results, the operands must be
> converted to true single precision values and use the single precision
> fused multiply/add routine.
> V3: Re-implemented per feedback from Richard Henderson (I did not
> fully understand his comment when I implemented V2).
> V4: Changed to use helper_frsp (inadvertently re-injected when I used an
> earlier patch).  Thanks to Richard Henderson for catching this.
> Signed-off-by: Tom Musta <address@hidden>
> ---
>  target-ppc/fpu_helper.c |   82 ++++++++++++++++++++++++++++++----------------
>  target-ppc/helper.h     |    8 ++++
>  target-ppc/translate.c  |   16 +++++++++
>  3 files changed, 77 insertions(+), 29 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>


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