[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [Qemu-ppc] [PATCH v1] target/ppc: rewrite f[n]m[add, su
|
From: |
Nikunj A Dadhania |
|
Subject: |
Re: [Qemu-devel] [Qemu-ppc] [PATCH v1] target/ppc: rewrite f[n]m[add, sub] using float64_muladd |
|
Date: |
Thu, 02 Mar 2017 10:33:05 +0530 |
|
User-agent: |
Notmuch/0.21 (https://notmuchmail.org) Emacs/25.0.94.1 (x86_64-redhat-linux-gnu) |
Oh, some gmail issues, resending:
> On 02-Mar-2017 7:53 AM, "Richard Henderson" <address@hidden> wrote:
>
> On 03/02/2017 11:29 AM, David Gibson wrote:
>
>> On Wed, Mar 01, 2017 at 08:54:14PM +0530, Nikunj A Dadhania wrote:
>>
>>> Use the softfloat api for fused multiply-add. Also, generate VXISI using
>>> a helper function by computing intermediate result.
>>>
>>
>> Um.. I really need some information on why this is a good thing to
>> do. Is it a bugfix? Enhancement? Simplification?
>>
>
> Looks like a bugfix to me. Previously we were attempting the operation via
> float128 as an intermediate type, which can result in double rounding
> errors.
>
Was discussed here
https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg02000.html
Nikunj