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Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching

From: Paolo Bonzini <bonzini at gnu dot org>
To: "Stubbs, Andrew" <Andrew_Stubbs at mentor dot com>
Cc: Michael Matz <matz at suse dot de>, Richard Guenther <richard dot guenther at gmail dot com>, gcc-patches at gcc dot gnu dot org, patches at linaro dot org
Date: Fri, 01 Jul 2011 17:54:38 +0200
Subject: Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
References: <4E034EF2.3070503@codesourcery.com> <4E03504B.9060305@codesourcery.com> <BANLkTi=a8B-DZZdG2bmOWQ8A+-pCSEsAbQ@mail.gmail.com> <4E044559.5000105@linaro.org> <BANLkTimfKyrARS+eRy+MWYVO2gLqp85JsQ@mail.gmail.com> <1A77B5B39081C241A68E6CF16983025F020906F6@EU1-MAIL.mgc.mentorg.com> <BANLkTi=1TRM7uHWxLD3Se=S-ibe0C13T-Q@mail.gmail.com> <4E09B142.4020402@codesourcery.com> <BANLkTim0wLcSTgAL9isO+dVXxgq-U8B4Sw@mail.gmail.com> <Pine.LNX.4.64.1106281741170.17115@wotan.suse.de> <4E09FDEA.3000004@gmail.com> <Pine.LNX.4.64.1106281827230.17115@wotan.suse.de> <1A77B5B39081C241A68E6CF16983025F0209071D@EU1-MAIL.mgc.mentorg.com> <4E0DBE96.4000809@gnu.org> <1A77B5B39081C241A68E6CF16983025F0209072A@EU1-MAIL.mgc.mentorg.com> <4E0DDC65.70701@gnu.org> <1A77B5B39081C241A68E6CF16983025F0209072B@EU1-MAIL.mgc.mentorg.com>

On 07/01/2011 04:55 PM, Stubbs, Andrew wrote:

>
>  What about (u128)c + (u64)((s8)a * (s8)b)? You cannot convert this to
>  (u128)c + (u128)((s8)a * (s8)b).

Oh I see, sorry. Yes, that's exactly what I'm trying to do here.

No, wait, I don't see. Where are these multiple widening multiplies
you're talking about? I only see one multiply?

I meant one multiplication with multiple widening steps. Not clear at all, sorry.

Paolo

Follow-Ups:
- Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
  - From: Stubbs, Andrew

References:
- Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
  - From: Stubbs, Andrew
- Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
  - From: Paolo Bonzini
- Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
  - From: Stubbs, Andrew
- Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
  - From: Paolo Bonzini
- Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
  - From: Stubbs, Andrew

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