[Pixman] [PATCH v13 09/14] pixman-filter: Nested polynomial for cubic

Bill Spitzak spitzak at gmail.com
Sat Mar 5 02:41:12 UTC 2016

On Fri, Mar 4, 2016 at 3:05 PM, Søren Sandmann <soren.sandmann at gmail.com>

> On Wed, Feb 10, 2016 at 1:25 AM, <spitzak at gmail.com> wrote:
>> From: Bill Spitzak <spitzak at gmail.com>
>> v11: Restored range checks
>> Signed-off-by: Bill Spitzak <spitzak at gmail.com>
>> Reviewed-by: Oded Gabbay <oded.gabbay at gmail.com>
> What's the point of this? All this does is putting ax^2 outside of the
> parenthesis?

Nested form reduces the number of multiplications (from 23 to 18 in this
case), without changing how many additions are done. And compilers can take
advantage of ax+b instructions with this (I did not check if that actually
happened, however).
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