[Mesa-dev] [PATCH 1/2] i965: Emit MOVs for neg/abs.

[Matt Turner]

On Thu, Aug 15, 2013 at 7:38 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 08/12/2013 01:18 PM, Matt Turner wrote:
>>
>> Necessary to avoid combining a bitcast and a modifier into a single
>> operation. Otherwise if safe, the MOV should be removed by
>> copy-propagation or register coalescing.
>
>
> Has that been verified with shaderdb?

Yes, there are only four changes -- four shaders in the Cave that do
something like mov a.w, -b.x which we now generate an extra
instruction for, because copy-propagation bails out for non-XYZW
swizzles. Seems acceptable, given the limitation of copy prop.