[Mesa-dev] [PATCH 5/5] i965/fs: Apply gl_FrontFacing ? -1 : 1 optimization only for floats

[Ian Romanick]

On 03/11/2015 04:10 PM, Matt Turner wrote:
> On Wed, Mar 11, 2015 at 1:44 PM, Ian Romanick <idr at freedesktop.org> wrote:
>> From: Ian Romanick <ian.d.romanick at intel.com>
>>
>> At the very least, unreal4/sun-temple/102.shader_test uses this pattern
>> for a signed integer result.  However, that shader did not hit the
>> optimization in the first place because it uses !gl_FronFacing.  I
>> changed the shader to use remove the logical-not and reverse the other
>> operands.  I verified that incorrect code is generated before this
>> change and correct code is generated after.
> 
> At one point I did have a patch that handled !gl_FrontFacing ? ... but
> I think it got lost.

I have a patch (somewhere) that converts (!b ? x : y) to (b ? y : x).  I
think that would make explicit handling of !gl_FrontFacing unnecessary.
 I also have some plan to add support for values other than +/-1.0.  I
think other optimizations in my queue make other values occur.

> 4-5 are
> 
> Reviewed-by: Matt Turner <mattst88 at gmail.com>