[Mesa-dev] [PATCH 2/2] i965/fs: Fix type of header register for sampler messages

Eric Anholt eric at anholt.net
Tue Oct 15 01:16:21 CEST 2013


Kenneth Graunke <kenneth at whitecape.org> writes:

> On 10/14/2013 10:44 AM, Eric Anholt wrote:
>> Chris Forbes <chrisf at ijw.co.nz> writes:
>> 
>>> Previously this was float, which caused the copy from g0 to mangle
>>> everything.
>> 
>> If we face a choice of types for a raw mov, we should choose float --
>> it's higher performance on IVB (they can get dispatched twice as fast,
>> when there's a hyperthread waiting to dispatch a float op)
>> 
>> Patch 1/2 is
>> 
>> Reviewed-by: Eric Anholt <eric at anholt.net>
>
> Using float for raw MOVs is unsafe for things exposed by
> ARB_fragment_program, ARB_vertex_program, or fixed-function vertex
> processing.  We still use ALT mode there so we get proper 0^0=1 handling
> for POW.
>
> We should really use IEEE everywhere and emit special code for POW in
> ARB_vp/fp.  But that's above and beyond fixing a regression.

Oh, right!  Thanks for the reminder.
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