[Mesa-dev] Allowing the reading of outputs for some drivers

[Henri Verbeet]

On 15 November 2011 14:52, Jose Fonseca <jfonseca at vmware.com> wrote:
> Developer time is important too. And having more code paths shared with other drivers (even at the expense of a few extra CPU cycles every time a shader is created) means that developers has more time to focus on features that can yield substantial improvements on true hotspots (e.g., every time a pixel is rendered).
>
> This particular case may not be the best example. But there is a trade off: more specialization means more maintenance burden.
>
I certainly agree with the general principle, though I think that you
should take the driver specific IR into account in that consideration.
I.e., I'm not sure that in terms of divergence of the generated code
you really gain a lot with undoing elimination of output reads in the
driver IR compared to not eliminating them in the first place for some
drivers.

On the other hand, I think it's certainly conceivable that if r600g
had a proper hardware specific optimizer it would end up eliminating
the code in question anyway as a side effect.