[Mesa-dev] Mesa IR as a list of instructions

[Kenneth Graunke]

On Wednesday, May 28, 2014 11:37:31 AM Eric Anholt wrote:
> Here's a series I started back in January as a little experiment.
> Basically, I feel guilty for pushing GLSL IR into the driver, and wish I'd
> just fixed up Mesa IR back in the day.  But, given that we're still
> feeding Mesa IR into drivers as well (ARB programs and fixed function
> vertex programs), it made me think: What if I fixed it up now, and got
> Mesa IR to the point that we could just garbage collect the GLSL IR input
> paths to drivers?
> 
> Mesa IR has a bunch of weaknesses that need to get sorted out if it's
> going to be useful:
> 
> - It's a single giant array of instructions, making modifications of the
>   instruction stream (instruction lowering, optimization, etc.) more
>   expensive in code and CPU time than it should be.
> - It doesn't have any variable declarations, so if you have dynamic array
>   indexing, optimization just shuts down (plus, no annotation on the
>   temps, so debugging is irritating).
> - It doesn't have integer instructions or anything else post-GLSL-1.30.
> - The optimization passes for it are totally ad-hoc and fairly weak.
> - It's not SSA.
> 
> I'm interested in fixing all of these.  How do people feel about this
> goal?
> 
> This series fixes the first bullet point above.  Patch 15 is huge, but I
> didn't see a way to chop it up smaller without maintaining the list
> alongside the array for some intermediate patches.  I'd be willing to do
> so if needed, though, to make review doable.  You can also find the
> changes in the "mesa-ir" branch of my git tree.


Patches 1-14 seem like nice cleanups, and get:

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

I agree in principle with the change to use linked lists, but I haven't looked 
at your code (and probably won't unless you really want me to).  I'm not a 
huge fan of simple_list, but you don't really have a better option currently, 
so I'm not really objecting.
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