[libclc] r186691 - Implement generic upsample()

[Tobias Grosser]

On 07/19/2013 09:44 AM, Aaron Watry wrote:
> Author: awatry
> Date: Fri Jul 19 11:44:37 2013
> New Revision: 186691
>
> URL: http://llvm.org/viewvc/llvm-project?rev=186691&view=rev
> Log:
> Implement generic upsample()
>
> Reduces all vector upsamples down to its scalar components, so probably
> not the most efficient thing in the world, but it does what the
> spec says it needs to do.
>
> Another possible implementation would be to convert/cast everything as
> unsigned if necessary, upsample the input vectors, create the upsampled
> value, and then cast back to signed if required.

I believe performing scalarization is a reasonable approach. 
Unfortunately, LLVM is not yet able to optimize this
(see http://llvm.org/PR6246), though such an optimization seems to be
very valueable.

Cheers.
Tobo