[opus] [PATCH] Optimize silk_LPC_inverse_pred_gain() for ARM NEON

[Jean-Marc Valin]

On 13/02/17 01:09 PM, Linfeng Zhang wrote:
> For 1), I agree that an explicit unit test would be a good plus to cover
> the cases that "make check" cannot trigger. If you like, we may submit
> an unit test patch for code review.

Yes, please include a unit test that triggers the overflow detection.
Once that works, I think we can merge this optimization.

Cheers,

	Jean-Marc

> Thanks,
> Linfeng
> 
> On Thu, Feb 9, 2017 at 4:48 PM Jean-Marc Valin <jmvalin at jmvalin.ca
> <mailto:jmvalin at jmvalin.ca>> wrote:
> 
>     Hi Linfeng,
> 
>     Can you confirm that you the patch went through the same internal review
>     (presumably from James) than the previous ones?
> 
>     I had a look and did some testing and it looked good to me. There's only
>     two issues I'd like to resolve first -- none of which directly related
>     to your code.
> 
>     1) The overflow condition is essentially untested because none of the
>     tests in "make check" reliably triggers it. That may be a good case for
>     an explicit unit test. IIRC, the case could be triggered by the
>     following input vector:
>     A_QA[] = { 46596096, -72118272, 78532608, -69447680, 52707328,
>     -22073344, -19890176, 50507776, -54829056, 45518848, -33939456,
>     21086208, -7127040, -4136960, 3993600, -1699840 }
> 
>     2) I'm not quite sure what to make of silk_LPC_inverse_pred_gain_Q24().
>     It seems to never be called anywhere -- except from the MIPS code. Maybe
>     it should just stay as it is (not renamed to _c()) but I need to check.
>     Any thoughts?
> 
>     Cheers,
> 
>             Jean-Marc
> 
>     On 07/02/17 04:06 PM, Linfeng Zhang wrote:
>     > Hi,
>     >
>     > Attached is a patch with arm neon optimizations for
>     > silk_LPC_inverse_pred_gain(). Please review.
>     >
>     > Thanks,
>     > Linfeng
>     >
>     >
>     >
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