[FFmpeg-devel] [PATCHv2 1/1] checkasm/lpc: test compute_autocorr

[Rémi Denis-Courmont]

Le sunnuntaina 17. joulukuuta 2023, 18.09.45 EET James Almer a écrit :
> On 12/17/2023 6:13 AM, Rémi Denis-Courmont wrote:
> > ---
> > 
> >   tests/checkasm/lpc.c | 47 ++++++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 45 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tests/checkasm/lpc.c b/tests/checkasm/lpc.c
> > index 592e34c03d..9b33f8a3b0 100644
> > --- a/tests/checkasm/lpc.c
> > +++ b/tests/checkasm/lpc.c
> > @@ -57,10 +57,46 @@ static void test_window(int len)
> > 
> >       bench_new(src, len, dst1);
> >   
> >   }
> > 
> > +static void test_compute_autocorr(ptrdiff_t len, int lag)
> > +{
> > +    LOCAL_ALIGNED(32, double, src, [5000 + 2 + MAX_LPC_ORDER]);
> > +    LOCAL_ALIGNED(16, double, dst0, [MAX_LPC_ORDER + 1]);
> > +    LOCAL_ALIGNED(16, double, dst1, [MAX_LPC_ORDER + 1]);
> > +
> > +    declare_func(void, const double *in, ptrdiff_t len, int lag, double
> > *out); +
> > +    av_assert0(lag >= 0 && lag <= MAX_LPC_ORDER);
> > +
> > +    for (int i = 0; i < MAX_LPC_ORDER; i++)
> > +        src[i] = 0.;
> > +
> > +    src += MAX_LPC_ORDER;
> > +
> > +    for (ptrdiff_t i = 0; i < len; i++) {
> > +        src[i] = (double)rnd() / (double)UINT_MAX;
> > +    }
> > +
> > +    call_ref(src, len, lag, dst0);
> > +    call_new(src, len, lag, dst1);
> > +
> > +    for (size_t i = 0; i < lag; i++) {
> > +        if (!double_near_abs_eps(dst0[i], dst1[i], EPS)) {
> 
> checkasm: using random seed 2504816888
> SSE2:
>   - lpc.apply_welch_window_even [OK]
>   - lpc.apply_welch_window_odd  [OK]
> 0:  770.224646270451 -  770.382378714191 = -0.15773244374
>     autocorr_10_sse2 (lpc.c:86)
>   - lpc.compute_autocorr_10     [FAILED]
> 0:  807.574416481743 -  807.732148925482 = -0.157732443739
>     autocorr_30_sse2 (lpc.c:86)
>   - lpc.compute_autocorr_30     [FAILED]
> 0:  787.329053288888 -  787.486785732628 = -0.15773244374
>     autocorr_32_sse2 (lpc.c:86)
>   - lpc.compute_autocorr_32     [FAILED]
> 
> checkasm: using random seed 827008587
> SSE2:
>   - lpc.apply_welch_window_even [OK]
>   - lpc.apply_welch_window_odd  [OK]
>   - lpc.compute_autocorr_10     [OK]
>   - lpc.compute_autocorr_30     [OK]
>   - lpc.compute_autocorr_32     [OK]
> 
> Some seeds work, others don't. So i guess EPS is too small

Rounding errors would not cause a constant gap across the different test cases. 
This is most likely an off-by-one in the x86 code. I don't know if this is a 
bug in the x86 code, or the test case being a little loose with input 
parameters, and I have neither time, nor motivation not to mention skills to 
figure that out, so there will be no test cases for this function form me 
afterall.

The RV loop has no such issue - always matches the C reference AFAICT.

-- 
Rémi Denis-Courmont
http://www.remlab.net/