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Estimate the inner product accuracy to fix check-asm

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Estimate the rounding error so that we can have a useful margin of
error when checking the asm against the C code even when the float
operations get reordered due to -ffast-math.
This commit is contained in:
Jean-Marc Valin 2022-06-30 16:44:34 -04:00
parent e0ca05b1ec
commit 60c48ade0a
1 changed files with 21 additions and 30 deletions

51
celt/arm/pitch_neon_intr.c
View file

@ -137,22 +137,27 @@ void dual_inner_prod_neon(const opus_val16 *x, const opus_val16 *y01, const opus
/* celt_inner_prod_neon_float_c_simulation() simulates the floating-point */
/* operations of celt_inner_prod_neon(), and both functions should have bit */
/* exact output. */
static opus_val32 celt_inner_prod_neon_float_c_simulation(const opus_val16 *x, const opus_val16 *y, int N)
static opus_val32 celt_inner_prod_neon_float_c_simulation(const opus_val16 *x, const opus_val16 *y, float *err, int N)
{
int i;
*err = 0;
opus_val32 xy, xy0 = 0, xy1 = 0, xy2 = 0, xy3 = 0;
for (i = 0; i < N - 3; i += 4) {
xy0 = MAC16_16(xy0, x[i + 0], y[i + 0]);
xy1 = MAC16_16(xy1, x[i + 1], y[i + 1]);
xy2 = MAC16_16(xy2, x[i + 2], y[i + 2]);
xy3 = MAC16_16(xy3, x[i + 3], y[i + 3]);
*err += ABS32(xy0)+ABS32(xy1)+ABS32(xy2)+ABS32(xy3);
}
xy0 += xy2;
xy1 += xy3;
xy = xy0 + xy1;
*err += ABS32(xy1)+ABS32(xy0)+ABS32(xy);
for (; i < N; i++) {
xy = MAC16_16(xy, x[i], y[i]);
*err += ABS32(xy);
}
*err = *err*2e-7 + N*1e-37;
return xy;
}
@ -160,32 +165,10 @@ static opus_val32 celt_inner_prod_neon_float_c_simulation(const opus_val16 *x, c
/* operations of dual_inner_prod_neon(), and both functions should have bit */
/* exact output. */
static void dual_inner_prod_neon_float_c_simulation(const opus_val16 *x, const opus_val16 *y01, const opus_val16 *y02,
int N, opus_val32 *xy1, opus_val32 *xy2)
int N, opus_val32 *xy1, opus_val32 *xy2, float *err)
{
int i;
opus_val32 xy01, xy02, xy01_0 = 0, xy01_1 = 0, xy01_2 = 0, xy01_3 = 0, xy02_0 = 0, xy02_1 = 0, xy02_2 = 0, xy02_3 = 0;
for (i = 0; i < N - 3; i += 4) {
xy01_0 = MAC16_16(xy01_0, x[i + 0], y01[i + 0]);
xy01_1 = MAC16_16(xy01_1, x[i + 1], y01[i + 1]);
xy01_2 = MAC16_16(xy01_2, x[i + 2], y01[i + 2]);
xy01_3 = MAC16_16(xy01_3, x[i + 3], y01[i + 3]);
xy02_0 = MAC16_16(xy02_0, x[i + 0], y02[i + 0]);
xy02_1 = MAC16_16(xy02_1, x[i + 1], y02[i + 1]);
xy02_2 = MAC16_16(xy02_2, x[i + 2], y02[i + 2]);
xy02_3 = MAC16_16(xy02_3, x[i + 3], y02[i + 3]);
}
xy01_0 += xy01_2;
xy02_0 += xy02_2;
xy01_1 += xy01_3;
xy02_1 += xy02_3;
xy01 = xy01_0 + xy01_1;
xy02 = xy02_0 + xy02_1;
for (; i < N; i++) {
xy01 = MAC16_16(xy01, x[i], y01[i]);
xy02 = MAC16_16(xy02, x[i], y02[i]);
}
*xy1 = xy01;
*xy2 = xy02;
*xy1 = celt_inner_prod_neon_float_c_simulation(x, y01, &err[0], N);
*xy2 = celt_inner_prod_neon_float_c_simulation(x, y02, &err[1], N);
}
#endif /* OPUS_CHECK_ASM */
@ -225,7 +208,12 @@ opus_val32 celt_inner_prod_neon(const opus_val16 *x, const opus_val16 *y, int N)
}
#ifdef OPUS_CHECK_ASM
celt_assert(ABS32(celt_inner_prod_neon_float_c_simulation(x, y, N) - xy) <= VERY_SMALL);
{
float err, res;
res = celt_inner_prod_neon_float_c_simulation(x, y, &err, N);
/*if (ABS32(res - xy) > err) fprintf(stderr, "%g %g %g\n", res, xy, err);*/
celt_assert(ABS32(res - xy) <= err);
}
#endif
return xy;
@ -280,9 +268,12 @@ void dual_inner_prod_neon(const opus_val16 *x, const opus_val16 *y01, const opus
#ifdef OPUS_CHECK_ASM
{
opus_val32 xy1_c, xy2_c;
dual_inner_prod_neon_float_c_simulation(x, y01, y02, N, &xy1_c, &xy2_c);
celt_assert(ABS32(xy1_c - *xy1) <= VERY_SMALL);
celt_assert(ABS32(xy2_c - *xy2) <= VERY_SMALL);
float err[2];
dual_inner_prod_neon_float_c_simulation(x, y01, y02, N, &xy1_c, &xy2_c, err);
/*if (ABS32(xy1_c - *xy1) > err[0]) fprintf(stderr, "dual1 fail: %g %g %g\n", xy1_c, *xy1, err[0]);
if (ABS32(xy2_c - *xy2) > err[1]) fprintf(stderr, "dual2 fail: %g %g %g\n", xy2_c, *xy2, err[1]);*/
celt_assert(ABS32(xy1_c - *xy1) <= err[0]);
celt_assert(ABS32(xy2_c - *xy2) <= err[1]);
}
#endif
}