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[move sift.cpp] Optimize SIFT with AVX2

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original commit: c5e55dfde9
pull/17119/head
Woody Chow 8 years ago
parent 8be0a3452d
commit 546239a3a8
1 changed files with 229 additions and 6 deletions
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  1. 235
      modules/features2d/src/sift.cpp

235
modules/features2d/src/sift.cpp
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@ -309,7 +309,40 @@ static float calcOrientationHist( const Mat& img, Point pt, int radius,
cv::hal::fastAtan2(Y, X, Ori, len, true); cv::hal::fastAtan2(Y, X, Ori, len, true);
cv::hal::magnitude32f(X, Y, Mag, len); cv::hal::magnitude32f(X, Y, Mag, len);
for( k = 0; k < len; k++ ) k = 0;
#if CV_AVX2
if( USE_AVX2 )
{
__m256 __nd360 = _mm256_set1_ps(n/360.f);
__m256i __n = _mm256_set1_epi32(n);
int CV_DECL_ALIGNED(32) bin_buf[8];
float CV_DECL_ALIGNED(32) w_mul_mag_buf[8];
for ( ; k <= len - 8; k+=8 )
{
__m256i __bin = _mm256_cvtps_epi32(_mm256_round_ps(_mm256_mul_ps(__nd360, _mm256_loadu_ps(&Ori[k])), _MM_FROUND_TO_NEAREST_INT |_MM_FROUND_NO_EXC));
__bin = _mm256_sub_epi32(__bin,
_mm256_and_si256(__n, _mm256_or_si256(_mm256_cmpeq_epi32(__bin, __n), _mm256_cmpgt_epi32(__bin, __n))));
__bin = _mm256_add_epi32(__bin,
_mm256_and_si256(__n, _mm256_cmpgt_epi32(_mm256_setzero_si256(), __bin)));
__m256 __w_mul_mag = _mm256_mul_ps(_mm256_loadu_ps(&W[k]), _mm256_loadu_ps(&Mag[k]));
_mm256_store_si256((__m256i *) bin_buf, __bin);
_mm256_store_ps(w_mul_mag_buf, __w_mul_mag);
temphist[bin_buf[0]] += w_mul_mag_buf[0];
temphist[bin_buf[1]] += w_mul_mag_buf[1];
temphist[bin_buf[2]] += w_mul_mag_buf[2];
temphist[bin_buf[3]] += w_mul_mag_buf[3];
temphist[bin_buf[4]] += w_mul_mag_buf[4];
temphist[bin_buf[5]] += w_mul_mag_buf[5];
temphist[bin_buf[6]] += w_mul_mag_buf[6];
temphist[bin_buf[7]] += w_mul_mag_buf[7];
}
}
#endif
for( ; k < len; k++ )
{ {
int bin = cvRound((n/360.f)*Ori[k]); int bin = cvRound((n/360.f)*Ori[k]);
if( bin >= n ) if( bin >= n )
@ -324,7 +357,40 @@ static float calcOrientationHist( const Mat& img, Point pt, int radius,
temphist[-2] = temphist[n-2]; temphist[-2] = temphist[n-2];
temphist[n] = temphist[0]; temphist[n] = temphist[0];
temphist[n+1] = temphist[1]; temphist[n+1] = temphist[1];
for( i = 0; i < n; i++ )
i = 0;
#if CV_AVX2
if( USE_AVX2 )
{
__m256 __d_1_16 = _mm256_set1_ps(1.f/16.f);
__m256 __d_4_16 = _mm256_set1_ps(4.f/16.f);
__m256 __d_6_16 = _mm256_set1_ps(6.f/16.f);
for( ; i <= n - 8; i+=8 )
{
#if CV_FMA3
__m256 __hist = _mm256_fmadd_ps(
_mm256_add_ps(_mm256_loadu_ps(&temphist[i-2]), _mm256_loadu_ps(&temphist[i+2])),
__d_1_16,
_mm256_fmadd_ps(
_mm256_add_ps(_mm256_loadu_ps(&temphist[i-1]), _mm256_loadu_ps(&temphist[i+1])),
__d_4_16,
_mm256_mul_ps(_mm256_loadu_ps(&temphist[i]), __d_6_16)));
#else
__m256 __hist = _mm256_add_ps(
_mm256_mul_ps(
_mm256_add_ps(_mm256_loadu_ps(&temphist[i-2]), _mm256_loadu_ps(&temphist[i+2])),
__d_1_16),
_mm256_add_ps(
_mm256_mul_ps(
_mm256_add_ps(_mm256_loadu_ps(&temphist[i-1]), _mm256_loadu_ps(&temphist[i+1])),
__d_4_16),
_mm256_mul_ps(_mm256_loadu_ps(&temphist[i]), __d_6_16)));
#endif
_mm256_storeu_ps(&hist[i], __hist);
}
}
#endif
for( ; i < n; i++ )
{ {
hist[i] = (temphist[i-2] + temphist[i+2])*(1.f/16.f) + hist[i] = (temphist[i-2] + temphist[i+2])*(1.f/16.f) +
(temphist[i-1] + temphist[i+1])*(4.f/16.f) + (temphist[i-1] + temphist[i+1])*(4.f/16.f) +
@ -592,7 +658,99 @@ static void calcSIFTDescriptor( const Mat& img, Point2f ptf, float ori, float sc
cv::hal::magnitude32f(X, Y, Mag, len); cv::hal::magnitude32f(X, Y, Mag, len);
cv::hal::exp32f(W, W, len); cv::hal::exp32f(W, W, len);
for( k = 0; k < len; k++ ) k = 0;
#if CV_AVX2
if( USE_AVX2 )
{
int CV_DECL_ALIGNED(32) idx_buf[8];
float CV_DECL_ALIGNED(32) rco_buf[64];
__m256 __ori = _mm256_set1_ps(ori);
__m256 __bins_per_rad = _mm256_set1_ps(bins_per_rad);
__m256i __n = _mm256_set1_epi32(n);
for( ; k <= len - 8; k+=8 )
{
__m256 __rbin = _mm256_loadu_ps(&RBin[k]);
__m256 __cbin = _mm256_loadu_ps(&CBin[k]);
__m256 __obin = _mm256_mul_ps(_mm256_sub_ps(_mm256_loadu_ps(&Ori[k]), __ori), __bins_per_rad);
__m256 __mag = _mm256_mul_ps(_mm256_loadu_ps(&Mag[k]), _mm256_loadu_ps(&W[k]));
__m256 __r0 = _mm256_floor_ps(__rbin);
__rbin = _mm256_sub_ps(__rbin, __r0);
__m256 __c0 = _mm256_floor_ps(__cbin);
__cbin = _mm256_sub_ps(__cbin, __c0);
__m256 __o0 = _mm256_floor_ps(__obin);
__obin = _mm256_sub_ps(__obin, __o0);
__m256i __o0i = _mm256_cvtps_epi32(__o0);
// _o0 += (o0 < 0) * n
__o0i = _mm256_add_epi32(__o0i, _mm256_and_si256(__n, _mm256_cmpgt_epi32(_mm256_setzero_si256(), __o0i)));
__o0i = _mm256_sub_epi32(__o0i,
_mm256_and_si256(__n, _mm256_or_si256(_mm256_cmpeq_epi32(__o0i, __n), _mm256_cmpgt_epi32(__o0i, __n))));
__m256 __v_r1 = _mm256_mul_ps(__mag, __rbin);
__m256 __v_r0 = _mm256_sub_ps(__mag, __v_r1);
__m256 __v_rc11 = _mm256_mul_ps(__v_r1, __cbin);
__m256 __v_rc10 = _mm256_sub_ps(__v_r1, __v_rc11);
__m256 __v_rc01 = _mm256_mul_ps(__v_r0, __cbin);
__m256 __v_rc00 = _mm256_sub_ps(__v_r0, __v_rc01);
__m256 __v_rco111 = _mm256_mul_ps(__v_rc11, __obin);
__m256 __v_rco110 = _mm256_sub_ps(__v_rc11, __v_rco111);
__m256 __v_rco101 = _mm256_mul_ps(__v_rc10, __obin);
__m256 __v_rco100 = _mm256_sub_ps(__v_rc10, __v_rco101);
__m256 __v_rco011 = _mm256_mul_ps(__v_rc01, __obin);
__m256 __v_rco010 = _mm256_sub_ps(__v_rc01, __v_rco011);
__m256 __v_rco001 = _mm256_mul_ps(__v_rc00, __obin);
__m256 __v_rco000 = _mm256_sub_ps(__v_rc00, __v_rco001);
__m256i __one = _mm256_set1_epi32(1);
__m256i __idx = _mm256_add_epi32(
_mm256_mullo_epi32(
_mm256_add_epi32(
_mm256_mullo_epi32(_mm256_add_epi32(_mm256_cvtps_epi32(__r0), __one), _mm256_set1_epi32(d + 2)),
_mm256_add_epi32(_mm256_cvtps_epi32(__c0), __one)),
_mm256_set1_epi32(n + 2)),
__o0i);
_mm256_store_si256((__m256i *)idx_buf, __idx);
_mm256_store_ps(&(rco_buf[0]), __v_rco000);
_mm256_store_ps(&(rco_buf[8]), __v_rco001);
_mm256_store_ps(&(rco_buf[16]), __v_rco010);
_mm256_store_ps(&(rco_buf[24]), __v_rco011);
_mm256_store_ps(&(rco_buf[32]), __v_rco100);
_mm256_store_ps(&(rco_buf[40]), __v_rco101);
_mm256_store_ps(&(rco_buf[48]), __v_rco110);
_mm256_store_ps(&(rco_buf[56]), __v_rco111);
#define HIST_SUM_HELPER(id) \
hist[idx_buf[(id)]] += rco_buf[(id)]; \
hist[idx_buf[(id)]+1] += rco_buf[8 + (id)]; \
hist[idx_buf[(id)]+(n+2)] += rco_buf[16 + (id)]; \
hist[idx_buf[(id)]+(n+3)] += rco_buf[24 + (id)]; \
hist[idx_buf[(id)]+(d+2)*(n+2)] += rco_buf[32 + (id)]; \
hist[idx_buf[(id)]+(d+2)*(n+2)+1] += rco_buf[40 + (id)]; \
hist[idx_buf[(id)]+(d+3)*(n+2)] += rco_buf[48 + (id)]; \
hist[idx_buf[(id)]+(d+3)*(n+2)+1] += rco_buf[56 + (id)];
HIST_SUM_HELPER(0);
HIST_SUM_HELPER(1);
HIST_SUM_HELPER(2);
HIST_SUM_HELPER(3);
HIST_SUM_HELPER(4);
HIST_SUM_HELPER(5);
HIST_SUM_HELPER(6);
HIST_SUM_HELPER(7);
#undef HIST_SUM_HELPER
}
}
#endif
for( ; k < len; k++ )
{ {
float rbin = RBin[k], cbin = CBin[k]; float rbin = RBin[k], cbin = CBin[k];
float obin = (Ori[k] - ori)*bins_per_rad; float obin = (Ori[k] - ori)*bins_per_rad;
@ -646,10 +804,59 @@ static void calcSIFTDescriptor( const Mat& img, Point2f ptf, float ori, float sc
// to byte array // to byte array
float nrm2 = 0; float nrm2 = 0;
len = d*d*n; len = d*d*n;
for( k = 0; k < len; k++ ) k = 0;
#if CV_AVX2
if( USE_AVX2 )
{
float CV_DECL_ALIGNED(32) nrm2_buf[8];
__m256 __nrm2 = _mm256_setzero_ps();
__m256 __dst;
for( ; k <= len - 8; k += 8 )
{
__dst = _mm256_loadu_ps(&dst[k]);
#if CV_FMA3
__nrm2 = _mm256_fmadd_ps(__dst, __dst, __nrm2);
#else
__nrm2 = _mm256_add_ps(__nrm2, _mm256_mul_ps(__dst, __dst));
#endif
}
_mm256_store_ps(nrm2_buf, __nrm2);
nrm2 = nrm2_buf[0] + nrm2_buf[1] + nrm2_buf[2] + nrm2_buf[3] +
nrm2_buf[4] + nrm2_buf[5] + nrm2_buf[6] + nrm2_buf[7];
}
#endif
for( ; k < len; k++ )
nrm2 += dst[k]*dst[k]; nrm2 += dst[k]*dst[k];
float thr = std::sqrt(nrm2)*SIFT_DESCR_MAG_THR; float thr = std::sqrt(nrm2)*SIFT_DESCR_MAG_THR;
for( i = 0, nrm2 = 0; i < k; i++ )
i = 0, nrm2 = 0;
#if 0 //CV_AVX2
// This code cannot be enabled because it sums nrm2 in a different order,
// thus producing slightly different results
if( USE_AVX2 )
{
float CV_DECL_ALIGNED(32) nrm2_buf[8];
__m256 __dst;
__m256 __nrm2 = _mm256_setzero_ps();
__m256 __thr = _mm256_set1_ps(thr);
for( ; i <= len - 8; i += 8 )
{
__dst = _mm256_loadu_ps(&dst[i]);
__dst = _mm256_min_ps(__dst, __thr);
_mm256_storeu_ps(&dst[i], __dst);
#if CV_FMA3
__nrm2 = _mm256_fmadd_ps(__dst, __dst, __nrm2);
#else
__nrm2 = _mm256_add_ps(__nrm2, _mm256_mul_ps(__dst, __dst));
#endif
}
_mm256_store_ps(nrm2_buf, __nrm2);
nrm2 = nrm2_buf[0] + nrm2_buf[1] + nrm2_buf[2] + nrm2_buf[3] +
nrm2_buf[4] + nrm2_buf[5] + nrm2_buf[6] + nrm2_buf[7];
}
#endif
for( ; i < len; i++ )
{ {
float val = std::min(dst[i], thr); float val = std::min(dst[i], thr);
dst[i] = val; dst[i] = val;
@ -658,7 +865,23 @@ static void calcSIFTDescriptor( const Mat& img, Point2f ptf, float ori, float sc
nrm2 = SIFT_INT_DESCR_FCTR/std::max(std::sqrt(nrm2), FLT_EPSILON); nrm2 = SIFT_INT_DESCR_FCTR/std::max(std::sqrt(nrm2), FLT_EPSILON);
#if 1 #if 1
for( k = 0; k < len; k++ ) k = 0;
#if CV_AVX2
if( USE_AVX2 )
{
__m256 __dst;
__m256 __min = _mm256_setzero_ps();
__m256 __max = _mm256_set1_ps(255.0f); // max of uchar
__m256 __nrm2 = _mm256_set1_ps(nrm2);
for( k = 0; k <= len - 8; k+=8 )
{
__dst = _mm256_loadu_ps(&dst[k]);
__dst = _mm256_min_ps(_mm256_max_ps(_mm256_round_ps(_mm256_mul_ps(__dst, __nrm2), _MM_FROUND_TO_NEAREST_INT |_MM_FROUND_NO_EXC), __min), __max);
_mm256_storeu_ps(&dst[k], __dst);
}
}
#endif
for( ; k < len; k++ )
{ {
dst[k] = saturate_cast<uchar>(dst[k]*nrm2); dst[k] = saturate_cast<uchar>(dst[k]*nrm2);
} }

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