Revision edd171a6
Added by David Sorber over 7 years ago
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#include <iostream>
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#include <x86intrin.h>
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// Return horizontal sum for 128 bit packed float vector
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float hsum_ps_sse3(__m128 val)
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{
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__m128 shuf = _mm_movehdup_ps(val); // broadcast elements 3,1 to 2,0
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__m128 sums = _mm_add_ps(val, shuf);
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shuf = _mm_movehl_ps(shuf, sums); // high half -> low half
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sums = _mm_add_ss(sums, shuf);
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return _mm_cvtss_f32(sums);
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}
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// Return horizontal sum for 256 bit packed float vector
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// https://stackoverflow.com/a/35270026/73878 -- Peter Cordes is da man
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float hsum256_ps_avx(__m256 val)
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{
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__m128 vlow = _mm256_castps256_ps128(val);
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__m128 vhigh = _mm256_extractf128_ps(val, 1); // high 128
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vlow = _mm_add_ps(vlow, vhigh); // add the low 128
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return hsum_ps_sse3(vlow); // and inline the sse3 version, which is optimal for AVX
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}
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void print_debug(__m256 val)
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{
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float temp[8];
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_mm256_store_ps(temp, val);
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std::cout << "DEBUG: "
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<< temp[0] << " -- " << temp[1] << " -- "
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<< temp[2] << " -- " << temp[3] << " -- "
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<< temp[4] << " -- " << temp[5] << " -- "
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<< temp[6] << " -- " << temp[7] << std::endl;
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}
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// Return max value across (i.e. horizontally) vector
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// Algorithm came from here: https://stackoverflow.com/a/9798369/73878
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float max_ps_avx(__m256 val)
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{
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__m256 m0 = _mm256_permute2f128_ps(val, val, 1); // Permute 128-bit values
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__m256 m1 = _mm256_max_ps(val, m0); // Compute max of 4 sets
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__m256 m2 = _mm256_permute_ps(m1, 0x4E); // Permute max values
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__m256 m3 = _mm256_max_ps(m1, m2); // Compute max of 2 sets
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__m256 m4 = _mm256_permute_ps(m3, 0x3B); // Permute max values
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__m256 m = _mm256_max_ps(m3, m4); // Compute (final) max
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return _mm_cvtss_f32(_mm256_extractf128_ps(m, 0));
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}
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// Return min value across (i.e. horizontally) vector
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// Algorithm came from here: https://stackoverflow.com/a/9798369/73878
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float min_ps_avx(__m256 val)
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{
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__m256 m0 = _mm256_permute2f128_ps(val, val, 1); // Permute 128-bit values
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__m256 m1 = _mm256_min_ps(val, m0); // Compute min of 4 sets
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__m256 m2 = _mm256_permute_ps(m1, 0x4E); // Permute max values
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__m256 m3 = _mm256_min_ps(m1, m2); // Compute min of 2 sets
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__m256 m4 = _mm256_permute_ps(m3, 0x3B); // Permute max values
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__m256 m = _mm256_min_ps(m3, m4); // Compute (final) min
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return _mm_cvtss_f32(_mm256_extractf128_ps(m, 0));
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}
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// g++ -std=c++11 -O3 -mavx -o ps_test ps_test.cc
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int main(int argc, char** argv)
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{
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std::cout << "Packed Float (PS) Test\n" << std::endl;
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float raw_data[8] = {1.0, 2.0, -3.0, 4.0, 5.0, -6.0, 7.0 , 8.0};
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// Generate signmask
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__m256 SIGNMASK = _mm256_castsi256_ps(_mm256_set1_epi32(0x80000000));
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// Load data
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__m256 data = _mm256_loadu_ps(raw_data);
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// Take absolute value of data
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__m256 abs_data = _mm256_andnot_ps(SIGNMASK, data);
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// Sum data
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float total = hsum256_ps_avx(data);
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float total_abs = hsum256_ps_avx(abs_data);
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std::cout << "Total: " << total << " -- " << total_abs << std::endl;
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std::cout << " Max: " << max_ps_avx(abs_data) << std::endl;
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std::cout << " Min: " << min_ps_avx(abs_data) << std::endl;
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return 0;
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}
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Adding packed single precision (aka "ps") intrinsic test. This includes
useful horizontal sum and horizontal min/max routines.