OpenBLAS/kernel/x86_64/dsymv_L_microk_skylakex-2.c

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/* need a new enough GCC for avx512 support */
#if (( defined(__GNUC__)  && __GNUC__   > 6 && defined(__AVX2__)) || (defined(__clang__) && __clang_major__ >= 6))

#include <immintrin.h>

#define HAVE_KERNEL_4x4 1

#if defined(__clang_patchlevel__) && __clang_major__ == 9 && __clang_minor__ == 0 && __clang_patchlevel__ == 0
#pragma clang optimize off
#endif
#if defined(__apple_build_version__) && __clang_major__ == 11 && __clang_minor__ == 0 && __clang_patchlevel__ == 3
#pragma clang optimize off
#endif
static void dsymv_kernel_4x4(BLASLONG from, BLASLONG to, FLOAT **a, FLOAT *x, FLOAT *y, FLOAT *temp1, FLOAT *temp2)
{


	__m256d accum_0, accum_1, accum_2, accum_3; 
	__m256d temp1_0, temp1_1, temp1_2, temp1_3;

	/* the 256 bit wide acculmulator vectors start out as zero */
	accum_0 = _mm256_setzero_pd();
	accum_1 = _mm256_setzero_pd();
	accum_2 = _mm256_setzero_pd();
	accum_3 = _mm256_setzero_pd();

	temp1_0 = _mm256_broadcastsd_pd(_mm_load_sd(&temp1[0]));
	temp1_1 = _mm256_broadcastsd_pd(_mm_load_sd(&temp1[1]));
	temp1_2 = _mm256_broadcastsd_pd(_mm_load_sd(&temp1[2]));
	temp1_3 = _mm256_broadcastsd_pd(_mm_load_sd(&temp1[3]));

#ifdef __AVX512CD__
	__m512d accum_05, accum_15, accum_25, accum_35;
	__m512d temp1_05, temp1_15, temp1_25, temp1_35;
	BLASLONG to2;
	int delta;

	/* the 512 bit wide accumulator vectors start out as zero */
	accum_05 = _mm512_setzero_pd();
	accum_15 = _mm512_setzero_pd();
	accum_25 = _mm512_setzero_pd();
	accum_35 = _mm512_setzero_pd();

	temp1_05 = _mm512_broadcastsd_pd(_mm_load_sd(&temp1[0]));
	temp1_15 = _mm512_broadcastsd_pd(_mm_load_sd(&temp1[1]));
	temp1_25 = _mm512_broadcastsd_pd(_mm_load_sd(&temp1[2]));
	temp1_35 = _mm512_broadcastsd_pd(_mm_load_sd(&temp1[3]));

	delta = (to - from) & ~7;
	to2 = from + delta;


	for (; from < to2; from += 8) {
		__m512d _x, _y;
		__m512d a0, a1, a2, a3;

		_y = _mm512_loadu_pd(&y[from]);
		_x = _mm512_loadu_pd(&x[from]);

		a0 = _mm512_loadu_pd(&a[0][from]);
		a1 = _mm512_loadu_pd(&a[1][from]);
		a2 = _mm512_loadu_pd(&a[2][from]);
		a3 = _mm512_loadu_pd(&a[3][from]);

		_y += temp1_05 * a0 + temp1_15 * a1 + temp1_25 * a2 + temp1_35 * a3;

		accum_05 += _x * a0;
		accum_15 += _x * a1;
		accum_25 += _x * a2;
		accum_35 += _x * a3;

		_mm512_storeu_pd(&y[from], _y);

	};

	/*
	 * we need to fold our 512 bit wide accumulator vectors into 256 bit wide vectors so that the AVX2 code
	 * below can continue using the intermediate results in its loop
	 */
	accum_0 = _mm256_add_pd(_mm512_extractf64x4_pd(accum_05, 0), _mm512_extractf64x4_pd(accum_05, 1));
	accum_1 = _mm256_add_pd(_mm512_extractf64x4_pd(accum_15, 0), _mm512_extractf64x4_pd(accum_15, 1));
	accum_2 = _mm256_add_pd(_mm512_extractf64x4_pd(accum_25, 0), _mm512_extractf64x4_pd(accum_25, 1));
	accum_3 = _mm256_add_pd(_mm512_extractf64x4_pd(accum_35, 0), _mm512_extractf64x4_pd(accum_35, 1));

#endif

	for (; from != to; from += 4) {
		__m256d _x, _y;
		__m256d a0, a1, a2, a3;

		_y = _mm256_loadu_pd(&y[from]);
		_x = _mm256_loadu_pd(&x[from]);

		/* load 4 rows of matrix data */
		a0 = _mm256_loadu_pd(&a[0][from]);
		a1 = _mm256_loadu_pd(&a[1][from]);
		a2 = _mm256_loadu_pd(&a[2][from]);
		a3 = _mm256_loadu_pd(&a[3][from]);

		_y += temp1_0 * a0 + temp1_1 * a1 + temp1_2 * a2 + temp1_3 * a3;

		accum_0 += _x * a0;
		accum_1 += _x * a1;
		accum_2 += _x * a2;
		accum_3 += _x * a3;

		_mm256_storeu_pd(&y[from], _y);

	};

	/*
	 * we now have 4 accumulator vectors. Each vector needs to be summed up element wise and stored in the temp2
	 * output array. There is no direct instruction for this in 256 bit space, only in 128 space.
	 */

	__m128d half_accum0, half_accum1, half_accum2, half_accum3;


	/* Add upper half to lower half of each of the four 256 bit vectors to get to four 128 bit vectors */
	half_accum0 = _mm_add_pd(_mm256_extractf128_pd(accum_0, 0), _mm256_extractf128_pd(accum_0, 1));
	half_accum1 = _mm_add_pd(_mm256_extractf128_pd(accum_1, 0), _mm256_extractf128_pd(accum_1, 1));
	half_accum2 = _mm_add_pd(_mm256_extractf128_pd(accum_2, 0), _mm256_extractf128_pd(accum_2, 1));
	half_accum3 = _mm_add_pd(_mm256_extractf128_pd(accum_3, 0), _mm256_extractf128_pd(accum_3, 1));

	/* in 128 bit land there is a hadd operation to do the rest of the element-wise sum in one go */
	half_accum0 = _mm_hadd_pd(half_accum0, half_accum0);
	half_accum1 = _mm_hadd_pd(half_accum1, half_accum1);
	half_accum2 = _mm_hadd_pd(half_accum2, half_accum2);
	half_accum3 = _mm_hadd_pd(half_accum3, half_accum3);

	/* and store the lowest double value from each of these vectors in the temp2 output */
	temp2[0] += half_accum0[0];
	temp2[1] += half_accum1[0];
	temp2[2] += half_accum2[0];
	temp2[3] += half_accum3[0];
}

#if defined(__clang_patchlevel__) && __clang_major__ == 9 && __clang_minor__ == 0 && __clang_patchlevel__ == 0
#pragma clang optimize on
#endif
#if defined(__apple_build_version__) && __clang_major__ == 11 && __clang_minor__ == 0 && __clang_patchlevel__ == 3
#pragma clang optimize on
#endif

#else
#include "dsymv_L_microk_haswell-2.c"
#endif