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#ifndef AVX512_FUNCS_H
#define AVX512_FUNCS_H
#include <immintrin.h>
#include <stdint.h>
/* Written because Visual C++ toolchains before v142 have constant overflow in AVX512 intrinsic macros */
#if defined(_MSC_VER) && !defined(_MM_K0_REG8)
# undef _mm512_extracti64x4_epi64
# define _mm512_extracti64x4_epi64(v1, e1) _mm512_maskz_extracti64x4_epi64(UINT8_MAX, v1, e1)
# undef _mm512_set1_epi16
# define _mm512_set1_epi16(e1) _mm512_maskz_set1_epi16(UINT32_MAX, e1)
# undef _mm512_maddubs_epi16
# define _mm512_maddubs_epi16(v1, v2) _mm512_maskz_maddubs_epi16(UINT32_MAX, v1, v2)
#endif
/* Written because *_add_epi32(a) sets off ubsan */
static inline uint32_t _mm512_reduce_add_epu32(__m512i x) {
__m256i a = _mm512_extracti64x4_epi64(x, 1);
__m256i b = _mm512_extracti64x4_epi64(x, 0);
__m256i a_plus_b = _mm256_add_epi32(a, b);
__m128i c = _mm256_extracti128_si256(a_plus_b, 1);
__m128i d = _mm256_extracti128_si256(a_plus_b, 0);
__m128i c_plus_d = _mm_add_epi32(c, d);
__m128i sum1 = _mm_unpackhi_epi64(c_plus_d, c_plus_d);
__m128i sum2 = _mm_add_epi32(sum1, c_plus_d);
__m128i sum3 = _mm_shuffle_epi32(sum2, 0x01);
__m128i sum4 = _mm_add_epi32(sum2, sum3);
return _mm_cvtsi128_si32(sum4);
}
static inline uint32_t partial_hsum(__m512i x) {
/* We need a permutation vector to extract every other integer. The
* rest are going to be zeros. Marking this const so the compiler stands
* a better chance of keeping this resident in a register through entire
* loop execution. We certainly have enough zmm registers (32) */
const __m512i perm_vec = _mm512_setr_epi32(0, 2, 4, 6, 8, 10, 12, 14,
1, 1, 1, 1, 1, 1, 1, 1);
__m512i non_zero = _mm512_permutexvar_epi32(perm_vec, x);
/* From here, it's a simple 256 bit wide reduction sum */
__m256i non_zero_avx = _mm512_castsi512_si256(non_zero);
/* See Agner Fog's vectorclass for a decent reference. Essentially, phadd is
* pretty slow, much slower than the longer instruction sequence below */
__m128i sum1 = _mm_add_epi32(_mm256_extracti128_si256(non_zero_avx, 1),
_mm256_castsi256_si128(non_zero_avx));
__m128i sum2 = _mm_add_epi32(sum1,_mm_unpackhi_epi64(sum1, sum1));
__m128i sum3 = _mm_add_epi32(sum2,_mm_shuffle_epi32(sum2, 1));
return (uint32_t)_mm_cvtsi128_si32(sum3);
}
#endif
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