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AVX512F double->int64_t cast

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Charles Schlosser 2024-06-15 17:45:02 +00:00 committed by Rasmus Munk Larsen
parent 02bcf9b591
commit b430eb31e2
1 changed files with 28 additions and 8 deletions
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36
Eigen/src/Core/arch/AVX512/TypeCasting.h
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@ -82,14 +82,34 @@ EIGEN_STRONG_INLINE Packet8d pcast<Packet8f, Packet8d>(const Packet8f& a) {
template <>
EIGEN_STRONG_INLINE Packet8l pcast<Packet8d, Packet8l>(const Packet8d& a) {
#if defined(EIGEN_VECTORIZE_AVX512DQ) && defined(EIGEN_VECTORIZE_AVS512VL)
#if defined(EIGEN_VECTORIZE_AVX512DQ) && defined(EIGEN_VECTORIZE_AVX512VL)
return _mm512_cvttpd_epi64(a);
#else
EIGEN_ALIGN16 double aux[8];
pstore(aux, a);
return _mm512_set_epi64(static_cast<int64_t>(aux[7]), static_cast<int64_t>(aux[6]), static_cast<int64_t>(aux[5]),
static_cast<int64_t>(aux[4]), static_cast<int64_t>(aux[3]), static_cast<int64_t>(aux[2]),
static_cast<int64_t>(aux[1]), static_cast<int64_t>(aux[0]));
constexpr int kTotalBits = sizeof(double) * CHAR_BIT, kMantissaBits = std::numeric_limits<double>::digits - 1,
kExponentBits = kTotalBits - kMantissaBits - 1, kBias = (1 << (kExponentBits - 1)) - 1;
const __m512i cst_one = _mm512_set1_epi64(1);
const __m512i cst_total_bits = _mm512_set1_epi64(kTotalBits);
const __m512i cst_bias = _mm512_set1_epi64(kBias);
__m512i a_bits = _mm512_castpd_si512(a);
// shift left by 1 to clear the sign bit, and shift right by kMantissaBits + 1 to recover biased exponent
__m512i biased_e = _mm512_srli_epi64(_mm512_slli_epi64(a_bits, 1), kMantissaBits + 1);
__m512i e = _mm512_sub_epi64(biased_e, cst_bias);
// shift to the left by kExponentBits + 1 to clear the sign and exponent bits
__m512i shifted_mantissa = _mm512_slli_epi64(a_bits, kExponentBits + 1);
// shift to the right by kTotalBits - e to convert the significand to an integer
__m512i result_significand = _mm512_srlv_epi64(shifted_mantissa, _mm512_sub_epi64(cst_total_bits, e));
// add the implied bit
__m512i result_exponent = _mm512_sllv_epi64(cst_one, e);
// e <= 0 is interpreted as a large positive shift (2's complement), which also conveniently results in zero
__m512i result = _mm512_add_epi64(result_significand, result_exponent);
// handle negative arguments
__mmask8 sign_mask = _mm512_cmplt_epi64_mask(a_bits, _mm512_setzero_si512());
result = _mm512_mask_sub_epi64(result, sign_mask, _mm512_setzero_si512(), result);
return result;
#endif
}
@ -110,10 +130,10 @@ EIGEN_STRONG_INLINE Packet8d pcast<Packet8i, Packet8d>(const Packet8i& a) {
template <>
EIGEN_STRONG_INLINE Packet8d pcast<Packet8l, Packet8d>(const Packet8l& a) {
#if defined(EIGEN_VECTORIZE_AVX512DQ) && defined(EIGEN_VECTORIZE_AVS512VL)
#if defined(EIGEN_VECTORIZE_AVX512DQ) && defined(EIGEN_VECTORIZE_AVX512VL)
return _mm512_cvtepi64_pd(a);
#else
EIGEN_ALIGN16 int64_t aux[8];
EIGEN_ALIGN64 int64_t aux[8];
pstore(aux, a);
return _mm512_set_pd(static_cast<double>(aux[7]), static_cast<double>(aux[6]), static_cast<double>(aux[5]),
static_cast<double>(aux[4]), static_cast<double>(aux[3]), static_cast<double>(aux[2]),