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Fixed the optimized AVX implementation of the fast rsqrt function

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Benoit Steiner 2015-03-02 13:49:39 -08:00
parent b0f2b6f297
commit 0196141938
1 changed files with 15 additions and 15 deletions
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30
Eigen/src/Core/arch/AVX/MathFunctions.h
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@ -312,31 +312,31 @@ Packet4d psqrt<Packet4d>(const Packet4d& x) {
#if EIGEN_FAST_MATH
template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
Packet4f prsqrt<Packet4f>(const Packet4f& _x) {
_EIGEN_DECLARE_CONST_Packet4f_FROM_INT(inf, 0x7f800000);
_EIGEN_DECLARE_CONST_Packet4f_FROM_INT(nan, 0x7fc00000);
_EIGEN_DECLARE_CONST_Packet4f(one_point_five, 1.5f);
_EIGEN_DECLARE_CONST_Packet4f(minus_half, -0.5f);
_EIGEN_DECLARE_CONST_Packet4f_FROM_INT(flt_min, 0x00800000);
Packet8f prsqrt<Packet8f>(const Packet8f& _x) {
_EIGEN_DECLARE_CONST_Packet8f_FROM_INT(inf, 0x7f800000);
_EIGEN_DECLARE_CONST_Packet8f_FROM_INT(nan, 0x7fc00000);
_EIGEN_DECLARE_CONST_Packet8f(one_point_five, 1.5f);
_EIGEN_DECLARE_CONST_Packet8f(minus_half, -0.5f);
_EIGEN_DECLARE_CONST_Packet8f_FROM_INT(flt_min, 0x00800000);
Packet4f neg_half = pmul(_x, p4f_minus_half);
Packet8f neg_half = pmul(_x, p8f_minus_half);
// select only the inverse sqrt of positive normal inputs (denormals are
// flushed to zero and cause infs as well).
Packet4f le_zero_mask = _mm_cmple_ps(_x, p4f_flt_min);
Packet4f x = _mm_andnot_ps(le_zero_mask, _mm_rsqrt_ps(_x));
Packet8f le_zero_mask = _mm256_cmp_ps(_x, p8f_flt_min, _CMP_LT_OQ);
Packet8f x = _mm256_andnot_ps(le_zero_mask, _mm256_rsqrt_ps(_x));
// Fill in NaNs and Infs for the negative/zero entries.
Packet4f neg_mask = _mm_cmplt_ps(_x, _mm_setzero_ps());
Packet4f zero_mask = _mm_andnot_ps(neg_mask, le_zero_mask);
Packet4f infs_and_nans = _mm_or_ps(_mm_and_ps(neg_mask, p4f_nan),
_mm_and_ps(zero_mask, p4f_inf));
Packet8f neg_mask = _mm256_cmp_ps(_x, _mm256_setzero_ps(), _CMP_LT_OQ);
Packet8f zero_mask = _mm256_andnot_ps(neg_mask, le_zero_mask);
Packet8f infs_and_nans = _mm256_or_ps(_mm256_and_ps(neg_mask, p8f_nan),
_mm256_and_ps(zero_mask, p8f_inf));
// Do a single step of Newton's iteration.
x = pmul(x, pmadd(neg_half, pmul(x, x), p4f_one_point_five));
x = pmul(x, pmadd(neg_half, pmul(x, x), p8f_one_point_five));
// Insert NaNs and Infs in all the right places.
return _mm_or_ps(x, infs_and_nans);
return _mm256_or_ps(x, infs_and_nans);
}
#else