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Re-enable FMA for fast sqrt functions

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This commit is contained in:
Mark D Ryan
2018-07-30 13:21:00 +02:00
parent 96b030a8e4
commit bc615e4585
1 changed files with 5 additions and 5 deletions
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10
Eigen/src/Core/arch/AVX512/MathFunctions.h
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@@ -258,7 +258,7 @@ pexp<Packet8d>(const Packet8d& _x) {
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet16f
psqrt<Packet16f>(const Packet16f& _x) {
Packet16f half = pmul(_x, pset1<Packet16f>(.5f));
Packet16f neg_half = pmul(_x, pset1<Packet16f>(-.5f));
__mmask16 denormal_mask = _mm512_kand(
_mm512_cmp_ps_mask(_x, pset1<Packet16f>((std::numeric_limits<float>::min)()),
_CMP_LT_OQ),
@@ -267,7 +267,7 @@ psqrt<Packet16f>(const Packet16f& _x) {
Packet16f x = _mm512_rsqrt14_ps(_x);
// Do a single step of Newton's iteration.
x = pmul(x, psub(pset1<Packet16f>(1.5f), pmul(half, pmul(x,x))));
x = pmul(x, pmadd(neg_half, pmul(x, x), pset1<Packet16f>(1.5f)));
// Flush results for denormals to zero.
return _mm512_mask_blend_ps(denormal_mask, pmul(_x,x), _mm512_setzero_ps());
@@ -276,7 +276,7 @@ psqrt<Packet16f>(const Packet16f& _x) {
template <>
EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED Packet8d
psqrt<Packet8d>(const Packet8d& _x) {
Packet8d half = pmul(_x, pset1<Packet8d>(.5f));
Packet8d neg_half = pmul(_x, pset1<Packet8d>(-.5f));
__mmask16 denormal_mask = _mm512_kand(
_mm512_cmp_pd_mask(_x, pset1<Packet8d>((std::numeric_limits<double>::min)()),
_CMP_LT_OQ),
@@ -285,10 +285,10 @@ psqrt<Packet8d>(const Packet8d& _x) {
Packet8d x = _mm512_rsqrt14_pd(_x);
// Do a single step of Newton's iteration.
x = pmul(x, psub(pset1<Packet8d>(1.5f), pmul(half, pmul(x,x))));
x = pmul(x, pmadd(neg_half, pmul(x, x), pset1<Packet8d>(1.5f)));
// Do a second step of Newton's iteration.
x = pmul(x, psub(pset1<Packet8d>(1.5f), pmul(half, pmul(x,x))));
x = pmul(x, pmadd(neg_half, pmul(x, x), pset1<Packet8d>(1.5f)));
return _mm512_mask_blend_pd(denormal_mask, pmul(_x,x), _mm512_setzero_pd());
}