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More accurate cost estimates for exp, log, tanh, and sqrt.

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This commit is contained in:
Benoit Steiner 2016-04-11 13:11:04 -07:00
parent 833efb39bf
commit 748c4c4599
1 changed files with 76 additions and 12 deletions
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88
Eigen/src/Core/functors/UnaryFunctors.h
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@ -234,9 +234,33 @@ template<typename Scalar> struct scalar_exp_op {
template <typename Packet>
EIGEN_DEVICE_FUNC inline Packet packetOp(const Packet& a) const { return internal::pexp(a); }
};
template<typename Scalar>
struct functor_traits<scalar_exp_op<Scalar> >
{ enum { Cost = 5 * NumTraits<Scalar>::MulCost, PacketAccess = packet_traits<Scalar>::HasExp }; };
template <typename Scalar>
struct functor_traits<scalar_exp_op<Scalar> > {
enum {
PacketAccess = packet_traits<Scalar>::HasExp,
// The following numbers are based on the AVX implementation.
#ifdef EIGEN_VECTORIZE_FMA
// Haswell can issue 2 add/mul/madd per cycle.
Cost =
(sizeof(Scalar) == 4
// float: 8 pmadd, 4 pmul, 2 padd/psub, 6 other
? (8 * NumTraits<Scalar>::AddCost + 6 * NumTraits<Scalar>::MulCost)
// double: 7 pmadd, 5 pmul, 3 padd/psub, 1 div, 13 other
: (14 * NumTraits<Scalar>::AddCost +
6 * NumTraits<Scalar>::MulCost +
NumTraits<Scalar>::template Div<packet_traits<Scalar>::HasDiv>::Cost)),
#else
Cost =
(sizeof(Scalar) == 4
// float: 7 pmadd, 6 pmul, 4 padd/psub, 10 other
? (21 * NumTraits<Scalar>::AddCost + 13 * NumTraits<Scalar>::MulCost)
// double: 7 pmadd, 5 pmul, 3 padd/psub, 1 div, 13 other
: (23 * NumTraits<Scalar>::AddCost +
12 * NumTraits<Scalar>::MulCost +
NumTraits<Scalar>::template Div<packet_traits<Scalar>::HasDiv>::Cost))
#endif
};
};
/** \internal
*
@ -250,9 +274,24 @@ template<typename Scalar> struct scalar_log_op {
template <typename Packet>
EIGEN_DEVICE_FUNC inline Packet packetOp(const Packet& a) const { return internal::plog(a); }
};
template<typename Scalar>
struct functor_traits<scalar_log_op<Scalar> >
{ enum { Cost = 5 * NumTraits<Scalar>::MulCost, PacketAccess = packet_traits<Scalar>::HasLog }; };
template <typename Scalar>
struct functor_traits<scalar_log_op<Scalar> > {
enum {
PacketAccess = packet_traits<Scalar>::HasLog,
Cost =
(PacketAccess
// The following numbers are based on the AVX implementation.
#ifdef EIGEN_VECTORIZE_FMA
// 8 pmadd, 6 pmul, 8 padd/psub, 16 other, can issue 2 add/mul/madd per cycle.
? (20 * NumTraits<Scalar>::AddCost + 7 * NumTraits<Scalar>::MulCost)
#else
// 8 pmadd, 6 pmul, 8 padd/psub, 20 other
? (36 * NumTraits<Scalar>::AddCost + 14 * NumTraits<Scalar>::MulCost)
#endif
// Measured cost of std::log.
: sizeof(Scalar)==4 ? 40 : 85)
};
};
/** \internal
*
@ -280,10 +319,19 @@ template<typename Scalar> struct scalar_sqrt_op {
template <typename Packet>
EIGEN_DEVICE_FUNC inline Packet packetOp(const Packet& a) const { return internal::psqrt(a); }
};
template<typename Scalar>
struct functor_traits<scalar_sqrt_op<Scalar> >
{ enum {
Cost = 5 * NumTraits<Scalar>::MulCost,
template <typename Scalar>
struct functor_traits<scalar_sqrt_op<Scalar> > {
enum {
#if EIGEN_FAST_MATH
// The following numbers are based on the AVX implementation.
Cost = (sizeof(Scalar) == 8 ? 28
// 4 pmul, 1 pmadd, 3 other
: (3 * NumTraits<Scalar>::AddCost +
5 * NumTraits<Scalar>::MulCost)),
#else
// The following numbers are based on min VSQRT throughput on Haswell.
Cost = (sizeof(Scalar) == 8 ? 28 : 14),
#endif
PacketAccess = packet_traits<Scalar>::HasSqrt
};
};
@ -574,8 +622,24 @@ template<typename Scalar>
struct functor_traits<scalar_tanh_op<Scalar> >
{
enum {
Cost = 5 * NumTraits<Scalar>::MulCost,
PacketAccess = packet_traits<Scalar>::HasTanh
PacketAccess = packet_traits<Scalar>::HasTanh,
Cost =
(PacketAccess
// The following numbers are based on the AVX implementation,
#ifdef EIGEN_VECTORIZE_FMA
// Haswell can issue 2 add/mul/madd per cycle.
// 9 pmadd, 2 pmul, 1 div, 2 other
? (2 * NumTraits<Scalar>::AddCost + 6 * NumTraits<Scalar>::MulCost +
NumTraits<Scalar>::template Div<packet_traits<Scalar>::HasDiv>::Cost)
#else
? (11 * NumTraits<Scalar>::AddCost +
11 * NumTraits<Scalar>::MulCost +
NumTraits<Scalar>::template Div<packet_traits<Scalar>::HasDiv>::Cost)
#endif
// This number assumes a naive implementation of tanh
: (6 * NumTraits<Scalar>::AddCost + 3 * NumTraits<Scalar>::MulCost +
2 * NumTraits<Scalar>::template Div<packet_traits<Scalar>::HasDiv>::Cost +
functor_traits<scalar_exp_op<Scalar> >::Cost))
};
};