devtools/eigen
1
0
Fork 0
mirror of https://gitlab.com/libeigen/eigen.git synced 2026-04-10 11:34:33 +08:00
Code Issues Packages Projects Releases Wiki Activity

Changes to fast SQRT/RSQRT

Browse Source
This commit is contained in:
Rasmus Munk Larsen
2022-02-23 17:32:21 +00:00
committed by Antonio Sánchez
parent f9b7564faa
commit 8b875dbef1
4 changed files with 92 additions and 67 deletions
Download Patch File Download Diff File Expand all files Collapse all files

95
test/packetmath.cpp
View File

@@ -657,6 +657,72 @@ Scalar log2(Scalar x) {
return Scalar(EIGEN_LOG2E) * std::log(x);
}
// TODO(rmlarsen): Run this test for more functions.
template <bool Cond, typename Scalar, typename Packet, typename REF_FUNCTOR_T, typename FUNCTOR_T>
void packetmath_test_IEEE_corner_cases(const REF_FUNCTOR_T& ref_fun,
const FUNCTOR_T& fun) {
const int PacketSize = internal::unpacket_traits<Packet>::size;
const Scalar norm_min = (std::numeric_limits<Scalar>::min)();
constexpr int size = PacketSize * 2;
EIGEN_ALIGN_MAX Scalar data1[size];
EIGEN_ALIGN_MAX Scalar data2[size];
EIGEN_ALIGN_MAX Scalar ref[size];
for (int i = 0; i < size; ++i) {
data1[i] = data2[i] = ref[i] = Scalar(0);
}
// Test for subnormals.
if (std::numeric_limits<Scalar>::has_denorm == std::denorm_present) {
// When EIGEN_FAST_MATH is 1 we relax the conditions slightly, and allow the function
// to return the same value for subnormals as the reference would return for zero with
// the same sign as the input.
// TODO(rmlarsen): Currently we ignore the error that occurs if the input is equal to
// denorm_min. Specifically, the term 0.5*x in the Newton iteration for reciprocal sqrt
// underflows to zero and the result ends up a factor of 2 too large.
#if EIGEN_FAST_MATH
// TODO(rmlarsen): Remove factor of 2 here if we can fix the underflow in reciprocal sqrt.
data1[0] = Scalar(2) * std::numeric_limits<Scalar>::denorm_min();
data1[1] = -data1[0];
test::packet_helper<Cond, Packet> h;
h.store(data2, fun(h.load(data1)));
for (int i=0; i < 2; ++i) {
const Scalar ref_zero = ref_fun(data1[i] < 0 ? -Scalar(0) : Scalar(0));
const Scalar ref_val = ref_fun(data1[i]);
// TODO(rmlarsen): Remove debug cruft.
// std::cerr << "x = " << data1[i] << "y = " << data2[i] << ", ref_val = " << ref_val << ", ref_zero " << ref_zero << std::endl;
VERIFY(((std::isnan)(data2[i]) && (std::isnan)(ref_val)) || data2[i] == ref_zero ||
verifyIsApprox(data2[i], ref_val));
}
#else
data1[0] = std::numeric_limits<Scalar>::denorm_min();
data1[1] = -data1[0];
CHECK_CWISE1_IF(Cond, ref_fun, fun);
#endif
}
// Test for smallest normalized floats.
data1[0] = norm_min;
data1[1] = -data1[0];
CHECK_CWISE1_IF(Cond, ref_fun, fun);
// Test for zeros.
data1[0] = Scalar(0.0);
data1[1] = -data1[0];
CHECK_CWISE1_IF(Cond, ref_fun, fun);
// Test for infinities.
data1[0] = NumTraits<Scalar>::infinity();
data1[1] = -data1[0];
CHECK_CWISE1_IF(Cond, ref_fun, fun);
// Test for quiet NaNs.
data1[0] = std::numeric_limits<Scalar>::quiet_NaN();
data1[1] = -std::numeric_limits<Scalar>::quiet_NaN();
CHECK_CWISE1_IF(Cond, ref_fun, fun);
}
template <typename Scalar, typename Packet>
void packetmath_real() {
typedef internal::packet_traits<Scalar> PacketTraits;
@@ -947,33 +1013,8 @@ void packetmath_real() {
VERIFY((numext::isnan)(data2[1]));
}
if (PacketTraits::HasSqrt) {
data1[0] = Scalar(-1.0f);
if (std::numeric_limits<Scalar>::has_denorm == std::denorm_present) {
data1[1] = -std::numeric_limits<Scalar>::denorm_min();
} else {
data1[1] = -((std::numeric_limits<Scalar>::min)());
}
CHECK_CWISE1_IF(PacketTraits::HasSqrt, numext::sqrt, internal::psqrt);
data1[0] = Scalar(0.0f);
data1[1] = NumTraits<Scalar>::infinity();
CHECK_CWISE1_IF(PacketTraits::HasSqrt, numext::sqrt, internal::psqrt);
}
if (PacketTraits::HasRsqrt) {
data1[0] = Scalar(-1.0f);
if (std::numeric_limits<Scalar>::has_denorm == std::denorm_present) {
data1[1] = -std::numeric_limits<Scalar>::denorm_min();
} else {
data1[1] = -((std::numeric_limits<Scalar>::min)());
}
CHECK_CWISE1_IF(PacketTraits::HasRsqrt, numext::rsqrt, internal::prsqrt);
data1[0] = Scalar(0.0f);
data1[1] = NumTraits<Scalar>::infinity();
CHECK_CWISE1_IF(PacketTraits::HasRsqrt, numext::rsqrt, internal::prsqrt);
}
packetmath_test_IEEE_corner_cases<PacketTraits::HasSqrt, Scalar, Packet>(numext::sqrt<Scalar>, internal::psqrt<Packet>);
packetmath_test_IEEE_corner_cases<PacketTraits::HasRsqrt, Scalar, Packet>(numext::rsqrt<Scalar>, internal::prsqrt<Packet>);
// TODO(rmlarsen): Re-enable for half and bfloat16.
if (PacketTraits::HasCos