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Use bit_cast to create -0.0 for floating point types to avoid compiler optimization changing sign with --ffast-math enabled.

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This commit is contained in:
Rasmus Munk Larsen
2021-06-10 19:18:50 -07:00
parent f64b2954c7
commit fc87e2cbaa
6 changed files with 16 additions and 12 deletions
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3
Eigen/src/Core/arch/AltiVec/PacketMath.h
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@@ -2260,7 +2260,8 @@ static Packet2ul p2ul_SIGN = { 0x8000000000000000ull, 0x8000000000000000ull };
static Packet2ul p2ul_PREV0DOT5 = { 0x3FDFFFFFFFFFFFFFull, 0x3FDFFFFFFFFFFFFFull };
static Packet2d p2d_ONE = { 1.0, 1.0 };
static Packet2d p2d_ZERO = reinterpret_cast<Packet2d>(p4f_ZERO);
static Packet2d p2d_MZERO = { -0.0, -0.0 };
static Packet2d p2d_MZERO = { numext::bit_cast<double>(0x8000000000000000ull),
numext::bit_cast<double>(0x8000000000000000ull) };
#ifdef _BIG_ENDIAN
static Packet2d p2d_COUNTDOWN = reinterpret_cast<Packet2d>(vec_sld(reinterpret_cast<Packet4f>(p2d_ZERO), reinterpret_cast<Packet4f>(p2d_ONE), 8));

3
Eigen/src/Core/arch/Default/GenericPacketMathFunctions.h
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@@ -839,7 +839,8 @@ Packet psqrt_complex(const Packet& a) {
// Step 4. Compute solution for inputs with negative real part:
// [|eta0|, sign(y0)*rho0, |eta1|, sign(y1)*rho1]
const RealPacket cst_imag_sign_mask = pset1<Packet>(Scalar(RealScalar(0.0), RealScalar(-0.0))).v;
const RealScalar neg_zero = RealScalar(numext::bit_cast<float>(0x80000000u));
const RealPacket cst_imag_sign_mask = pset1<Packet>(Scalar(RealScalar(0.0), neg_zero)).v;
RealPacket imag_signs = pand(a.v, cst_imag_sign_mask);
Packet negative_real_result;
// Notice that rho is positive, so taking it's absolute value is a noop.

6
Eigen/src/Core/arch/NEON/PacketMath.h
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@@ -866,12 +866,12 @@ template<> EIGEN_STRONG_INLINE Packet2ul psub<Packet2ul>(const Packet2ul& a, con
template<> EIGEN_STRONG_INLINE Packet2f pxor<Packet2f>(const Packet2f& a, const Packet2f& b);
template<> EIGEN_STRONG_INLINE Packet2f paddsub<Packet2f>(const Packet2f& a, const Packet2f & b) {
Packet2f mask = {-0.0f, 0.0f};
Packet2f mask = {numext::bit_cast<float>(0x80000000u), 0.0f};
return padd(a, pxor(mask, b));
}
template<> EIGEN_STRONG_INLINE Packet4f pxor<Packet4f>(const Packet4f& a, const Packet4f& b);
template<> EIGEN_STRONG_INLINE Packet4f paddsub<Packet4f>(const Packet4f& a, const Packet4f& b) {
Packet4f mask = {-0.0f, 0.0f, -0.0f, 0.0f};
Packet4f mask = {numext::bit_cast<float>(0x80000000u), 0.0f, numext::bit_cast<float>(0x80000000u), 0.0f};
return padd(a, pxor(mask, b));
}
@@ -3751,7 +3751,7 @@ template<> EIGEN_STRONG_INLINE Packet2d psub<Packet2d>(const Packet2d& a, const
template<> EIGEN_STRONG_INLINE Packet2d pxor<Packet2d>(const Packet2d& , const Packet2d& );
template<> EIGEN_STRONG_INLINE Packet2d paddsub<Packet2d>(const Packet2d& a, const Packet2d& b){
const Packet2d mask = {-0.0,0.0};
const Packet2d mask = {numext::bit_cast<double>(0x8000000000000000ull),0.0};
return padd(a, pxor(mask, b));
}

5
Eigen/src/Core/arch/ZVector/PacketMath.h
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@@ -94,8 +94,9 @@ static _EIGEN_DECLARE_CONST_FAST_Packet2d(ZERO, 0);
static _EIGEN_DECLARE_CONST_FAST_Packet2l(ZERO, 0);
static _EIGEN_DECLARE_CONST_FAST_Packet2l(ONE, 1);
static Packet2d p2d_ONE = { 1.0, 1.0 };
static Packet2d p2d_ZERO_ = { -0.0, -0.0 };
static Packet2d p2d_ONE = { 1.0, 1.0 };
static Packet2d p2d_ZERO_ = { numext::bit_cast<double>0x8000000000000000ull),
numext::bit_cast<double>0x8000000000000000ull) };
#if !defined(__ARCH__) || (defined(__ARCH__) && __ARCH__ >= 12)
#define _EIGEN_DECLARE_CONST_FAST_Packet4f(NAME,X) \