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Optimize various mathematical packet ops

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This commit is contained in:
Charles Schlosser
2023-01-28 01:34:26 +00:00
committed by Rasmus Munk Larsen
parent 1aa6dc2007
commit 0471e61b4c
3 changed files with 79 additions and 67 deletions
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38
Eigen/src/Core/GenericPacketMath.h
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@@ -1234,38 +1234,36 @@ EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Packet patan2(const Packet& y, const Packe
// for how corner cases are supposed to be handled according to the
// IEEE floating-point standard (IEC 60559).
// bend two rules:
// 1) inf / inf == 1
// 2) 0 / 0 == 0
// otherwise, evaluate atan(y/x) as usual and shift to the appropriate quadrant
const Packet kSignMask = pset1<Packet>(-Scalar(0));
const Packet kZero = pzero(x);
const Packet kOne = pset1<Packet>(Scalar(1));
const Packet kPi = pset1<Packet>(Scalar(EIGEN_PI));
const Packet kInf = pset1<Packet>(NumTraits<Scalar>::infinity());
const Packet abs_x = pabs(x);
const Packet x_is_zero = pcmp_eq(abs_x, kZero);
const Packet x_is_inf = pcmp_eq(abs_x, kInf);
const Packet x_has_signbit = psignbit(x);
const Packet abs_y = pabs(y);
const Packet y_is_zero = pcmp_eq(abs_y, kZero);
const Packet y_is_inf = pcmp_eq(abs_y, kInf);
const Packet y_signmask = pand(y, kSignMask);
const Packet shift = por(pand(x_has_signbit, kPi), y_signmask);
const Packet arg_signmask = pand(pxor(x, y), kSignMask);
const Packet shift = pxor(pand(x_has_signbit, kPi), y_signmask);
const Packet xor_xy = pxor(x, y);
// if x and y have the same absolute value, then xor(x,y) is zero
// make sure that neither x nor y is nan
// furthermore, xor(x,y) has the sign of the result
const Packet x_and_y_are_same = pand(pcmp_eq(xor_xy, kZero), pcmp_eq(x, x));
// more strictly, if x and y are both zero, then or(x,y) is zero
// this implicitly checks for nan
// the sign of or(x,y) is not meaningful
const Packet x_and_y_are_zero = pcmp_eq(por(x, y), kZero);
// bend two rules:
// 1) 0 / 0 == 0
// 2) inf / inf == 1
// otherwise, evaluate atan(y/x) as usual and shift to the appropriate quadrant
Packet arg = pdiv(abs_y, abs_x);
arg = pselect(pand(x_is_zero, y_is_zero), kZero, arg);
arg = pselect(pand(x_is_inf, y_is_inf), kOne, arg);
Packet arg = pdiv(y, x);
arg = pselect(x_and_y_are_same, por(kOne, xor_xy), arg);
arg = pselect(x_and_y_are_zero, xor_xy, arg);
Packet result = patan(arg);
result = pxor(result, arg_signmask);
result = padd(result, shift);
return result;
}