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Unify Altivec/VSX pexp(double) with default implementation
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Gael Guennebaud
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7655a8af6e
commit
b5695a6008
@ -9,10 +9,6 @@
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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/* The exp function of this file comes from
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* Julien Pommier's sse math library: http://gruntthepeon.free.fr/ssemath/
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*/
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#ifndef EIGEN_MATH_FUNCTIONS_ALTIVEC_H
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#define EIGEN_MATH_FUNCTIONS_ALTIVEC_H
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@ -22,35 +18,6 @@ namespace Eigen {
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namespace internal {
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#ifdef __VSX__
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static _EIGEN_DECLARE_CONST_Packet2d(1 , 1.0);
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static _EIGEN_DECLARE_CONST_Packet2d(2 , 2.0);
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static _EIGEN_DECLARE_CONST_Packet2d(half, 0.5);
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static _EIGEN_DECLARE_CONST_Packet2d(exp_hi, 709.437);
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static _EIGEN_DECLARE_CONST_Packet2d(exp_lo, -709.436139303);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_LOG2EF, 1.4426950408889634073599);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_p0, 1.26177193074810590878e-4);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_p1, 3.02994407707441961300e-2);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_p2, 9.99999999999999999910e-1);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q0, 3.00198505138664455042e-6);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q1, 2.52448340349684104192e-3);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q2, 2.27265548208155028766e-1);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_q3, 2.00000000000000000009e0);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_C1, 0.693145751953125);
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static _EIGEN_DECLARE_CONST_Packet2d(cephes_exp_C2, 1.42860682030941723212e-6);
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#ifdef __POWER8_VECTOR__
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static Packet2l p2l_1023 = { 1023, 1023 };
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static Packet2ul p2ul_52 = { 52, 52 };
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#endif
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#endif
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template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
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Packet4f plog<Packet4f>(const Packet4f& _x)
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{
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@ -92,93 +59,10 @@ Packet2d psqrt<Packet2d>(const Packet2d& x)
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return vec_sqrt(x);
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}
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// VSX support varies between different compilers and even different
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// versions of the same compiler. For gcc version >= 4.9.3, we can use
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// vec_cts to efficiently convert Packet2d to Packet2l. Otherwise, use
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// a slow version that works with older compilers.
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// Update: apparently vec_cts/vec_ctf intrinsics for 64-bit doubles
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// are buggy, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70963
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static inline Packet2l ConvertToPacket2l(const Packet2d& x) {
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#if EIGEN_GNUC_AT_LEAST(5, 4) || \
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(EIGEN_GNUC_AT(6, 1) && __GNUC_PATCHLEVEL__ >= 1)
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return vec_cts(x, 0); // TODO: check clang version.
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#else
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double tmp[2];
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memcpy(tmp, &x, sizeof(tmp));
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Packet2l l = { static_cast<long long>(tmp[0]),
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static_cast<long long>(tmp[1]) };
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return l;
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#endif
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}
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template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
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Packet2d pexp<Packet2d>(const Packet2d& _x)
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{
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Packet2d x = _x;
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Packet2d tmp, fx;
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Packet2l emm0;
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// clamp x
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x = pmax(pmin(x, p2d_exp_hi), p2d_exp_lo);
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/* express exp(x) as exp(g + n*log(2)) */
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fx = pmadd(x, p2d_cephes_LOG2EF, p2d_half);
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fx = pfloor(fx);
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tmp = pmul(fx, p2d_cephes_exp_C1);
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Packet2d z = pmul(fx, p2d_cephes_exp_C2);
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x = psub(x, tmp);
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x = psub(x, z);
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Packet2d x2 = pmul(x,x);
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Packet2d px = p2d_cephes_exp_p0;
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px = pmadd(px, x2, p2d_cephes_exp_p1);
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px = pmadd(px, x2, p2d_cephes_exp_p2);
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px = pmul (px, x);
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Packet2d qx = p2d_cephes_exp_q0;
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qx = pmadd(qx, x2, p2d_cephes_exp_q1);
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qx = pmadd(qx, x2, p2d_cephes_exp_q2);
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qx = pmadd(qx, x2, p2d_cephes_exp_q3);
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x = pdiv(px,psub(qx,px));
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x = pmadd(p2d_2,x,p2d_1);
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// build 2^n
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emm0 = ConvertToPacket2l(fx);
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#ifdef __POWER8_VECTOR__
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emm0 = vec_add(emm0, p2l_1023);
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emm0 = vec_sl(emm0, p2ul_52);
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#else
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// Code is a bit complex for POWER7. There is actually a
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// vec_xxsldi intrinsic but it is not supported by some gcc versions.
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// So we shift (52-32) bits and do a word swap with zeros.
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_EIGEN_DECLARE_CONST_Packet4i(1023, 1023);
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_EIGEN_DECLARE_CONST_Packet4i(20, 20); // 52 - 32
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Packet4i emm04i = reinterpret_cast<Packet4i>(emm0);
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emm04i = vec_add(emm04i, p4i_1023);
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emm04i = vec_sl(emm04i, reinterpret_cast<Packet4ui>(p4i_20));
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static const Packet16uc perm = {
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0x14, 0x15, 0x16, 0x17, 0x00, 0x01, 0x02, 0x03,
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0x1c, 0x1d, 0x1e, 0x1f, 0x08, 0x09, 0x0a, 0x0b };
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#ifdef _BIG_ENDIAN
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emm0 = reinterpret_cast<Packet2l>(vec_perm(p4i_ZERO, emm04i, perm));
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#else
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emm0 = reinterpret_cast<Packet2l>(vec_perm(emm04i, p4i_ZERO, perm));
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#endif
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#endif
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// Altivec's max & min operators just drop silent NaNs. Check NaNs in
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// inputs and return them unmodified.
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Packet2ul isnumber_mask = reinterpret_cast<Packet2ul>(vec_cmpeq(_x, _x));
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return vec_sel(_x, pmax(pmul(x, reinterpret_cast<Packet2d>(emm0)), _x),
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isnumber_mask);
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return pexp_double(_x);
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}
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#endif
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@ -1024,6 +1024,59 @@ template<> EIGEN_STRONG_INLINE Packet2d preverse(const Packet2d& a)
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}
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template<> EIGEN_STRONG_INLINE Packet2d pabs(const Packet2d& a) { return vec_abs(a); }
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// VSX support varies between different compilers and even different
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// versions of the same compiler. For gcc version >= 4.9.3, we can use
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// vec_cts to efficiently convert Packet2d to Packet2l. Otherwise, use
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// a slow version that works with older compilers.
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// Update: apparently vec_cts/vec_ctf intrinsics for 64-bit doubles
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// are buggy, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70963
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static inline Packet2l ConvertToPacket2l(const Packet2d& x) {
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#if EIGEN_GNUC_AT_LEAST(5, 4) || \
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(EIGEN_GNUC_AT(6, 1) && __GNUC_PATCHLEVEL__ >= 1)
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return vec_cts(x, 0); // TODO: check clang version.
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#else
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double tmp[2];
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memcpy(tmp, &x, sizeof(tmp));
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Packet2l l = { static_cast<long long>(tmp[0]),
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static_cast<long long>(tmp[1]) };
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return l;
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#endif
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}
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template<> EIGEN_STRONG_INLINE Packet2d pldexp<Packet2d>(const Packet2d& a, const Packet2d& exponent) {
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// build 2^n
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Packet2l emm0 = ConvertToPacket2l(exponent);
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#ifdef __POWER8_VECTOR__
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const Packet2l p2l_1023 = { 1023, 1023 };
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const Packet2ul p2ul_52 = { 52, 52 };
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emm0 = vec_add(emm0, p2l_1023);
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emm0 = vec_sl(emm0, p2ul_52);
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#else
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// Code is a bit complex for POWER7. There is actually a
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// vec_xxsldi intrinsic but it is not supported by some gcc versions.
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// So we shift (52-32) bits and do a word swap with zeros.
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const Packet4i p4i_1023 = pset1<Packet4i>(1023);
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const Packet4i p4i_20 = pset1<Packet4i>(20); // 52 - 32
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Packet4i emm04i = reinterpret_cast<Packet4i>(emm0);
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emm04i = vec_add(emm04i, p4i_1023);
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emm04i = vec_sl(emm04i, reinterpret_cast<Packet4ui>(p4i_20));
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static const Packet16uc perm = {
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0x14, 0x15, 0x16, 0x17, 0x00, 0x01, 0x02, 0x03,
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0x1c, 0x1d, 0x1e, 0x1f, 0x08, 0x09, 0x0a, 0x0b };
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#ifdef _BIG_ENDIAN
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emm0 = reinterpret_cast<Packet2l>(vec_perm(p4i_ZERO, emm04i, perm));
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#else
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emm0 = reinterpret_cast<Packet2l>(vec_perm(emm04i, p4i_ZERO, perm));
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#endif
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#endif
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return pmul(a, reinterpret_cast<Packet2d>(emm0));
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}
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template<> EIGEN_STRONG_INLINE double predux<Packet2d>(const Packet2d& a)
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{
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Packet2d b, sum;
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