glibc/sysdeps/ieee754/ldbl-128/e_powl.c
Wilco Dijkstra 220622dde5 Add libm_alias_finite for _finite symbols
This patch adds a new macro, libm_alias_finite, to define all _finite
symbol.  It sets all _finite symbol as compat symbol based on its first
version (obtained from the definition at built generated first-versions.h).

The <fn>f128_finite symbols were introduced in GLIBC 2.26 and so need
special treatment in code that is shared between long double and float128.
It is done by adding a list, similar to internal symbol redifinition,
on sysdeps/ieee754/float128/float128_private.h.

Alpha also needs some tricky changes to ensure we still emit 2 compat
symbols for sqrt(f).

Passes buildmanyglibc.

Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2020-01-03 10:02:04 -03:00

454 lines
12 KiB
C

/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/* Expansions and modifications for 128-bit long double are
Copyright (C) 2001 Stephen L. Moshier <moshier@na-net.ornl.gov>
and are incorporated herein by permission of the author. The author
reserves the right to distribute this material elsewhere under different
copying permissions. These modifications are distributed here under
the following terms:
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see
<https://www.gnu.org/licenses/>. */
/* __ieee754_powl(x,y) return x**y
*
* n
* Method: Let x = 2 * (1+f)
* 1. Compute and return log2(x) in two pieces:
* log2(x) = w1 + w2,
* where w1 has 113-53 = 60 bit trailing zeros.
* 2. Perform y*log2(x) = n+y' by simulating muti-precision
* arithmetic, where |y'|<=0.5.
* 3. Return x**y = 2**n*exp(y'*log2)
*
* Special cases:
* 1. (anything) ** 0 is 1
* 2. (anything) ** 1 is itself
* 3. (anything) ** NAN is NAN
* 4. NAN ** (anything except 0) is NAN
* 5. +-(|x| > 1) ** +INF is +INF
* 6. +-(|x| > 1) ** -INF is +0
* 7. +-(|x| < 1) ** +INF is +0
* 8. +-(|x| < 1) ** -INF is +INF
* 9. +-1 ** +-INF is NAN
* 10. +0 ** (+anything except 0, NAN) is +0
* 11. -0 ** (+anything except 0, NAN, odd integer) is +0
* 12. +0 ** (-anything except 0, NAN) is +INF
* 13. -0 ** (-anything except 0, NAN, odd integer) is +INF
* 14. -0 ** (odd integer) = -( +0 ** (odd integer) )
* 15. +INF ** (+anything except 0,NAN) is +INF
* 16. +INF ** (-anything except 0,NAN) is +0
* 17. -INF ** (anything) = -0 ** (-anything)
* 18. (-anything) ** (integer) is (-1)**(integer)*(+anything**integer)
* 19. (-anything except 0 and inf) ** (non-integer) is NAN
*
*/
#include <math.h>
#include <math-barriers.h>
#include <math_private.h>
#include <libm-alias-finite.h>
static const _Float128 bp[] = {
1,
L(1.5),
};
/* log_2(1.5) */
static const _Float128 dp_h[] = {
0.0,
L(5.8496250072115607565592654282227158546448E-1)
};
/* Low part of log_2(1.5) */
static const _Float128 dp_l[] = {
0.0,
L(1.0579781240112554492329533686862998106046E-16)
};
static const _Float128 zero = 0,
one = 1,
two = 2,
two113 = L(1.0384593717069655257060992658440192E34),
huge = L(1.0e3000),
tiny = L(1.0e-3000);
/* 3/2 log x = 3 z + z^3 + z^3 (z^2 R(z^2))
z = (x-1)/(x+1)
1 <= x <= 1.25
Peak relative error 2.3e-37 */
static const _Float128 LN[] =
{
L(-3.0779177200290054398792536829702930623200E1),
L(6.5135778082209159921251824580292116201640E1),
L(-4.6312921812152436921591152809994014413540E1),
L(1.2510208195629420304615674658258363295208E1),
L(-9.9266909031921425609179910128531667336670E-1)
};
static const _Float128 LD[] =
{
L(-5.129862866715009066465422805058933131960E1),
L(1.452015077564081884387441590064272782044E2),
L(-1.524043275549860505277434040464085593165E2),
L(7.236063513651544224319663428634139768808E1),
L(-1.494198912340228235853027849917095580053E1)
/* 1.0E0 */
};
/* exp(x) = 1 + x - x / (1 - 2 / (x - x^2 R(x^2)))
0 <= x <= 0.5
Peak relative error 5.7e-38 */
static const _Float128 PN[] =
{
L(5.081801691915377692446852383385968225675E8),
L(9.360895299872484512023336636427675327355E6),
L(4.213701282274196030811629773097579432957E4),
L(5.201006511142748908655720086041570288182E1),
L(9.088368420359444263703202925095675982530E-3),
};
static const _Float128 PD[] =
{
L(3.049081015149226615468111430031590411682E9),
L(1.069833887183886839966085436512368982758E8),
L(8.259257717868875207333991924545445705394E5),
L(1.872583833284143212651746812884298360922E3),
/* 1.0E0 */
};
static const _Float128
/* ln 2 */
lg2 = L(6.9314718055994530941723212145817656807550E-1),
lg2_h = L(6.9314718055994528622676398299518041312695E-1),
lg2_l = L(2.3190468138462996154948554638754786504121E-17),
ovt = L(8.0085662595372944372e-0017),
/* 2/(3*log(2)) */
cp = L(9.6179669392597560490661645400126142495110E-1),
cp_h = L(9.6179669392597555432899980587535537779331E-1),
cp_l = L(5.0577616648125906047157785230014751039424E-17);
_Float128
__ieee754_powl (_Float128 x, _Float128 y)
{
_Float128 z, ax, z_h, z_l, p_h, p_l;
_Float128 y1, t1, t2, r, s, sgn, t, u, v, w;
_Float128 s2, s_h, s_l, t_h, t_l, ay;
int32_t i, j, k, yisint, n;
uint32_t ix, iy;
int32_t hx, hy;
ieee854_long_double_shape_type o, p, q;
p.value = x;
hx = p.parts32.w0;
ix = hx & 0x7fffffff;
q.value = y;
hy = q.parts32.w0;
iy = hy & 0x7fffffff;
/* y==zero: x**0 = 1 */
if ((iy | q.parts32.w1 | q.parts32.w2 | q.parts32.w3) == 0
&& !issignaling (x))
return one;
/* 1.0**y = 1; -1.0**+-Inf = 1 */
if (x == one && !issignaling (y))
return one;
if (x == -1 && iy == 0x7fff0000
&& (q.parts32.w1 | q.parts32.w2 | q.parts32.w3) == 0)
return one;
/* +-NaN return x+y */
if ((ix > 0x7fff0000)
|| ((ix == 0x7fff0000)
&& ((p.parts32.w1 | p.parts32.w2 | p.parts32.w3) != 0))
|| (iy > 0x7fff0000)
|| ((iy == 0x7fff0000)
&& ((q.parts32.w1 | q.parts32.w2 | q.parts32.w3) != 0)))
return x + y;
/* determine if y is an odd int when x < 0
* yisint = 0 ... y is not an integer
* yisint = 1 ... y is an odd int
* yisint = 2 ... y is an even int
*/
yisint = 0;
if (hx < 0)
{
if (iy >= 0x40700000) /* 2^113 */
yisint = 2; /* even integer y */
else if (iy >= 0x3fff0000) /* 1.0 */
{
if (floorl (y) == y)
{
z = 0.5 * y;
if (floorl (z) == z)
yisint = 2;
else
yisint = 1;
}
}
}
/* special value of y */
if ((q.parts32.w1 | q.parts32.w2 | q.parts32.w3) == 0)
{
if (iy == 0x7fff0000) /* y is +-inf */
{
if (((ix - 0x3fff0000) | p.parts32.w1 | p.parts32.w2 | p.parts32.w3)
== 0)
return y - y; /* +-1**inf is NaN */
else if (ix >= 0x3fff0000) /* (|x|>1)**+-inf = inf,0 */
return (hy >= 0) ? y : zero;
else /* (|x|<1)**-,+inf = inf,0 */
return (hy < 0) ? -y : zero;
}
if (iy == 0x3fff0000)
{ /* y is +-1 */
if (hy < 0)
return one / x;
else
return x;
}
if (hy == 0x40000000)
return x * x; /* y is 2 */
if (hy == 0x3ffe0000)
{ /* y is 0.5 */
if (hx >= 0) /* x >= +0 */
return sqrtl (x);
}
}
ax = fabsl (x);
/* special value of x */
if ((p.parts32.w1 | p.parts32.w2 | p.parts32.w3) == 0)
{
if (ix == 0x7fff0000 || ix == 0 || ix == 0x3fff0000)
{
z = ax; /*x is +-0,+-inf,+-1 */
if (hy < 0)
z = one / z; /* z = (1/|x|) */
if (hx < 0)
{
if (((ix - 0x3fff0000) | yisint) == 0)
{
z = (z - z) / (z - z); /* (-1)**non-int is NaN */
}
else if (yisint == 1)
z = -z; /* (x<0)**odd = -(|x|**odd) */
}
return z;
}
}
/* (x<0)**(non-int) is NaN */
if (((((uint32_t) hx >> 31) - 1) | yisint) == 0)
return (x - x) / (x - x);
/* sgn (sign of result -ve**odd) = -1 else = 1 */
sgn = one;
if (((((uint32_t) hx >> 31) - 1) | (yisint - 1)) == 0)
sgn = -one; /* (-ve)**(odd int) */
/* |y| is huge.
2^-16495 = 1/2 of smallest representable value.
If (1 - 1/131072)^y underflows, y > 1.4986e9 */
if (iy > 0x401d654b)
{
/* if (1 - 2^-113)^y underflows, y > 1.1873e38 */
if (iy > 0x407d654b)
{
if (ix <= 0x3ffeffff)
return (hy < 0) ? huge * huge : tiny * tiny;
if (ix >= 0x3fff0000)
return (hy > 0) ? huge * huge : tiny * tiny;
}
/* over/underflow if x is not close to one */
if (ix < 0x3ffeffff)
return (hy < 0) ? sgn * huge * huge : sgn * tiny * tiny;
if (ix > 0x3fff0000)
return (hy > 0) ? sgn * huge * huge : sgn * tiny * tiny;
}
ay = y > 0 ? y : -y;
if (ay < 0x1p-128)
y = y < 0 ? -0x1p-128 : 0x1p-128;
n = 0;
/* take care subnormal number */
if (ix < 0x00010000)
{
ax *= two113;
n -= 113;
o.value = ax;
ix = o.parts32.w0;
}
n += ((ix) >> 16) - 0x3fff;
j = ix & 0x0000ffff;
/* determine interval */
ix = j | 0x3fff0000; /* normalize ix */
if (j <= 0x3988)
k = 0; /* |x|<sqrt(3/2) */
else if (j < 0xbb67)
k = 1; /* |x|<sqrt(3) */
else
{
k = 0;
n += 1;
ix -= 0x00010000;
}
o.value = ax;
o.parts32.w0 = ix;
ax = o.value;
/* compute s = s_h+s_l = (x-1)/(x+1) or (x-1.5)/(x+1.5) */
u = ax - bp[k]; /* bp[0]=1.0, bp[1]=1.5 */
v = one / (ax + bp[k]);
s = u * v;
s_h = s;
o.value = s_h;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
s_h = o.value;
/* t_h=ax+bp[k] High */
t_h = ax + bp[k];
o.value = t_h;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
t_h = o.value;
t_l = ax - (t_h - bp[k]);
s_l = v * ((u - s_h * t_h) - s_h * t_l);
/* compute log(ax) */
s2 = s * s;
u = LN[0] + s2 * (LN[1] + s2 * (LN[2] + s2 * (LN[3] + s2 * LN[4])));
v = LD[0] + s2 * (LD[1] + s2 * (LD[2] + s2 * (LD[3] + s2 * (LD[4] + s2))));
r = s2 * s2 * u / v;
r += s_l * (s_h + s);
s2 = s_h * s_h;
t_h = 3.0 + s2 + r;
o.value = t_h;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
t_h = o.value;
t_l = r - ((t_h - 3.0) - s2);
/* u+v = s*(1+...) */
u = s_h * t_h;
v = s_l * t_h + t_l * s;
/* 2/(3log2)*(s+...) */
p_h = u + v;
o.value = p_h;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
p_h = o.value;
p_l = v - (p_h - u);
z_h = cp_h * p_h; /* cp_h+cp_l = 2/(3*log2) */
z_l = cp_l * p_h + p_l * cp + dp_l[k];
/* log2(ax) = (s+..)*2/(3*log2) = n + dp_h + z_h + z_l */
t = (_Float128) n;
t1 = (((z_h + z_l) + dp_h[k]) + t);
o.value = t1;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
t1 = o.value;
t2 = z_l - (((t1 - t) - dp_h[k]) - z_h);
/* split up y into y1+y2 and compute (y1+y2)*(t1+t2) */
y1 = y;
o.value = y1;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
y1 = o.value;
p_l = (y - y1) * t1 + y * t2;
p_h = y1 * t1;
z = p_l + p_h;
o.value = z;
j = o.parts32.w0;
if (j >= 0x400d0000) /* z >= 16384 */
{
/* if z > 16384 */
if (((j - 0x400d0000) | o.parts32.w1 | o.parts32.w2 | o.parts32.w3) != 0)
return sgn * huge * huge; /* overflow */
else
{
if (p_l + ovt > z - p_h)
return sgn * huge * huge; /* overflow */
}
}
else if ((j & 0x7fffffff) >= 0x400d01b9) /* z <= -16495 */
{
/* z < -16495 */
if (((j - 0xc00d01bc) | o.parts32.w1 | o.parts32.w2 | o.parts32.w3)
!= 0)
return sgn * tiny * tiny; /* underflow */
else
{
if (p_l <= z - p_h)
return sgn * tiny * tiny; /* underflow */
}
}
/* compute 2**(p_h+p_l) */
i = j & 0x7fffffff;
k = (i >> 16) - 0x3fff;
n = 0;
if (i > 0x3ffe0000)
{ /* if |z| > 0.5, set n = [z+0.5] */
n = floorl (z + L(0.5));
t = n;
p_h -= t;
}
t = p_l + p_h;
o.value = t;
o.parts32.w3 = 0;
o.parts32.w2 &= 0xf8000000;
t = o.value;
u = t * lg2_h;
v = (p_l - (t - p_h)) * lg2 + t * lg2_l;
z = u + v;
w = v - (z - u);
/* exp(z) */
t = z * z;
u = PN[0] + t * (PN[1] + t * (PN[2] + t * (PN[3] + t * PN[4])));
v = PD[0] + t * (PD[1] + t * (PD[2] + t * (PD[3] + t)));
t1 = z - t * u / v;
r = (z * t1) / (t1 - two) - (w + z * w);
z = one - (r - z);
o.value = z;
j = o.parts32.w0;
j += (n << 16);
if ((j >> 16) <= 0)
{
z = __scalbnl (z, n); /* subnormal output */
_Float128 force_underflow = z * z;
math_force_eval (force_underflow);
}
else
{
o.parts32.w0 = j;
z = o.value;
}
return sgn * z;
}
libm_alias_finite (__ieee754_powl, __powl)