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8304028: Port fdlibm IEEEremainder to Java

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Reviewed-by: bpb
This commit is contained in:
Joe Darcy 2023-03-31 19:48:03 +00:00
parent a565be4dc5
commit abfb900829
7 changed files with 716 additions and 129 deletions
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192
src/java.base/share/classes/java/lang/FdLibm.java
View file

@ -3301,4 +3301,196 @@ class FdLibm {
return (jx >= 0)? z: -z;
}
}
static final class IEEEremainder {
private IEEEremainder() {throw new UnsupportedOperationException();}
static double compute(double x, double p) {
int hx, hp;
/*unsigned*/ int sx, lx, lp;
double p_half;
hx = __HI(x); // high word of x
lx = __LO(x); // low word of x
hp = __HI(p); // high word of p
lp = __LO(p); // low word of p
sx = hx & 0x8000_0000;
hp &= 0x7fff_ffff;
hx &= 0x7fff_ffff;
// purge off exception values
if ((hp | lp) == 0) {// p = 0
return (x*p)/(x*p);
}
if ((hx >= 0x7ff0_0000) || // not finite
((hp >= 0x7ff0_0000) && // p is NaN
(((hp - 0x7ff0_0000) | lp) != 0)))
return (x*p)/(x*p);
if (hp <= 0x7fdf_ffff) { // now x < 2p
x = __ieee754_fmod(x, p + p);
}
if (((hx - hp) | (lx - lp)) == 0) {
return 0.0*x;
}
x = Math.abs(x);
p = Math.abs(p);
if (hp < 0x0020_0000) {
if (x + x > p) {
x -= p;
if (x + x >= p) {
x -= p;
}
}
} else {
p_half = 0.5*p;
if (x > p_half) {
x -= p;
if (x >= p_half) {
x -= p;
}
}
}
return __HI(x, __HI(x)^sx);
}
private static double __ieee754_fmod(double x, double y) {
int n, hx, hy, hz, ix, iy, sx;
/*unsigned*/ int lx, ly, lz;
hx = __HI(x); // high word of x
lx = __LO(x); // low word of x
hy = __HI(y); // high word of y
ly = __LO(y); // low word of y
sx = hx & 0x8000_0000; // sign of x
hx ^= sx; // |x|
hy &= 0x7fff_ffff; // |y|
// purge off exception values
if ((hy | ly) == 0 || (hx >= 0x7ff0_0000)|| // y = 0, or x not finite
((hy | ((ly | -ly) >>> 31)) > 0x7ff0_0000)) // or y is NaN, unsigned shift
return (x*y)/(x*y);
if (hx <= hy) {
if ((hx < hy) || (Integer.compareUnsigned(lx, ly) < 0)) { // |x| < |y| return x
return x;
}
if (lx == ly) {
return signedZero(sx); // |x| = |y| return x*0
}
}
ix = ilogb(hx, lx);
iy = ilogb(hy, ly);
// set up {hx, lx}, {hy, ly} and align y to x
if (ix >= -1022)
hx = 0x0010_0000 | (0x000f_ffff & hx);
else { // subnormal x, shift x to normal
n = -1022 - ix;
if (n <= 31) {
hx = (hx << n) | (lx >>> (32 - n)); // unsigned shift
lx <<= n;
} else {
hx = lx << (n - 32);
lx = 0;
}
}
if (iy >= -1022)
hy = 0x0010_0000 | (0x000f_ffff & hy);
else { // subnormal y, shift y to normal
n = -1022 - iy;
if (n <= 31) {
hy = (hy << n)|(ly >>> (32 - n)); // unsigned shift
ly <<= n;
} else {
hy = ly << (n - 32);
ly = 0;
}
}
// fix point fmod
n = ix - iy;
while (n-- != 0) {
hz = hx - hy;
lz = lx - ly;
if (Integer.compareUnsigned(lx, ly) < 0) {
hz -= 1;
}
if (hz < 0){
hx = hx + hx +(lx >>> 31); // unsigned shift
lx = lx + lx;
} else {
if ((hz | lz) == 0) { // return sign(x)*0
return signedZero(sx);
}
hx = hz + hz + (lz >>> 31); // unsigned shift
lx = lz + lz;
}
}
hz = hx - hy;
lz = lx - ly;
if (Integer.compareUnsigned(lx, ly) < 0) {
hz -= 1;
}
if (hz >= 0) {
hx = hz;
lx = lz;
}
// convert back to floating value and restore the sign
if ((hx | lx) == 0) { // return sign(x)*0
return signedZero(sx);
}
while (hx < 0x0010_0000) { // normalize x
hx = hx + hx + (lx >>> 31); // unsigned shift
lx = lx + lx;
iy -= 1;
}
if (iy >= -1022) { // normalize output
hx = ((hx - 0x0010_0000) | ((iy + 1023) << 20));
x = __HI_LO(hx | sx, lx);
} else { // subnormal output
n = -1022 - iy;
if (n <= 20) {
lx = (lx >>> n)|(/*(unsigned)*/hx << (32 - n)); // unsigned shift
hx >>= n;
} else if (n <= 31) {
lx = (hx << (32 - n))|(lx >>> n); // unsigned shift
hx = sx;
} else {
lx = hx >>(n - 32);
hx = sx;
}
x = __HI_LO(hx | sx, lx);
x *= 1.0; // create necessary signal
}
return x; // exact output
}
/*
* Return a double zero with the same sign as the int argument.
*/
private static double signedZero(int sign) {
return +0.0 * ( (double)sign);
}
private static int ilogb(int hz, int lz) {
int iz, i;
if (hz < 0x0010_0000) { // subnormal z
if (hz == 0) {
for (iz = -1043, i = lz; i > 0; i <<= 1) {
iz -= 1;
}
} else {
for (iz = -1022, i = (hz << 11); i > 0; i <<= 1) {
iz -= 1;
}
}
} else {
iz = (hz >> 20) - 1023;
}
return iz;
}
}
}

4
src/java.base/share/classes/java/lang/StrictMath.java
View file

@ -369,7 +369,9 @@ public final class StrictMath {
* @return the remainder when {@code f1} is divided by
* {@code f2}.
*/
public static native double IEEEremainder(double f1, double f2);
public static double IEEEremainder(double f1, double f2) {
return FdLibm.IEEEremainder.compute(f1, f2);
}
/**
* Returns the smallest (closest to negative infinity)