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powerpc: Apply r178139 from sparc64 to powerpc's fpu_sqrt

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This fix was committed less than 2 months after the code was forked into the
powerpc kernel.  Though powerpc doesn't use quad-precision floating point,
or need it for emulation, the changes do look like correctness fixes
overall.

This was found while trying to get fsqrt emulation working on e5500, which
does have a real FPU, but lacks the fsqrt instruction.  This is not the
complete fix, the rest is to be committed separately.

MFC after:	1 week
This commit is contained in:
jhibbits 2019-04-03 03:54:30 +00:00
parent c5f8d6c34f
commit acf1cd99b3
1 changed files with 5 additions and 5 deletions
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10
sys/powerpc/fpu/fpu_sqrt.c
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@ -353,7 +353,7 @@ fpu_sqrt(struct fpemu *fe)
FPU_SUBC(d0, x0, t0);
if ((int)d0 >= 0) {
x0 = d0, x1 = d1, x2 = d2;
q |= bit;
q = bit;
y1 |= 1; /* now t1, y1 are set in concrete */
}
ODD_DOUBLE;
@ -385,12 +385,12 @@ fpu_sqrt(struct fpemu *fe)
FPU_SUBCS(d2, x2, t2);
FPU_SUBCS(d1, x1, t1);
FPU_SUBC(d0, x0, t0);
ODD_DOUBLE;
if ((int)d0 >= 0) {
x0 = d0, x1 = d1, x2 = d2;
q |= bit;
x0 = d0, x1 = d1, x2 = d2; x3 = d3;
q = bit;
y2 |= 1;
}
ODD_DOUBLE;
while ((bit >>= 1) != 0) {
EVEN_DOUBLE;
t3 = y3 | bit;
@ -399,7 +399,7 @@ fpu_sqrt(struct fpemu *fe)
FPU_SUBCS(d1, x1, t1);
FPU_SUBC(d0, x0, t0);
if ((int)d0 >= 0) {
x0 = d0, x1 = d1, x2 = d2;
x0 = d0, x1 = d1, x2 = d2; x3 = d3;
q |= bit;
y3 |= bit << 1;
}