for floating point operations, reuse the return register
on the right hand side if it has higher complex number
than the left hand side to conserve registers.
this makes the following code compile, that was previously
run out of floating point register:
float
f(float r[15])
{
return (r[0] + (r[1] * (r[2] + r[3] * (r[4] + r[5] * (r[6] + r[7] * (r[8] + r[9] * (r[10] + r[11] * (r[12] + r[13] * r[14]))))))));
}
the downside is that this produces extra move operations.
e6634fbd0c