🚀 go-pugleaf

I count 16 instructions used to perform the double -> int conversion on
the RS/6000:
	4 are used for +/- checking and compensation.
	4 are used for range checking.
	4 are used to manipulate the FP status register.
	4 are used to truncate and move the number to an integer register.

The cc compiler calls a subroutine to perform the conversion, so the
actual number of instructions required in C is larger.


As long as I'm wasting bandwidth on this, here is the code sequence:
The double value is initially in f1.  r2 and r6 point to memory containing
constants.  c6 and c0 are condition code registers.

        lfs     f0,12(r2)       f0 <- 0.0
        fcmpu   c6,f1,f0        c6 <- f1 ? f0           [X >= 0]
        l       r6,16(r2)       r6 <- 0x10000778
        fabs    f5,f1           f5 <- abs( f1 )
        lfd     f2,8(r6)        f2 <- 2^31
        mffs    f4              f4 <- floating status
        fcmpu   c0,f5,f2        c0 <- f5 ? f2
        lfd     f3,0(r6)        f3 <- 4512395720392704.0
        bc      12,24,L2        branch if c6 less than [X negative]
        mtfsb1  30              set floating status bit 30
        mtfsb1  31              (re)set floating status bit 31
        fa      f6,f1,f3        f6 <- f1 + f3 [truncates value]
        stfd    f6,-8(r1)       mem <- f6
        mtfsf   1,f4            floating status <- f4
        bc      4,0,L3          branch if c0 greater than [X out of range]
        l       r3,-4(r1)       r3 <- mem

If the double is negative a similar sequence of instructions is executed,
except that bit 31 of the status register is reset rather than set.

-- Bryce