On 5/16/2016 3:33 AM, Andrei Alexandrescu wrote:
On 5/16/16 4:10 AM, Walter Bright wrote:
FP behavior has complex trade-offs with speed, accuracy, compatibility,
and size. There are no easy, obvious answers.
That's a fair statement. My understanding is also that 80-bit math is on the
wrong side of the tradeoff simply because it's disproportionately slow (again I
cite http://nicolas.limare.net/pro/notes/2014/12/12_arit_speed/). All modern
ALUs I looked at have 32- and 64-bit FP units only. I'm trying to figure why. --
I think it is slow because no effort has been put into speeding it up. All the
effort went into SIMD. The x87 FPU is a library module that is just plopped onto
the chip for compatibility.
The x87 register stack also sux because it's hard to generate good code for.
That didn't help.
