Always false float comparisons

[Andrei Alexandrescu via Digitalmars-d]

On 5/16/16 7:53 AM, Walter Bright wrote:
> 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.

That makes sense.

> The x87 register stack also sux because it's hard to generate good code
> for. That didn't help.

It may indeed be a bummer but it's the way it is. So we should act 
accordingly. -- Andrei