Always false float comparisons

[Walter Bright via Digitalmars-d]

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.