[Vm-dev] Integer comparition primitive failures on Cog

[Nicolas Cellier]

I always refused to learn x86 assembler, but by code imitation I can
give my own try in attachment.
Note that I did not use the trick to invert FP comparison operands
since this does not seem necessary.

Nicolas


2011/5/2 Eliot Miranda <eliot.miranda at gmail.com>:
>
> Hi Henrik,
>
> Eliot (phone)
>
> On May 2, 2011, at 3:12 AM, Henrik Sperre Johansen <henrik.s.johansen at veloxit.no> wrote:
>
>> As per my comment on the recent Morphic performance graphs,(http://blog.openinworld.com/2011/03/morphic-flavour-performance/#comment-59) on a Cog VM these primitives fail with a Float parameter, which leads to a huge performance hit when comparing Ints to Floats by doing silly things in the fallback code.
>>
>> Cog:
>> [1 to: 2000000 do: [:i |
>>    i < 2354.234.
>>    i <= 2354.234.
>>    i >= 2354.234.
>>     i > 2354.234.]] timeToRun 26594
>>
>> Trunk:
>> [1 to: 2000000 do: [:i |
>>    i < 2354.234.
>>    i <= 2354.234.
>>    i >= 2354.234.
>>     i > 2354.234.]] timeToRun 229
>>
>> Should this be changed in the VM,
>
> I think so.  When I first wrote the SmallInteger translated prims I hadn't yet written the JIT support for floats and so couldn't write int/float comparison.  Now all the support is there and it should be straight-forward.  Do you fancy trying to write this yourself?  Would be a fun exercise.  Let me know and I can hand-hold with using the simulator.
>
>
> Best
> Eliot (phone)
>
>
>> or is the difference for pure int/int comparition large enough that we should instead change
>> Float>>adaptToInteger: andCompare:
>> to use the corresponding comparitions with Float as receiver, which does work?
>> That's still slower than trunk in my image, but quite a bit better, above test takes about 1s.
>>
>> Cheers,
>> Henry
>
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