[Vm-dev] Integer comparition primitive failures on Cog

[Nicolas Cellier]

Apart another declaration bug (FP missing in function name...) there
is a killer :

StackToRegisterMappingCogit inherits silently from
SimpleStackBasedCogit>>#genSmallIntegerComparison:orDoubleComparison:
though it does not share the stack structure. This is fatal...

So an override StackToRegisterMappingCogit>>#genSmallIntegerComparison:orDoubleComparison:
is mandatory

Bad, bad inheritance...

Now compiling the VM again...

Nicolas


2011/5/3 Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com>:
> Hem, some declaration were missing... and the argument for FP
> comparison is tricky indeed...
> Sorry for the noise, but this is a direct live
>
> Nicolas
>
> 2011/5/3 Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com>:
>> And if  genSmallIntegerComparison:orDoubleComparison: is correct, then
>> usage shall be quite straight forward
>>
>> Nicolas
>>
>> 2011/5/3 Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com>:
>>> 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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