[Vm-dev] pluginizing Galois Fields

Eliot Miranda eliot.miranda at gmail.com
Sat Dec 19 07:09:39 UTC 2015


Hi Robert,

> On Dec 18, 2015, at 9:51 PM, Robert Withers <robert.w.withers at gmail.com> wrote:
> 
> Eliot, what does Sista do and how is that accomplished?

Run-time adaptive optimisation via an SSA-based image-level bytecode-to-bytecode inlining compiler.  See

http://www.mirandabanda.org/cogblog/on-line-papers-and-presentations/


> It sounds like a next level kind of system. Does it compare to what other JITs are doing in various VMs?

Yes it does. Clément recently attended a workshop at Google and found that Sista is very similar in the kinds of optimisations it performs to V8 and Dart.  The key research funding will be how close the performance of targeting stack-oriented bytecode that the Cog JIT converts to register-based code can be made to JITs that directly target register-based machine code.

_,,,^..^,,,_ (phone)

> 
> thank you,
> robert
> 
> .    ..               ...                                                 ^,^
> 
> 
> 
>> On 12/18/2015 11:11 PM, Eliot Miranda wrote:
>>  Further, please keep the original Smalltalk non-primitive implementation around do that when we deliver Sista we can see how well we stack up against C.
>> 
>> _,,,^..^,,,_ (phone)
>> 
>>> On Dec 18, 2015, at 5:59 PM, David T. Lewis <lewis at mail.msen.com> wrote:
>>> 
>>> 
>>>>> On Fri, Dec 18, 2015 at 08:13:00PM -0500, Robert Withers wrote:
>>>>> 
>>>>> On 12/18/2015 08:07 PM, David T. Lewis wrote:
>>>>> 
>>>>> If you are implementing your algorithm from scratch, then it would be
>>>>> nice if it could be done in Smalltalk, because that means we can all
>>>>> read it, play with it in the image, and write unit tests to validate and
>>>>> document its behavior. We can figure out the translation to C afterwords,
>>>>> once you have a good implementation in Smalltalk (and yes I will help
>>>>> with that).
>>>> I have a smalltalk implmentation that came from Google Java code and is
>>>> fully implemented in squeak/pharo. I am intermittently fixing byte
>>>> mutations in the payload, so it is working to a degree. Check out the
>>>> classes GenericGF, GenericGFPoly and GaloisField to see the insides.
>>>> FECEncoder and FECDecoder are calling the galoisField which builds a
>>>> ReedSolomon Decoder. That last is where the error detection occurs.
>>>> 
>>>> Thank you all very much for looking out!
>>> I guess my suggestion would be that once you have a fairly good working
>>> implementation that you are comfortable with from a functional point of
>>> view, then let's look at which methods in that implementation would benefit
>>> from being translated to primitives in C. It would be especially good if
>>> you can run a profiler on your Smalltalk implementation and see where the
>>> time is being spent. Those would be the things we would want to turn into
>>> primitives. But first things first, let's get it working 100% (not "to a
>>> degree") and then we can do the translation to primitives.
>>> 
>>> Dave
> 
> -- 
> . .. .. ^,^ robert
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