[Vm-dev] Accelerating LargeInteger Plugin

Levente Uzonyi leves at elte.hu
Sat Dec 29 05:45:22 UTC 2012

On Sat, 29 Dec 2012, Nicolas Cellier wrote:

> See http://smallissimo.blogspot.fr/2012/12/accelerating-largeinteger-in-squeak.html
> This simple experiment is interesting but is not ready to use.
> If we change LargeIntegersPlugin to use 32bits words rather than
> bytes, we are introducing one more clever hack in the system (two for
> handling MSB efficiently).
> If we want to make LargeInteger a word array, then we have a transition problem.
> I thought of a few more or less evil solutions, but I fail to see how
> to not break the smooth trunk update
> - perform the operation on a stripped image not requiring LargeIntegers...
> - remove the LargeIntegerPlugin, redefine digitAt: digitAt:put: and
> digitLength as a hack answering proper byte for both a Byte and
> WordArray, then redefine LargePositiveInteger as word Array on such
> VM, then add the new plugin...
> - use an image tracer
> Thoughts?

I think the reason why the difference in case of #+ and #- is not 
significant is because of the overhead of #bench. The actual numbers 
(for all cases) are probably better than your numbers for the 10000 
bits case.

I wonder if it's possible to keep the current format of the classes 
(variableByte), but do the computation using 32/64-bit operations. 
Writing it in slang wouldn't be easy, but it would let us use the new code 
with existing images.


> Nicolas

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