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[Python-Dev] Speeding up CPython 5-10%

Cesare Di Mauro cesare.di.mauro at gmail.com
Sun May 15 10:00:09 EDT 2016 
2016-02-01 17:54 GMT+01:00 Yury Selivanov <yselivanov.ml at gmail.com>:

> Thanks for bringing this up!
>
> IIRC wpython was about using "fat" bytecodes, i.e. using 64bits per
> bytecode instead of 8.


No, it used 16, 32, and 48-bit per opcode (1, 2, or 3 16-bit words).


> That allows to minimize the number of bytecodes, thus having some
> performance increase.  TBH, I don't think it was "significantly faster".
>

Please, take a look at the benchmarks, or compile it and check yourself. ;-)

If I were to do some big refactoring of the ceval loop, I'd probably
> consider implementing a register VM.  While register VMs are a bit faster
> than stack VMs (up to 20-30%), they would also allow us to apply more
> optimizations, and even bolt on a simple JIT compiler.
>
> Yury


WPython was an hybrid-VM: it supported both a stack-based and a
register-based approach.

I think that it's needed, since the nature of Python, because you can have
operations with intermixed operands: constants, locals, globals, names.
It's quite difficult to handle all possible cases with a register-based VM.

Regards,
Cesare
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