[pypy-dev] numpy plans in the next 6 months?

[Armin Rigo]

Hi Ian,

On 20 February 2014 12:59, Ian Ozsvald <ian at ianozsvald.com> wrote:
> Hi again. In relation to my other mail, I'm curious about the plans
> for numpy in the next 6 months. Is there an expectation that
> better-than-numpy results might be obtained (e.g. using AVX/SSE or
> being cache friendly)? I'll mention these as they will probably be
> relevant to some of the audience.

The most relevant way to answer is probably to say that we're not
looking at AVX/SSE or cache friendlyness to get better-than-numpy
results.  These are things that can be (and, I'm sure, have been)
experimented with in CPython too.  The real advantage that PyPy has is
a JIT that can "unconventionally" be taught to produce code handling a
combination of matrix operations at a time.

If you say in numpy "a + b + c", the intermediate matrix "a + b" is
built and forgotten.  This would not be needed if we had a way to do
the sum of the three input matrices in one go.  But that needs some
JIT somewhere, to produce the code doing this particular operation (in
this case, the sum of three matrices).  The point of PyPy is to
provide precisely such a JIT for free.

Unless I'm missing something, the plans for numpy in the next 6 months
include doing this --- or rather, re-doing it.  It used to work
already at the beginning of numpypy, but was temporarily dropped to
make it easier to progress on completeness.  I can imagine that this
would definitely give better-than-numpy results on a large fraction of
programs.


A bientôt,

Armin.