[pypy-dev] Vectorizing numpy traces

[Richard Plangger]

Sorry, I put https instead of http:

http://postimg.org/image/kbntluw55/full/

On 02/24/2015 07:36 PM, Maciej Fijalkowski wrote:
> before I answer, any clue why I get:
> 
> Google Chrome's connection attempt to postimg.org was rejected. The
> website may be down, or your network may not be properly configured.
> 
> On Tue, Feb 24, 2015 at 8:18 PM, Richard Plangger <rich at pasra.at> wrote:
>> hi,
>>
>> i'm currently trying to find a way to generate simd code for python
>> loops that operate on numpy arrays.
>> The IRC is quite busy so I think I'd rather post it as an email...
>>
>> I have familiarized myself with pypy and read most of the docs and read
>> the code in the metainterp to understand how the traces are built.
>>
>> I translated pypy with --withmod-micronumpy enabled (installed numpy
>> pypy fork in an virtual env) and gave the jitviewer a try.
>> Here is a sample program that does not really make sense, but I think it
>> would contain opportunity to generate SIMD instructions.
>>
>> ```
>> import numpy
>> def invoke():
>>     a = numpy.zeros(1024)
>>     b = numpy.zeros(1024)
>>     c = numpy.zeros(1024)
>>     # (2)
>>     for i in range(0,1024):
>>         c[i] = a[i] + b[i]
>>     # (3)
>>     c = a + b
>>
>> if __name__ == '__main__':
>>     i = 0
>>     # (1)
>>     while i < 500:
>>         invoke()
>>         i += 1
>> ```
>>
>> Here is the trace of invoke visible in jitviewer (uploaded to
>> https://postimg.org/image/kbntluw55/full/).
>>
>> Here are some questions I have that would really help me to get going:
>>
>> (1) Is there a better way to get loops hot?
>>
>> (2) I cannot really figure out what all those trace/loop parameters are.
>> obviously i can guess some but most of them do not really make sense to
>> me. Am I missing some settings to be able to display more information
>> for the trace?
>>     In addition to that I do not really see any chance to generate a
>> simd loop for (2). Every array access is (arguably) guarded by an array
>> index overflow and I think to skip that check would be invalid.
>>
>> (3) There is no trace generated for this instruction? Does this
>> internally call a c function?
>>
>> (4) What in our opinion makes sense to vectorize with simd instructions?
>> Could you provide some sample loops/code (ranging from simple to complex
>> loops)?
>>
>> I would really appreciate any help and/or push into the right direction.
>>
>> Best,
>> Richard
>>
>>
>> _______________________________________________
>> pypy-dev mailing list
>> pypy-dev at python.org
>> https://mail.python.org/mailman/listinfo/pypy-dev
>>

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