Python's biggest compromises

Robin Becker robin at jessikat.fsnet.co.uk
Fri Aug 1 17:25:37 CEST 2003


In article <vikh3ink3djc7c at news.supernews.com>, John Roth
<newsgroups at jhrothjr.com> writes
>>
>> I don't have any data here, but I believe Python is just a little too
>> weakly typed for compiling to float*float type assembler efficiently.
>
>The trick with JITs is that they don't depend on absolute type
>consistency. They depend on the observation that 99.44% of your
>code is type consistent, and that consistency will turn up at run time. So
>the code they generate depends on that discovered consistency, and
>checks in front of each section to discover if the types are what the
>code expects.
>
>If it is, they execute it, if it isn't, they abandon it and go back to
>the intepreter to discover what happened.
>
>John Roth
Yes I suspected they have to do that, but that implies that a discovered
'float' object must carry along a whole lot of baggage (I guess I mean
be a more generic object) to allow for the testing. Loops without method
or function calls would be good candidates for JIT as methods and
functions could alter attribute types.

Is the JIT object literally just a union of

        type,values

or would it be an actual Python object? For example would an
innerproduct be over a pair of lists or would the magic convert these
into actual double arrays.
-- 
Robin Becker




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