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[Python-Dev] default of returning None hurts performance?

Scott Dial scott+python-dev at scottdial.com
Tue Sep 1 09:52:51 CEST 2009 
Raymond Hettinger wrote:
>> I was just wondering if a bytecode for a superinstruction of the common
>> sequence:
>>
>> 6 POP_TOP
>> 7 LOAD_CONST 0 (None)
>> 10 RETURN_VALUE
>>
>> might be worth it.
> 
> [Collin Winter]
>> I doubt it. You'd save a bit of stack manipulation, but since this
>> will only appear at the end of a function, I'd be skeptical that this
>> would make any macrobenchmarks (statistically) significantly faster.
> 
> I concur with Collin.  And since it appears only at the end of a function,
> the optimization doesn't help inner-loops in a function (where most of
> the time usually spent).
> 

I fail to understand this crude logic. How often is the inner-loop
really going to solely call C code? Any call to Python in an inner-loop
is going to suffer this penalty on the order of the number of loop
iterations)?

-Scott

-- 
Scott Dial
scott at scottdial.com
scodial at cs.indiana.edu
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