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

Gregory P. Smith greg at krypto.org
Tue Sep 1 00:07:49 CEST 2009 
On Mon, Aug 31, 2009 at 2:20 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

> Gregory P. Smith <greg <at> krypto.org> writes:
> >
> > food for thought as noticed by a coworker who has been profiling some hot
> code
> to optimize a library...If a function does not have a return statement we
> return
> None.  Ironically this makes the foo2 function below faster than the bar2
> function at least as measured using bytecode size
>
> I would be surprised if this "bytecode size" difference made a significant
> difference in runtimes, given that function call cost should dwarf the
> cumulated
> cost of POP_TOP and LOAD_CONST (two of the simplest opcodes you could
> find).
>
>
the attached sample code repeatably shows that it makes a difference though
its really not much of one (2-3%).

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.
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