Vitja Makarov, 21.12.2011 19:48:
Some time ago we were talking about generators optimization by copying
local variables from closure into local scope.
Yes, I think that will make it easier for the C compiler to make optimistic
assumptions about external values.
Now I think that should be a good idea to implement this for both
generators and regular closure functions. So local var will be used
for reference and assignment should be made to both copies. Of course
there are some variables that shouldn't be copied: non-local vars,
arrays, C++ classes and structures.
Basically, anything that external code can modify. That makes it a bit
tricky to do it also for 'normal' closure functions - the whole idea is
that there is more than one function that can refer to a variable.
Also it may be a good idea to move outer scope pointer into local variable.
So I'm wondering what is a good test to measure actual speedup?
http://blog.behnel.de/index.php?p=163
Just take the plain Python versions of the iterparse functions and compare
them before and after the change. The raw C implementation in CPython gives
a good baseline.
Actually, it would be generally interesting to run the Cython versions
through callgrind to see where the time is actually being spent.
Stefan
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