[Python-Dev] Speeding up CPython 5-10% (original) (raw)

Cesare Di Mauro cesare.di.mauro at gmail.com
Wed May 18 14:06:08 EDT 2016

If you feel like I've attacked you, I apologize: it wasn't my intention. Please, don't get it personal: I only reported my honest opinion, albeit after a re-read it looks too rude, and I'm sorry for that.

Regarding the post-bytecode optimization issues, they are mainly represented by the constant folding code, which is still in the peephole stage. Once it's moved to the proper place (ASDL/AST), then such kind of issues with the stack calculations disappear, whereas the remaining ones can be addressed by a fix of the current stackdepth_walk function.

And just to be clear, I've nothing against your code. I simply think that, due to my experience, it doesn't fit in CPython.

Regards Cesare

2016-05-18 18:50 GMT+02:00 <zreed at fastmail.com>:

Your criticisms may very well be true. IIRC though, I wrote that pass because what was available was not general enough. The stackdepthwalk function made assumptions that, while true of code generated by the current cpython frontend, were not universally true. If a goal is to move this calculation after any bytecode optimization, something along these lines seems like it will eventually be necessary.

Anyway, just offering things already written. If you don't feel it's useful, no worries.

On Wed, May 18, 2016, at 11:35 AM, Cesare Di Mauro wrote: 2016-05-17 8:25 GMT+02:00 <zreed at fastmail.com>: In the project https://github.com/zachariahreed/byteasm I mentioned on the list earlier this month, I have a pass that to computes stack usage for a given sequence of bytecodes. It seems to be a fair bit more agressive than cpython. Maybe it's more generally useful. It's pure python rather than C though. IMO it's too big, resource hungry, and slower, even if you convert it in C. If you take a look at the current stackdepthwalk function which CPython uses, it's much smaller (not even 50 lines in simple C code) and quite efficient. Currently the problem is that it doesn't return the maximum depth of the tree, but it updates the intermediate/current maximum, and then it uses it for the subsequent calculations. So, the depth artificially grows, like in the reported cases. It doesn't require a complete rewrite, but spending some time for fine-tuning it. Regards Cesare -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20160518/7c8f011c/attachment.html>

More information about the Python-Dev mailing list