[Python-Dev] Generated Bytecode ... (original) (raw)

Brett Cannon brett at python.org
Thu Oct 22 13:02:48 EDT 2015

On Thu, 22 Oct 2015 at 09:37 Stéphane Wirtel <stephane at wirtel.be> wrote:

Hi all,

When we compile a python script # test.py if 0: x = 1 python -mdis test.py There is no byte code for the condition. So my question is, the byte code generator removes the unused functions, variables etc…, is it right?

Technically the peepholer removes the dead branch, but since the peepholer is run on all bytecode you can't avoid it.

What are the cases where the generator does not generate the byte codes ?

It's not specified anywhere; it's just what the peepholer decides to remove. The exact code can be found at https://hg.python.org/cpython/file/default/Python/peephole.c . There has been talk in the past for adding a -X flag to disable the peepholer, but it never went any farther beyond that. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20151022/763e686f/attachment-0001.html>

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