[Python-Dev] lnotab and the AST optimizer (original) (raw)

Thomas Lee tom at vector-seven.com
Thu Jul 24 16:56:35 CEST 2008

I'm making some good progress with the AST optimizer, and now the main thing standing in my way is lnotab. Currently lnotab expects bytecode sequencing to be roughly in-sync with the order of the source file and a few things that the optimizer does (e.g. swapping the bodies of an if/else after removing negation such that "if not X: A; else: B" becomes "if X: B; else A") breaks this assumption. This will result in either an assertion failure or incorrect line numbers being reported.

It seems that lnotab is used in relatively few places in the source code at the moment, but if I'm going to make a change to how lnotab works I want to do so in a way that's going to allow me to move forward while keeping everybody happy.

I'm away for a few days so I probably won't be able to get back to anybody until either Sunday or Monday, but I'd appreciate it if anybody in the know can weigh in on this.

Cheers, Tom

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