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

Thomas Lee tom at vector-seven.com
Thu Jul 24 18:23:00 CEST 2008

Antoine Pitrou wrote:

Thomas Lee <tom vector-seven.com> writes:

By the way, you were right about JUMPIFTRUE/JUMPIFFALSE. It's far too late. Apologies.

I'm still pretty sure this is the peepholer's doing, Yes indeed. Which is what's being achieved with the AST optimization I originally proposed, right? Well, not exactly, your optimization eliminates the UNARYNOT by swapping the if/else blocks, while the peepholer eliminates the UNARYNOT by fusing it with the subsequent jump opcode. In this case it doesn't make much of a difference, but if there is only an "if" without an "else", the peepholer's optimization is still possible while yours is not.

Unless a pass is injected into the if body, which will generate no additional bytecode and still have the same net effect.

(bottom line: the peepholer is not dead!)

We'll see ;)

Thanks for all your help, I'm looking forward to getting my hands on that patch.

Cheers, T

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