[Python-Dev] lnotab and the AST optimizer (original) (raw)
Antoine Pitrou solipsis at pitrou.net
Thu Jul 24 18:15:57 CEST 2008
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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 UNARY_NOT by swapping the if/else blocks, while the peepholer eliminates the UNARY_NOT 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.
(bottom line: the peepholer is not dead!)
cheers,
Antoine.
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