[Python-Dev] lnotab and the AST optimizer
tom at vector-seven.com
Thu Jul 24 18:23:00 CEST 2008
Antoine Pitrou wrote:
> Thomas Lee <tom <at> vector-seven.com> writes:
>> By the way, you were right about JUMP_IF_TRUE/JUMP_IF_FALSE. 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.
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
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