[Python-Dev] Rattlesnake progress

2002年2月25日 10:45:17 -0600

 Tim> Excellent advice that almost nobody follows <0.5 wink>: choose a
 Tim> flexible intermediate representation, then structure all your
 Tim> transformations as independent passes, such that the output of
 Tim> every pass is acceptable as the input to every pass. 
I did this with my peephole optimizer. It worked great. Each peephole
optimization is a very simple subclass of an OptimizeFilter base class. The
IR is essentially the bytecode split into basic blocks, with each basic
block a list of (opcode argument) tuples. Jump targets are represented as
simple indexes into the block list. (In fact, my Rattlesnake converter was
just a "peephole optimizer" named InstructionSetConverter.) As Tim
mentioned about KISS, this means you sometimes have to run particular
optimizations or groups of optimizations multiple times.
I want to get it checked into the sandbox where others can play with it, but
time has shifted its foundation a tad and a couple optimizations don't work
any longer.
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