Experience shows that optimizations are always error prone, no matter what framework or internal representation you use. I don't think we should assume that simply rewriting all optimizations to work on AST will make them bug free once and for all. On the contrary, I think such a rewrite will introduce some bugs of it's own.
The remedy against this is well known. Instead of being afraid to touch the code we should add more tests and verifiers. If had written tests are not enough, test generator that produces python programs with different structures can be written. Such generators are used by many compiler writers. For verifiers, a function that checks that bytecode is sane (doesn't reference invalid names or consts, doesn't jump between instructions, all joins have same stack depth? etc) that runs after optimizer in debug builds can save a lot of time. Eugene _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
