[issue11462] Peephole creates duplicate and unused constants

[Eugene Toder]

Eugene Toder <eltoder at gmail.com> added the comment:

> Right now, the pattern is tokenize -> parse -> AST -> genbytecode ->
> peephole optimization (which disassembles the bytecode, analyzed it
> and rewrites it) -> final bytecode.   The correct pattern is tokenize
> -> parse -> AST -> optimize -> genbytecode -> peephole optimization
> with minimal disassembly, analysis, and opcode rewrites -> final bytecode.

Actually, optimizing on AST is not ideal too. Ideally you should convert it into a specialized IR, preferably in SSA form and with explicit control flow.

Re size saving: I've ran make test with and without my patch and measured total size of all generated pyc files:
without patch: 16_619_340
with patch: 16_467_867
So it's about 150KB or 1% of the size, not just a few bytes.

----------

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue11462>
_______________________________________