New submission from Brandt Bucher <brandtbuc...@gmail.com>:
The attached PR contains a small change to the peephole optimizer that converts sequences of: LOAD_CONST(a), LOAD_CONST(b), ..., BUILD_LIST(n) to LOAD_CONST((a, b, ...)), BUILD_LIST_UNPACK(1) The improvement quickly becomes significant for lists larger than a few items (elements vs speedup): 5: ~5% 10: ~20% 15: ~25% 20: ~30% 25: ~35% 30: ~45% 35: ~50% This can be tested on any version of Python by comparing the performance of "[0, 1, 2, ...]" vs "[*(0, 1, 2, ...)]". The common cases of empty and single-element lists are not affected by this change. This is related to bpo-33325, but that was an invasive change for all collection literals that had an unknown affect on performance. I've limited this one to lists and kept it to a few lines in the peephole optimizer. ---------- components: Interpreter Core messages: 353599 nosy: brandtbucher priority: normal severity: normal status: open title: Speed up the creation time of constant list literals. type: performance versions: Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue38328> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
