René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Optimizing FOR_ITER bytecode","articleBody":"We can execute one less opcode in every iteration (except for the first) of every for-loop by changing from\r\n\r\n```\r\n    GET_ITER\r\ntop:\r\n    FOR_ITER\r\n    [body]\r\n    JUMP_BACKWARDS(top)\r\ncleanup:\r\nend:\r\n```\r\n\r\nto\r\n\r\n```\r\n    GET_ITER\r\n    JUMP_FORWARD(bottom)\r\nbody:\r\n    [body]\r\nbottom:\r\n    FOR_END(body)\r\ncleanup:\r\nend:\r\n```\r\n\r\nThis was suggested by @markshannon [here](https://github.com/faster-cpython/ideas/issues/67#issuecomment-881358019), but it appears to be similar in spirit to [Loop Inversion](https://en.wikipedia.org/wiki/Loop_inversion).\r\n\r\nThere seems to be a small (on the order of 1%) benefit, but I imagine the benefit will be magnified after any specialization.","author":{"url":"https://github.com/sweeneyde","@type":"Person","name":"sweeneyde"},"datePublished":"2022-04-10T23:28:00.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":14},"url":"https://github.com/91432/cpython/issues/91432"}