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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Clean up the `CALL` sequence","articleBody":"The bytecode sequence for calls has gotten better in 3.12, but I think it can still be improved in a couple of ways:\r\n- First, we can start either pushing `NULL` or a tuple of `kwnames` onto the stack immediately before calls, rather than sometimes stashing `kwnames` away in a local eval loop variable via the `KW_NAMES` opcode. This *should* free up a register around calls, and it's nice to do anyways since it makes the bytecode more regular (and the stack is really where this sort of stuff belongs).\r\n- Once that is done, we can use the low bit of the `CALL` oparg to indicate whether or not to expect `kwnames` on the stack. This should get rid of lots of new `PUSH_NULL`/`CALL` pairs.\r\n- Separate from the above, but still sort of related: it's a bit awkward that our method call optimization either leaves `[callable, self, args...]` or `[NULL, callable, args...]` on the stack, since it means that `CALL` (and most of its specializations) have to do an awkward swap in order to load the \"correct\" callable. This can be simplified by always entering calls with `[callable, self_or_null, args...]` on the stack, so that the callable is always in the same position.\r\n\r\nAfter this is all said and done, the `CALL` stack effect will look something like:\r\n\r\n```c\r\ninst(CALL, (counter/1, cache/2, callable, self_or_null, args[oparg \u003e\u003e 1], kwnames if (oparg \u0026 1) -- res)) {\r\n    // ...\r\n}\r\n```\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-105849\n* gh-107788\n* gh-108496\n* gh-109300\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/brandtbucher","@type":"Person","name":"brandtbucher"},"datePublished":"2023-06-16T05:54:45.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/105848/cpython/issues/105848"}