René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Interpreter code generators need to be able to handle basic flow control","articleBody":"In order to be able to flush the stack efficiently around escaping calls, the interpreter code generators need to be able to handle simple-ish flow control.\r\n\r\nFor example, in this code:\r\n```\r\n  op(_CHECK_PERIODIC, (--)) {\r\n      if (_Py_atomic_load_uintptr_relaxed(\u0026tstate-\u003eeval_breaker) \u0026 _PY_EVAL_EVENTS_MASK) {\r\n          int err = _Py_HandlePending(tstate);\r\n          ERROR_IF(err != 0, error);\r\n      }\r\n  }\r\n```\r\nThe general shape is:\r\n```\r\n    if (cond) {\r\n        *escaping_call()*\r\n    }\r\n```\r\n\r\nWe want to be able to track the flow control so that we can spill around the call, but not on the fast path:\r\n```\r\n   if (cond) {\r\n        SPILL_STACK();\r\n        *escaping_call()*\r\n        RELOAD_STACK();\r\n    }\r\n```\r\n\r\nWe cannot currently do this.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-123397\n* gh-123469\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/markshannon","@type":"Person","name":"markshannon"},"datePublished":"2024-08-27T13:26:26.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/123391/cpython/issues/123391"}