René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Jump-To-Jump elimination could be more aggressive.","articleBody":"Example:\r\n\r\n```python\r\ndef f():\r\n    for i in range(5):\r\n        if i \u003e 3:\r\n            print(i)\r\n```\r\n\r\n```\r\n  1           0 RESUME                   0\r\n\r\n  2           2 LOAD_GLOBAL              1 (NULL + range)\r\n             14 LOAD_CONST               1 (5)\r\n             16 CALL                     1\r\n             26 GET_ITER\r\n        \u003e\u003e   28 FOR_ITER                21 (to 72)\r\n             30 STORE_FAST               0 (i)\r\n\r\n  3          32 LOAD_FAST                0 (i)\r\n             34 LOAD_CONST               2 (3)\r\n             36 COMPARE_OP               4 (\u003e)\r\n             42 POP_JUMP_FORWARD_IF_FALSE    13 (to 70)     \u003c--------- could be BACKWARD to 28\r\n\r\n  4          44 LOAD_GLOBAL              3 (NULL + print)\r\n             56 LOAD_FAST                0 (i)\r\n             58 CALL                     1\r\n             68 POP_TOP\r\n        \u003e\u003e   70 JUMP_BACKWARD           22 (to 28)\r\n\r\n  2     \u003e\u003e   72 LOAD_CONST               0 (None)\r\n             74 RETURN_VALUE\r\n```\r\n\r\n\r\nSomething like this should suffice:\r\n```diff\r\n static bool\r\n jump_thread(struct instr *inst, struct instr *target, int opcode)\r\n {\r\n     assert(!IS_VIRTUAL_OPCODE(opcode) || IS_VIRTUAL_JUMP_OPCODE(opcode));\r\n     assert(is_jump(inst));\r\n     assert(is_jump(target));\r\n     // bpo-45773: If inst-\u003ei_target == target-\u003ei_target, then nothing actually\r\n     // changes (and we fall into an infinite loop):\r\n-    if (inst-\u003ei_lineno == target-\u003ei_lineno \u0026\u0026\r\n+    if ((inst-\u003ei_lineno == target-\u003ei_lineno || target-\u003ei_lineno == -1) \u0026\u0026\r\n         inst-\u003ei_target != target-\u003ei_target)\r\n     {\r\n         inst-\u003ei_target = target-\u003ei_target;\r\n         inst-\u003ei_opcode = opcode;\r\n         return true;\r\n     }\r\n     return false;\r\n }\r\n```\r\n\r\ncc @markshannon @iritkatriel @brandtbucher ","author":{"url":"https://github.com/sweeneyde","@type":"Person","name":"sweeneyde"},"datePublished":"2022-05-25T16:57:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/93223/cpython/issues/93223"}