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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"new `TestUopsOptimization` test case failing an assert","articleBody":"# Bug report\n\n### Bug description:\n\nWhile writing test cases for #116168, I ran into a case that failed on `main` too. Here's the test as a diff. It's under `test_opt.TestUopsOptimization`:\n\n```diff\ndiff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py\nindex b0859a382d..269753e4c1 100644\n--- a/Lib/test/test_capi/test_opt.py\n+++ b/Lib/test/test_capi/test_opt.py\n@@ -955,6 +955,31 @@ def testfunc(n):\n         _, ex = self._run_with_optimizer(testfunc, 16)\n         self.assertIsNone(ex)\n\n+    def test_many_nested(self):\n+        # overflow the trace_stack\n+        def dummy_a(x):\n+            return x\n+        def dummy_b(x):\n+            return dummy_a(x)\n+        def dummy_c(x):\n+            return dummy_b(x)\n+        def dummy_d(x):\n+            return dummy_c(x)\n+        def dummy_e(x):\n+            return dummy_d(x)\n+        def dummy_f(x):\n+            return dummy_e(x)\n+        def dummy_g(x):\n+            return dummy_f(x)\n+        def dummy_h(x):\n+            return dummy_g(x)\n+        def testfunc(n):\n+            a = 0\n+            for _ in range(n):\n+                a += dummy_h(n)\n+            return a\n+\n+        self._run_with_optimizer(testfunc, 32)\n\n if __name__ == \"__main__\":\n     unittest.main()\n```\n\nI'm running this locally (source build of `main` `9967b568edd2e35b0415c14c7242f3ca2c0dc03d` on an M1 mac).\n\nCommand:\n\n```\n./python.exe -m test test.test_capi.test_opt\n```\n\nOutput:\n\n```\nUsing random seed: 1780919823\nRaised RLIMIT_NOFILE: 256 -\u003e 1024\n0:00:00 load avg: 2.88 Run 1 test sequentially\n0:00:00 load avg: 2.88 [1/1] test.test_capi.test_opt\nAssertion failed: ((this_instr + 2)-\u003eopcode == _PUSH_FRAME), function optimize_uops, file optimizer_cases.c.h, line 1600.\nFatal Python error: Aborted\n\nCurrent thread 0x000000020140a100 (most recent call first):\n  File \"/Users/peterlazorchak/repos/oss-clones/forks/cpython/Lib/test/test_capi/test_opt.py\", line 979 in testfunc\n  File \"/Users/peterlazorchak/repos/oss-clones/forks/cpython/Lib/test/test_capi/test_opt.py\", line 588 in _run_with_optimizer\n  File \"/Users/peterlazorchak/repos/oss-clones/forks/cpython/Lib/test/test_capi/test_opt.py\", line 982 in test_many_nested\n  File \"/Users/peterlazorchak/repos/oss-clones/forks/cpython/Lib/unittest/case.py\", line 589 in _callTestMethod\n....[truncated for brevity]....\n  File \"/Users/peterlazorchak/repos/oss-clones/forks/cpython/Lib/runpy.py\", line 88 in _run_code\n  File \"/Users/peterlazorchak/repos/oss-clones/forks/cpython/Lib/runpy.py\", line 198 in _run_module_as_main\n\nExtension modules: _testcapi, _testinternalcapi (total: 2)\nzsh: abort      ./python.exe -m test test.test_capi.test_opt\n```\n\nThis assertion is in the optimizer case for `_INIT_CALL_PY_EXACT_ARGS`. I haven't investigated any further beyond that.\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nmacOS\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-117184\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/lazorchakp","@type":"Person","name":"lazorchakp"},"datePublished":"2024-03-23T13:26:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/117180/cpython/issues/117180"}