Remove GC Header from constant tuples. #31627
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| static int | ||
| tuple_is_gc(PyObject *op) |
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FWIW, I considered using tp_is_gc like this but was worried it would have too big an impact on performance. Apparently that wasn't the case. 🙂
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Most tuples like (1,2) or ("foo","bar) are untracked at first GC cycle.
So calling one callback on each tuple is not a big problem.
When adding callback for list, dict, or function objects, we need to measure the performance impact.
| #define PyTuple_GET_SIZE(op) Py_SIZE(_PyTuple_CAST(op)) | ||
| #define _PyTuple_NOGC_FLAG (PY_SSIZE_T_MIN) | ||
| #define _PyTuple_HAS_NO_GC(op) (Py_SIZE(_PyTuple_CAST(op)) & _PyTuple_NOGC_FLAG) | ||
| #define PyTuple_GET_SIZE(op) (Py_SIZE(_PyTuple_CAST(op)) & ~_PyTuple_NOGC_FLAG) |
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Py_SIZE() will still work, right? It will just return a bad value. Won't this break users?
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It will.
Py_SIZE() returns bad value for set, long already.
Maybe, we should officially deprecate using Py_SIZE() to get length of container.
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
faster-cpython/ideas#304