[issue43760] The DISPATCH() macro is not as efficient as it could be (move PyThreadState.use_tracing)

[STINNER Victor]

STINNER Victor <vstinner at python.org> added the comment:

greenlet now uses PyThreadState_EnterTracing() and PyThreadState_LeaveTracing() rather than accessing directly use_tracing:

https://github.com/python-greenlet/greenlet/commit/9b49da5c7e4808bd61b992e40f5b5243bfa9be6f

On Python 3.10, it implements these functions with:
---

// bpo-43760 added PyThreadState_EnterTracing() to Python 3.11.0a2
#if PY_VERSION_HEX < 0x030B00A2 && !defined(PYPY_VERSION)
static inline void PyThreadState_EnterTracing(PyThreadState *tstate)
{
    tstate->tracing++;
#if PY_VERSION_HEX >= 0x030A00A1
    tstate->cframe->use_tracing = 0;
#else
    tstate->use_tracing = 0;
#endif
}
#endif

// bpo-43760 added PyThreadState_LeaveTracing() to Python 3.11.0a2
#if PY_VERSION_HEX < 0x030B00A2 && !defined(PYPY_VERSION)
static inline void PyThreadState_LeaveTracing(PyThreadState *tstate)
{
    tstate->tracing--;
    int use_tracing = (tstate->c_tracefunc != NULL
                       || tstate->c_profilefunc != NULL);
#if PY_VERSION_HEX >= 0x030A00A1
    tstate->cframe->use_tracing = use_tracing;
#else
    tstate->use_tracing = use_tracing;
#endif
}
#endif
---

This code was copied from my https://github.com/pythoncapi/pythoncapi_compat project. (I wrote the greenlet change.)

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<https://bugs.python.org/issue43760>
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