Simplify DISPATCH by hoisting eval_breaker ahead of time. (pythongh-12243)

Author: ericsnowcurrently

Python/ceval.c

@@ -602,6 +602,7 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
  PyObject **fastlocals, **freevars;
  PyObject *retval = NULL; /* Return value */
  PyThreadState *tstate = _PyThreadState_GET();
+ _Py_atomic_int *eval_breaker = &_PyRuntime.ceval.eval_breaker;
  PyCodeObject *co;
 
  /* when tracing we set things up so that
@@ -687,7 +688,7 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
 
 #define DISPATCH() \
  { \
- if (!_Py_atomic_load_relaxed(&_PyRuntime.ceval.eval_breaker)) { \
+ if (!_Py_atomic_load_relaxed(eval_breaker)) { \
  FAST_DISPATCH(); \
  } \
  continue; \
@@ -989,7 +990,7 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
  async I/O handler); see Py_AddPendingCall() and
  Py_MakePendingCalls() above. */
 
- if (_Py_atomic_load_relaxed(&_PyRuntime.ceval.eval_breaker)) {
+ if (_Py_atomic_load_relaxed(eval_breaker)) {
  opcode = _Py_OPCODE(*next_instr);
  if (opcode == SETUP_FINALLY ||
  opcode == SETUP_WITH ||