fix infinite deopt involving monitoring

Author: Fidget-Spinner

Python/bytecodes.c

@@ -3051,7 +3051,9 @@ dummy_func(
             /* If the eval breaker is set then stay in tier 1.
              * This avoids any potentially infinite loops
              * involving _RESUME_CHECK */
-            if (_Py_atomic_load_uintptr_relaxed(&tstate->eval_breaker) & _PY_EVAL_EVENTS_MASK) {
+            uintptr_t eval_breaker = _Py_atomic_load_uintptr_relaxed(&tstate->eval_breaker);
+            int dont_enter = !(tstate->tracing || eval_breaker == FT_ATOMIC_LOAD_UINTPTR_ACQUIRE(_PyFrame_GetCode(frame)->_co_instrumentation_version));
+            if (dont_enter || _Py_atomic_load_uintptr_relaxed(&tstate->eval_breaker) & _PY_EVAL_EVENTS_MASK) {
                 opcode = executor->vm_data.opcode;
                 oparg = (oparg & ~255) | executor->vm_data.oparg;
                 next_instr = this_instr;
@@ -5376,15 +5378,15 @@ dummy_func(
         }
 
         /* Progress is guaranteed if we DEOPT on the eval breaker, because
-         * ENTER_EXECUTOR will not re-enter tier 2 with the eval breaker set. */
+         * ENTER_EXECUTOR will not re-enter tier 2 wiFth the eval breaker set. */
         tier2 op(_TIER2_RESUME_CHECK, (--)) {
 #if defined(__EMSCRIPTEN__)
             HANDLE_PENDING_AND_DEOPT_IF(_Py_emscripten_signal_clock == 0);
             _Py_emscripten_signal_clock -= Py_EMSCRIPTEN_SIGNAL_HANDLING;
 #endif
             uintptr_t eval_breaker = _Py_atomic_load_uintptr_relaxed(&tstate->eval_breaker);
             HANDLE_PENDING_AND_DEOPT_IF(eval_breaker & _PY_EVAL_EVENTS_MASK);
-            HANDLE_PENDING_AND_DEOPT_IF(!(tstate->tracing || eval_breaker == FT_ATOMIC_LOAD_UINTPTR_ACQUIRE(_PyFrame_GetCode(frame)->_co_instrumentation_version)));
+            assert(tstate->tracing || eval_breaker == FT_ATOMIC_LOAD_UINTPTR_ACQUIRE(_PyFrame_GetCode(frame)->_co_instrumentation_version));
         }
 
         tier2 op(_COLD_EXIT, ( -- )) {