GH-133231: Changes to executor management to support proposed `sys._jit` module (GH-133287)

* Track the current executor, not the previous one, on the thread-state. 

* Batch executors for deallocation to avoid having to constantly incref executors; this is an ad-hoc form of deferred reference counting.

1 files changed, 24 insertions, 10 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index f145bde..5a52efa 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -1169,6 +1169,17 @@ dummy_func(
             tstate->current_frame = frame->previous;
             assert(!_PyErr_Occurred(tstate));
             PyObject *result = PyStackRef_AsPyObjectSteal(retval);
+#if !Py_TAIL_CALL_INTERP
+            assert(frame == &entry.frame);
+#endif
+#ifdef _Py_TIER2
+            _PyStackRef executor = frame->localsplus[0];
+            assert(tstate->current_executor == NULL);
+            if (!PyStackRef_IsNull(executor)) {
+                tstate->current_executor = PyStackRef_AsPyObjectBorrow(executor);
+                PyStackRef_CLOSE(executor);
+            }
+#endif
             LLTRACE_RESUME_FRAME();
             return result;
         }
@@ -2912,8 +2923,7 @@ dummy_func(
                 }
                 else {
                     this_instr[1].counter = initial_jump_backoff_counter();
-                    assert(tstate->previous_executor == NULL);
-                    tstate->previous_executor = Py_None;
+                    assert(tstate->current_executor == NULL);
                     GOTO_TIER_TWO(executor);
                 }
             }
@@ -2965,7 +2975,7 @@ dummy_func(
             assert(executor->vm_data.index == INSTR_OFFSET() - 1);
             assert(executor->vm_data.code == code);
             assert(executor->vm_data.valid);
-            assert(tstate->previous_executor == NULL);
+            assert(tstate->current_executor == NULL);
             /* If the eval breaker is set then stay in tier 1.
              * This avoids any potentially infinite loops
              * involving _RESUME_CHECK */
@@ -2978,8 +2988,6 @@ dummy_func(
                 }
                 DISPATCH_GOTO();
             }
-            tstate->previous_executor = Py_None;
-            Py_INCREF(executor);
             GOTO_TIER_TWO(executor);
             #else
             Py_FatalError("ENTER_EXECUTOR is not supported in this build");
@@ -5254,7 +5262,6 @@ dummy_func(
                 exit->temperature = initial_temperature_backoff_counter();
                 Py_CLEAR(exit->executor);
             }
-            tstate->previous_executor = (PyObject *)current_executor;
             if (exit->executor == NULL) {
                 _Py_BackoffCounter temperature = exit->temperature;
                 if (!backoff_counter_triggers(temperature)) {
@@ -5277,7 +5284,6 @@ dummy_func(
                 }
                 exit->executor = executor;
             }
-            Py_INCREF(exit->executor);
             GOTO_TIER_TWO(exit->executor);
         }
 
@@ -5316,7 +5322,6 @@ dummy_func(
         }
 
         tier2 op(_START_EXECUTOR, (executor/4 --)) {
-            Py_CLEAR(tstate->previous_executor);
 #ifndef _Py_JIT
             current_executor = (_PyExecutorObject*)executor;
 #endif
@@ -5337,12 +5342,10 @@ dummy_func(
         }
 
         tier2 op(_DEOPT, (--)) {
-            tstate->previous_executor = (PyObject *)current_executor;
             GOTO_TIER_ONE(_PyFrame_GetBytecode(frame) + CURRENT_TARGET());
         }
 
         tier2 op(_ERROR_POP_N, (target/2 --)) {
-            tstate->previous_executor = (PyObject *)current_executor;
             assert(oparg == 0);
             frame->instr_ptr = _PyFrame_GetBytecode(frame) + target;
             SYNC_SP();
@@ -5463,6 +5466,17 @@ dummy_func(
             if (frame->owner == FRAME_OWNED_BY_INTERPRETER) {
                 /* Restore previous frame and exit */
                 tstate->current_frame = frame->previous;
+#if !Py_TAIL_CALL_INTERP
+                assert(frame == &entry.frame);
+#endif
+#ifdef _Py_TIER2
+                _PyStackRef executor = frame->localsplus[0];
+                assert(tstate->current_executor == NULL);
+                if (!PyStackRef_IsNull(executor)) {
+                    tstate->current_executor = PyStackRef_AsPyObjectBorrow(executor);
+                    PyStackRef_CLOSE(executor);
+                }
+#endif
                 return NULL;
             }
             next_instr = frame->instr_ptr;