GH-96421: Insert shim frame on entry to interpreter (GH-96319)

* Adds EXIT_INTERPRETER instruction to exit PyEval_EvalDefault()

* Simplifies RETURN_VALUE, YIELD_VALUE and RETURN_GENERATOR instructions as they no longer need to check for entry frames.

1 files changed, 61 insertions, 80 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index c1f416e..ed12b94 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -97,8 +97,7 @@ dummy_func(
     PyObject *consts,
     _Py_CODEUNIT *next_instr,
     PyObject **stack_pointer,
-    CallShape call_shape,
-    _Py_CODEUNIT *first_instr,
+    PyObject *kwnames,
     int throwflag,
     binaryfunc binary_ops[]
 )
@@ -618,32 +617,34 @@ dummy_func(
         }
 
         // stack effect: (__0 -- )
-        inst(RETURN_VALUE) {
+        inst(INTERPRETER_EXIT) {
+            assert(frame == &entry_frame);
+            assert(_PyFrame_IsIncomplete(frame));
             PyObject *retval = POP();
             assert(EMPTY());
-            _PyFrame_SetStackPointer(frame, stack_pointer);
-            TRACE_FUNCTION_EXIT();
-            DTRACE_FUNCTION_EXIT();
-            _Py_LeaveRecursiveCallPy(tstate);
-            if (!frame->is_entry) {
-                frame = cframe.current_frame = pop_frame(tstate, frame);
-                _PyFrame_StackPush(frame, retval);
-                goto resume_frame;
-            }
-            _Py_LeaveRecursiveCallTstate(tstate);
-            if (frame->owner == FRAME_OWNED_BY_GENERATOR) {
-                PyGenObject *gen = _PyFrame_GetGenerator(frame);
-                tstate->exc_info = gen->gi_exc_state.previous_item;
-                gen->gi_exc_state.previous_item = NULL;
-            }
             /* Restore previous cframe and return. */
             tstate->cframe = cframe.previous;
             tstate->cframe->use_tracing = cframe.use_tracing;
             assert(tstate->cframe->current_frame == frame->previous);
             assert(!_PyErr_Occurred(tstate));
+            _Py_LeaveRecursiveCallTstate(tstate);
             return retval;
         }
 
+        // stack effect: (__0 -- )
+        inst(RETURN_VALUE) {
+            PyObject *retval = POP();
+            assert(EMPTY());
+            _PyFrame_SetStackPointer(frame, stack_pointer);
+            TRACE_FUNCTION_EXIT();
+            DTRACE_FUNCTION_EXIT();
+            _Py_LeaveRecursiveCallPy(tstate);
+            assert(frame != &entry_frame);
+            frame = cframe.current_frame = pop_frame(tstate, frame);
+            _PyFrame_StackPush(frame, retval);
+            goto resume_frame;
+        }
+
         // stack effect: ( -- )
         inst(GET_AITER) {
             unaryfunc getter = NULL;
@@ -775,6 +776,7 @@ dummy_func(
 
         // error: SEND stack effect depends on jump flag
         inst(SEND) {
+            assert(frame != &entry_frame);
             assert(STACK_LEVEL() >= 2);
             PyObject *v = POP();
             PyObject *receiver = TOP();
@@ -839,6 +841,7 @@ dummy_func(
             // The compiler treats any exception raised here as a failed close()
             // or throw() call.
             assert(oparg == STACK_LEVEL());
+            assert(frame != &entry_frame);
             PyObject *retval = POP();
             PyGenObject *gen = _PyFrame_GetGenerator(frame);
             gen->gi_frame_state = FRAME_SUSPENDED;
@@ -848,19 +851,12 @@ dummy_func(
             tstate->exc_info = gen->gi_exc_state.previous_item;
             gen->gi_exc_state.previous_item = NULL;
             _Py_LeaveRecursiveCallPy(tstate);
-            if (!frame->is_entry) {
-                frame = cframe.current_frame = frame->previous;
-                frame->prev_instr -= frame->yield_offset;
-                _PyFrame_StackPush(frame, retval);
-                goto resume_frame;
-            }
-            _Py_LeaveRecursiveCallTstate(tstate);
-            /* Restore previous cframe and return. */
-            tstate->cframe = cframe.previous;
-            tstate->cframe->use_tracing = cframe.use_tracing;
-            assert(tstate->cframe->current_frame == frame->previous);
-            assert(!_PyErr_Occurred(tstate));
-            return retval;
+            _PyInterpreterFrame *gen_frame = frame;
+            frame = cframe.current_frame = frame->previous;
+            gen_frame->previous = NULL;
+            frame->prev_instr -= frame->yield_offset;
+            _PyFrame_StackPush(frame, retval);
+            goto resume_frame;
         }
 
         // stack effect: (__0 -- )
@@ -876,7 +872,7 @@ dummy_func(
             if (oparg) {
                 PyObject *lasti = PEEK(oparg + 1);
                 if (PyLong_Check(lasti)) {
-                    frame->prev_instr = first_instr + PyLong_AsLong(lasti);
+                    frame->prev_instr = _PyCode_CODE(frame->f_code) + PyLong_AsLong(lasti);
                     assert(!_PyErr_Occurred(tstate));
                 }
                 else {
@@ -2696,12 +2692,10 @@ dummy_func(
             gen->gi_exc_state.previous_item = tstate->exc_info;
             tstate->exc_info = &gen->gi_exc_state;
             gen_frame->previous = frame;
-            gen_frame->is_entry = false;
             frame = cframe.current_frame = gen_frame;
             goto start_frame;
         }
 
-
         // stack effect: ( -- __0)
         inst(BEFORE_ASYNC_WITH) {
             PyObject *mgr = TOP();
@@ -2929,9 +2923,9 @@ dummy_func(
 
         // stack effect: ( -- )
         inst(KW_NAMES) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             assert(oparg < PyTuple_GET_SIZE(consts));
-            call_shape.kwnames = GETITEM(consts, oparg);
+            kwnames = GETITEM(consts, oparg);
         }
 
         // stack effect: (__0, __array[oparg] -- )
@@ -2943,7 +2937,7 @@ dummy_func(
                 int nargs = oparg + is_meth;
                 PyObject *callable = PEEK(nargs + 1);
                 next_instr--;
-                _Py_Specialize_Call(callable, next_instr, nargs, call_shape.kwnames);
+                _Py_Specialize_Call(callable, next_instr, nargs, kwnames);
                 DISPATCH_SAME_OPARG();
             }
             STAT_INC(CALL, deferred);
@@ -2972,9 +2966,9 @@ dummy_func(
                 STACK_SHRINK(total_args);
                 _PyInterpreterFrame *new_frame = _PyEvalFramePushAndInit(
                     tstate, (PyFunctionObject *)function, locals,
-                    stack_pointer, positional_args, call_shape.kwnames
+                    stack_pointer, positional_args, kwnames
                 );
-                call_shape.kwnames = NULL;
+                kwnames = NULL;
                 STACK_SHRINK(2-is_meth);
                 // The frame has stolen all the arguments from the stack,
                 // so there is no need to clean them up.
@@ -2994,15 +2988,15 @@ dummy_func(
             if (cframe.use_tracing) {
                 res = trace_call_function(
                     tstate, function, stack_pointer-total_args,
-                    positional_args, call_shape.kwnames);
+                    positional_args, kwnames);
             }
             else {
                 res = PyObject_Vectorcall(
                     function, stack_pointer-total_args,
                     positional_args | PY_VECTORCALL_ARGUMENTS_OFFSET,
-                    call_shape.kwnames);
+                    kwnames);
             }
-            call_shape.kwnames = NULL;
+            kwnames = NULL;
             assert((res != NULL) ^ (_PyErr_Occurred(tstate) != NULL));
             Py_DECREF(function);
             /* Clear the stack */
@@ -3021,7 +3015,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_PY_EXACT_ARGS) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             DEOPT_IF(tstate->interp->eval_frame, CALL);
             _PyCallCache *cache = (_PyCallCache *)next_instr;
             int is_meth = is_method(stack_pointer, oparg);
@@ -3054,7 +3048,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_PY_WITH_DEFAULTS) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             DEOPT_IF(tstate->interp->eval_frame, CALL);
             _PyCallCache *cache = (_PyCallCache *)next_instr;
             int is_meth = is_method(stack_pointer, oparg);
@@ -3094,7 +3088,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_TYPE_1) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             assert(cframe.use_tracing == 0);
             assert(oparg == 1);
             DEOPT_IF(is_method(stack_pointer, 1), CALL);
@@ -3112,7 +3106,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_STR_1) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             assert(cframe.use_tracing == 0);
             assert(oparg == 1);
             DEOPT_IF(is_method(stack_pointer, 1), CALL);
@@ -3134,7 +3128,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_TUPLE_1) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             assert(oparg == 1);
             DEOPT_IF(is_method(stack_pointer, 1), CALL);
             PyObject *callable = PEEK(2);
@@ -3166,8 +3160,8 @@ dummy_func(
             JUMPBY(INLINE_CACHE_ENTRIES_CALL);
             STACK_SHRINK(total_args);
             PyObject *res = tp->tp_vectorcall((PyObject *)tp, stack_pointer,
-                                              total_args-kwnames_len, call_shape.kwnames);
-            call_shape.kwnames = NULL;
+                                              total_args-kwnames_len, kwnames);
+            kwnames = NULL;
             /* Free the arguments. */
             for (int i = 0; i < total_args; i++) {
                 Py_DECREF(stack_pointer[i]);
@@ -3185,7 +3179,7 @@ dummy_func(
         inst(CALL_NO_KW_BUILTIN_O) {
             assert(cframe.use_tracing == 0);
             /* Builtin METH_O functions */
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
             DEOPT_IF(total_args != 1, CALL);
@@ -3219,7 +3213,7 @@ dummy_func(
         inst(CALL_NO_KW_BUILTIN_FAST) {
             assert(cframe.use_tracing == 0);
             /* Builtin METH_FASTCALL functions, without keywords */
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
             PyObject *callable = PEEK(total_args + 1);
@@ -3276,10 +3270,10 @@ dummy_func(
                 PyCFunction_GET_SELF(callable),
                 stack_pointer,
                 total_args - KWNAMES_LEN(),
-                call_shape.kwnames
+                kwnames
             );
             assert((res != NULL) ^ (_PyErr_Occurred(tstate) != NULL));
-            call_shape.kwnames = NULL;
+            kwnames = NULL;
 
             /* Free the arguments. */
             for (int i = 0; i < total_args; i++) {
@@ -3297,7 +3291,7 @@ dummy_func(
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_LEN) {
             assert(cframe.use_tracing == 0);
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             /* len(o) */
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
@@ -3327,7 +3321,7 @@ dummy_func(
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_ISINSTANCE) {
             assert(cframe.use_tracing == 0);
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             /* isinstance(o, o2) */
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
@@ -3360,7 +3354,7 @@ dummy_func(
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_LIST_APPEND) {
             assert(cframe.use_tracing == 0);
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             assert(oparg == 1);
             PyObject *callable = PEEK(3);
             PyInterpreterState *interp = _PyInterpreterState_GET();
@@ -3382,7 +3376,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_METHOD_DESCRIPTOR_O) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
             PyMethodDescrObject *callable =
@@ -3435,9 +3429,9 @@ dummy_func(
             _PyCFunctionFastWithKeywords cfunc =
                 (_PyCFunctionFastWithKeywords)(void(*)(void))meth->ml_meth;
             PyObject *res = cfunc(self, stack_pointer, nargs - KWNAMES_LEN(),
-                                  call_shape.kwnames);
+                                  kwnames);
             assert((res != NULL) ^ (_PyErr_Occurred(tstate) != NULL));
-            call_shape.kwnames = NULL;
+            kwnames = NULL;
 
             /* Free the arguments. */
             for (int i = 0; i < nargs; i++) {
@@ -3455,7 +3449,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_METHOD_DESCRIPTOR_NOARGS) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             assert(oparg == 0 || oparg == 1);
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
@@ -3489,7 +3483,7 @@ dummy_func(
 
         // stack effect: (__0, __array[oparg] -- )
         inst(CALL_NO_KW_METHOD_DESCRIPTOR_FAST) {
-            assert(call_shape.kwnames == NULL);
+            assert(kwnames == NULL);
             int is_meth = is_method(stack_pointer, oparg);
             int total_args = oparg + is_meth;
             PyMethodDescrObject *callable =
@@ -3606,25 +3600,12 @@ dummy_func(
             gen->gi_frame_state = FRAME_CREATED;
             gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
             _Py_LeaveRecursiveCallPy(tstate);
-            if (!frame->is_entry) {
-                _PyInterpreterFrame *prev = frame->previous;
-                _PyThreadState_PopFrame(tstate, frame);
-                frame = cframe.current_frame = prev;
-                _PyFrame_StackPush(frame, (PyObject *)gen);
-                goto resume_frame;
-            }
-            _Py_LeaveRecursiveCallTstate(tstate);
-            /* Make sure that frame is in a valid state */
-            frame->stacktop = 0;
-            frame->f_locals = NULL;
-            Py_INCREF(frame->f_funcobj);
-            Py_INCREF(frame->f_code);
-            /* Restore previous cframe and return. */
-            tstate->cframe = cframe.previous;
-            tstate->cframe->use_tracing = cframe.use_tracing;
-            assert(tstate->cframe->current_frame == frame->previous);
-            assert(!_PyErr_Occurred(tstate));
-            return (PyObject *)gen;
+            assert(frame != &entry_frame);
+            _PyInterpreterFrame *prev = frame->previous;
+            _PyThreadState_PopFrame(tstate, frame);
+            frame = cframe.current_frame = prev;
+            _PyFrame_StackPush(frame, (PyObject *)gen);
+            goto resume_frame;
         }
 
         // error: BUILD_SLICE has irregular stack effect