pythonGH-118095: Handle RETURN_GENERATOR in tier 2 (pythonGH-118180)

Author: markshannon

Include/internal/pycore_ceval.h

@@ -182,7 +182,7 @@ static inline void _Py_LeaveRecursiveCall(void)  {
 
 extern struct _PyInterpreterFrame* _PyEval_GetFrame(void);
 
-extern PyObject* _Py_MakeCoro(PyFunctionObject *func);
+PyAPI_FUNC(PyObject *)_Py_MakeCoro(PyFunctionObject *func);
 
 /* Handle signals, pending calls, GIL drop request
    and asynchronous exception */

Include/internal/pycore_frame.h

@@ -110,7 +110,17 @@ _PyFrame_NumSlotsForCodeObject(PyCodeObject *code)
     return code->co_framesize - FRAME_SPECIALS_SIZE;
 }
 
-void _PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *dest);
+static inline void _PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *dest)
+{
+    assert(src->stacktop >= _PyFrame_GetCode(src)->co_nlocalsplus);
+    *dest = *src;
+    for (int i = 1; i < src->stacktop; i++) {
+        dest->localsplus[i] = src->localsplus[i];
+    }
+    // Don't leave a dangling pointer to the old frame when creating generators
+    // and coroutines:
+    dest->previous = NULL;
+}
 
 /* Consumes reference to func and locals.
    Does not initialize frame->previous, which happens
@@ -256,7 +266,7 @@ _PyThreadState_HasStackSpace(PyThreadState *tstate, int size)
 extern _PyInterpreterFrame *
 _PyThreadState_PushFrame(PyThreadState *tstate, size_t size);
 
-void _PyThreadState_PopFrame(PyThreadState *tstate, _PyInterpreterFrame *frame);
+PyAPI_FUNC(void) _PyThreadState_PopFrame(PyThreadState *tstate, _PyInterpreterFrame *frame);
 
 /* Pushes a frame without checking for space.
  * Must be guarded by _PyThreadState_HasStackSpace()

Include/internal/pycore_opcode_metadata.h

@@ -1286,5 +1286,17 @@ def testfunc(n):
         self.assertEqual(res, 32 * 32)
         self.assertIsNone(ex)
 
+    def test_return_generator(self):
+        def gen():
+            yield None
+        def testfunc(n):
+            for i in range(n):
+                gen()
+            return i
+        res, ex = self._run_with_optimizer(testfunc, 20)
+        self.assertEqual(res, 19)
+        self.assertIsNotNone(ex)
+        self.assertIn("_RETURN_GENERATOR", get_opnames(ex))
+
 if __name__ == "__main__":
     unittest.main()

Include/internal/pycore_uop_ids.h

@@ -304,11 +304,6 @@ mark_stacks(PyCodeObject *code_obj, int len)
         stacks[i] = UNINITIALIZED;
     }
     stacks[0] = EMPTY_STACK;
-    if (code_obj->co_flags & (CO_GENERATOR | CO_COROUTINE | CO_ASYNC_GENERATOR))
-    {
-        // Generators get sent None while starting:
-        stacks[0] = push_value(stacks[0], Object);
-    }
     int todo = 1;
     while (todo) {
         todo = 0;

Include/internal/pycore_uop_metadata.h

@@ -837,12 +837,7 @@ dummy_func(
             _PyFrame_StackPush(frame, retval);
             LOAD_SP();
             LOAD_IP(frame->return_offset);
-#if LLTRACE && TIER_ONE
-            lltrace = maybe_lltrace_resume_frame(frame, &entry_frame, GLOBALS());
-            if (lltrace < 0) {
-                goto exit_unwind;
-            }
-#endif
+            LLTRACE_RESUME_FRAME();
         }
 
         macro(RETURN_VALUE) =
@@ -3186,12 +3181,7 @@ dummy_func(
             tstate->py_recursion_remaining--;
             LOAD_SP();
             LOAD_IP(0);
-#if LLTRACE && TIER_ONE
-            lltrace = maybe_lltrace_resume_frame(frame, &entry_frame, GLOBALS());
-            if (lltrace < 0) {
-                goto exit_unwind;
-            }
-#endif
+            LLTRACE_RESUME_FRAME();
         }
 
         macro(CALL_BOUND_METHOD_EXACT_ARGS) =
@@ -3877,7 +3867,7 @@ dummy_func(
             }
         }
 
-        tier1 inst(RETURN_GENERATOR, (--)) {
+        inst(RETURN_GENERATOR, (-- res)) {
             assert(PyFunction_Check(frame->f_funcobj));
             PyFunctionObject *func = (PyFunctionObject *)frame->f_funcobj;
             PyGenObject *gen = (PyGenObject *)_Py_MakeCoro(func);
@@ -3887,19 +3877,19 @@ dummy_func(
             assert(EMPTY());
             _PyFrame_SetStackPointer(frame, stack_pointer);
             _PyInterpreterFrame *gen_frame = (_PyInterpreterFrame *)gen->gi_iframe;
-            frame->instr_ptr = next_instr;
+            frame->instr_ptr++;
             _PyFrame_Copy(frame, gen_frame);
             assert(frame->frame_obj == NULL);
             gen->gi_frame_state = FRAME_CREATED;
             gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
             _Py_LeaveRecursiveCallPy(tstate);
-            assert(frame != &entry_frame);
+            res = (PyObject *)gen;
             _PyInterpreterFrame *prev = frame->previous;
             _PyThreadState_PopFrame(tstate, frame);
             frame = tstate->current_frame = prev;
-            _PyFrame_StackPush(frame, (PyObject *)gen);
             LOAD_IP(frame->return_offset);
-            goto resume_frame;
+            LOAD_SP();
+            LLTRACE_RESUME_FRAME();
         }
 
         inst(BUILD_SLICE, (start, stop, step if (oparg == 3) -- slice)) {

Lib/test/test_capi/test_opt.py

@@ -86,6 +86,18 @@
 #define PRE_DISPATCH_GOTO() ((void)0)
 #endif
 
+#if LLTRACE
+#define LLTRACE_RESUME_FRAME() \
+do { \
+    lltrace = maybe_lltrace_resume_frame(frame, &entry_frame, GLOBALS()); \
+    if (lltrace < 0) { \
+        goto exit_unwind; \
+    } \
+} while (0)
+#else
+#define LLTRACE_RESUME_FRAME() ((void)0)
+#endif
+
 #ifdef Py_GIL_DISABLED
 #define QSBR_QUIESCENT_STATE(tstate) _Py_qsbr_quiescent_state(((_PyThreadStateImpl *)tstate)->qsbr)
 #else

Objects/frameobject.c

@@ -53,18 +53,6 @@ _PyFrame_MakeAndSetFrameObject(_PyInterpreterFrame *frame)
     return f;
 }
 
-void
-_PyFrame_Copy(_PyInterpreterFrame *src, _PyInterpreterFrame *dest)
-{
-    assert(src->stacktop >= _PyFrame_GetCode(src)->co_nlocalsplus);
-    Py_ssize_t size = ((char*)&src->localsplus[src->stacktop]) - (char *)src;
-    memcpy(dest, src, size);
-    // Don't leave a dangling pointer to the old frame when creating generators
-    // and coroutines:
-    dest->previous = NULL;
-}
-
-
 static void
 take_ownership(PyFrameObject *f, _PyInterpreterFrame *frame)
 {

Python/bytecodes.c

@@ -697,7 +697,8 @@ translate_bytecode_to_trace(
                     // Reserve space for nuops (+ _SET_IP + _EXIT_TRACE)
                     int nuops = expansion->nuops;
                     RESERVE(nuops + 1); /* One extra for exit */
-                    if (expansion->uops[nuops-1].uop == _POP_FRAME) {
+                    int16_t last_op = expansion->uops[nuops-1].uop;
+                    if (last_op == _POP_FRAME || last_op == _RETURN_GENERATOR) {
                         // Check for trace stack underflow now:
                         // We can't bail e.g. in the middle of
                         // LOAD_CONST + _POP_FRAME.
@@ -756,7 +757,7 @@ translate_bytecode_to_trace(
                                 Py_FatalError("garbled expansion");
                         }
 
-                        if (uop == _POP_FRAME) {
+                        if (uop == _POP_FRAME || uop == _RETURN_GENERATOR) {
                             TRACE_STACK_POP();
                             /* Set the operand to the function or code object returned to,
                              * to assist optimization passes. (See _PUSH_FRAME below.)

Python/ceval_macros.h

@@ -369,7 +369,7 @@ eliminate_pop_guard(_PyUOpInstruction *this_instr, bool exit)
 static PyCodeObject *
 get_code(_PyUOpInstruction *op)
 {
-    assert(op->opcode == _PUSH_FRAME || op->opcode == _POP_FRAME);
+    assert(op->opcode == _PUSH_FRAME || op->opcode == _POP_FRAME || op->opcode == _RETURN_GENERATOR);
     PyCodeObject *co = NULL;
     uint64_t operand = op->operand;
     if (operand == 0) {