GH-125837: Split `LOAD_CONST` into three. (GH-125972)

* Add LOAD_CONST_IMMORTAL opcode

* Add LOAD_SMALL_INT opcode

* Remove RETURN_CONST opcode

1 files changed, 19 insertions, 13 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 057ee0a92d9..b7469c2dd8d 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -255,10 +255,26 @@ dummy_func(
             value2 = PyStackRef_DUP(GETLOCAL(oparg2));
         }
 
+        family(LOAD_CONST, 0) = {
+            LOAD_CONST_IMMORTAL,
+        };
+
         pure inst(LOAD_CONST, (-- value)) {
             value = PyStackRef_FromPyObjectNew(GETITEM(FRAME_CO_CONSTS, oparg));
         }
 
+        inst(LOAD_CONST_IMMORTAL, (-- value)) {
+            PyObject *obj = GETITEM(FRAME_CO_CONSTS, oparg);
+            assert(_Py_IsImmortal(obj));
+            value = PyStackRef_FromPyObjectImmortal(obj);
+        }
+
+        replicate(4) inst(LOAD_SMALL_INT, (-- value)) {
+            assert(oparg < _PY_NSMALLPOSINTS);
+            PyObject *obj = (PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS + oparg];
+            value = PyStackRef_FromPyObjectImmortal(obj);
+        }
+
         replicate(8) inst(STORE_FAST, (value --)) {
             SETLOCAL(oparg, value);
             DEAD(value);
@@ -979,10 +995,9 @@ dummy_func(
             return result;
         }
 
-        // The stack effect here is ambiguous.
-        // We definitely pop the return value off the stack on entry.
-        // We also push it onto the stack on exit, but that's a
-        // different frame, and it's accounted for by _PUSH_FRAME.
+        // The stack effect here is a bit misleading.
+        // retval is popped from the stack, but res
+        // is pushed to a different frame, the callers' frame.
         inst(RETURN_VALUE, (retval -- res)) {
             #if TIER_ONE
             assert(frame != &entry_frame);
@@ -1013,15 +1028,6 @@ dummy_func(
             _RETURN_VALUE_EVENT +
             RETURN_VALUE;
 
-        macro(RETURN_CONST) =
-            LOAD_CONST +
-            RETURN_VALUE;
-
-        macro(INSTRUMENTED_RETURN_CONST) =
-            LOAD_CONST +
-            _RETURN_VALUE_EVENT +
-            RETURN_VALUE;
-
         inst(GET_AITER, (obj -- iter)) {
             unaryfunc getter = NULL;
             PyObject *obj_o = PyStackRef_AsPyObjectBorrow(obj);