pythonGH-134282: Always borrow references LOAD_CONST (pythonGH-134284)

Author: markshannon

Include/internal/pycore_magic_number.h

@@ -278,6 +278,7 @@ Known values:
     Python 3.14a7 3623 (Add BUILD_INTERPOLATION & BUILD_TEMPLATE opcodes)
     Python 3.14b1 3624 (Don't optimize LOAD_FAST when local is killed by DELETE_FAST)
     Python 3.15a0 3650 (Initial version)
+    Python 3.15a1 3651 (Simplify LOAD_CONST)
 
     Python 3.16 will start with 3700
 
@@ -290,7 +291,7 @@ PC/launcher.c must also be updated.
 
 */
 
-#define PYC_MAGIC_NUMBER 3650
+#define PYC_MAGIC_NUMBER 3651
 /* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
    (little-endian) and then appending b'\r\n'. */
 #define PYC_MAGIC_NUMBER_TOKEN \

Include/internal/pycore_opcode_metadata.h

@@ -134,12 +134,11 @@ _PyStackRef_FromPyObjectSteal(PyObject *obj, const char *filename, int linenumbe
 #define PyStackRef_FromPyObjectSteal(obj) _PyStackRef_FromPyObjectSteal(_PyObject_CAST(obj), __FILE__, __LINE__)
 
 static inline _PyStackRef
-_PyStackRef_FromPyObjectImmortal(PyObject *obj, const char *filename, int linenumber)
+_PyStackRef_FromPyObjectBorrow(PyObject *obj, const char *filename, int linenumber)
 {
-    assert(_Py_IsImmortal(obj));
     return _Py_stackref_create(obj, filename, linenumber);
 }
-#define PyStackRef_FromPyObjectImmortal(obj) _PyStackRef_FromPyObjectImmortal(_PyObject_CAST(obj), __FILE__, __LINE__)
+#define PyStackRef_FromPyObjectBorrow(obj) _PyStackRef_FromPyObjectBorrow(_PyObject_CAST(obj), __FILE__, __LINE__)
 
 static inline void
 _PyStackRef_CLOSE(_PyStackRef ref, const char *filename, int linenumber)
@@ -366,15 +365,14 @@ PyStackRef_FromPyObjectNew(PyObject *obj)
 #define PyStackRef_FromPyObjectNew(obj) PyStackRef_FromPyObjectNew(_PyObject_CAST(obj))
 
 static inline _PyStackRef
-PyStackRef_FromPyObjectImmortal(PyObject *obj)
+PyStackRef_FromPyObjectBorrow(PyObject *obj)
 {
     // Make sure we don't take an already tagged value.
     assert(((uintptr_t)obj & Py_TAG_BITS) == 0);
     assert(obj != NULL);
-    assert(_Py_IsImmortal(obj));
     return (_PyStackRef){ .bits = (uintptr_t)obj | Py_TAG_DEFERRED };
 }
-#define PyStackRef_FromPyObjectImmortal(obj) PyStackRef_FromPyObjectImmortal(_PyObject_CAST(obj))
+#define PyStackRef_FromPyObjectBorrow(obj) PyStackRef_FromPyObjectBorrow(_PyObject_CAST(obj))
 
 #define PyStackRef_CLOSE(REF)                                        \
         do {                                                            \
@@ -582,9 +580,8 @@ _PyStackRef_FromPyObjectNewMortal(PyObject *obj)
 
 /* Create a new reference from an object with an embedded reference count */
 static inline _PyStackRef
-PyStackRef_FromPyObjectImmortal(PyObject *obj)
+PyStackRef_FromPyObjectBorrow(PyObject *obj)
 {
-    assert(_Py_IsImmortal(obj));
     return (_PyStackRef){ .bits = (uintptr_t)obj | Py_TAG_REFCNT};
 }
 

Include/internal/pycore_stackref.h

@@ -180,7 +180,7 @@ def test_is_uniquely_referenced(self):
         self.assertTrue(_testcapi.is_uniquely_referenced(object()))
         self.assertTrue(_testcapi.is_uniquely_referenced([]))
         # Immortals
-        self.assertFalse(_testcapi.is_uniquely_referenced("spanish inquisition"))
+        self.assertFalse(_testcapi.is_uniquely_referenced(()))
         self.assertFalse(_testcapi.is_uniquely_referenced(42))
         # CRASHES is_uniquely_referenced(NULL)
 

Include/internal/pycore_uop_ids.h

@@ -902,7 +902,7 @@ def loop_test():
 %3d           RESUME_CHECK             0
 
 %3d           BUILD_LIST               0
-              LOAD_CONST_MORTAL        2 ((1, 2, 3))
+              LOAD_CONST               2 ((1, 2, 3))
               LIST_EXTEND              1
               LOAD_SMALL_INT           3
               BINARY_OP                5 (*)
@@ -918,7 +918,7 @@ def loop_test():
 
 %3d   L2:     END_FOR
               POP_ITER
-              LOAD_CONST_IMMORTAL      1 (None)
+              LOAD_CONST               1 (None)
               RETURN_VALUE
 """ % (loop_test.__code__.co_firstlineno,
        loop_test.__code__.co_firstlineno + 1,
@@ -1304,7 +1304,7 @@ def test_load_attr_specialize(self):
         load_attr_quicken = """\
   0           RESUME_CHECK             0
 
-  1           LOAD_CONST_IMMORTAL      0 ('a')
+  1           LOAD_CONST               0 ('a')
               LOAD_ATTR_SLOT           0 (__class__)
               RETURN_VALUE
 """

Include/internal/pycore_uop_metadata.h

@@ -1810,20 +1810,6 @@ def compare_op_str():
         self.assert_specialized(compare_op_str, "COMPARE_OP_STR")
         self.assert_no_opcode(compare_op_str, "COMPARE_OP")
 
-    @cpython_only
-    @requires_specialization_ft
-    def test_load_const(self):
-        def load_const():
-            def unused(): pass
-            # Currently, the empty tuple is immortal, and the otherwise
-            # unused nested function's code object is mortal. This test will
-            # have to use different values if either of that changes.
-            return ()
-
-        load_const()
-        self.assert_specialized(load_const, "LOAD_CONST_IMMORTAL")
-        self.assert_specialized(load_const, "LOAD_CONST_MORTAL")
-        self.assert_no_opcode(load_const, "LOAD_CONST")
 
     @cpython_only
     @requires_specialization_ft