gh-120780: Show attribute name for LOAD_SPECIAL in dis output

Lib/dis.py

@@ -14,6 +14,7 @@
     _common_constants,
     _intrinsic_1_descs,
     _intrinsic_2_descs,
+    _special_method_names,
     _specializations,
     _specialized_opmap,
 )
@@ -46,6 +47,7 @@
 CALL_INTRINSIC_1 = opmap['CALL_INTRINSIC_1']
 CALL_INTRINSIC_2 = opmap['CALL_INTRINSIC_2']
 LOAD_COMMON_CONSTANT = opmap['LOAD_COMMON_CONSTANT']
+LOAD_SPECIAL = opmap['LOAD_SPECIAL']
 LOAD_FAST_LOAD_FAST = opmap['LOAD_FAST_LOAD_FAST']
 STORE_FAST_LOAD_FAST = opmap['STORE_FAST_LOAD_FAST']
 STORE_FAST_STORE_FAST = opmap['STORE_FAST_STORE_FAST']
@@ -609,6 +611,8 @@ def get_argval_argrepr(self, op, arg, offset):
                     argrepr = obj.__name__
                 else:
                     argrepr = repr(obj)
+            elif deop == LOAD_SPECIAL:
+                argrepr = _special_method_names[arg]
         return argval, argrepr
 
 def get_instructions(x, *, first_line=None, show_caches=None, adaptive=False):

Lib/opcode.py

@@ -36,6 +36,7 @@
 
 _intrinsic_1_descs = _opcode.get_intrinsic1_descs()
 _intrinsic_2_descs = _opcode.get_intrinsic2_descs()
+_special_method_names = _opcode.get_special_method_names()
 _common_constants = [AssertionError, NotImplementedError]
 _nb_ops = _opcode.get_nb_ops()
 

Lib/test/test_dis.py

@@ -481,10 +481,10 @@ def _with(c):
 
 %4d           LOAD_FAST                0 (c)
                COPY                     1
-               LOAD_SPECIAL             1
+               LOAD_SPECIAL             1 (__exit__)
                SWAP                     2
                SWAP                     3
-               LOAD_SPECIAL             0
+               LOAD_SPECIAL             0 (__enter__)
                CALL                     0
        L1:     POP_TOP
 
@@ -543,10 +543,10 @@ async def _asyncwith(c):
 
 %4d            LOAD_FAST                0 (c)
                 COPY                     1
-                LOAD_SPECIAL             3
+                LOAD_SPECIAL             3 (__aexit__)
                 SWAP                     2
                 SWAP                     3
-                LOAD_SPECIAL             2
+                LOAD_SPECIAL             2 (__aenter__)
                 CALL                     0
                 GET_AWAITABLE            1
                 LOAD_CONST               0 (None)
@@ -1738,10 +1738,10 @@ def _prepare_test_cases():
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=240, start_offset=240, starts_line=False, line_number=21, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=83, arg=0, argval='i', argrepr='i', offset=242, start_offset=242, starts_line=True, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='COPY', opcode=58, arg=1, argval=1, argrepr='', offset=244, start_offset=244, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_SPECIAL', opcode=91, arg=1, argval=1, argrepr='', offset=246, start_offset=246, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_SPECIAL', opcode=91, arg=1, argval=1, argrepr='__exit__', offset=246, start_offset=246, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='SWAP', opcode=114, arg=2, argval=2, argrepr='', offset=248, start_offset=248, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='SWAP', opcode=114, arg=3, argval=3, argrepr='', offset=250, start_offset=250, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_SPECIAL', opcode=91, arg=0, argval=0, argrepr='', offset=252, start_offset=252, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_SPECIAL', opcode=91, arg=0, argval=0, argrepr='__enter__', offset=252, start_offset=252, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=50, arg=0, argval=0, argrepr='', offset=254, start_offset=254, starts_line=False, line_number=25, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='STORE_FAST', opcode=109, arg=1, argval='dodgy', argrepr='dodgy', offset=262, start_offset=262, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_GLOBAL', opcode=89, arg=3, argval='print', argrepr='print + NULL', offset=264, start_offset=264, starts_line=True, line_number=26, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('index', 1, b'\x00\x00'), ('module_keys_version', 1, b'\x00\x00'), ('builtin_keys_version', 1, b'\x00\x00')]),

Misc/NEWS.d/next/Library/2024-06-19-23-08-25.gh-issue-120780.0Omopb.rst

@@ -0,0 +1 @@
+Show string value of LOAD_SPECIAL oparg in :mod:`dis` output.

Modules/_opcode.c

@@ -5,6 +5,7 @@
 #include "Python.h"
 #include "compile.h"
 #include "opcode.h"
+#include "internal/pycore_ceval.h"
 #include "internal/pycore_code.h"
 #include "internal/pycore_compile.h"
 #include "internal/pycore_intrinsics.h"
@@ -349,6 +350,32 @@ _opcode_get_intrinsic2_descs_impl(PyObject *module)
 
 /*[clinic input]
 
+_opcode.get_special_method_names
+
+Return a list of special method names.
+[clinic start generated code]*/
+
+static PyObject *
+_opcode_get_special_method_names_impl(PyObject *module)
+/*[clinic end generated code: output=fce72614cd988d17 input=25f2115560bdf163]*/
+{
+    PyObject *list = PyList_New(SPECIAL_MAX + 1);
+    if (list == NULL) {
+        return NULL;
+    }
+    for (int i=0; i <= SPECIAL_MAX; i++) {
+        PyObject *name = _Py_SpecialMethods[i].name;
+        if (name == NULL) {
+            Py_DECREF(list);
+            return NULL;
+        }
+        PyList_SET_ITEM(list, i, name);
+    }
+    return list;
+}
+
+/*[clinic input]
+
 _opcode.get_executor
 
   code: object
@@ -392,6 +419,7 @@ opcode_functions[] =  {
     _OPCODE_GET_INTRINSIC1_DESCS_METHODDEF
     _OPCODE_GET_INTRINSIC2_DESCS_METHODDEF
     _OPCODE_GET_EXECUTOR_METHODDEF
+    _OPCODE_GET_SPECIAL_METHOD_NAMES_METHODDEF
     {NULL, NULL, 0, NULL}
 };