bpo-47186: Replace JUMP_IF_NOT_EG_MATCH by CHECK_EG_MATCH + jump

iritkatriel · iritkatriel · commit 4525e3c0d3ab · 2022-04-04T18:38:36.000+01:00
diff --git a/Doc/library/dis.rst b/Doc/library/dis.rst
@@ -635,6 +635,28 @@ iterations of the loop.
 
    .. versionadded:: 3.11
 
+.. opcode:: CHECK_EG_MATCH
+
+   Performs exception matching for ``except*``. Applies ``split(TOS)`` on
+   the exception group representing TOS1.
+
+   In case of a match, pops two items from the stack and pushes the
+   non-matching subgroup (``None`` in case of full match) followed by the
+   matching subgroup. When there is no match, pops one item (the match
+   type) and pushes ``None``.
+
+   .. versionadded:: 3.11
+
+.. opcode:: PREP_RERAISE_STAR
+
+   Combines the raised and reraised exceptions list from TOS, into an exception
+   group to propagate from a try-except* block. Uses the original exception
+   group from TOS1 to reconstruct the structure of reraised exceptions. Pops
+   two items from the stack and pushes the exception to reraise or ``None``
+   if there isn't one.
+
+   .. versionadded:: 3.11
+
 .. opcode:: WITH_EXCEPT_START
 
     Calls the function in position 4 on the stack with arguments (type, val, tb)
@@ -922,18 +944,6 @@ iterations of the loop.
    .. versionadded:: 3.1
 
 
-.. opcode:: JUMP_IF_NOT_EG_MATCH (target)
-
-   Performs exception matching for ``except*``. Applies ``split(TOS)`` on
-   the exception group representing TOS1. Jumps if no match is found.
-
-   Pops one item from the stack (the match type). If a match was found,
-   next item (the exception) and pushes the non-matching part of the
-   exception group followed by the matching part.
-
-   .. versionadded:: 3.11
-
-
 .. opcode:: POP_JUMP_IF_NOT_NONE (target)
 
    If TOS is not none, sets the bytecode counter to *target*.  TOS is popped.
@@ -948,17 +958,6 @@ iterations of the loop.
    .. versionadded:: 3.11
 
 
-.. opcode:: PREP_RERAISE_STAR
-
-   Combines the raised and reraised exceptions list from TOS, into an exception
-   group to propagate from a try-except* block. Uses the original exception
-   group from TOS1 to reconstruct the structure of reraised exceptions. Pops
-   two items from the stack and pushes the exception to reraise or ``None``
-   if there isn't one.
-
-   .. versionadded:: 3.11
-
-
 .. opcode:: JUMP_IF_TRUE_OR_POP (target)
 
    If TOS is true, sets the bytecode counter to *target* and leaves TOS on the
diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
@@ -523,6 +523,9 @@ CPython bytecode changes
 * Replaced :opcode:`JUMP_IF_NOT_EXC_MATCH` by :opcode:`CHECK_EXC_MATCH` which
   performs the check but does not jump.
 
+* Replaced :opcode:`JUMP_IF_NOT_EG_MATCH` by :opcode:`CHECK_EG_MATCH` which
+  performs the check but does not jump.
+
 * Replaced :opcode:`JUMP_ABSOLUTE` by the relative :opcode:`JUMP_BACKWARD`.
 
 Deprecated
diff --git a/Include/opcode.h b/Include/opcode.h
diff --git a/Lib/importlib/_bootstrap_external.py b/Lib/importlib/_bootstrap_external.py
@@ -398,6 +398,7 @@ def _write_atomic(path, data, mode=0o666):
 #     Python 3.11a6 3488 (LOAD_GLOBAL can push additional NULL)
 #     Python 3.11a6 3489 (Add JUMP_BACKWARD, remove JUMP_ABSOLUTE)
 #     Python 3.11a6 3490 (remove JUMP_IF_NOT_EXC_MATCH, add CHECK_EXC_MATCH)
+#     Python 3.11a6 3491 (remove JUMP_IF_NOT_EG_MATCH, add CHECK_EG_MATCH)
 
 #     Python 3.12 will start with magic number 3500
 
@@ -412,7 +413,7 @@ def _write_atomic(path, data, mode=0o666):
 # Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
 # in PC/launcher.c must also be updated.
 
-MAGIC_NUMBER = (3490).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3491).to_bytes(2, 'little') + b'\r\n'
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # For import.c
 
 _PYCACHE = '__pycache__'
diff --git a/Lib/opcode.py b/Lib/opcode.py
@@ -77,6 +77,7 @@ def jabs_op(name, op, entries=0):
 
 def_op('PUSH_EXC_INFO', 35)
 def_op('CHECK_EXC_MATCH', 36)
+def_op('CHECK_EG_MATCH', 37)
 
 def_op('WITH_EXCEPT_START', 49)
 def_op('GET_AITER', 50)
@@ -147,7 +148,6 @@ def jabs_op(name, op, entries=0):
 haslocal.append(125)
 def_op('DELETE_FAST', 126)      # Local variable number
 haslocal.append(126)
-jabs_op('JUMP_IF_NOT_EG_MATCH', 127)
 jabs_op('POP_JUMP_IF_NOT_NONE', 128)
 jabs_op('POP_JUMP_IF_NONE', 129)
 def_op('RAISE_VARARGS', 130)    # Number of raise arguments (1, 2, or 3)
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
@@ -207,21 +207,15 @@ mark_stacks(PyCodeObject *code_obj, int len)
                 case JUMP_IF_TRUE_OR_POP:
                 case POP_JUMP_IF_FALSE:
                 case POP_JUMP_IF_TRUE:
-                case JUMP_IF_NOT_EG_MATCH:
                 {
                     int64_t target_stack;
                     int j = get_arg(code, i);
                     assert(j < len);
                     if (stacks[j] == UNINITIALIZED && j < i) {
                         todo = 1;
                     }
-                    if (opcode == JUMP_IF_NOT_EG_MATCH)
-                    {
-                        next_stack = pop_value(pop_value(next_stack));
-                        target_stack = next_stack;
-                    }
-                    else if (opcode == JUMP_IF_FALSE_OR_POP ||
-                             opcode == JUMP_IF_TRUE_OR_POP)
+                    if (opcode == JUMP_IF_FALSE_OR_POP ||
+                        opcode == JUMP_IF_TRUE_OR_POP)
                     {
                         target_stack = next_stack;
                         next_stack = pop_value(next_stack);
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -3804,7 +3804,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             DISPATCH();
         }
 
-        TARGET(JUMP_IF_NOT_EG_MATCH) {
+        TARGET(CHECK_EG_MATCH) {
             PyObject *match_type = POP();
             if (check_except_star_type_valid(tstate, match_type) < 0) {
                 Py_DECREF(match_type);
@@ -3825,33 +3825,23 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
                 assert(rest == NULL);
                 goto error;
             }
-
             if (Py_IsNone(match)) {
-                Py_DECREF(match);
+                PUSH(match);
                 Py_XDECREF(rest);
-                /* no match - jump to target */
-                JUMPTO(oparg);
             }
             else {
-
                 /* Total or partial match - update the stack from
                  * [val]
                  * to
                  * [rest, match]
                  * (rest can be Py_None)
                  */
 
-                PyObject *exc = TOP();
-
                 SET_TOP(rest);
                 PUSH(match);
-
                 PyErr_SetExcInfo(NULL, Py_NewRef(match), NULL);
-
-                Py_DECREF(exc);
-
+                Py_DECREF(exc_value);
             }
-
             DISPATCH();
         }
 
diff --git a/Python/compile.c b/Python/compile.c
@@ -1000,8 +1000,8 @@ stack_effect(int opcode, int oparg, int jump)
             return -1;
         case CHECK_EXC_MATCH:
             return 0;
-        case JUMP_IF_NOT_EG_MATCH:
-            return jump > 0 ? -1 : 0;
+        case CHECK_EG_MATCH:
+            return 0;
         case IMPORT_NAME:
             return -1;
         case IMPORT_FROM:
@@ -3622,6 +3622,10 @@ compiler_try_star_except(struct compiler *c, stmt_ty s)
         if (except == NULL) {
             return 0;
         }
+        basicblock *handle_match = compiler_new_block(c);
+        if (handle_match == NULL) {
+            return 0;
+        }
         if (i == 0) {
             /* Push the original EG into the stack */
             /*
@@ -3641,9 +3645,15 @@ compiler_try_star_except(struct compiler *c, stmt_ty s)
         }
         if (handler->v.ExceptHandler.type) {
             VISIT(c, expr, handler->v.ExceptHandler.type);
-            ADDOP_JUMP(c, JUMP_IF_NOT_EG_MATCH, except);
+            ADDOP(c, CHECK_EG_MATCH);
+            ADDOP_I(c, COPY, 1);
+            ADDOP_JUMP(c, POP_JUMP_IF_NOT_NONE, handle_match);
+            ADDOP(c, POP_TOP);  // match
+            ADDOP_JUMP(c, JUMP, except);
         }
 
+        compiler_use_next_block(c, handle_match);
+
         basicblock *cleanup_end = compiler_new_block(c);
         if (cleanup_end == NULL) {
             return 0;
@@ -3657,7 +3667,7 @@ compiler_try_star_except(struct compiler *c, stmt_ty s)
             compiler_nameop(c, handler->v.ExceptHandler.name, Store);
         }
         else {
-            ADDOP(c, POP_TOP);  // exc
+            ADDOP(c, POP_TOP);  // match
         }
 
         /*
diff --git a/Python/opcode_targets.h b/Python/opcode_targets.h
