gh-93554: Conditional jump opcodes only jump forward (GH-96318)

Author: iritkatriel

Doc/library/dis.rst

@@ -999,60 +999,48 @@ iterations of the loop.
    .. versionadded:: 3.11
 
 
-.. opcode:: POP_JUMP_FORWARD_IF_TRUE (delta)
+.. opcode:: POP_JUMP_IF_TRUE (delta)
 
    If TOS is true, increments the bytecode counter by *delta*.  TOS is popped.
 
-   .. versionadded:: 3.11
-
-
-.. opcode:: POP_JUMP_BACKWARD_IF_TRUE (delta)
-
-   If TOS is true, decrements the bytecode counter by *delta*.  TOS is popped.
-
-   .. versionadded:: 3.11
+   .. versionchanged:: 3.11
+      The oparg is now a relative delta rather than an absolute target.
+      This opcode is a pseudo-instruction, replaced in final bytecode by
+      the directed versions (forward/backward).
 
+   .. versionchanged:: 3.12
+      This is no longer a pseudo-instruction.
 
-.. opcode:: POP_JUMP_FORWARD_IF_FALSE (delta)
+.. opcode:: POP_JUMP_IF_FALSE (delta)
 
    If TOS is false, increments the bytecode counter by *delta*.  TOS is popped.
 
-   .. versionadded:: 3.11
-
-
-.. opcode:: POP_JUMP_BACKWARD_IF_FALSE (delta)
-
-   If TOS is false, decrements the bytecode counter by *delta*.  TOS is popped.
-
-   .. versionadded:: 3.11
+   .. versionchanged:: 3.11
+      The oparg is now a relative delta rather than an absolute target.
+      This opcode is a pseudo-instruction, replaced in final bytecode by
+      the directed versions (forward/backward).
 
+   .. versionchanged:: 3.12
+      This is no longer a pseudo-instruction.
 
-.. opcode:: POP_JUMP_FORWARD_IF_NOT_NONE (delta)
+.. opcode:: POP_JUMP_IF_NOT_NONE (delta)
 
    If TOS is not ``None``, increments the bytecode counter by *delta*.  TOS is popped.
 
    .. versionadded:: 3.11
 
-
-.. opcode:: POP_JUMP_BACKWARD_IF_NOT_NONE (delta)
-
-   If TOS is not ``None``, decrements the bytecode counter by *delta*.  TOS is popped.
-
-   .. versionadded:: 3.11
+   .. versionchanged:: 3.12
+      This is no longer a pseudo-instruction.
 
 
-.. opcode:: POP_JUMP_FORWARD_IF_NONE (delta)
+.. opcode:: POP_JUMP_IF_NONE (delta)
 
    If TOS is ``None``, increments the bytecode counter by *delta*.  TOS is popped.
 
    .. versionadded:: 3.11
 
-
-.. opcode:: POP_JUMP_BACKWARD_IF_NONE (delta)
-
-   If TOS is ``None``, decrements the bytecode counter by *delta*.  TOS is popped.
-
-   .. versionadded:: 3.11
+   .. versionchanged:: 3.12
+      This is no longer a pseudo-instruction.
 
 
 .. opcode:: JUMP_IF_TRUE_OR_POP (delta)
@@ -1433,10 +1421,6 @@ but are replaced by real opcodes or removed before bytecode is generated.
 
 .. opcode:: JUMP
 .. opcode:: JUMP_NO_INTERRUPT
-.. opcode:: POP_JUMP_IF_FALSE
-.. opcode:: POP_JUMP_IF_TRUE
-.. opcode:: POP_JUMP_IF_NONE
-.. opcode:: POP_JUMP_IF_NOT_NONE
 
    Undirected relative jump instructions which are replaced by their
    directed (forward/backward) counterparts by the assembler.

Include/internal/pycore_opcode.h

@@ -412,6 +412,7 @@ def _write_atomic(path, data, mode=0o666):
 #     Python 3.12a1 3506 (Add BINARY_SLICE and STORE_SLICE instructions)
 #     Python 3.12a1 3507 (Set lineno of module's RESUME to 0)
 #     Python 3.12a1 3508 (Add CLEANUP_THROW)
+#     Python 3.12a1 3509 (Conditional jumps only jump forward)
 
 #     Python 3.13 will start with 3550
 
@@ -424,7 +425,7 @@ 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 = (3508).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3509).to_bytes(2, 'little') + b'\r\n'
 
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # For import.c
 

Include/opcode.h

@@ -153,8 +153,8 @@ def pseudo_op(name, op, real_ops):
 jrel_op('JUMP_FORWARD', 110)    # Number of words to skip
 jrel_op('JUMP_IF_FALSE_OR_POP', 111) # Number of words to skip
 jrel_op('JUMP_IF_TRUE_OR_POP', 112)  # ""
-jrel_op('POP_JUMP_FORWARD_IF_FALSE', 114)
-jrel_op('POP_JUMP_FORWARD_IF_TRUE', 115)
+jrel_op('POP_JUMP_IF_FALSE', 114)
+jrel_op('POP_JUMP_IF_TRUE', 115)
 name_op('LOAD_GLOBAL', 116)     # Index in name list
 def_op('IS_OP', 117)
 def_op('CONTAINS_OP', 118)
@@ -170,8 +170,8 @@ def pseudo_op(name, op, real_ops):
 haslocal.append(126)
 def_op('LOAD_FAST_CHECK', 127)  # Local variable number
 haslocal.append(127)
-jrel_op('POP_JUMP_FORWARD_IF_NOT_NONE', 128)
-jrel_op('POP_JUMP_FORWARD_IF_NONE', 129)
+jrel_op('POP_JUMP_IF_NOT_NONE', 128)
+jrel_op('POP_JUMP_IF_NONE', 129)
 def_op('RAISE_VARARGS', 130)    # Number of raise arguments (1, 2, or 3)
 def_op('GET_AWAITABLE', 131)
 def_op('MAKE_FUNCTION', 132)    # Flags
@@ -216,10 +216,6 @@ def pseudo_op(name, op, real_ops):
 def_op('KW_NAMES', 172)
 hasconst.append(172)
 
-jrel_op('POP_JUMP_BACKWARD_IF_NOT_NONE', 173)
-jrel_op('POP_JUMP_BACKWARD_IF_NONE', 174)
-jrel_op('POP_JUMP_BACKWARD_IF_FALSE', 175)
-jrel_op('POP_JUMP_BACKWARD_IF_TRUE', 176)
 
 hasarg.extend([op for op in opmap.values() if op >= HAVE_ARGUMENT])
 
@@ -235,11 +231,8 @@ def pseudo_op(name, op, real_ops):
 
 pseudo_op('JUMP', 260, ['JUMP_FORWARD', 'JUMP_BACKWARD'])
 pseudo_op('JUMP_NO_INTERRUPT', 261, ['JUMP_FORWARD', 'JUMP_BACKWARD_NO_INTERRUPT'])
-pseudo_op('POP_JUMP_IF_FALSE', 262, ['POP_JUMP_FORWARD_IF_FALSE', 'POP_JUMP_BACKWARD_IF_FALSE'])
-pseudo_op('POP_JUMP_IF_TRUE', 263, ['POP_JUMP_FORWARD_IF_TRUE', 'POP_JUMP_BACKWARD_IF_TRUE'])
-pseudo_op('POP_JUMP_IF_NONE', 264, ['POP_JUMP_FORWARD_IF_NONE', 'POP_JUMP_BACKWARD_IF_NONE'])
-pseudo_op('POP_JUMP_IF_NOT_NONE', 265, ['POP_JUMP_FORWARD_IF_NOT_NONE', 'POP_JUMP_BACKWARD_IF_NOT_NONE'])
-pseudo_op('LOAD_METHOD', 266, ['LOAD_ATTR'])
+
+pseudo_op('LOAD_METHOD', 262, ['LOAD_ATTR'])
 
 MAX_PSEUDO_OPCODE = MIN_PSEUDO_OPCODE + len(_pseudo_ops) - 1