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bpo-32949: Simplify "with"-related opcodes. #5883

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31 changes: 16 additions & 15 deletions Doc/library/dis.rst
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Original file line number Diff line number Diff line change
@@ -726,9 +726,8 @@ iterations of the loop.

.. opcode:: BEGIN_FINALLY

Pushes ``NULL`` onto the stack for using it in :opcode:`END_FINALLY`,
:opcode:`POP_FINALLY`, :opcode:`WITH_CLEANUP_START` and
:opcode:`WITH_CLEANUP_FINISH`. Starts the :keyword:`finally` block.

.. versionadded:: 3.8

Expand Up @@ -774,29 +773,31 @@ iterations of the loop.

Starts cleaning up the stack when a :keyword:`with` statement block exits.

At the top of the stack are either ``NULL`` (pushed by
:opcode:`BEGIN_FINALLY`) or 6 values pushed if an exception has been
raised in the with block. Below is the context manager's
:meth:`~object.__exit__` or :meth:`~object.__aexit__` bound method.

If TOS is ``NULL``, calls ``SECOND(None, None, None)``,
removes the function from the stack, leaving TOS, and pushes ``None``
to the stack. Otherwise calls ``SEVENTH(TOP, SECOND, THIRD)``,
shifts the bottom 3 values of the stack down, replaces the empty spot
with ``NULL`` and pushes TOS. Finally pushes the result of the call.


.. opcode:: WITH_CLEANUP_FINISH

Finishes cleaning up the stack when a :keyword:`with` statement block exits.

TOS is result of ``__exit__()`` or ``__aexit__()`` function call pushed
by :opcode:`WITH_CLEANUP_START`. SECOND is ``None`` or an exception type
(pushed when an exception has been raised).

Pops two values from the stack. If SECOND is not None and TOS is true
unwinds the EXCEPT_HANDLER block which was created when the exception
was caught and pushes ``NULL`` to the stack.


All of the following opcodes use their arguments.
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3 changes: 2 additions & 1 deletion Lib/importlib/_bootstrap_external.py
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@@ -266,6 +266,7 @@ def _write_atomic(path, data, mode=0o666):
# Python 3.8a1 3400 (move frame block handling to compiler #17611)
# Python 3.8a1 3401 (add END_ASYNC_FOR #33041)
# Python 3.8a1 3410 (PEP570 Python Positional-Only Parameters #36540)
#
# MAGIC must change whenever the bytecode emitted by the compiler may no
# longer be understood by older implementations of the eval loop (usually
Expand All @@ -274,7 +275,7 @@ 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 = (3410).to_bytes(2, 'little') + b'\r\n'
_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c

_PYCACHE = '__pycache__'
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39 changes: 21 additions & 18 deletions Lib/test/test_dis.py
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Expand Up @@ -752,11 +752,12 @@ async def async_def():
Positional-only arguments: 0
Kw-only arguments: 0
Number of locals: 2
Stack size: 10
Flags: OPTIMIZED, NEWLOCALS, NOFREE, COROUTINE
Constants:
0: None
1: 1
Names:
0: b
1: c
Expand Down Expand Up @@ -977,7 +978,7 @@ def jumpy():
Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=96, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=98, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=100, starts_line=None, is_jump_target=False),
Instruction(opname='SETUP_FINALLY', opcode=122, arg=70, argval=174, argrepr='to 174', offset=102, starts_line=20, is_jump_target=True),
Instruction(opname='SETUP_FINALLY', opcode=122, arg=12, argval=118, argrepr='to 118', offset=104, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=106, starts_line=21, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=108, starts_line=None, is_jump_target=False),
Expand All @@ -997,29 +998,31 @@ def jumpy():
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=136, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=138, starts_line=None, is_jump_target=False),
Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=140, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_FORWARD', opcode=110, arg=26, argval=170, argrepr='to 170', offset=142, starts_line=None, is_jump_target=False),
Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=144, starts_line=None, is_jump_target=True),
Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=146, starts_line=25, is_jump_target=True),
Instruction(opname='SETUP_WITH', opcode=143, arg=14, argval=164, argrepr='to 164', offset=148, starts_line=None, is_jump_target=False),
Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=150, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=152, starts_line=26, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=154, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=156, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=158, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=160, starts_line=None, is_jump_target=False),
Instruction(opname='BEGIN_FINALLY', opcode=53, arg=None, argval=None, argrepr='', offset=162, starts_line=None, is_jump_target=False),
Instruction(opname='WITH_CLEANUP_START', opcode=81, arg=None, argval=None, argrepr='', offset=164, starts_line=None, is_jump_target=True),
Instruction(opname='WITH_CLEANUP_FINISH', opcode=82, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=168, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=True),
Instruction(opname='BEGIN_FINALLY', opcode=53, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=174, starts_line=28, is_jump_target=True),
Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=176, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=178, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=180, starts_line=None, is_jump_target=False),
Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=182, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=184, starts_line=None, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
]

# One last piece of inspect fodder to check the default line number handling
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2018-02-25-15-47-11.bpo-32949.LXdL0x.rst
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@@ -0,0 +1,2 @@
2 changes: 1 addition & 1 deletion Objects/frameobject.c
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Expand Up @@ -269,7 +269,7 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
delta++;
}
}
if (op != FOR_ITER && code[target_addr] != END_ASYNC_FOR) {
blockstack[blockstack_top++] = target_addr;
}
break;
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