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

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e0ea8b0
bpo-32949: Simplify "with"-related opcodes.
serhiy-storchaka Jan 12, 2018
0baf092
Add a news entry.
serhiy-storchaka Feb 26, 2018
31f433b
Prevent interrapting before calling __exit__.
serhiy-storchaka Feb 26, 2018
b76bda3
Update comments and rename variables.
serhiy-storchaka Mar 7, 2018
a796d94
Merge branch 'master' into with-opcodes
serhiy-storchaka Mar 7, 2018
b35543f
Merge branch 'master' into with-opcodes
serhiy-storchaka Mar 13, 2018
67885e2
Simplify WITH_CLEANUP_START.
serhiy-storchaka Mar 13, 2018
1b2e262
Merge branch 'master' into with-opcodes
serhiy-storchaka Mar 23, 2018
825a7e8
No need to release the reference to __exit__ earlier.
serhiy-storchaka Mar 23, 2018
c5c14b7
Merge branch 'master' into with-opcodes
serhiy-storchaka Apr 4, 2018
ee03531
Fix error message for non-awaitable __aexit__().
serhiy-storchaka Apr 4, 2018
e308f5e
Merge branch 'master' into with-opcodes
serhiy-storchaka Apr 4, 2018
4799bea
Merge branch 'master' into with-opcodes
serhiy-storchaka Jul 7, 2018
fb505aa
Merge commit 'ddd1949fea59f256e51191540a4446f75ed608fa~' into with-op…
serhiy-storchaka Sep 27, 2018
31ed8c7
Merge branch 'master' into with-opcodes
serhiy-storchaka Sep 27, 2018
97f7978
Merge branch 'master' into with-opcodes
serhiy-storchaka Sep 27, 2018
7b7ec7d
Merge branch 'master' into with-opcodes
serhiy-storchaka Jan 12, 2019
a545df9
Merge branch 'master' into with-opcodes
serhiy-storchaka Jun 2, 2019
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31 changes: 16 additions & 15 deletions Doc/library/dis.rst
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Expand Up @@ -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.
Pushes ``NULL`` onto the stack for using it in :opcode:`END_FINALLY` and
:opcode:`POP_FINALLY`. Starts the :keyword:`finally` block.

.. versionadded:: 3.8

Expand Down 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
At the top of the stack are 6 values pushed when 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.
Pushes the result of ``TOS6(TOS, TOS1, TOS2)``.

.. versionchanged:: 3.8


.. 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).
by :opcode:`WITH_CLEANUP_START`. Below are 6 values pushed when an exception
has been raised in the with block and the exit function.

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.
Pops TOS from the stack. If it is true unwinds the EXCEPT_HANDLER block
which was created when the exception was caught. Otherwise the next three
values will be used to re-raise the exception, the other three
values will be used to restore the exception state, and the exit function
will be popped from the stack. An exception handler block will be removed
from the block stack.

.. versionchanged:: 3.8


All of the following opcodes use their arguments.
Expand Down
3 changes: 2 additions & 1 deletion Lib/importlib/_bootstrap_external.py
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Expand Up @@ -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)
# Python 3.8b1 3411 (simplify "with"-related opcodes #32949)
#
# 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'
MAGIC_NUMBER = (3411).to_bytes(2, 'little') + b'\r\n'
_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c

_PYCACHE = '__pycache__'
Expand Down
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
Stack size: 9
Flags: OPTIMIZED, NEWLOCALS, NOFREE, COROUTINE
Constants:
0: None
1: 1
2: \\(None, None, None\\)
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=74, argval=178, argrepr='to 178', 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='JUMP_FORWARD', opcode=110, arg=30, argval=174, argrepr='to 174', 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='SETUP_WITH', opcode=143, arg=20, argval=170, argrepr='to 170', 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),
Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval=(None, None, None), argrepr='(None, None, None)', offset=160, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=162, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION_EX', opcode=142, arg=0, argval=0, argrepr='', offset=164, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_FORWARD', opcode=110, arg=4, argval=174, argrepr='to 174', offset=168, starts_line=None, is_jump_target=False),
Instruction(opname='WITH_CLEANUP_START', opcode=81, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=True),
Instruction(opname='WITH_CLEANUP_FINISH', opcode=82, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=174, starts_line=None, is_jump_target=True),
Instruction(opname='BEGIN_FINALLY', opcode=53, arg=None, argval=None, argrepr='', offset=176, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=178, starts_line=28, is_jump_target=True),
Instruction(opname='LOAD_CONST', opcode=100, arg=11, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=180, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=182, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=184, starts_line=None, is_jump_target=False),
Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=188, starts_line=None, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=190, 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 @@
Simplified and changed opcodes WITH_CLEANUP_START and WITH_CLEANUP_FINISH.
The trivial "with" statement is now up to 10% faster.
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) {
if (op == SETUP_FINALLY && code[target_addr] != END_ASYNC_FOR) {
blockstack[blockstack_top++] = target_addr;
}
break;
Expand Down
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