dis — Disassembler for Python bytecode¶Source code: Lib/dis.py
The dis module supports the analysis of CPython bytecode by
disassembling it. The CPython bytecode which this module takes as an input is
defined in the file Include/opcode.h and used by the compiler and the
interpreter.
CPython implementation detail: Bytecode is an implementation detail of the CPython interpreter. No guarantees are made that bytecode will not be added, removed, or changed between versions of Python. Use of this module should not be considered to work across Python VMs or Python releases.
Changed in version 3.6: Use 2 bytes for each instruction. Previously the number of bytes varied by instruction.
Changed in version 3.10: The argument of jump, exception handling and loop instructions is now the instruction offset rather than the byte offset.
Changed in version 3.11: Some instructions are accompanied by one or more inline cache entries,
which take the form of CACHE instructions. These instructions
are hidden by default, but can be shown by passing show_caches=True to
any dis utility. Furthermore, the interpreter now adapts the
bytecode to specialize it for different runtime conditions. The
adaptive bytecode can be shown by passing adaptive=True.
Changed in version 3.12: The argument of a jump is the offset of the target instruction relative
to the instruction that appears immediately after the jump instruction’s
CACHE entries.
As a consequence, the presence of the CACHE instructions is
transparent for forward jumps but needs to be taken into account when
reasoning about backward jumps.
Changed in version 3.13: The output shows logical labels rather than instruction offsets
for jump targets and exception handlers. The -O command line
option and the show_offsets argument were added.
Example: Given the function myfunc():
def myfunc(alist):
return len(alist)
the following command can be used to display the disassembly of
myfunc():
>>> dis.dis(myfunc)
2 RESUME 0
3 LOAD_GLOBAL 1 (len + NULL)
LOAD_FAST_BORROW 0 (alist)
CALL 1
RETURN_VALUE
(The “2” is a line number).
The dis module can be invoked as a script from the command line:
python -m dis [-h] [-C] [-O] [-P] [-S] [infile]
The following options are accepted:
Display usage and exit.
Show inline caches.
Added in version 3.13.
Show offsets of instructions.
Added in version 3.13.
Show positions of instructions in the source code.
Added in version 3.14.
Show specialized bytecode.
Added in version 3.14.
If infile is specified, its disassembled code will be written to stdout.
Otherwise, disassembly is performed on compiled source code received from stdin.
Added in version 3.4.
The bytecode analysis API allows pieces of Python code to be wrapped in a
Bytecode object that provides easy access to details of the compiled
code.
Analyse the bytecode corresponding to a function, generator, asynchronous
generator, coroutine, method, string of source code, or a code object (as
returned by compile()).
This is a convenience wrapper around many of the functions listed below, most
notably get_instructions(), as iterating over a Bytecode
instance yields the bytecode operations as Instruction instances.
If first_line is not None, it indicates the line number that should be
reported for the first source line in the disassembled code. Otherwise, the
source line information (if any) is taken directly from the disassembled code
object.
If current_offset is not None, it refers to an instruction offset in the
disassembled code. Setting this means dis() will display a “current
instruction” marker against the specified opcode.
If show_caches is True, dis() will display inline cache
entries used by the interpreter to specialize the bytecode.
If adaptive is True, dis() will display specialized bytecode
that may be different from the original bytecode.
If show_offsets is True, dis() will include instruction
offsets in the output.
If show_positions is True, dis() will include instruction
source code positions in the output.
Construct a Bytecode instance from the given traceback, setting
current_offset to the instruction responsible for the exception.
The compiled code object.
The first source line of the code object (if available)
Return a formatted view of the bytecode operations (the same as printed by
dis.dis(), but returned as a multi-line string).
Return a formatted multi-line string with detailed information about the
code object, like code_info().
Changed in version 3.7: This can now handle coroutine and asynchronous generator objects.
Changed in version 3.11: Added the show_caches and adaptive parameters.
Changed in version 3.13: Added the show_offsets parameter
Changed in version 3.14: Added the show_positions parameter.
Example:
>>> bytecode = dis.Bytecode(myfunc)
>>> for instr in bytecode:
... print(instr.opname)
...
RESUME
LOAD_GLOBAL
LOAD_FAST_BORROW
CALL
RETURN_VALUE
The dis module also defines the following analysis functions that convert
the input directly to the desired output. They can be useful if only a single
operation is being performed, so the intermediate analysis object isn’t useful:
Return a formatted multi-line string with detailed code object information for the supplied function, generator, asynchronous generator, coroutine, method, source code string or code object.
Note that the exact contents of code info strings are highly implementation dependent and they may change arbitrarily across Python VMs or Python releases.
Added in version 3.2.
Changed in version 3.7: This can now handle coroutine and asynchronous generator objects.
Print detailed code object information for the supplied function, method,
source code string or code object to file (or sys.stdout if file
is not specified).
This is a convenient shorthand for print(code_info(x), file=file),
intended for interactive exploration at the interpreter prompt.
Added in version 3.2.
Changed in version 3.4: Added file parameter.
Disassemble the x object. x can denote either a module, a class, a
method, a function, a generator, an asynchronous generator, a coroutine,
a code object, a string of source code or a byte sequence of raw bytecode.
For a module, it disassembles all functions. For a class, it disassembles
all methods (including class and static methods). For a code object or
sequence of raw bytecode, it prints one line per bytecode instruction.
It also recursively disassembles nested code objects. These can include
generator expressions, nested functions, the bodies of nested classes,
and the code objects used for annotation scopes.
Strings are first compiled to code objects with the compile()
built-in function before being disassembled. If no object is provided, this
function disassembles the last traceback.
The disassembly is written as text to the supplied file argument if
provided and to sys.stdout otherwise.
The maximal depth of recursion is limited by depth unless it is None.
depth=0 means no recursion.
If show_caches is True, this function will display inline cache
entries used by the interpreter to specialize the bytecode.
If adaptive is True, this function will display specialized bytecode
that may be different from the original bytecode.
Changed in version 3.4: Added file parameter.
Changed in version 3.7: Implemented recursive disassembling and added depth parameter.
Changed in version 3.7: This can now handle coroutine and asynchronous generator objects.
Changed in version 3.11: Added the show_caches and adaptive parameters.
Changed in version 3.13: Added the show_offsets parameter.
Changed in version 3.14: Added the show_positions parameter.
Disassemble the top-of-stack function of a traceback, using the last traceback if none was passed. The instruction causing the exception is indicated.
The disassembly is written as text to the supplied file argument if
provided and to sys.stdout otherwise.
Changed in version 3.4: Added file parameter.
Changed in version 3.11: Added the show_caches and adaptive parameters.
Changed in version 3.13: Added the show_offsets parameter.
Changed in version 3.14: Added the show_positions parameter.
Disassemble a code object, indicating the last instruction if lasti was provided. The output is divided in the following columns:
the source code location of the instruction. Complete location information is shown if show_positions is true. Otherwise (the default) only the line number is displayed.
the current instruction, indicated as -->,
a labelled instruction, indicated with >>,
the address of the instruction,
the operation code name,
operation parameters, and
interpretation of the parameters in parentheses.
The parameter interpretation recognizes local and global variable names, constant values, branch targets, and compare operators.
The disassembly is written as text to the supplied file argument if
provided and to sys.stdout otherwise.
Changed in version 3.4: Added file parameter.
Changed in version 3.11: Added the show_caches and adaptive parameters.
Changed in version 3.13: Added the show_offsets parameter.
Changed in version 3.14: Added the show_positions parameter.
Return an iterator over the instructions in the supplied function, method, source code string or code object.
The iterator generates a series of Instruction named tuples giving
the details of each operation in the supplied code.
If first_line is not None, it indicates the line number that should be
reported for the first source line in the disassembled code. Otherwise, the
source line information (if any) is taken directly from the disassembled code
object.
The adaptive parameter works as it does in dis().
Added in version 3.4.
Changed in version 3.11: Added the show_caches and adaptive parameters.
Changed in version 3.13: The show_caches parameter is deprecated and has no effect. The iterator
generates the Instruction instances with the cache_info
field populated (regardless of the value of show_caches) and it no longer
generates separate items for the cache entries.
This generator function uses the co_lines() method
of the code object code to find the offsets which
are starts of
lines in the source code. They are generated as (offset, lineno) pairs.
Changed in version 3.6: Line numbers can be decreasing. Before, they were always increasing.
Changed in version 3.10: The PEP 626 co_lines() method is used instead of the
co_firstlineno and co_lnotab
attributes of the code object.
Changed in version 3.13: Line numbers can be None for bytecode that does not map to source lines.
Detect all offsets in the raw compiled bytecode string code which are jump targets, and return a list of these offsets.
Compute the stack effect of opcode with argument oparg.
If the code has a jump target and jump is True, stack_effect()
will return the stack effect of jumping. If jump is False,
it will return the stack effect of not jumping. And if jump is
None (default), it will return the maximal stack effect of both cases.
Added in version 3.4.
Changed in version 3.8: Added jump parameter.
Changed in version 3.13: If oparg is omitted (or None), the stack effect is now returned
for oparg=0. Previously this was an error for opcodes that use their
arg. It is also no longer an error to pass an integer oparg when
the opcode does not use it; the oparg in this case is ignored.
The get_instructions() function and Bytecode class provide
details of bytecode instructions as Instruction instances:
Details for a bytecode operation
numeric code for operation, corresponding to the opcode values listed below and the bytecode values in the Opcode collections.
human readable name for operation
numeric code for the base operation if operation is specialized;
otherwise equal to opcode
human readable name for the base operation if operation is specialized;
otherwise equal to opname
numeric argument to operation (if any), otherwise None
resolved arg value (if any), otherwise None
human readable description of operation argument (if any), otherwise an empty string.
start index of operation within bytecode sequence
start index of operation within bytecode sequence, including prefixed
EXTENDED_ARG operations if present; otherwise equal to offset
start index of the cache entries following the operation
end index of the cache entries following the operation
True if this opcode starts a source line, otherwise False
source line number associated with this opcode (if any), otherwise None
True if other code jumps to here, otherwise False
bytecode index of the jump target if this is a jump operation,
otherwise None
dis.Positions object holding the
start and end locations that are covered by this instruction.
Information about the cache entries of this instruction, as
triplets of the form (name, size, data), where the name
and size describe the cache format and data is the contents
of the cache. cache_info is None if the instruction does not have
caches.
Added in version 3.4.
Changed in version 3.11: Field positions is added.
Changed in version 3.13: Changed field starts_line.
Added fields start_offset, cache_offset, end_offset,
baseopname, baseopcode, jump_target, oparg,
line_number and cache_info.
In case the information is not available, some fields might be None.
Added in version 3.11.
The Python compiler currently generates the following bytecode instructions.
General instructions
In the following, We will refer to the interpreter stack as STACK and describe
operations on it as if it was a Python list. The top of the stack corresponds to
STACK[-1] in this language.
Do nothing code. Used as a placeholder by the bytecode optimizer, and to generate line tracing events.
Do nothing code.
Used by the interpreter to record BRANCH_LEFT
and BRANCH_RIGHT events for sys.monitoring.
Added in version 3.14.
Removes the iterator from the top of the stack.
Added in version 3.14.
Removes the top-of-stack item:
STACK.pop()
Removes the top-of-stack item.
Equivalent to POP_TOP.
Used to clean up at the end of loops, hence the name.
Added in version 3.12.
Implements del STACK[-2].
Used to clean up when a generator exits.
Added in version 3.12.
Push the i-th item to the top of the stack without removing it from its original location:
assert i > 0
STACK.append(STACK[-i])
Added in version 3.11.
Swap the top of the stack with the i-th element:
STACK[-i], STACK[-1] = STACK[-1], STACK[-i]
Added in version 3.11.
Rather than being an actual instruction, this opcode is used to mark extra
space for the interpreter to cache useful data directly in the bytecode
itself. It is automatically hidden by all dis utilities, but can be
viewed with show_caches=True.
Logically, this space is part of the preceding instruction. Many opcodes expect to be followed by an exact number of caches, and will instruct the interpreter to skip over them at runtime.
Populated caches can look like arbitrary instructions, so great care should be taken when reading or modifying raw, adaptive bytecode containing quickened data.
Added in version 3.11.
Unary operations
Unary operations take the top of the stack, apply the operation, and push the result back on the stack.
Implements STACK[-1] = -STACK[-1].
Implements STACK[-1] = not STACK[-1].
Changed in version 3.13: This instruction now requires an exact bool operand.
Implements STACK[-1] = ~STACK[-1].
Implements STACK[-1] = iter(STACK[-1]).
If STACK[-1] is a generator iterator or coroutine object
it is left as is. Otherwise, implements STACK[-1] = iter(STACK[-1]).
Added in version 3.5.
Implements STACK[-1] = bool(STACK[-1]).
Added in version 3.13.
Binary and in-place operations
Binary operations remove the top two items from the stack (STACK[-1] and
STACK[-2]). They perform the operation, then put the result back on the stack.
In-place operations are like binary operations, but the operation is done in-place
when STACK[-2] supports it, and the resulting STACK[-1] may be (but does
not have to be) the original STACK[-2].
Implements the binary and in-place operators (depending on the value of op):
rhs = STACK.pop()
lhs = STACK.pop()
STACK.append(lhs op rhs)
Added in version 3.11.
Changed in version 3.14: With oparg :NB_SUBSCR, implements binary subscript (replaces opcode BINARY_SUBSCR)
Implements:
key = STACK.pop()
container = STACK.pop()
value = STACK.pop()
container[key] = value
Implements:
key = STACK.pop()
container = STACK.pop()
del container[key]
Implements:
end = STACK.pop()
start = STACK.pop()
container = STACK.pop()
STACK.append(container[start:end])
Added in version 3.12.
Implements:
end = STACK.pop()
start = STACK.pop()
container = STACK.pop()
value = STACK.pop()
container[start:end] = value
Added in version 3.12.
Coroutine opcodes
Implements STACK[-1] = get_awaitable(STACK[-1]), where get_awaitable(o)
returns o if o is a coroutine object or a generator object with
the CO_ITERABLE_COROUTINE flag, or resolves
o.__await__.
If the
whereoperand is nonzero, it indicates where the instruction occurs:
1: After a call to__aenter__
2: After a call to__aexit__
Added in version 3.5.
Changed in version 3.11: Previously, this instruction did not have an oparg.
Implements STACK[-1] = STACK[-1].__aiter__().
Added in version 3.5.
Changed in version 3.7: Returning awaitable objects from __aiter__ is no longer
supported.
Implement STACK.append(get_awaitable(STACK[-1].__anext__())) to the stack.
See GET_AWAITABLE for details about get_awaitable.
Added in version 3.5.
Terminates an async for loop. Handles an exception raised
when awaiting a next item. The stack contains the async iterable in
STACK[-2] and the raised exception in STACK[-1]. Both are popped.
If the exception is not StopAsyncIteration, it is re-raised.
Added in version 3.8.
Changed in version 3.11: Exception representation on the stack now consist of one, not three, items.
Handles an exception raised during a throw() or
close() call through the current frame. If STACK[-1] is an
instance of StopIteration, pop three values from the stack and push
its value member. Otherwise, re-raise STACK[-1].
Added in version 3.12.
Miscellaneous opcodes
Implements:
item = STACK.pop()
set.add(STACK[-i], item)
Used to implement set comprehensions.
Implements:
item = STACK.pop()
list.append(STACK[-i], item)
Used to implement list comprehensions.
Implements:
value = STACK.pop()
key = STACK.pop()
dict.__setitem__(STACK[-i], key, value)
Used to implement dict comprehensions.
Added in version 3.1.
Changed in version 3.8: Map value is STACK[-1] and map key is STACK[-2]. Before, those
were reversed.
For all of the SET_ADD, LIST_APPEND and MAP_ADD
instructions, while the added value or key/value pair is popped off, the
container object remains on the stack so that it is available for further
iterations of the loop.
Returns with STACK[-1] to the caller of the function.
Yields STACK.pop() from a generator.
Changed in version 3.11: oparg set to be the stack depth.
Changed in version 3.12: oparg set to be the exception block depth, for efficient closing of generators.
Changed in version 3.13: oparg is 1 if this instruction is part of a yield-from or await, and 0
otherwise.
Checks whether __annotations__ is defined in locals(), if not it is
set up to an empty dict. This opcode is only emitted if a class
or module body contains variable annotations
statically.
Added in version 3.6.
Pops a value from the stack, which is used to restore the exception state.
Changed in version 3.11: Exception representation on the stack now consist of one, not three, items.
Re-raises the exception currently on top of the stack. If oparg is non-zero,
pops an additional value from the stack which is used to set
f_lasti of the current frame.
Added in version 3.9.
Changed in version 3.11: Exception representation on the stack now consist of one, not three, items.
Pops a value from the stack. Pushes the current exception to the top of the stack. Pushes the value originally popped back to the stack. Used in exception handlers.
Added in version 3.11.
Performs exception matching for except. Tests whether the STACK[-2]
is an exception matching STACK[-1]. Pops STACK[-1] and pushes the boolean
result of the test.
Added in version 3.11.
Performs exception matching for except*. Applies split(STACK[-1]) on
the exception group representing STACK[-2].
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.
Added in version 3.11.
Calls the function in position 4 on the stack with arguments (type, val, tb)
representing the exception at the top of the stack.
Used to implement the call context_manager.__exit__(*exc_info()) when an exception
has occurred in a with statement.
Added in version 3.9.
Changed in version 3.11: The __exit__ function is in position 4 of the stack rather than 7.
Exception representation on the stack now consist of one, not three, items.
Pushes a common constant onto the stack. The interpreter contains a hardcoded
list of constants supported by this instruction. Used by the assert
statement to load AssertionError.
Added in version 3.14.
Pushes builtins.__build_class__() onto the stack. It is later called
to construct a class.
Perform STACK.append(len(STACK[-1])). Used in match statements where
comparison with structure of pattern is needed.
Added in version 3.10.
If STACK[-1] is an instance of collections.abc.Mapping (or, more
technically: if it has the Py_TPFLAGS_MAPPING flag set in its
tp_flags), push True onto the stack. Otherwise,
push False.
Added in version 3.10.
If STACK[-1] is an instance of collections.abc.Sequence and is not an instance
of str/bytes/bytearray (or, more technically: if it has
the Py_TPFLAGS_SEQUENCE flag set in its tp_flags),
push True onto the stack. Otherwise, push False.
Added in version 3.10.
STACK[-1] is a tuple of mapping keys, and STACK[-2] is the match subject.
If STACK[-2] contains all of the keys in STACK[-1], push a tuple
containing the corresponding values. Otherwise, push None.
Added in version 3.10.
Changed in version 3.11: Previously, this instruction also pushed a boolean value indicating
success (True) or failure (False).
Implements name = STACK.pop(). namei is the index of name in the attribute
co_names of the code object.
The compiler tries to use STORE_FAST or STORE_GLOBAL if possible.
Implements del name, where namei is the index into co_names
attribute of the code object.
Unpacks STACK[-1] into count individual values, which are put onto the stack
right-to-left. Require there to be exactly count values.:
assert(len(STACK[-1]) == count)
STACK.extend(STACK.pop()[:-count-1:-1])
Implements assignment with a starred target: Unpacks an iterable in STACK[-1]
into individual values, where the total number of values can be smaller than the
number of items in the iterable: one of the new values will be a list of all
leftover items.
The number of values before and after the list value is limited to 255.
The number of values before the list value is encoded in the argument of the
opcode. The number of values after the list if any is encoded using an
EXTENDED_ARG. As a consequence, the argument can be seen as a two bytes values
where the low byte of counts is the number of values before the list value, the
high byte of counts the number of values after it.
The extracted values are put onto the stack right-to-left, i.e. a, *b, c = d
will be stored after execution as STACK.extend((a, b, c)).
Implements:
obj = STACK.pop()
value = STACK.pop()
obj.name = value
where namei is the index of name in co_names of the
code object.
Implements:
obj = STACK.pop()
del obj.name
where namei is the index of name into co_names of the
code object.
Works as STORE_NAME, but stores the name as a global.
Works as DELETE_NAME, but deletes a global name.
Pushes co_consts[consti] onto the stack.
Pushes the integer i onto the stack.
i must be in range(256)
Added in version 3.14.
Pushes the value associated with co_names[namei] onto the stack.
The name is looked up within the locals, then the globals, then the builtins.
Pushes a reference to the locals dictionary onto the stack. This is used
to prepare namespace dictionaries for LOAD_FROM_DICT_OR_DEREF
and LOAD_FROM_DICT_OR_GLOBALS.
Added in version 3.12.
Pops a mapping off the stack and looks up the value for co_names[namei].
If the name is not found there, looks it up in the globals and then the builtins,
similar to LOAD_GLOBAL.
This is used for loading global variables in
annotation scopes within class bodies.
Added in version 3.12.
Constructs a new Template instance from a tuple
of strings and a tuple of interpolations and pushes the resulting object
onto the stack:
interpolations = STACK.pop()
strings = STACK.pop()
STACK.append(_build_template(strings, interpolations))
Added in version 3.14.
Constructs a new Interpolation instance from a
value and its source expression and pushes the resulting object onto the
stack.
If no conversion or format specification is present, format is set to
2.
If the low bit of format is set, it indicates that the interpolation
contains a format specification.
If format >> 2 is non-zero, it indicates that the interpolation
contains a conversion. The value of format >> 2 is the conversion type
(0 for no conversion, 1 for !s, 2 for !r, and
3 for !a):
conversion = format >> 2
if format & 1:
format_spec = STACK.pop()
else:
format_spec = None
expression = STACK.pop()
value = STACK.pop()
STACK.append(_build_interpolation(value, expression, conversion, format_spec))
Added in version 3.14.
Creates a tuple consuming count items from the stack, and pushes the resulting tuple onto the stack:
if count == 0:
value = ()
else:
value = tuple(STACK[-count:])
STACK = STACK[:-count]
STACK.append(value)
Works as BUILD_TUPLE, but creates a list.
Works as BUILD_TUPLE, but creates a set.
Pushes a new dictionary object onto the stack. Pops 2 * count items
so that the dictionary holds count entries:
{..., STACK[-4]: STACK[-3], STACK[-2]: STACK[-1]}.
Changed in version 3.5: The dictionary is created from stack items instead of creating an empty dictionary pre-sized to hold count items.
Concatenates count strings from the stack and pushes the resulting string onto the stack.
Added in version 3.6.
Implements:
seq = STACK.pop()
list.extend(STACK[-i], seq)
Used to build lists.
Added in version 3.9.
Implements:
seq = STACK.pop()
set.update(STACK[-i], seq)
Used to build sets.
Added in version 3.9.
Implements:
map = STACK.pop()
dict.update(STACK[-i], map)
Used to build dicts.
Added in version 3.9.
Like DICT_UPDATE but raises an exception for duplicate keys.
Added in version 3.9.
If the low bit of namei is not set, this replaces STACK[-1] with
getattr(STACK[-1], co_names[namei>>1]).
If the low bit of namei is set, this will attempt to load a method named
co_names[namei>>1] from the STACK[-1] object. STACK[-1] is popped.
This bytecode distinguishes two cases: if STACK[-1] has a method with the
correct name, the bytecode pushes the unbound method and STACK[-1].
STACK[-1] will be used as the first argument (self) by CALL
or CALL_KW when calling the unbound method.
Otherwise, NULL and the object returned by
the attribute lookup are pushed.
Changed in version 3.12: If the low bit of namei is set, then a NULL or self is
pushed to the stack before the attribute or unbound method respectively.
This opcode implements super(), both in its zero-argument and
two-argument forms (e.g. super().method(), super().attr and
super(cls, self).method(), super(cls, self).attr).
It pops three values from the stack (from top of stack down):
self: the first argument to the current method
cls: the class within which the current method was defined
the global super
With respect to its argument, it works similarly to LOAD_ATTR,
except that namei is shifted left by 2 bits instead of 1.
The low bit of namei signals to attempt a method load, as with
LOAD_ATTR, which results in pushing NULL and the loaded method.
When it is unset a single value is pushed to the stack.
The second-low bit of namei, if set, means that this was a two-argument
call to super() (unset means zero-argument).
Added in version 3.12.
Performs a Boolean operation. The operation name can be found in
cmp_op[opname >> 5]. If the fifth-lowest bit of opname is set
(opname & 16), the result should be coerced to bool.
Changed in version 3.13: The fifth-lowest bit of the oparg now indicates a forced conversion to
bool.
Performs is comparison, or is not if invert is 1.
Added in version 3.9.
Performs in comparison, or not in if invert is 1.
Added in version 3.9.
Imports the module co_names[namei]. STACK[-1] and STACK[-2] are
popped and provide the fromlist and level arguments of __import__().
The module object is pushed onto the stack. The current namespace is not affected: for a proper import statement, a subsequent STORE_FAST instruction
modifies the namespace.
Loads the attribute co_names[namei] from the module found in STACK[-1].
The resulting object is pushed onto the stack, to be subsequently stored by a
STORE_FAST instruction.
Increments bytecode counter by delta.
Decrements bytecode counter by delta. Checks for interrupts.
Added in version 3.11.
Decrements bytecode counter by delta. Does not check for interrupts.
Added in version 3.11.
If STACK[-1] is true, increments the bytecode counter by delta.
STACK[-1] is popped.
Changed in version 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).
Changed in version 3.12: This is no longer a pseudo-instruction.
Changed in version 3.13: This instruction now requires an exact bool operand.
If STACK[-1] is false, increments the bytecode counter by delta.
STACK[-1] is popped.
Changed in version 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).
Changed in version 3.12: This is no longer a pseudo-instruction.
Changed in version 3.13: This instruction now requires an exact bool operand.
If STACK[-1] is not None, increments the bytecode counter by delta.
STACK[-1] is popped.
Added in version 3.11.
Changed in version 3.12: This is no longer a pseudo-instruction.
If STACK[-1] is None, increments the bytecode counter by delta.
STACK[-1] is popped.
Added in version 3.11.
Changed in version 3.12: This is no longer a pseudo-instruction.
STACK[-1] is an iterator. Call its __next__() method.
If this yields a new value, push it on the stack (leaving the iterator below
it). If the iterator indicates it is exhausted then the byte code counter is
incremented by delta.
Changed in version 3.12: Up until 3.11 the iterator was popped when it was exhausted.
Loads the global named co_names[namei>>1] onto the stack.
Changed in version 3.11: If the low bit of namei is set, then a NULL is pushed to the
stack before the global variable.
Pushes a reference to the local co_varnames[var_num] onto the stack.
Changed in version 3.12: This opcode is now only used in situations where the local variable is
guaranteed to be initialized. It cannot raise UnboundLocalError.
Pushes a borrowed reference to the local co_varnames[var_num] onto the
stack.
Added in version 3.14.
Pushes references to co_varnames[var_nums >> 4] and
co_varnames[var_nums & 15] onto the stack.
Added in version 3.13.
Pushes borrowed references to co_varnames[var_nums >> 4] and
co_varnames[var_nums & 15] onto the stack.
Added in version 3.14.
Pushes a reference to the local co_varnames[var_num] onto the stack,
raising an UnboundLocalError if the local variable has not been
initialized.
Added in version 3.12.
Pushes a reference to the local co_varnames[var_num] onto the stack (or
pushes NULL onto the stack if the local variable has not been
initialized) and sets co_varnames[var_num] to NULL.
Added in version 3.12.
Stores STACK.pop() into the local co_varnames[var_num].
Stores STACK[-1] into co_varnames[var_nums >> 4]
and STACK[-2] into co_varnames[var_nums & 15].
Added in version 3.13.
Stores STACK.pop() into the local co_varnames[var_nums >> 4]
and pushes a reference to the local co_varnames[var_nums & 15]
onto the stack.
Added in version 3.13.
Deletes local co_varnames[var_num].
Creates a new cell in slot i. If that slot is nonempty then
that value is stored into the new cell.
Added in version 3.11.
Loads the cell contained in slot i of the “fast locals” storage.
Pushes a reference to the object the cell contains on the stack.
Changed in version 3.11: i is no longer offset by the length of co_varnames.
Pops a mapping off the stack and looks up the name associated with
slot i of the “fast locals” storage in this mapping.
If the name is not found there, loads it from the cell contained in
slot i, similar to LOAD_DEREF. This is used for loading
closure variables in class bodies (which previously used
LOAD_CLASSDEREF) and in
annotation scopes within class bodies.
Added in version 3.12.
Stores STACK.pop() into the cell contained in slot i of the “fast locals”
storage.
Changed in version 3.11: i is no longer offset by the length of co_varnames.
Empties the cell contained in slot i of the “fast locals” storage.
Used by the del statement.
Added in version 3.2.
Changed in version 3.11: i is no longer offset by the length of co_varnames.
Copies the n free (closure) variables from the closure
into the frame. Removes the need for special code on the caller’s side when calling
closures.
Added in version 3.11.
Raises an exception using one of the 3 forms of the raise statement,
depending on the value of argc:
0: raise (re-raise previous exception)
1: raise STACK[-1] (raise exception instance or type at STACK[-1])
2: raise STACK[-2] from STACK[-1] (raise exception instance or type at
STACK[-2] with __cause__ set to STACK[-1])
Calls a callable object with the number of arguments specified by argc.
On the stack are (in ascending order):
The callable
self or NULL
The remaining positional arguments
argc is the total of the positional arguments, excluding self.
CALL pops all arguments and the callable object off the stack,
calls the callable object with those arguments, and pushes the return value
returned by the callable object.
Added in version 3.11.
Changed in version 3.13: The callable now always appears at the same position on the stack.
Changed in version 3.13: Calls with keyword arguments are now handled by CALL_KW.
Calls a callable object with the number of arguments specified by argc,
including one or more named arguments. On the stack are (in ascending order):
The callable
self or NULL
The remaining positional arguments
The named arguments
A tuple of keyword argument names
argc is the total of the positional and named arguments, excluding self.
The length of the tuple of keyword argument names is the number of named arguments.
CALL_KW pops all arguments, the keyword names, and the callable object
off the stack, calls the callable object with those arguments, and pushes the
return value returned by the callable object.
Added in version 3.13.
Calls a callable object with variable set of positional and keyword
arguments. If the lowest bit of flags is set, the top of the stack
contains a mapping object containing additional keyword arguments.
Before the callable is called, the mapping object and iterable object
are each “unpacked” and their contents passed in as keyword and
positional arguments respectively.
CALL_FUNCTION_EX pops all arguments and the callable object off the stack,
calls the callable object with those arguments, and pushes the return value
returned by the callable object.
Added in version 3.6.
Pushes a NULL to the stack.
Used in the call sequence to match the NULL pushed by
LOAD_METHOD for non-method calls.
Added in version 3.11.
Pushes a new function object on the stack built from the code object at STACK[-1].
Changed in version 3.10: Flag value 0x04 is a tuple of strings instead of dictionary
Changed in version 3.11: Qualified name at STACK[-1] was removed.
Changed in version 3.13: Extra function attributes on the stack, signaled by oparg flags, were
removed. They now use SET_FUNCTION_ATTRIBUTE.
Sets an attribute on a function object. Expects the function at STACK[-1]
and the attribute value to set at STACK[-2]; consumes both and leaves the
function at STACK[-1]. The flag determines which attribute to set:
0x01 a tuple of default values for positional-only and
positional-or-keyword parameters in positional order
0x02 a dictionary of keyword-only parameters’ default values
0x04 a tuple of strings containing parameters’ annotations
0x08 a tuple containing cells for free variables, making a closure
0x10 the annotate function for the function object
Added in version 3.13.
Changed in version 3.14: Added 0x10 to indicate the annotate function for the function object.
Pushes a slice object on the stack. argc must be 2 or 3. If it is 2, implements:
end = STACK.pop()
start = STACK.pop()
STACK.append(slice(start, end))
if it is 3, implements:
step = STACK.pop()
end = STACK.pop()
start = STACK.pop()
STACK.append(slice(start, end, step))
See the slice() built-in function for more information.
Prefixes any opcode which has an argument too big to fit into the default one
byte. ext holds an additional byte which act as higher bits in the argument.
For each opcode, at most three prefixal EXTENDED_ARG are allowed, forming
an argument from two-byte to four-byte.
Convert value to a string, depending on oparg:
value = STACK.pop()
result = func(value)
STACK.append(result)
Used for implementing formatted string literals (f-strings).
Added in version 3.13.
Formats the value on top of stack:
value = STACK.pop()
result = value.__format__("")
STACK.append(result)
Used for implementing formatted string literals (f-strings).
Added in version 3.13.
Formats the given value with the given format spec:
spec = STACK.pop()
value = STACK.pop()
result = value.__format__(spec)
STACK.append(result)
Used for implementing formatted string literals (f-strings).
Added in version 3.13.
STACK[-1] is a tuple of keyword attribute names, STACK[-2] is the class
being matched against, and STACK[-3] is the match subject. count is the
number of positional sub-patterns.
Pop STACK[-1], STACK[-2], and STACK[-3]. If STACK[-3] is an
instance of STACK[-2] and has the positional and keyword attributes
required by count and STACK[-1], push a tuple of extracted attributes.
Otherwise, push None.
Added in version 3.10.
Changed in version 3.11: Previously, this instruction also pushed a boolean value indicating
success (True) or failure (False).
A no-op. Performs internal tracing, debugging and optimization checks.
The context operand consists of two parts. The lowest two bits
indicate where the RESUME occurs:
0 The start of a function, which is neither a generator, coroutine
nor an async generator
1 After a yield expression
2 After a yield from expression
3 After an await expression
The next bit is 1 if the RESUME is at except-depth 1, and 0
otherwise.
Added in version 3.11.
Changed in version 3.13: The oparg value changed to include information about except-depth
Create a generator, coroutine, or async generator from the current frame. Used as first opcode of in code object for the above mentioned callables. Clear the current frame and return the newly created generator.
Added in version 3.11.
Equivalent to STACK[-1] = STACK[-2].send(STACK[-1]). Used in yield from
and await statements.
If the call raises StopIteration, pop the top value from the stack,
push the exception’s value attribute, and increment the bytecode counter
by delta.
Added in version 3.11.
This is not really an opcode. It identifies the dividing line between
opcodes in the range [0,255] which don’t use their argument and those
that do (< HAVE_ARGUMENT and >= HAVE_ARGUMENT, respectively).
If your application uses pseudo instructions or specialized instructions,
use the hasarg collection instead.
Changed in version 3.6: Now every instruction has an argument, but opcodes < HAVE_ARGUMENT
ignore it. Before, only opcodes >= HAVE_ARGUMENT had an argument.
Changed in version 3.12: Pseudo instructions were added to the dis module, and for them
it is not true that comparison with HAVE_ARGUMENT indicates whether
they use their arg.
Deprecated since version 3.13: Use hasarg instead.
Calls an intrinsic function with one argument. Passes STACK[-1] as the
argument and sets STACK[-1] to the result. Used to implement
functionality that is not performance critical.
The operand determines which intrinsic function is called:
Operand |
Description |
|---|---|
|
Not valid |
|
Prints the argument to standard out. Used in the REPL. |
|
Performs |
|
Extracts the return value from a
|
|
Wraps an async generator value |
|
Performs the unary |
|
Converts a list to a tuple |
|
Creates a |
|
Creates a
|
|
Creates a
|
|
Returns |
|
Creates a
|
Added in version 3.12.
Calls an intrinsic function with two arguments. Used to implement functionality that is not performance critical:
arg2 = STACK.pop()
arg1 = STACK.pop()
result = intrinsic2(arg1, arg2)
STACK.append(result)
The operand determines which intrinsic function is called:
Operand |
Description |
|---|---|
|
Not valid |
|
Calculates the
|
|
Creates a |
|
Creates a
|
|
Sets the |
Added in version 3.12.
Performs special method lookup on STACK[-1].
If type(STACK[-1]).__xxx__ is a method, leave
type(STACK[-1]).__xxx__; STACK[-1] on the stack.
If type(STACK[-1]).__xxx__ is not a method, leave
STACK[-1].__xxx__; NULL on the stack.
Added in version 3.14.
Pseudo-instructions
These opcodes do not appear in Python bytecode. They are used by the compiler but are replaced by real opcodes or removed before bytecode is generated.
Set up an exception handler for the following code block. If an exception
occurs, the value stack level is restored to its current state and control
is transferred to the exception handler at target.
Like SETUP_FINALLY, but in case of an exception also pushes the last
instruction (lasti) to the stack so that RERAISE can restore it.
If an exception occurs, the value stack level and the last instruction on
the frame are restored to their current state, and control is transferred
to the exception handler at target.
Like SETUP_CLEANUP, but in case of an exception one more item is popped
from the stack before control is transferred to the exception handler at
target.
This variant is used in with and async with
constructs, which push the return value of the context manager’s
__enter__() or __aenter__() to the stack.
Marks the end of the code block associated with the last SETUP_FINALLY,
SETUP_CLEANUP or SETUP_WITH.
Works as LOAD_CONST, but is more efficient for immortal objects.
Undirected relative jump instructions which are replaced by their directed (forward/backward) counterparts by the assembler.
Conditional jumps which do not impact the stack. Replaced by the sequence
COPY 1, TO_BOOL, POP_JUMP_IF_TRUE/FALSE.
Pushes a reference to the cell contained in slot i of the “fast locals”
storage.
Note that LOAD_CLOSURE is replaced with LOAD_FAST in the assembler.
Changed in version 3.13: This opcode is now a pseudo-instruction.
These collections are provided for automatic introspection of bytecode instructions:
Changed in version 3.12: The collections now contain pseudo instructions and instrumented
instructions as well. These are opcodes with values >= MIN_PSEUDO_OPCODE
and >= MIN_INSTRUMENTED_OPCODE.
Sequence of operation names, indexable using the bytecode.
Dictionary mapping operation names to bytecodes.
Sequence of all compare operation names.
Sequence of bytecodes that use their argument.
Added in version 3.12.
Sequence of bytecodes that access a constant.
Sequence of bytecodes that access a free (closure) variable. ‘free’ in this context refers to names in the current scope that are referenced by inner scopes or names in outer scopes that are referenced from this scope. It does not include references to global or builtin scopes.
Sequence of bytecodes that access an attribute by name.
Sequence of bytecodes that have a jump target. All jumps are relative.
Added in version 3.13.
Sequence of bytecodes that access a local variable.
Sequence of bytecodes of Boolean operations.
Sequence of bytecodes that set an exception handler.
Added in version 3.12.
Sequence of bytecodes that have a relative jump target.
Deprecated since version 3.13: All jumps are now relative. Use hasjump.
Sequence of bytecodes that have an absolute jump target.
Deprecated since version 3.13: All jumps are now relative. This list is empty.