`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.

Detail implementasi CPython: 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.

Berubah pada versi 3.6: Use 2 bytes for each instruction. Previously the number of bytes varied by instruction.

Berubah pada versi 3.10: The argument of jump, exception handling and loop instructions is now the instruction offset rather than the byte offset.

Berubah pada versi 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.

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           0 RESUME                   0

  3           2 LOAD_GLOBAL              1 (NULL + len)
             14 LOAD_FAST                0 (alist)
             16 PRECALL                  1
             20 CALL                     1
             30 RETURN_VALUE

(The "2" is a line number).

Command-line interface¶

The dis module can be invoked as a script from the command line:

python -m dis [-h] [-C] [infile]

The following options are accepted:

-h, --help¶: Display usage and exit.

-C, --show-caches¶: Show inline caches.

If infile is specified, its disassembled code will be written to stdout. Otherwise, disassembly is performed on compiled source code recieved from stdin.

Bytecode analysis¶

Baru pada versi 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.

class dis.Bytecode(x, *, first_line=None, current_offset=None, show_caches=False, adaptive=False)¶

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.

classmethod from_traceback(tb, *, show_caches=False)¶: Construct a Bytecode instance from the given traceback, setting current_offset to the instruction responsible for the exception.

codeobj¶: The compiled code object.

first_line¶: The first source line of the code object (if available)

dis()¶: Return a formatted view of the bytecode operations (the same as printed by dis.dis(), but returned as a multi-line string).

info()¶: Return a formatted multi-line string with detailed information about the code object, like code_info().

Berubah pada versi 3.7: This can now handle coroutine and asynchronous generator objects.

Berubah pada versi 3.11: Added the show_caches and adaptive parameters.

Example:

>>> bytecode = dis.Bytecode(myfunc)
>>> for instr in bytecode:
...     print(instr.opname)
...
RESUME
LOAD_GLOBAL
LOAD_FAST
PRECALL
CALL
RETURN_VALUE

Analysis functions¶

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:

dis.code_info(x)¶

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.

Baru pada versi 3.2.

Berubah pada versi 3.7: This can now handle coroutine and asynchronous generator objects.

dis.show_code(x, *, file=None)¶

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.

Baru pada versi 3.2.

Berubah pada versi 3.4: Added file parameter.

dis.dis(x=None, *, file=None, depth=None, show_caches=False, adaptive=False)¶

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 (the code of comprehensions, generator expressions and nested functions, and the code used for building nested classes). 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.

Berubah pada versi 3.4: Added file parameter.

Berubah pada versi 3.7: Implemented recursive disassembling and added depth parameter.

Berubah pada versi 3.7: This can now handle coroutine and asynchronous generator objects.

Berubah pada versi 3.11: Added the show_caches and adaptive parameters.

dis.distb(tb=None, *, file=None, show_caches=False, adaptive=False)¶

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.

Berubah pada versi 3.4: Added file parameter.

Berubah pada versi 3.11: Added the show_caches and adaptive parameters.

dis.disassemble(code, lasti=-1, *, file=None, show_caches=False, adaptive=False)¶

dis.disco(code, lasti=-1, *, file=None, show_caches=False, adaptive=False)¶

Disassemble a code object, indicating the last instruction if lasti was provided. The output is divided in the following columns:

the line number, for the first instruction of each line
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.

Berubah pada versi 3.4: Added file parameter.

Berubah pada versi 3.11: Added the show_caches and adaptive parameters.

dis.get_instructions(x, *, first_line=None, show_caches=False, adaptive=False)¶

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 show_caches and adaptive parameters work as they do in dis().

Baru pada versi 3.4.

Berubah pada versi 3.11: Added the show_caches and adaptive parameters.

dis.findlinestarts(code)¶: 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.

Berubah pada versi 3.6: Line numbers can be decreasing. Before, they were always increasing.

Berubah pada versi 3.10: The PEP 626 co_lines() method is used instead of the co_firstlineno and co_lnotab attributes of the code object.

dis.findlabels(code)¶: Detect all offsets in the raw compiled bytecode string code which are jump targets, and return a list of these offsets.

dis.stack_effect(opcode, oparg=None, *, jump=None)¶

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.

Baru pada versi 3.4.

Berubah pada versi 3.8: Added jump parameter.

Python Bytecode Instructions¶

The get_instructions() function and Bytecode class provide details of bytecode instructions as Instruction instances:

class dis.Instruction¶

Details for a bytecode operation

opcode¶: numeric code for operation, corresponding to the opcode values listed below and the bytecode values in the Opcode collections.

opname¶: human readable name for operation

arg¶: numeric argument to operation (if any), otherwise None

argval¶: resolved arg value (if any), otherwise None

argrepr¶: human readable description of operation argument (if any), otherwise an empty string.

offset¶: start index of operation within bytecode sequence

starts_line¶: line started by this opcode (if any), otherwise None

is_jump_target¶: True if other code jumps to here, otherwise False

positions¶: dis.Positions object holding the start and end locations that are covered by this instruction.

Baru pada versi 3.4.

Berubah pada versi 3.11: Field positions is added.

class dis.Positions¶

In case the information is not available, some fields might be None.

lineno¶

end_lineno¶

col_offset¶

end_col_offset¶

Baru pada versi 3.11.

The Python compiler currently generates the following bytecode instructions.

General instructions

NOP¶: Do nothing code. Used as a placeholder by the bytecode optimizer, and to generate line tracing events.

POP_TOP¶: Removes the top-of-stack (TOS) item.

COPY(i)¶: Push the i-th item to the top of the stack. The item is not removed from its original location.

Baru pada versi 3.11.

SWAP(i)¶: Swap TOS with the item at position i.

Baru pada versi 3.11.

CACHE¶

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.

Baru pada versi 3.11.

Unary operations

Unary operations take the top of the stack, apply the operation, and push the result back on the stack.

UNARY_POSITIVE¶: Implements TOS = +TOS.

UNARY_NEGATIVE¶: Implements TOS = -TOS.

UNARY_NOT¶: Implements TOS = not TOS.

UNARY_INVERT¶: Implements TOS = ~TOS.

GET_ITER¶: Implements TOS = iter(TOS).

GET_YIELD_FROM_ITER¶: If TOS is a generator iterator or coroutine object it is left as is. Otherwise, implements TOS = iter(TOS).

Baru pada versi 3.5.

Binary and in-place operations

Binary operations remove the top of the stack (TOS) and the second top-most stack item (TOS1) from the stack. They perform the operation, and put the result back on the stack.

In-place operations are like binary operations, in that they remove TOS and TOS1, and push the result back on the stack, but the operation is done in-place when TOS1 supports it, and the resulting TOS may be (but does not have to be) the original TOS1.

BINARY_OP(op)¶: Implements the binary and in-place operators (depending on the value of op).

Baru pada versi 3.11.

BINARY_SUBSCR¶: Implements TOS = TOS1[TOS].

STORE_SUBSCR¶: Implements TOS1[TOS] = TOS2.

DELETE_SUBSCR¶: Implements del TOS1[TOS].

Coroutine opcodes

GET_AWAITABLE(where)¶

Implements TOS = get_awaitable(TOS), 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 where operand is nonzero, it indicates where the instruction occurs:

1 After a call to __aenter__

2 After a call to __aexit__

Baru pada versi 3.5.

Berubah pada versi 3.11: Previously, this instruction did not have an oparg.

GET_AITER¶: Implements TOS = TOS.__aiter__().

Baru pada versi 3.5.

Berubah pada versi 3.7: Returning awaitable objects from __aiter__ is no longer supported.

GET_ANEXT¶: Pushes get_awaitable(TOS.__anext__()) to the stack. See GET_AWAITABLE for details about get_awaitable.

Baru pada versi 3.5.

END_ASYNC_FOR¶: Terminates an async for loop. Handles an exception raised when awaiting a next item. The stack contains the async iterable in TOS1 and the raised exception in TOS. Both are popped. If the exception is not StopAsyncIteration, it is re-raised.

Baru pada versi 3.8.

Berubah pada versi 3.11: Exception representation on the stack now consist of one, not three, items.

BEFORE_ASYNC_WITH¶: Resolves __aenter__ and __aexit__ from the object on top of the stack. Pushes __aexit__ and result of __aenter__() to the stack.

Baru pada versi 3.5.

Miscellaneous opcodes

PRINT_EXPR¶: Implements the expression statement for the interactive mode. TOS is removed from the stack and printed. In non-interactive mode, an expression statement is terminated with POP_TOP.

SET_ADD(i)¶: Calls set.add(TOS1[-i], TOS). Used to implement set comprehensions.

LIST_APPEND(i)¶: Calls list.append(TOS1[-i], TOS). Used to implement list comprehensions.

MAP_ADD(i)¶: Calls dict.__setitem__(TOS1[-i], TOS1, TOS). Used to implement dict comprehensions.

Baru pada versi 3.1.

Berubah pada versi 3.8: Map value is TOS and map key is TOS1. 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.

RETURN_VALUE¶: Returns with TOS to the caller of the function.

YIELD_VALUE¶: Pops TOS and yields it from a generator.

SETUP_ANNOTATIONS¶: 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.

Baru pada versi 3.6.

IMPORT_STAR¶: Loads all symbols not starting with '_' directly from the module TOS to the local namespace. The module is popped after loading all names. This opcode implements from module import *.

POP_EXCEPT¶: Pops a value from the stack, which is used to restore the exception state.

Berubah pada versi 3.11: Exception representation on the stack now consist of one, not three, items.

RERAISE¶: 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.

Baru pada versi 3.9.

Berubah pada versi 3.11: Exception representation on the stack now consist of one, not three, items.

PUSH_EXC_INFO¶: 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.

Baru pada versi 3.11.

CHECK_EXC_MATCH¶: Performs exception matching for except. Tests whether the TOS1 is an exception matching TOS. Pops TOS and pushes the boolean result of the test.

Baru pada versi 3.11.

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.

Baru pada versi 3.11.

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.

Baru pada versi 3.11.

WITH_EXCEPT_START¶: 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.

Baru pada versi 3.9.

Berubah pada versi 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.

LOAD_ASSERTION_ERROR¶: Pushes AssertionError onto the stack. Used by the assert statement.

Baru pada versi 3.9.

LOAD_BUILD_CLASS¶: Pushes builtins.__build_class__() onto the stack. It is later called to construct a class.

BEFORE_WITH(delta)¶: This opcode performs several operations before a with block starts. First, it loads __exit__() from the context manager and pushes it onto the stack for later use by WITH_EXCEPT_START. Then, __enter__() is called. Finally, the result of calling the __enter__() method is pushed onto the stack.

Baru pada versi 3.11.

GET_LEN¶: Push len(TOS) onto the stack.

Baru pada versi 3.10.

MATCH_MAPPING¶: If TOS 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.

Baru pada versi 3.10.

MATCH_SEQUENCE¶: If TOS 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.

Baru pada versi 3.10.

MATCH_KEYS¶: TOS is a tuple of mapping keys, and TOS1 is the match subject. If TOS1 contains all of the keys in TOS, push a tuple containing the corresponding values. Otherwise, push None.

Baru pada versi 3.10.

Berubah pada versi 3.11: Previously, this instruction also pushed a boolean value indicating success (True) or failure (False).

STORE_NAME(namei)¶: Implements name = TOS. 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.

DELETE_NAME(namei)¶: Implements del name, where namei is the index into co_names attribute of the code object.

UNPACK_SEQUENCE(count)¶: Unpacks TOS into count individual values, which are put onto the stack right-to-left.

UNPACK_EX(counts)¶

Implements assignment with a starred target: Unpacks an iterable in TOS 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 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 resulting values are put onto the stack right-to-left.

STORE_ATTR(namei)¶: Implements TOS.name = TOS1, where namei is the index of name in co_names.

DELETE_ATTR(namei)¶: Implements del TOS.name, using namei as index into co_names of the code object.

STORE_GLOBAL(namei)¶: Works as STORE_NAME, but stores the name as a global.

DELETE_GLOBAL(namei)¶: Works as DELETE_NAME, but deletes a global name.

LOAD_CONST(consti)¶: Pushes co_consts[consti] onto the stack.

LOAD_NAME(namei)¶: Pushes the value associated with co_names[namei] onto the stack.

BUILD_TUPLE(count)¶: Creates a tuple consuming count items from the stack, and pushes the resulting tuple onto the stack.

BUILD_LIST(count)¶: Works as BUILD_TUPLE, but creates a list.

BUILD_SET(count)¶: Works as BUILD_TUPLE, but creates a set.

BUILD_MAP(count)¶: Pushes a new dictionary object onto the stack. Pops 2 * count items so that the dictionary holds count entries: {..., TOS3: TOS2, TOS1: TOS}.

Berubah pada versi 3.5: The dictionary is created from stack items instead of creating an empty dictionary pre-sized to hold count items.

BUILD_CONST_KEY_MAP(count)¶: The version of BUILD_MAP specialized for constant keys. Pops the top element on the stack which contains a tuple of keys, then starting from TOS1, pops count values to form values in the built dictionary.

Baru pada versi 3.6.

BUILD_STRING(count)¶: Concatenates count strings from the stack and pushes the resulting string onto the stack.

Baru pada versi 3.6.

LIST_TO_TUPLE¶: Pops a list from the stack and pushes a tuple containing the same values.

Baru pada versi 3.9.

LIST_EXTEND(i)¶: Calls list.extend(TOS1[-i], TOS). Used to build lists.

Baru pada versi 3.9.

SET_UPDATE(i)¶: Calls set.update(TOS1[-i], TOS). Used to build sets.

Baru pada versi 3.9.

DICT_UPDATE(i)¶: Calls dict.update(TOS1[-i], TOS). Used to build dicts.

Baru pada versi 3.9.

DICT_MERGE(i)¶: Like DICT_UPDATE but raises an exception for duplicate keys.

Baru pada versi 3.9.

LOAD_ATTR(namei)¶: Replaces TOS with getattr(TOS, co_names[namei]).

COMPARE_OP(opname)¶: Performs a Boolean operation. The operation name can be found in cmp_op[opname].

IS_OP(invert)¶: Performs is comparison, or is not if invert is 1.

Baru pada versi 3.9.

CONTAINS_OP(invert)¶: Performs in comparison, or not in if invert is 1.

Baru pada versi 3.9.

IMPORT_NAME(namei)¶: Imports the module co_names[namei]. TOS and TOS1 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.

IMPORT_FROM(namei)¶: Loads the attribute co_names[namei] from the module found in TOS. The resulting object is pushed onto the stack, to be subsequently stored by a STORE_FAST instruction.

JUMP_FORWARD(delta)¶: Increments bytecode counter by delta.

JUMP_BACKWARD(delta)¶: Decrements bytecode counter by delta. Checks for interrupts.

Baru pada versi 3.11.

JUMP_BACKWARD_NO_INTERRUPT(delta)¶: Decrements bytecode counter by delta. Does not check for interrupts.

Baru pada versi 3.11.

POP_JUMP_FORWARD_IF_TRUE(delta)¶: If TOS is true, increments the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_BACKWARD_IF_TRUE(delta)¶: If TOS is true, decrements the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_FORWARD_IF_FALSE(delta)¶: If TOS is false, increments the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_BACKWARD_IF_FALSE(delta)¶: If TOS is false, decrements the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_FORWARD_IF_NOT_NONE(delta)¶: If TOS is not None, increments the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_BACKWARD_IF_NOT_NONE(delta)¶: If TOS is not None, decrements the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_FORWARD_IF_NONE(delta)¶: If TOS is None, increments the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

POP_JUMP_BACKWARD_IF_NONE(delta)¶: If TOS is None, decrements the bytecode counter by delta. TOS is popped.

Baru pada versi 3.11.

JUMP_IF_TRUE_OR_POP(delta)¶: If TOS is true, increments the bytecode counter by delta and leaves TOS on the stack. Otherwise (TOS is false), TOS is popped.

Baru pada versi 3.1.

Berubah pada versi 3.11: The oparg is now a relative delta rather than an absolute target.

JUMP_IF_FALSE_OR_POP(delta)¶: If TOS is false, increments the bytecode counter by delta and leaves TOS on the stack. Otherwise (TOS is true), TOS is popped.

Baru pada versi 3.1.

Berubah pada versi 3.11: The oparg is now a relative delta rather than an absolute target.

FOR_ITER(delta)¶: TOS 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, TOS is popped, and the byte code counter is incremented by delta.

LOAD_GLOBAL(namei)¶: Loads the global named co_names[namei>>1] onto the stack.

Berubah pada versi 3.11: If the low bit of namei is set, then a NULL is pushed to the stack before the global variable.

LOAD_FAST(var_num)¶: Pushes a reference to the local co_varnames[var_num] onto the stack.

STORE_FAST(var_num)¶: Stores TOS into the local co_varnames[var_num].

DELETE_FAST(var_num)¶: Deletes local co_varnames[var_num].

MAKE_CELL(i)¶: Creates a new cell in slot i. If that slot is nonempty then that value is stored into the new cell.

Baru pada versi 3.11.

LOAD_CLOSURE(i)¶

Pushes a reference to the cell contained in slot i of the "fast locals" storage. The name of the variable is co_fastlocalnames[i].

Note that LOAD_CLOSURE is effectively an alias for LOAD_FAST. It exists to keep bytecode a little more readable.

Berubah pada versi 3.11: i is no longer offset by the length of co_varnames.

LOAD_DEREF(i)¶: Loads the cell contained in slot i of the "fast locals" storage. Pushes a reference to the object the cell contains on the stack.

Berubah pada versi 3.11: i is no longer offset by the length of co_varnames.

LOAD_CLASSDEREF(i)¶: Much like LOAD_DEREF but first checks the locals dictionary before consulting the cell. This is used for loading free variables in class bodies.

Baru pada versi 3.4.

Berubah pada versi 3.11: i is no longer offset by the length of co_varnames.

STORE_DEREF(i)¶: Stores TOS into the cell contained in slot i of the "fast locals" storage.

Berubah pada versi 3.11: i is no longer offset by the length of co_varnames.

DELETE_DEREF(i)¶: Empties the cell contained in slot i of the "fast locals" storage. Used by the del statement.

Baru pada versi 3.2.

Berubah pada versi 3.11: i is no longer offset by the length of co_varnames.

COPY_FREE_VARS(n)¶: Copies the n free variables from the closure into the frame. Removes the need for special code on the caller's side when calling closures.

Baru pada versi 3.11.

RAISE_VARARGS(argc)¶

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 TOS (raise exception instance or type at TOS)
2: raise TOS1 from TOS (raise exception instance or type at TOS1 with __cause__ set to TOS)

CALL(argc)¶

Calls a callable object with the number of arguments specified by argc, including the named arguments specified by the preceding KW_NAMES, if any. On the stack are (in ascending order), either:

NULL
The callable
The positional arguments
The named arguments

or:

The callable
self
The remaining positional arguments
The named arguments

argc is the total of the positional and named arguments, excluding self when a NULL is not present.

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.

Baru pada versi 3.11.

CALL_FUNCTION_EX(flags)¶: 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.

Baru pada versi 3.6.

LOAD_METHOD(namei)¶: Loads a method named co_names[namei] from the TOS object. TOS is popped. This bytecode distinguishes two cases: if TOS has a method with the correct name, the bytecode pushes the unbound method and TOS. TOS will be used as the first argument (self) by CALL when calling the unbound method. Otherwise, NULL and the object return by the attribute lookup are pushed.

Baru pada versi 3.7.

PRECALL(argc)¶: Prefixes CALL. Logically this is a no op. It exists to enable effective specialization of calls. argc is the number of arguments as described in CALL.

Baru pada versi 3.11.

PUSH_NULL¶: Pushes a NULL to the stack. Used in the call sequence to match the NULL pushed by LOAD_METHOD for non-method calls.

Baru pada versi 3.11.

KW_NAMES(i)¶: Prefixes PRECALL. Stores a reference to co_consts[consti] into an internal variable for use by CALL. co_consts[consti] must be a tuple of strings.

Baru pada versi 3.11.

MAKE_FUNCTION(flags)¶

Pushes a new function object on the stack. From bottom to top, the consumed stack must consist of values if the argument carries a specified flag value

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
the code associated with the function (at TOS)

Berubah pada versi 3.10: Flag value 0x04 is a tuple of strings instead of dictionary

Berubah pada versi 3.11: Qualified name at TOS was removed.

BUILD_SLICE(argc)¶: Pushes a slice object on the stack. argc must be 2 or 3. If it is 2, slice(TOS1, TOS) is pushed; if it is 3, slice(TOS2, TOS1, TOS) is pushed. See the slice() built-in function for more information.

EXTENDED_ARG(ext)¶: 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.

FORMAT_VALUE(flags)¶

Used for implementing formatted literal strings (f-strings). Pops an optional fmt_spec from the stack, then a required value. flags is interpreted as follows:

(flags & 0x03) == 0x00: value is formatted as-is.
(flags & 0x03) == 0x01: call str() on value before formatting it.
(flags & 0x03) == 0x02: call repr() on value before formatting it.
(flags & 0x03) == 0x03: call ascii() on value before formatting it.
(flags & 0x04) == 0x04: pop fmt_spec from the stack and use it, else use an empty fmt_spec.

Formatting is performed using PyObject_Format(). The result is pushed on the stack.

Baru pada versi 3.6.

MATCH_CLASS(count)¶

TOS is a tuple of keyword attribute names, TOS1 is the class being matched against, and TOS2 is the match subject. count is the number of positional sub-patterns.

Pop TOS, TOS1, and TOS2. If TOS2 is an instance of TOS1 and has the positional and keyword attributes required by count and TOS, push a tuple of extracted attributes. Otherwise, push None.

Baru pada versi 3.10.

Berubah pada versi 3.11: Previously, this instruction also pushed a boolean value indicating success (True) or failure (False).

RESUME(where)¶

A no-op. Performs internal tracing, debugging and optimization checks.

The where operand marks where the RESUME occurs:

0 The start of a function

1 After a yield expression

2 After a yield from expression

3 After an await expression

Baru pada versi 3.11.

RETURN_GENERATOR¶: Create a generator, coroutine, or async generator from the current frame. Clear the current frame and return the newly created generator.

Baru pada versi 3.11.

SEND¶: Sends None to the sub-generator of this generator. Used in yield from and await statements.

Baru pada versi 3.11.

ASYNC_GEN_WRAP¶: Wraps the value on top of the stack in an async_generator_wrapped_value. Used to yield in async generators.

Baru pada versi 3.11.

HAVE_ARGUMENT¶: This is not really an opcode. It identifies the dividing line between opcodes which don't use their argument and those that do (< HAVE_ARGUMENT and >= HAVE_ARGUMENT, respectively).

Berubah pada versi 3.6: Now every instruction has an argument, but opcodes < HAVE_ARGUMENT ignore it. Before, only opcodes >= HAVE_ARGUMENT had an argument.

Opcode collections¶

These collections are provided for automatic introspection of bytecode instructions:

dis.opname¶: Sequence of operation names, indexable using the bytecode.

dis.opmap¶: Dictionary mapping operation names to bytecodes.

dis.cmp_op¶: Sequence of all compare operation names.

dis.hasconst¶: Sequence of bytecodes that access a constant.

dis.hasfree¶: Sequence of bytecodes that access a free variable (note that '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).

dis.hasname¶: Sequence of bytecodes that access an attribute by name.

dis.hasjrel¶: Sequence of bytecodes that have a relative jump target.

dis.hasjabs¶: Sequence of bytecodes that have an absolute jump target.

dis.haslocal¶: Sequence of bytecodes that access a local variable.

dis.hascompare¶: Sequence of bytecodes of Boolean operations.

`dis` --- Disassembler for Python bytecode¶

Command-line interface¶

Bytecode analysis¶

Analysis functions¶

Python Bytecode Instructions¶

Opcode collections¶

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dis --- Disassembler for Python bytecode¶

Command-line interface¶

Bytecode analysis¶

Analysis functions¶

Python Bytecode Instructions¶

Opcode collections¶

`dis` --- Disassembler for Python bytecode¶