dis – Désassembleur pour le code intermédiaire de Python

Code source : Lib/dis.py

La bibliothèque dis supporte l'analyse du bytecode CPython en le désassemblant. Le code intermédiaire CPython, que cette bibliothèque prend en paramètre, est défini dans le fichier Include/opcode.h et est utilisé par le compilateur et l'interpréteur.

Particularité de l'implémentation CPython : Le code intermédiaire est un détail d'implémentation de l'interpréteur CPython. Il n'y a pas de garantie que le code intermédiaire sera ajouté, retiré, ou modifié dans les différentes versions de Python. L'utilisation de cette bibliothèque ne fonctionne pas nécessairement sur les machines virtuelles Python ni les différentes versions de Python.

Modifié dans la version 3.6: Utilisez 2 bits pour chaque instruction. Avant, le nombre de bits variait par instruction.

Modifié dans la version 3.10: The argument of jump, exception handling and loop instructions is now the instruction offset rather than the byte offset.

Modifié dans la 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.

Modifié dans la 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.

Modifié dans la 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                0 (alist)
              CALL                     1
              RETURN_VALUE

(Le "2" est un numéro de ligne).

Command-line interface

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

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

The following options are accepted:

-h, --help

Display usage and exit.

-C, --show-caches

Show inline caches.

-O, --show-offsets

Show offsets of instructions.

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

Analyse du code intermédiaire

Nouveau dans la version 3.4.

L'analyse de l'API code intermédiaire permet de rassembler des blocs de code en Python dans une classe Bytecode, qui permet un accès facile aux détails du code compilé.

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

Analyse le code intermédiaire correspondant à une fonction, un générateur, un générateur asynchrone, une coroutine, une méthode, une chaîne de caractères du code source, ou bien une classe (comme retourne la fonction compile()).

Ceci est wrapper sur plusieurs fonctions de la liste ci-dessous, notamment get_instructions(), étant donné qu'une itération sur une instance de la classe Bytecode rend les opérations du code intermédiaire des instances de Instruction.

Si first_line ne vaut pas None, elle indique le nombre de la ligne qui doit être considérée comme première ligne source dans le code désassemblé. Autrement, les informations sur la ligne source sont prises directement à partir de la classe du code désassemblé.

Si la valeur de current_offset est différente de None, c'est une référence à un offset d'une instruction dans le code désassemblé. Cela veut dire que dis() va générer un marqueur de " l'instruction en cours" contre le code d'opération donné.

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.

classmethod from_traceback(tb, *, show_caches=False)

Construisez une instance Bytecode à partir de la trace d'appel, en mettant current_offet à l'instruction responsable de l'exception.

codeobj

Le code compilé objet.

first_line

La première ligne source du code objet (si disponible)

dis()

Retourne une vue formatée des opérations du code intermédiaire (la même que celle envoyée par dis.dis(), mais comme une chaîne de caractères de plusieurs lignes ).

info()

Retourne une chaîne de caractères de plusieurs lignes formatée avec des informations détaillées sur l'objet code comme code_info().

Modifié dans la version 3.7: Cette version supporte la coroutine et les objets générateurs asynchrones.

Modifié dans la version 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
CALL
RETURN_VALUE

Analyse de fonctions

La bibliothèque dis comprend également l'analyse des fonctions suivantes, qui envoient l'entrée directement à la sortie souhaitée. Elles peuvent être utiles si il n'y a qu'une seule opération à effectuer, la représentation intermédiaire objet n'étant donc pas utile dans ce cas :

dis.code_info(x)

Retourne une chaîne de caractères de plusieurs lignes formatée avec des informations détaillées sur l'objet code pour les fonctions données, les générateurs asynchrone, coroutine, la méthode, la chaine de caractères du code source ou objet.

Il est à noter que le contenu exact des chaînes de caractères figurant dans les informations du code dépendent fortement sur l'implémentation, et peuvent changer arbitrairement sous machines virtuelles Python ou les versions de Python.

Nouveau dans la version 3.2.

Modifié dans la version 3.7: Cette version supporte la coroutine et les objets générateurs asynchrones.

dis.show_code(x, *, file=None)

Affiche des informations détaillées sur le code de la fonction fournie, la méthode, la chaîne de caractère du code source ou du code objet à file (ou bien sys.stdout si file n'est pas spécifié).

Ceci est un raccourci convenable de print(code_info(x), file=file), principalement fait pour l'exploration interactive sur l'invite de l'interpréteur.

Nouveau dans la version 3.2.

Modifié dans la version 3.4: Ajout du paramètre file.

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. 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.

Le désassemblage est envoyé sous forme de texte à l'argument du fichier file si il est fourni, et à sys.stdout sinon.

La profondeur maximale de récursion est limitée par depth sauf si elle correspond à None. depth=0 indique qu'il n'y a pas de récursion.

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.

Modifié dans la version 3.4: Ajout du paramètre file.

Modifié dans la version 3.7: Le désassemblage récursif a été implémenté, et le paramètre depth a été ajouté.

Modifié dans la version 3.7: Cette version supporte la coroutine et les objets générateurs asynchrones.

Modifié dans la version 3.11: Added the show_caches and adaptive parameters.

distb(tb=None, *, file=None, show_caches=False, adaptive=False,
show_offset=False)

Désassemble la fonction du haut de la pile des traces d'appels, en utilisant la dernière trace d'appels si rien n'a été envoyé. L'instruction à l'origine de l'exception est indiquée.

Le désassemblage est envoyé sous forme de texte à l'argument du fichier file si il est fourni, et à sys.stdout sinon.

Modifié dans la version 3.4: Ajout du paramètre file.

Modifié dans la version 3.11: Added the show_caches and adaptive parameters.

Modifié dans la version 3.13: Added the show_offsets parameter.

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

Désassemble un code objet, en indiquant la dernière instruction si lasti est fournie. La sortie est répartie sur les colonnes suivantes :

  1. le numéro de ligne, pour la première instruction de chaque ligne

  2. l'instruction en cours, indiquée par -->,

  3. une instruction libellée, indiquée par > >,

  4. l'adresse de l'instruction,

  5. le nom de le code d'opération,

  6. paramètres de l'opération, et

  7. interprétation des paramètres entre parenthèses.

L'interprétation du paramètre reconnaît les noms des variables locales et globales, des valeurs constantes, des branchements cibles, et des opérateurs de comparaison.

Le désassemblage est envoyé sous forme de texte à l'argument du fichier file si il est fourni, et à sys.stdout sinon.

Modifié dans la version 3.4: Ajout du paramètre file.

Modifié dans la version 3.11: Added the show_caches and adaptive parameters.

Modifié dans la version 3.13: Added the show_offsets parameter.

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

Retourne un itérateur sur les instructions dans la fonction fournie, la méthode, les chaînes de caractères du code source ou objet.

Cet itérateur génère une série de n-uplets de Instruction qui donnent les détails de chacune des opérations dans le code fourni.

Si first_line ne vaut pas None, elle indique le nombre de la ligne qui doit être considérée comme première ligne source dans le code désassemblé. Autrement, les informations sur la ligne source sont prises directement à partir de la classe du code désassemblé.

The adaptive parameter works as it does in dis().

Nouveau dans la version 3.4.

Modifié dans la version 3.11: Added the show_caches and adaptive parameters.

Modifié dans la version 3.13: The show_caches parameter is deprecated and has no effect. The cache_info field of each instruction is populated regardless of its value.

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.

Modifié dans la version 3.6: Les numéros de lignes peuvent être décroissants. Avant, ils étaient toujours croissants.

Modifié dans la version 3.10: The PEP 626 co_lines() method is used instead of the co_firstlineno and co_lnotab attributes of the code object.

Modifié dans la version 3.13: Line numbers can be None for bytecode that does not map to source lines.

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.

Nouveau dans la version 3.4.

Modifié dans la version 3.8: Added jump parameter.

Modifié dans la 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.

Les instructions du code intermédiaire en Python

La fonction get_instructions() et la méthode Bytecode fournit des détails sur le code intermédiaire des instructions comme Instruction instances :

class dis.Instruction

Détails sur le code intermédiaire de l'opération

opcode

code numérique pour l'opération, correspondant aux valeurs de l'opcode ci-dessous et les valeurs du code intermédiaire dans la Opcode collections.

opname

nom lisible/compréhensible de l'opération

baseopcode

numeric code for the base operation if operation is specialized; otherwise equal to opcode

baseopname

human readable name for the base operation if operation is specialized; otherwise equal to opname

arg

le cas échéant, argument numérique de l'opération sinon None

oparg

alias for arg

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

start_offset

start index of operation within bytecode sequence, including prefixed EXTENDED_ARG operations if present; otherwise equal to offset

cache_offset

start index of the cache entries following the operation

end_offset

end index of the cache entries following the operation

starts_line

True if this opcode starts a source line, otherwise False

line_number

source line number associated with this opcode (if any), otherwise None

is_jump_target

True if other code jumps to here, otherwise False

jump_target

bytecode index of the jump target if this is a jump operation, otherwise None

positions

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

Nouveau dans la version 3.4.

Modifié dans la version 3.11: Field positions is added.

Modifié dans la 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.

class dis.Positions

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

lineno
end_lineno
col_offset
end_col_offset

Nouveau dans la 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.

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 item:

STACK.pop()
END_FOR

Removes the top-of-stack item. Equivalent to POP_TOP. Used to clean up at the end of loops, hence the name.

Nouveau dans la version 3.12.

END_SEND

Implements del STACK[-2]. Used to clean up when a generator exits.

Nouveau dans la version 3.12.

COPY(i)

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])

Nouveau dans la version 3.11.

SWAP(i)

Swap the top of the stack with the i-th element:

STACK[-i], STACK[-1] = STACK[-1], STACK[-i]

Nouveau dans la version 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.

Nouveau dans la version 3.11.

Unary operations

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

UNARY_NEGATIVE

Implements STACK[-1] = -STACK[-1].

UNARY_NOT

Implements STACK[-1] = not STACK[-1].

Modifié dans la version 3.13: This instruction now requires an exact bool operand.

UNARY_INVERT

Implements STACK[-1] = ~STACK[-1].

GET_ITER

Implements STACK[-1] = iter(STACK[-1]).

GET_YIELD_FROM_ITER

If STACK[-1] is a generator iterator or coroutine object it is left as is. Otherwise, implements STACK[-1] = iter(STACK[-1]).

Nouveau dans la version 3.5.

TO_BOOL

Implements STACK[-1] = bool(STACK[-1]).

Nouveau dans la 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].

BINARY_OP(op)

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

rhs = STACK.pop()
lhs = STACK.pop()
STACK.append(lhs op rhs)

Nouveau dans la version 3.11.

BINARY_SUBSCR

Implements:

key = STACK.pop()
container = STACK.pop()
STACK.append(container[key])
STORE_SUBSCR

Implements:

key = STACK.pop()
container = STACK.pop()
value = STACK.pop()
container[key] = value
DELETE_SUBSCR

Implements:

key = STACK.pop()
container = STACK.pop()
del container[key]
BINARY_SLICE

Implements:

end = STACK.pop()
start = STACK.pop()
container = STACK.pop()
STACK.append(container[start:end])

Nouveau dans la version 3.12.

STORE_SLICE

Implements:

end = STACK.pop()
start = STACK.pop()
container = STACK.pop()
values = STACK.pop()
container[start:end] = value

Nouveau dans la version 3.12.

Coroutine opcodes

GET_AWAITABLE(where)

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 where operand is nonzero, it indicates where the instruction occurs:

  • 1: After a call to __aenter__

  • 2: After a call to __aexit__

Nouveau dans la version 3.5.

Modifié dans la version 3.11: Previously, this instruction did not have an oparg.

GET_AITER

Implements STACK[-1] = STACK[-1].__aiter__().

Nouveau dans la version 3.5.

Modifié dans la version 3.7: Returning awaitable objects from __aiter__ is no longer supported.

GET_ANEXT

Implement STACK.append(get_awaitable(STACK[-1].__anext__())) to the stack. See GET_AWAITABLE for details about get_awaitable.

Nouveau dans la version 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 STACK[-2] and the raised exception in STACK[-1]. Both are popped. If the exception is not StopAsyncIteration, it is re-raised.

Nouveau dans la version 3.8.

Modifié dans la version 3.11: Exception representation on the stack now consist of one, not three, items.

CLEANUP_THROW

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].

Nouveau dans la version 3.12.

BEFORE_ASYNC_WITH

Resolves __aenter__ and __aexit__ from STACK[-1]. Pushes __aexit__ and result of __aenter__() to the stack:

STACK.extend((__aexit__, __aenter__())

Nouveau dans la version 3.5.

Miscellaneous opcodes

SET_ADD(i)

Implements:

item = STACK.pop()
set.add(STACK[-i], item)

Used to implement set comprehensions.

LIST_APPEND(i)

Implements:

item = STACK.pop()
list.append(STACK[-i], item)

Used to implement list comprehensions.

MAP_ADD(i)

Implements:

value = STACK.pop()
key = STACK.pop()
dict.__setitem__(STACK[-i], key, value)

Used to implement dict comprehensions.

Nouveau dans la version 3.1.

Modifié dans la 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.

RETURN_VALUE

Returns with STACK[-1] to the caller of the function.

RETURN_CONST(consti)

Returns with co_consts[consti] to the caller of the function.

Nouveau dans la version 3.12.

YIELD_VALUE

Yields STACK.pop() from a generator.

Modifié dans la version 3.11: oparg set to be the stack depth.

Modifié dans la version 3.12: oparg set to be the exception block depth, for efficient closing of generators.

Modifié dans la version 3.13: oparg is 1 if this instruction is part of a yield-from or await, and 0 otherwise.

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.

Nouveau dans la version 3.6.

POP_EXCEPT

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

Modifié dans la version 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.

Nouveau dans la version 3.9.

Modifié dans la version 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.

Nouveau dans la version 3.11.

CHECK_EXC_MATCH

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.

Nouveau dans la version 3.11.

CHECK_EG_MATCH

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.

Nouveau dans la version 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.

Nouveau dans la version 3.9.

Modifié dans la 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.

LOAD_ASSERTION_ERROR

Pushes AssertionError onto the stack. Used by the assert statement.

Nouveau dans la version 3.9.

LOAD_BUILD_CLASS

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

BEFORE_WITH

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.

Nouveau dans la version 3.11.

GET_LEN

Perform STACK.append(len(STACK[-1])).

Nouveau dans la version 3.10.

MATCH_MAPPING

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.

Nouveau dans la version 3.10.

MATCH_SEQUENCE

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.

Nouveau dans la version 3.10.

MATCH_KEYS

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.

Nouveau dans la version 3.10.

Modifié dans la version 3.11: Previously, this instruction also pushed a boolean value indicating success (True) or failure (False).

STORE_NAME(namei)

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.

DELETE_NAME(namei)

Implements del name, where namei is the index into co_names attribute of the code object.

UNPACK_SEQUENCE(count)

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])
UNPACK_EX(counts)

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)).

STORE_ATTR(namei)

Implements:

obj = STACK.pop()
value = STACK.pop()
obj.name = value

where namei is the index of name in co_names of the code object.

DELETE_ATTR(namei)

Implements:

obj = STACK.pop()
del obj.name

where namei is the index of name 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. The name is looked up within the locals, then the globals, then the builtins.

LOAD_LOCALS

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.

Nouveau dans la version 3.12.

LOAD_FROM_DICT_OR_GLOBALS(i)

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.

Nouveau dans la version 3.12.

BUILD_TUPLE(count)

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

assert count > 0
STACK, values = STACK[:-count], STACK[-count:]
STACK.append(tuple(values))
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: {..., STACK[-4]: STACK[-3], STACK[-2]: STACK[-1]}.

Modifié dans la version 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 STACK[-2], pops count values to form values in the built dictionary.

Nouveau dans la version 3.6.

BUILD_STRING(count)

Concatenates count strings from the stack and pushes the resulting string onto the stack.

Nouveau dans la version 3.6.

LIST_EXTEND(i)

Implements:

seq = STACK.pop()
list.extend(STACK[-i], seq)

Used to build lists.

Nouveau dans la version 3.9.

SET_UPDATE(i)

Implements:

seq = STACK.pop()
set.update(STACK[-i], seq)

Used to build sets.

Nouveau dans la version 3.9.

DICT_UPDATE(i)

Implements:

map = STACK.pop()
dict.update(STACK[-i], map)

Used to build dicts.

Nouveau dans la version 3.9.

DICT_MERGE(i)

Like DICT_UPDATE but raises an exception for duplicate keys.

Nouveau dans la version 3.9.

LOAD_ATTR(namei)

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.

Modifié dans la 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.

LOAD_SUPER_ATTR(namei)

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).

Nouveau dans la version 3.12.

COMPARE_OP(opname)

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.

Modifié dans la version 3.13: The fifth-lowest bit of the oparg now indicates a forced conversion to bool.

IS_OP(invert)

Performs is comparison, or is not if invert is 1.

Nouveau dans la version 3.9.

CONTAINS_OP(invert)

Performs in comparison, or not in if invert is 1.

Nouveau dans la version 3.9.

IMPORT_NAME(namei)

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.

IMPORT_FROM(namei)

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.

JUMP_FORWARD(delta)

Increments bytecode counter by delta.

JUMP_BACKWARD(delta)

Decrements bytecode counter by delta. Checks for interrupts.

Nouveau dans la version 3.11.

JUMP_BACKWARD_NO_INTERRUPT(delta)

Decrements bytecode counter by delta. Does not check for interrupts.

Nouveau dans la version 3.11.

POP_JUMP_IF_TRUE(delta)

If STACK[-1] is true, increments the bytecode counter by delta. STACK[-1] is popped.

Modifié dans la 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).

Modifié dans la version 3.12: This is no longer a pseudo-instruction.

Modifié dans la version 3.13: This instruction now requires an exact bool operand.

POP_JUMP_IF_FALSE(delta)

If STACK[-1] is false, increments the bytecode counter by delta. STACK[-1] is popped.

Modifié dans la 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).

Modifié dans la version 3.12: This is no longer a pseudo-instruction.

Modifié dans la version 3.13: This instruction now requires an exact bool operand.

POP_JUMP_IF_NOT_NONE(delta)

If STACK[-1] is not None, increments the bytecode counter by delta. STACK[-1] is popped.

This opcode is a pseudo-instruction, replaced in final bytecode by the directed versions (forward/backward).

Nouveau dans la version 3.11.

Modifié dans la version 3.12: This is no longer a pseudo-instruction.

POP_JUMP_IF_NONE(delta)

If STACK[-1] is None, increments the bytecode counter by delta. STACK[-1] is popped.

This opcode is a pseudo-instruction, replaced in final bytecode by the directed versions (forward/backward).

Nouveau dans la version 3.11.

Modifié dans la version 3.12: This is no longer a pseudo-instruction.

FOR_ITER(delta)

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.

Modifié dans la version 3.12: Up until 3.11 the iterator was popped when it was exhausted.

LOAD_GLOBAL(namei)

Loads the global named co_names[namei>>1] onto the stack.

Modifié dans la version 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.

Modifié dans la version 3.12: This opcode is now only used in situations where the local variable is guaranteed to be initialized. It cannot raise UnboundLocalError.

LOAD_FAST_CHECK(var_num)

Pushes a reference to the local co_varnames[var_num] onto the stack, raising an UnboundLocalError if the local variable has not been initialized.

Nouveau dans la version 3.12.

LOAD_FAST_AND_CLEAR(var_num)

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.

Nouveau dans la version 3.12.

STORE_FAST(var_num)

Stores STACK.pop() 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.

Nouveau dans la version 3.11.

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.

Modifié dans la version 3.11: i is no longer offset by the length of co_varnames.

LOAD_FROM_DICT_OR_DEREF(i)

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 free variables in class bodies (which previously used LOAD_CLASSDEREF) and in annotation scopes within class bodies.

Nouveau dans la version 3.12.

STORE_DEREF(i)

Stores STACK.pop() into the cell contained in slot i of the "fast locals" storage.

Modifié dans la version 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.

Nouveau dans la version 3.2.

Modifié dans la version 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.

Nouveau dans la version 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 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])

CALL(argc)

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.

Nouveau dans la version 3.11.

Modifié dans la version 3.13: The callable now always appears at the same position on the stack.

Modifié dans la version 3.13: Calls with keyword arguments are now handled by CALL_KW.

CALL_KW(argc)

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.

Nouveau dans la version 3.13.

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.

Nouveau dans la version 3.6.

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.

Nouveau dans la version 3.11.

MAKE_FUNCTION

Pushes a new function object on the stack built from the code object at STACK[1].

Modifié dans la version 3.10: Flag value 0x04 is a tuple of strings instead of dictionary

Modifié dans la version 3.11: Qualified name at STACK[-1] was removed.

Modifié dans la version 3.13: Extra function attributes on the stack, signaled by oparg flags, were removed. They now use SET_FUNCTION_ATTRIBUTE.

SET_FUNCTION_ATTRIBUTE(flag)

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

Nouveau dans la version 3.13.

BUILD_SLICE(argc)

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, stop))

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.

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.

CONVERT_VALUE(oparg)

Convert value to a string, depending on oparg:

value = STACK.pop()
result = func(value)
STACK.append(result)

  • oparg == 1: call str() on value

  • oparg == 2: call repr() on value

  • oparg == 3: call ascii() on value

Used for implementing formatted literal strings (f-strings).

Nouveau dans la version 3.13.

FORMAT_SIMPLE

Formats the value on top of stack:

value = STACK.pop()
result = value.__format__("")
STACK.append(result)

Used for implementing formatted literal strings (f-strings).

Nouveau dans la version 3.13.

FORMAT_SPEC

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 literal strings (f-strings).

Nouveau dans la version 3.13.

MATCH_CLASS(count)

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.

Nouveau dans la version 3.10.

Modifié dans la version 3.11: Previously, this instruction also pushed a boolean value indicating success (True) or failure (False).

RESUME(context)

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

The context oparand 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.

Nouveau dans la version 3.11.

Modifié dans la version 3.13: The oparg value changed to include information about except-depth

RETURN_GENERATOR

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.

Nouveau dans la version 3.11.

SEND(delta)

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.

Nouveau dans la version 3.11.

HAVE_ARGUMENT

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.

Modifié dans la version 3.6: Now every instruction has an argument, but opcodes < HAVE_ARGUMENT ignore it. Before, only opcodes >= HAVE_ARGUMENT had an argument.

Modifié dans la 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.

Obsolète depuis la version 3.13: Use hasarg instead.

CALL_INTRINSIC_1

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

INTRINSIC_1_INVALID

Not valid

INTRINSIC_PRINT

Prints the argument to standard out. Used in the REPL.

INTRINSIC_IMPORT_STAR

Performs import * for the named module.

INTRINSIC_STOPITERATION_ERROR

Extracts the return value from a StopIteration exception.

INTRINSIC_ASYNC_GEN_WRAP

Wraps an aync generator value

INTRINSIC_UNARY_POSITIVE

Performs the unary + operation

INTRINSIC_LIST_TO_TUPLE

Converts a list to a tuple

INTRINSIC_TYPEVAR

Creates a typing.TypeVar

INTRINSIC_PARAMSPEC

Creates a typing.ParamSpec

INTRINSIC_TYPEVARTUPLE

Creates a typing.TypeVarTuple

INTRINSIC_SUBSCRIPT_GENERIC

Returns typing.Generic subscripted with the argument

INTRINSIC_TYPEALIAS

Creates a typing.TypeAliasType; used in the type statement. The argument is a tuple of the type alias's name, type parameters, and value.

Nouveau dans la version 3.12.

CALL_INTRINSIC_2

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

INTRINSIC_2_INVALID

Not valid

INTRINSIC_PREP_RERAISE_STAR

Calculates the ExceptionGroup to raise from a try-except*.

INTRINSIC_TYPEVAR_WITH_BOUND

Creates a typing.TypeVar with a bound.

INTRINSIC_TYPEVAR_WITH_CONSTRAINTS

Creates a typing.TypeVar with constraints.

INTRINSIC_SET_FUNCTION_TYPE_PARAMS

Sets the __type_params__ attribute of a function.

Nouveau dans la version 3.12.

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.

SETUP_FINALLY(target)

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.

SETUP_CLEANUP(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.

SETUP_WITH(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.

POP_BLOCK

Marks the end of the code block associated with the last SETUP_FINALLY, SETUP_CLEANUP or SETUP_WITH.

JUMP
JUMP_NO_INTERRUPT

Undirected relative jump instructions which are replaced by their directed (forward/backward) counterparts by the assembler.

LOAD_CLOSURE(i)

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.

Modifié dans la version 3.13: This opcode is now a pseudo-instruction.

LOAD_METHOD

Optimized unbound method lookup. Emitted as a LOAD_ATTR opcode with a flag set in the arg.

Opcode collections

These collections are provided for automatic introspection of bytecode instructions:

Modifié dans la 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.

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.hasarg

Sequence of bytecodes that use their argument.

Nouveau dans la version 3.12.

dis.hasconst

Sequence of bytecodes that access a constant.

dis.hasfree

Sequence of bytecodes that access a free 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.

dis.hasname

Sequence of bytecodes that access an attribute by name.

dis.hasjump

Sequence of bytecodes that have a jump target. All jumps are relative.

Nouveau dans la version 3.13.

dis.haslocal

Sequence of bytecodes that access a local variable.

dis.hascompare

Sequence of bytecodes of Boolean operations.

dis.hasexc

Sequence of bytecodes that set an exception handler.

Nouveau dans la version 3.12.

dis.hasjrel

Sequence of bytecodes that have a relative jump target.

Obsolète depuis la version 3.13: All jumps are now relative. Use hasjump.

dis.hasjabs

Sequence of bytecodes that have an absolute jump target.

Obsolète depuis la version 3.13: All jumps are now relative. This list is empty.