"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.

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)
                12 LOAD_FAST                0 (alist)
                14 CALL                     1
                22 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] [infile]

The following options are accepted:

-h, --help

   Display usage and exit.

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
=================

New 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.

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()".

   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.

Example:

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

   New in version 3.2.

   Changed in version 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.

   New in version 3.2.

   Changed in version 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. 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.

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.

   Changed in version 3.4: Added *file* parameter.

   Changed in version 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:

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

   2. the current instruction, indicated as "-->",

   3. a labelled instruction, indicated with ">>",

   4. the address of the instruction,

   5. the operation code name,

   6. operation parameters, and

   7. 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.

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()".

   New in version 3.4.

   Changed in version 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.

   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.

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.

   New in version 3.4.

   Changed in version 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.

   New in version 3.4.

   Changed in version 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

   New 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.

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 two values from the stack. Equivalent to "POP_TOP";
   "POP_TOP". Used to clean up at the end of loops, hence the name.

   New in version 3.12.

END_SEND

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

   New in 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])

   New in version 3.11.

SWAP(i)

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

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

   New in 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.

   New 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.

UNARY_NEGATIVE

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

UNARY_NOT

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

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])".

   New in version 3.5.

**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)

   New in 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])

   New in version 3.12.

STORE_SLICE

   Implements:

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

   New in 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__"

   New in version 3.5.

   Changed in version 3.11: Previously, this instruction did not have
   an oparg.

GET_AITER

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

   New in version 3.5.

   Changed in 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".

   New in 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.

   New in version 3.8.

   Changed in 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]".

   New in 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__())

   New in 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.

   New 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.

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.

   New in version 3.12.

YIELD_VALUE

   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.

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.

   New in version 3.6.

POP_EXCEPT

   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.

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.

   New in version 3.9.

   Changed in 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.

   New in 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.

   New in 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".

   New in 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.

   New 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.

LOAD_ASSERTION_ERROR

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

   New in 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.

   New in version 3.11.

GET_LEN

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

   New in 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".

   New in 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".

   New in 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".

   New in version 3.10.

   Changed in 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".

   New in 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.

   New in 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]}".

   Changed in 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.

   New in version 3.6.

BUILD_STRING(count)

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

   New in version 3.6.

LIST_EXTEND(i)

   Implements:

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

   Used to build lists.

   New in version 3.9.

SET_UPDATE(i)

   Implements:

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

   Used to build sets.

   New in version 3.9.

DICT_UPDATE(i)

   Implements:

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

   Used to build dicts.

   New in version 3.9.

DICT_MERGE(i)

   Like "DICT_UPDATE" but raises an exception for duplicate keys.

   New in 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" 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.

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 "None" 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).

   New in version 3.12.

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.

   New in version 3.9.

CONTAINS_OP(invert)

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

   New in 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.

   New in version 3.11.

JUMP_BACKWARD_NO_INTERRUPT(delta)

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

   New in version 3.11.

POP_JUMP_IF_TRUE(delta)

   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.

POP_JUMP_IF_FALSE(delta)

   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.

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).

   New in version 3.11.

   Changed in 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).

   New in version 3.11.

   Changed in 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*.

   Changed in 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.

   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.

LOAD_FAST(var_num)

   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".

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.

   New in 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".

   New in 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.

   New in version 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.

   Changed in version 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.

   Changed in 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.

   New in version 3.12.

STORE_DEREF(i)

   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".

DELETE_DEREF(i)

   Empties the cell contained in slot "i" of the “fast locals”
   storage. Used by the "del" statement.

   New in version 3.2.

   Changed in 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.

   New in 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", 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.

   New in version 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.

   New in 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.

   New in version 3.11.

KW_NAMES(consti)

   Prefixes "CALL". Stores a reference to "co_consts[consti]" into an
   internal variable for use by "CALL". "co_consts[consti]" must be a
   tuple of strings.

   New in version 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 "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.

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.

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.

   New in version 3.6.

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".

   New in version 3.10.

   Changed in version 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, 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

   New in version 3.11.

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.

   New in 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*.

   New in 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, 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.

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.                              |
   +-------------------------------------+-------------------------------------+

   New in 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.push(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.            |
   +------------------------------------------+-------------------------------------+

   New in 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_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:

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".

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.

   New in 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.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.hasexc

   Sequence of bytecodes that set an exception handler.

   New in version 3.12.
