Command-line interface¶

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

python-mdis[-h][-C][infile]

The following options are accepted:

-h,--help¶

Display usage and exit.

-C,--show-caches¶

Show inline caches.

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

Bytecode analysis¶

The bytecode analysis API allows pieces of Python code to be wrapped in aBytecode object that provides easy access to details of the compiledcode.

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

Analyse the bytecode corresponding to a function, generator, asynchronousgenerator, coroutine, method, string of source code, or a code object (asreturned bycompile()).

This is a convenience wrapper around many of the functions listed below, mostnotablyget_instructions(), as iterating over aBytecodeinstance yields the bytecode operations asInstruction instances.

Iffirst_line is notNone, it indicates the line number that should bereported for the first source line in the disassembled code. Otherwise, thesource line information (if any) is taken directly from the disassembled codeobject.

Ifcurrent_offset is notNone, it refers to an instruction offset in thedisassembled code. Setting this meansdis() will display a “currentinstruction” marker against the specified opcode.

Ifshow_caches isTrue,dis() will display inline cacheentries used by the interpreter to specialize the bytecode.

Ifadaptive isTrue,dis() will display specialized bytecodethat may be different from the original bytecode.

classmethodfrom_traceback(tb,*,show_caches=False)¶

Construct aBytecode instance from the given traceback, settingcurrent_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 bydis.dis(), but returned as a multi-line string).

info()¶

Return a formatted multi-line string with detailed information about thecode object, likecode_info().

Changed in version 3.7:This can now handle coroutine and asynchronous generator objects.

Changed in version 3.11:Added theshow_caches andadaptive parameters.

Example:

>>>bytecode=dis.Bytecode(myfunc)>>>forinstrinbytecode:...print(instr.opname)...RESUMELOAD_GLOBALLOAD_FASTPRECALLCALLRETURN_VALUE

Analysis functions¶

Thedis module also defines the following analysis functions that convertthe input directly to the desired output. They can be useful if only a singleoperation 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 informationfor 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 implementationdependent and they may change arbitrarily across Python VMs or Pythonreleases.

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 tofile (orsys.stdout iffileis not specified).

This is a convenient shorthand forprint(code_info(x),file=file),intended for interactive exploration at the interpreter prompt.

New in version 3.2.

Changed in version 3.4:Addedfile parameter.

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

Disassemble thex object.x can denote either a module, a class, amethod, 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 disassemblesall methods (including class and static methods). For a code object orsequence of raw bytecode, it prints one line per bytecode instruction.It also recursively disassembles nested code objects (the code ofcomprehensions, generator expressions and nested functions, and the codeused for building nested classes).Strings are first compiled to code objects with thecompile()built-in function before being disassembled. If no object is provided, thisfunction disassembles the last traceback.

The disassembly is written as text to the suppliedfile argument ifprovided and tosys.stdout otherwise.

The maximal depth of recursion is limited bydepth unless it isNone.depth=0 means no recursion.

Ifshow_caches isTrue, this function will display inline cacheentries used by the interpreter to specialize the bytecode.

Ifadaptive isTrue, this function will display specialized bytecodethat may be different from the original bytecode.

Changed in version 3.4:Addedfile parameter.

Changed in version 3.7:Implemented recursive disassembling and addeddepth parameter.

Changed in version 3.7:This can now handle coroutine and asynchronous generator objects.

Changed in version 3.11:Added theshow_caches andadaptive parameters.

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

Disassemble the top-of-stack function of a traceback, using the lasttraceback if none was passed. The instruction causing the exception isindicated.

The disassembly is written as text to the suppliedfile argument ifprovided and tosys.stdout otherwise.

Changed in version 3.4:Addedfile parameter.

Changed in version 3.11:Added theshow_caches andadaptive 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 iflasti wasprovided. 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 suppliedfile argument ifprovided and tosys.stdout otherwise.

Changed in version 3.4:Addedfile parameter.

Changed in version 3.11:Added theshow_caches andadaptive 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 ofInstruction named tuples givingthe details of each operation in the supplied code.

Iffirst_line is notNone, it indicates the line number that should bereported for the first source line in the disassembled code. Otherwise, thesource line information (if any) is taken directly from the disassembled codeobject.

Theshow_caches andadaptive parameters work as they do indis().

New in version 3.4.

Changed in version 3.11:Added theshow_caches andadaptive parameters.

dis.findlinestarts(code)¶

This generator function uses theco_lines() methodof thecode objectcode to find the offsets whichare starts oflines 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:ThePEP 626co_lines() method is used instead of theco_firstlineno andco_lnotabattributes of thecode object.

dis.findlabels(code)¶

Detect all offsets in the raw compiled bytecode stringcode which are jump targets, andreturn a list of these offsets.

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

Compute the stack effect ofopcode with argumentoparg.

If the code has a jump target andjump isTrue,stack_effect()will return the stack effect of jumping. Ifjump isFalse,it will return the stack effect of not jumping. And ifjump isNone (default), it will return the maximal stack effect of both cases.

New in version 3.4.

Changed in version 3.8:Addedjump parameter.

Python Bytecode Instructions¶

Theget_instructions() function andBytecode class providedetails of bytecode instructions asInstruction instances:

classdis.Instruction¶

Details for a bytecode operation

opcode¶

numeric code for operation, corresponding to the opcode values listedbelow and the bytecode values in theOpcode collections.

opname¶

human readable name for operation

arg¶

numeric argument to operation (if any), otherwiseNone

argval¶

resolved arg value (if any), otherwiseNone

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), otherwiseNone

is_jump_target¶

True if other code jumps to here, otherwiseFalse

positions¶

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

New in version 3.4.

Changed in version 3.11:Fieldpositions is added.

classdis.Positions¶

In case the information is not available, some fields might beNone.

lineno¶

end_lineno¶

col_offset¶

end_col_offset¶

New in version 3.11.

The Python compiler currently generates the following bytecode instructions.

General instructions

NOP¶

Do nothing code. Used as a placeholder by the bytecode optimizer, and togenerate line tracing events.

POP_TOP¶

Removes the top-of-stack (TOS) item.

COPY(i)¶

Push thei-th item to the top of the stack. The item is not removed from itsoriginal location.

New in version 3.11.

SWAP(i)¶

Swap TOS with the item at positioni.

New in version 3.11.

CACHE¶

Rather than being an actual instruction, this opcode is used to mark extraspace for the interpreter to cache useful data directly in the bytecodeitself. It is automatically hidden by alldis utilities, but can beviewed withshow_caches=True.

Logically, this space is part of the preceding instruction. Many opcodesexpect to be followed by an exact number of caches, and will instruct theinterpreter to skip over them at runtime.

Populated caches can look like arbitrary instructions, so great care shouldbe taken when reading or modifying raw, adaptive bytecode containingquickened data.

New in version 3.11.

Unary operations

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

UNARY_POSITIVE¶

ImplementsTOS=+TOS.

UNARY_NEGATIVE¶

ImplementsTOS=-TOS.

UNARY_NOT¶

ImplementsTOS=notTOS.

UNARY_INVERT¶

ImplementsTOS=~TOS.

GET_ITER¶

ImplementsTOS=iter(TOS).

GET_YIELD_FROM_ITER¶

IfTOS is agenerator iterator orcoroutine objectit is left as is. Otherwise, implementsTOS=iter(TOS).

New in version 3.5.

Binary and in-place operations

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

In-place operations are like binary operations, in that they remove TOS andTOS1, and push the result back on the stack, but the operation is done in-placewhen TOS1 supports it, and the resulting TOS may be (but does not have to be)the original TOS1.

BINARY_OP(op)¶

Implements the binary and in-place operators (depending on the value ofop).

New in version 3.11.

BINARY_SUBSCR¶

ImplementsTOS=TOS1[TOS].

STORE_SUBSCR¶

ImplementsTOS1[TOS]=TOS2.

DELETE_SUBSCR¶

ImplementsdelTOS1[TOS].

Coroutine opcodes

GET_AWAITABLE(where)¶

ImplementsTOS=get_awaitable(TOS), whereget_awaitable(o)returnso ifo is a coroutine object or a generator object withthe CO_ITERABLE_COROUTINE flag, or resolveso.__await__.

If thewhere operand is nonzero, it indicates where the instructionoccurs:

• 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¶

ImplementsTOS=TOS.__aiter__().

New in version 3.5.

Changed in version 3.7:Returning awaitable objects from__aiter__ is no longersupported.

GET_ANEXT¶

Pushesget_awaitable(TOS.__anext__()) to the stack. SeeGET_AWAITABLE for details aboutget_awaitable.

New in version 3.5.

END_ASYNC_FOR¶

Terminates anasyncfor loop. Handles an exception raisedwhen awaiting a next item. The stack contains the async iterable inTOS1 and the raised exception in TOS. Both are popped.If the exception is notStopAsyncIteration, 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.

BEFORE_ASYNC_WITH¶

Resolves__aenter__ and__aexit__ from the object on top of thestack. Pushes__aexit__ and result of__aenter__() to the stack.

New in version 3.5.

Miscellaneous opcodes

PRINT_EXPR¶

Implements the expression statement for the interactive mode. TOS is removedfrom the stack and printed. In non-interactive mode, an expression statementis terminated withPOP_TOP.

SET_ADD(i)¶

Callsset.add(TOS1[-i],TOS). Used to implement set comprehensions.

LIST_APPEND(i)¶

Callslist.append(TOS1[-i],TOS). Used to implement list comprehensions.

MAP_ADD(i)¶

Callsdict.__setitem__(TOS1[-i],TOS1,TOS). Used to implement dictcomprehensions.

New in version 3.1.

Changed in version 3.8:Map value is TOS and map key is TOS1. Before, those were reversed.

For all of theSET_ADD,LIST_APPEND andMAP_ADDinstructions, while the added value or key/value pair is popped off, thecontainer object remains on the stack so that it is available for furtheriterations of the loop.

RETURN_VALUE¶

Returns with TOS to the caller of the function.

YIELD_VALUE¶

Pops TOS and yields it from agenerator.

SETUP_ANNOTATIONS¶

Checks whether__annotations__ is defined inlocals(), if not it isset up to an emptydict. This opcode is only emitted if a classor module body containsvariable annotationsstatically.

New in version 3.6.

IMPORT_STAR¶

Loads all symbols not starting with'_' directly from the module TOS tothe local namespace. The module is popped after loading all names. Thisopcode implementsfrommoduleimport*.

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 setf_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 forexcept. Tests whether the TOS1 is an exceptionmatching TOS. Pops TOS and pushes the boolean result of the test.

New in version 3.11.

CHECK_EG_MATCH¶

Performs exception matching forexcept*. Appliessplit(TOS) onthe exception group representing TOS1.

In case of a match, pops two items from the stack and pushes thenon-matching subgroup (None in case of full match) followed by thematching subgroup. When there is no match, pops one item (the matchtype) and pushesNone.

New in version 3.11.

PREP_RERAISE_STAR¶

Combines the raised and reraised exceptions list from TOS, into an exceptiongroup to propagate from a try-except* block. Uses the original exceptiongroup from TOS1 to reconstruct the structure of reraised exceptions. Popstwo items from the stack and pushes the exception to reraise orNoneif there isn’t one.

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 callcontext_manager.__exit__(*exc_info()) when an exceptionhas occurred in awith 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¶

PushesAssertionError onto the stack. Used by theassertstatement.

New in version 3.9.

LOAD_BUILD_CLASS¶

Pushesbuiltins.__build_class__() onto the stack. It is later calledto construct a class.

BEFORE_WITH(delta)¶

This opcode performs several operations before a with block starts. First,it loads__exit__() from the context manager and pushes it ontothe stack for later use byWITH_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¶

Pushlen(TOS) onto the stack.

New in version 3.10.

MATCH_MAPPING¶

If TOS is an instance ofcollections.abc.Mapping (or, more technically: ifit has thePy_TPFLAGS_MAPPING flag set in itstp_flags), pushTrue onto the stack. Otherwise, pushFalse.

New in version 3.10.

MATCH_SEQUENCE¶

If TOS is an instance ofcollections.abc.Sequence and isnot an instanceofstr/bytes/bytearray (or, more technically: if it hasthePy_TPFLAGS_SEQUENCE flag set in itstp_flags),pushTrue onto the stack. Otherwise, pushFalse.

New in version 3.10.

MATCH_KEYS¶

TOS is a tuple of mapping keys, and TOS1 is the match subject. If TOS1contains all of the keys in TOS, push atuple containing thecorresponding values. Otherwise, pushNone.

New in version 3.10.

Changed in version 3.11:Previously, this instruction also pushed a boolean value indicatingsuccess (True) or failure (False).

STORE_NAME(namei)¶

Implementsname=TOS.namei is the index ofname in the attributeco_names of thecode object.The compiler tries to useSTORE_FAST orSTORE_GLOBAL if possible.

DELETE_NAME(namei)¶

Implementsdelname, wherenamei is the index intoco_namesattribute of thecode object.

UNPACK_SEQUENCE(count)¶

Unpacks TOS intocount individual values, which are put onto the stackright-to-left.

UNPACK_EX(counts)¶

Implements assignment with a starred target: Unpacks an iterable in TOS intoindividual values, where the total number of values can be smaller than thenumber of items in the iterable: one of the new values will be a list of allleftover items.

The low byte ofcounts is the number of values before the list value, thehigh byte ofcounts the number of values after it. The resulting valuesare put onto the stack right-to-left.

STORE_ATTR(namei)¶

ImplementsTOS.name=TOS1, wherenamei is the index of name inco_names.

DELETE_ATTR(namei)¶

ImplementsdelTOS.name, usingnamei as index intoco_names of thecode object.

STORE_GLOBAL(namei)¶

Works asSTORE_NAME, but stores the name as a global.

DELETE_GLOBAL(namei)¶

Works asDELETE_NAME, but deletes a global name.

LOAD_CONST(consti)¶

Pushesco_consts[consti] onto the stack.

LOAD_NAME(namei)¶

Pushes the value associated withco_names[namei] onto the stack.

BUILD_TUPLE(count)¶

Creates a tuple consumingcount items from the stack, and pushes theresulting tuple onto the stack.

BUILD_LIST(count)¶

Works asBUILD_TUPLE, but creates a list.

BUILD_SET(count)¶

Works asBUILD_TUPLE, but creates a set.

BUILD_MAP(count)¶

Pushes a new dictionary object onto the stack. Pops2*count itemsso that the dictionary holdscount entries:{...,TOS3:TOS2,TOS1:TOS}.

Changed in version 3.5:The dictionary is created from stack items instead of creating anempty dictionary pre-sized to holdcount items.

BUILD_CONST_KEY_MAP(count)¶

The version ofBUILD_MAP specialized for constant keys. Pops thetop element on the stack which contains a tuple of keys, then starting fromTOS1, popscount values to form values in the built dictionary.

New in version 3.6.

BUILD_STRING(count)¶

Concatenatescount strings from the stack and pushes the resulting stringonto the stack.

New in version 3.6.

LIST_TO_TUPLE¶

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

New in version 3.9.

LIST_EXTEND(i)¶

Callslist.extend(TOS1[-i],TOS). Used to build lists.

New in version 3.9.

SET_UPDATE(i)¶

Callsset.update(TOS1[-i],TOS). Used to build sets.

New in version 3.9.

DICT_UPDATE(i)¶

Callsdict.update(TOS1[-i],TOS). Used to build dicts.

New in version 3.9.

DICT_MERGE(i)¶

LikeDICT_UPDATE but raises an exception for duplicate keys.

New in version 3.9.

LOAD_ATTR(namei)¶

Replaces TOS withgetattr(TOS,co_names[namei]).

COMPARE_OP(opname)¶

Performs a Boolean operation. The operation name can be found incmp_op[opname].

IS_OP(invert)¶

Performsis comparison, orisnot ifinvert is 1.

New in version 3.9.

CONTAINS_OP(invert)¶

Performsin comparison, ornotin ifinvert is 1.

New in version 3.9.

IMPORT_NAME(namei)¶

Imports the moduleco_names[namei]. TOS and TOS1 are popped and providethefromlist andlevel arguments of__import__(). The moduleobject is pushed onto the stack. The current namespace is not affected: fora proper import statement, a subsequentSTORE_FAST instructionmodifies the namespace.

IMPORT_FROM(namei)¶

Loads the attributeco_names[namei] from the module found in TOS. Theresulting object is pushed onto the stack, to be subsequently stored by aSTORE_FAST instruction.

JUMP_FORWARD(delta)¶

Increments bytecode counter bydelta.

JUMP_BACKWARD(delta)¶

Decrements bytecode counter bydelta. Checks for interrupts.

New in version 3.11.

JUMP_BACKWARD_NO_INTERRUPT(delta)¶

Decrements bytecode counter bydelta. Does not check for interrupts.

New in version 3.11.

POP_JUMP_FORWARD_IF_TRUE(delta)¶

If TOS is true, increments the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_BACKWARD_IF_TRUE(delta)¶

If TOS is true, decrements the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_FORWARD_IF_FALSE(delta)¶

If TOS is false, increments the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_BACKWARD_IF_FALSE(delta)¶

If TOS is false, decrements the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_FORWARD_IF_NOT_NONE(delta)¶

If TOS is notNone, increments the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_BACKWARD_IF_NOT_NONE(delta)¶

If TOS is notNone, decrements the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_FORWARD_IF_NONE(delta)¶

If TOS isNone, increments the bytecode counter bydelta. TOS is popped.

New in version 3.11.

POP_JUMP_BACKWARD_IF_NONE(delta)¶

If TOS isNone, decrements the bytecode counter bydelta. TOS is popped.

New in version 3.11.

JUMP_IF_TRUE_OR_POP(delta)¶

If TOS is true, increments the bytecode counter bydelta and leaves TOS on thestack. Otherwise (TOS is false), TOS is popped.

New in version 3.1.

Changed in version 3.11:The oparg is now a relative delta rather than an absolute target.

JUMP_IF_FALSE_OR_POP(delta)¶

If TOS is false, increments the bytecode counter bydelta and leaves TOS on thestack. Otherwise (TOS is true), TOS is popped.

New in version 3.1.

Changed in version 3.11:The oparg is now a relative delta rather than an absolute target.

FOR_ITER(delta)¶

TOS is aniterator. Call its__next__() method. Ifthis yields a new value, push it on the stack (leaving the iterator belowit). If the iterator indicates it is exhausted, TOS is popped, and the bytecode counter is incremented bydelta.

LOAD_GLOBAL(namei)¶

Loads the global namedco_names[namei>>1] onto the stack.

Changed in version 3.11:If the low bit ofnamei is set, then aNULL is pushed to thestack before the global variable.

LOAD_FAST(var_num)¶

Pushes a reference to the localco_varnames[var_num] onto the stack.

STORE_FAST(var_num)¶

Stores TOS into the localco_varnames[var_num].

DELETE_FAST(var_num)¶

Deletes localco_varnames[var_num].

MAKE_CELL(i)¶

Creates a new cell in sloti. If that slot is nonempty thenthat value is stored into the new cell.

New in version 3.11.

LOAD_CLOSURE(i)¶

Pushes a reference to the cell contained in sloti of the “fast locals”storage. The name of the variable isco_fastlocalnames[i].

Note thatLOAD_CLOSURE is effectively an alias forLOAD_FAST.It exists to keep bytecode a little more readable.

Changed in version 3.11:i is no longer offset by the length ofco_varnames.

LOAD_DEREF(i)¶

Loads the cell contained in sloti 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 ofco_varnames.

LOAD_CLASSDEREF(i)¶

Much likeLOAD_DEREF but first checks the locals dictionary beforeconsulting the cell. This is used for loading free variables in classbodies.

New in version 3.4.

Changed in version 3.11:i is no longer offset by the length ofco_varnames.

STORE_DEREF(i)¶

Stores TOS into the cell contained in sloti of the “fast locals”storage.

Changed in version 3.11:i is no longer offset by the length ofco_varnames.

DELETE_DEREF(i)¶

Empties the cell contained in sloti of the “fast locals” storage.Used by thedel statement.

New in version 3.2.

Changed in version 3.11:i is no longer offset by the length ofco_varnames.

COPY_FREE_VARS(n)¶

Copies then free variables from the closure into the frame.Removes the need for special code on the caller’s side when callingclosures.

New in version 3.11.

RAISE_VARARGS(argc)¶

Raises an exception using one of the 3 forms of theraise statement,depending on the value ofargc:

• 0:raise (re-raise previous exception)

• 1:raiseTOS (raise exception instance or type atTOS)

• 2:raiseTOS1fromTOS (raise exception instance or type atTOS1with__cause__ set toTOS)

CALL(argc)¶

Calls a callable object with the number of arguments specified byargc,including the named arguments specified by the precedingKW_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, excludingself when aNULL 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 valuereturned by the callable object.

New in version 3.11.

CALL_FUNCTION_EX(flags)¶

Calls a callable object with variable set of positional and keywordarguments. If the lowest bit offlags is set, the top of the stackcontains a mapping object containing additional keyword arguments.Before the callable is called, the mapping object and iterable objectare each “unpacked” and their contents passed in as keyword andpositional 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 valuereturned by the callable object.

New in version 3.6.

LOAD_METHOD(namei)¶

Loads a method namedco_names[namei] from the TOS object. TOS is popped.This bytecode distinguishes two cases: if TOS has a method with the correctname, the bytecode pushes the unbound method and TOS. TOS will be used asthe first argument (self) byCALL when calling theunbound method. Otherwise,NULL and the object return by the attributelookup are pushed.

New in version 3.7.

PRECALL(argc)¶

PrefixesCALL. Logically this is a no op.It exists to enable effective specialization of calls.argc is the number of arguments as described inCALL.

New in version 3.11.

PUSH_NULL¶

Pushes aNULL to the stack.Used in the call sequence to match theNULL pushed byLOAD_METHOD for non-method calls.

New in version 3.11.

KW_NAMES(i)¶

PrefixesPRECALL.Stores a reference toco_consts[consti] into an internal variablefor use byCALL.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 consumedstack must consist of values if the argument carries a specified flag value

• 0x01 a tuple of default values for positional-only andpositional-or-keyword parameters in positional order

• 0x02 a dictionary of keyword-only parameters’ default values

• 0x04 a tuple of strings containing parameters’ annotations

• 0x08 a tuple containing cells for free variables, making a closure

• the code associated with the function (at TOS)

Changed in version 3.10:Flag value0x04 is a tuple of strings instead of dictionary

Changed in version 3.11:Qualified name at TOS was removed.

BUILD_SLICE(argc)¶

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

EXTENDED_ARG(ext)¶

Prefixes any opcode which has an argument too big to fit into the default onebyte.ext holds an additional byte which act as higher bits in the argument.For each opcode, at most three prefixalEXTENDED_ARG are allowed, formingan argument from two-byte to four-byte.

FORMAT_VALUE(flags)¶

Used for implementing formatted literal strings (f-strings). Popsan optionalfmt_spec from the stack, then a requiredvalue.flags is interpreted as follows:

• (flags&0x03)==0x00:value is formatted as-is.

• (flags&0x03)==0x01: callstr() onvalue beforeformatting it.

• (flags&0x03)==0x02: callrepr() onvalue beforeformatting it.

• (flags&0x03)==0x03: callascii() onvalue beforeformatting it.

• (flags&0x04)==0x04: popfmt_spec from the stack and useit, else use an emptyfmt_spec.

Formatting is performed usingPyObject_Format(). Theresult is pushed on the stack.

New in version 3.6.

MATCH_CLASS(count)¶

TOS is a tuple of keyword attribute names, TOS1 is the class being matchedagainst, and TOS2 is the match subject.count is the number of positionalsub-patterns.

Pop TOS, TOS1, and TOS2. If TOS2 is an instance of TOS1 and has thepositional and keyword attributes required bycount and TOS, push a tupleof extracted attributes. Otherwise, pushNone.

New in version 3.10.

Changed in version 3.11:Previously, this instruction also pushed a boolean value indicatingsuccess (True) or failure (False).

RESUME(where)¶

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

Thewhere operand marks where theRESUME occurs:

• 0 The start of a function

• 1 After ayield expression

• 2 After ayieldfrom expression

• 3 After anawait expression

New in version 3.11.

RETURN_GENERATOR¶

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

New in version 3.11.

SEND¶

SendsNone to the sub-generator of this generator.Used inyieldfrom andawait statements.

New in version 3.11.

ASYNC_GEN_WRAP¶

Wraps the value on top of the stack in anasync_generator_wrapped_value.Used to yield in async generators.

New in version 3.11.

HAVE_ARGUMENT¶

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

Changed in version 3.6:Now every instruction has an argument, but opcodes<HAVE_ARGUMENTignore it. Before, only opcodes>=HAVE_ARGUMENT had an argument.

Opcode collections¶

These collections are provided for automatic introspection of bytecodeinstructions:

dis.opname¶

Sequence of operation names, indexable using the bytecode.

dis.opmap¶

Dictionary mapping operation names to bytecodes.

dis.cmp_op¶

Sequence of all compare operation names.

dis.hasconst¶

Sequence of bytecodes that access a constant.

dis.hasfree¶

Sequence of bytecodes that access a free variable (note that ‘free’ in thiscontext refers to names in the current scope that are referenced by innerscopes or names in outer scopes that are referenced from this scope. It doesnot 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.