The Python compiler currently generates the following byte code
instructions.
STOP_CODE
Indicates end-of-code to the compiler, not used by the interpreter.
NOP
Do nothing code. Used as a placeholder by the bytecode optimizer.
POP_TOP
Removes the top-of-stack (TOS) item.
ROT_TWO
Swaps the two top-most stack items.
ROT_THREE
Lifts second and third stack item one position up, moves top down
to position three.
ROT_FOUR
Lifts second, third and forth stack item one position up, moves top down to
position four.
DUP_TOP
Duplicates the reference on top of the stack.
Unary Operations take the top of the stack, apply the operation, and
push the result back on the stack.
UNARY_POSITIVE
Implements TOS = +TOS.
UNARY_NEGATIVE
Implements TOS = -TOS.
UNARY_NOT
Implements TOS = not TOS.
UNARY_CONVERT
Implements TOS = `TOS`.
UNARY_INVERT
Implements TOS = ~TOS.
GET_ITER
Implements TOS = iter(TOS).
Binary operations remove the top of the stack (TOS) and the second top-most
stack item (TOS1) from the stack. They perform the operation, and put the
result back on the stack.
BINARY_POWER
Implements TOS = TOS1 ** TOS.
BINARY_MULTIPLY
Implements TOS = TOS1 * TOS.
BINARY_DIVIDE
Implements TOS = TOS1 / TOS when
from __future__ import division is not in effect.
BINARY_FLOOR_DIVIDE
Implements TOS = TOS1 // TOS.
BINARY_TRUE_DIVIDE
Implements TOS = TOS1 / TOS when
from __future__ import division is in effect.
BINARY_MODULO
Implements TOS = TOS1 % TOS.
BINARY_ADD
Implements TOS = TOS1 + TOS.
BINARY_SUBTRACT
Implements TOS = TOS1 - TOS.
BINARY_SUBSCR
Implements TOS = TOS1[TOS].
BINARY_LSHIFT
Implements TOS = TOS1 << TOS.
BINARY_RSHIFT
Implements TOS = TOS1 >> TOS.
BINARY_AND
Implements TOS = TOS1 & TOS.
BINARY_XOR
Implements TOS = TOS1 ^ TOS.
BINARY_OR
Implements TOS = TOS1 | TOS.
In-place operations are like binary operations, in that they remove TOS and
TOS1, and push the result back on the stack, but the operation is done
in-place when TOS1 supports it, and the resulting TOS may be (but does not
have to be) the original TOS1.
INPLACE_POWER
Implements in-place TOS = TOS1 ** TOS.
INPLACE_MULTIPLY
Implements in-place TOS = TOS1 * TOS.
INPLACE_DIVIDE
Implements in-place TOS = TOS1 / TOS when
from __future__ import division is not in effect.
INPLACE_FLOOR_DIVIDE
Implements in-place TOS = TOS1 // TOS.
INPLACE_TRUE_DIVIDE
Implements in-place TOS = TOS1 / TOS when
from __future__ import division is in effect.
INPLACE_MODULO
Implements in-place TOS = TOS1 % TOS.
INPLACE_ADD
Implements in-place TOS = TOS1 + TOS.
INPLACE_SUBTRACT
Implements in-place TOS = TOS1 - TOS.
INPLACE_LSHIFT
Implements in-place TOS = TOS1 << TOS.
INPLACE_RSHIFT
Implements in-place TOS = TOS1 >> TOS.
INPLACE_AND
Implements in-place TOS = TOS1 & TOS.
INPLACE_XOR
Implements in-place TOS = TOS1 ^ TOS.
INPLACE_OR
Implements in-place TOS = TOS1 | TOS.
The slice opcodes take up to three parameters.
SLICE+0
Implements TOS = TOS[:].
SLICE+1
Implements TOS = TOS1[TOS:].
SLICE+2
Implements TOS = TOS1[:TOS].
SLICE+3
Implements TOS = TOS2[TOS1:TOS].
Slice assignment needs even an additional parameter. As any statement,
they put nothing on the stack.
STORE_SLICE+0
Implements TOS[:] = TOS1.
STORE_SLICE+1
Implements TOS1[TOS:] = TOS2.
STORE_SLICE+2
Implements TOS1[:TOS] = TOS2.
STORE_SLICE+3
Implements TOS2[TOS1:TOS] = TOS3.
DELETE_SLICE+0
Implements del TOS[:].
DELETE_SLICE+1
Implements del TOS1[TOS:].
DELETE_SLICE+2
Implements del TOS1[:TOS].
DELETE_SLICE+3
Implements del TOS2[TOS1:TOS].
STORE_SUBSCR
Implements TOS1[TOS] = TOS2.
DELETE_SUBSCR
Implements del TOS1[TOS].
Miscellaneous opcodes.
PRINT_EXPR
Implements the expression statement for the interactive mode. TOS is
removed from the stack and printed. In non-interactive mode, an
expression statement is terminated with POP_STACK.
PRINT_ITEM
Prints TOS to the file-like object bound to sys.stdout. There
is one such instruction for each item in the print statement.
PRINT_ITEM_TO
Like PRINT_ITEM, but prints the item second from TOS to the
file-like object at TOS. This is used by the extended print statement.
PRINT_NEWLINE
Prints a new line on sys.stdout. This is generated as the
last operation of a print statement, unless the statement
ends with a comma.
PRINT_NEWLINE_TO
Like PRINT_NEWLINE, but prints the new line on the file-like
object on the TOS. This is used by the extended print statement.
BREAK_LOOP
Terminates a loop due to a break statement.
CONTINUE_LOOPtarget
Continues a loop due to a continue statement. target
is the address to jump to (which should be a FOR_ITER
instruction).
LIST_APPEND
Calls list.append(TOS1, TOS). Used to implement list comprehensions.
LOAD_LOCALS
Pushes a reference to the locals of the current scope on the stack.
This is used in the code for a class definition: After the class body
is evaluated, the locals are passed to the class definition.
RETURN_VALUE
Returns with TOS to the caller of the function.
YIELD_VALUE
Pops TOS and yields it from a generator.
IMPORT_STAR
Loads all symbols not starting with "_" directly from the module TOS
to the local namespace. The module is popped after loading all names.
This opcode implements from module import *.
EXEC_STMT
Implements exec TOS2,TOS1,TOS. The compiler fills
missing optional parameters with None.
POP_BLOCK
Removes one block from the block stack. Per frame, there is a
stack of blocks, denoting nested loops, try statements, and such.
END_FINALLY
Terminates a finally clause. The interpreter recalls
whether the exception has to be re-raised, or whether the function
returns, and continues with the outer-next block.
BUILD_CLASS
Creates a new class object. TOS is the methods dictionary, TOS1
the tuple of the names of the base classes, and TOS2 the class name.
All of the following opcodes expect arguments. An argument is two
bytes, with the more significant byte last.
STORE_NAMEnamei
Implements name = TOS. namei is the index of name
in the attribute co_names of the code object.
The compiler tries to use STORE_LOCAL or STORE_GLOBAL
if possible.
DELETE_NAMEnamei
Implements del name, where namei is the index into
co_names attribute of the code object.
UNPACK_SEQUENCEcount
Unpacks TOS into count individual values, which are put onto
the stack right-to-left.
DUP_TOPXcount
Duplicate count items, keeping them in the same order. Due to
implementation limits, count should be between 1 and 5 inclusive.
STORE_ATTRnamei
Implements TOS.name = TOS1, where namei is the index
of name in co_names.
DELETE_ATTRnamei
Implements del TOS.name, using namei as index into
co_names.
STORE_GLOBALnamei
Works as STORE_NAME, but stores the name as a global.
DELETE_GLOBALnamei
Works as DELETE_NAME, but deletes a global name.
LOAD_CONSTconsti
Pushes "co_consts[consti]" onto the stack.
LOAD_NAMEnamei
Pushes the value associated with "co_names[namei]" onto the stack.
BUILD_TUPLEcount
Creates a tuple consuming count items from the stack, and pushes
the resulting tuple onto the stack.
BUILD_LISTcount
Works as BUILD_TUPLE, but creates a list.
BUILD_MAPzero
Pushes a new empty dictionary object onto the stack. The argument is
ignored and set to zero by the compiler.
LOAD_ATTRnamei
Replaces TOS with getattr(TOS, co_names[namei]).
COMPARE_OPopname
Performs a Boolean operation. The operation name can be found
in cmp_op[opname].
IMPORT_NAMEnamei
Imports the module co_names[namei]. 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_FROMnamei
Loads the attribute co_names[namei] from the module found in
TOS. The resulting object is pushed onto the stack, to be subsequently
stored by a STORE_FAST instruction.
JUMP_FORWARDdelta
Increments byte code counter by delta.
JUMP_IF_TRUEdelta
If TOS is true, increment the byte code counter by delta. TOS is
left on the stack.
JUMP_IF_FALSEdelta
If TOS is false, increment the byte code counter by delta. TOS
is not changed.
JUMP_ABSOLUTEtarget
Set byte code counter to target.
FOR_ITERdelta
TOS is an iterator. Call its next() method. If this
yields a new value, push it on the stack (leaving the iterator below
it). If the iterator indicates it is exhausted TOS is
popped, and the byte code counter is incremented by delta.
LOAD_GLOBALnamei
Loads the global named co_names[namei] onto the stack.
SETUP_LOOPdelta
Pushes a block for a loop onto the block stack. The block spans
from the current instruction with a size of delta bytes.
SETUP_EXCEPTdelta
Pushes a try block from a try-except clause onto the block stack.
delta points to the first except block.
SETUP_FINALLYdelta
Pushes a try block from a try-except clause onto the block stack.
delta points to the finally block.
LOAD_FASTvar_num
Pushes a reference to the local co_varnames[var_num] onto
the stack.
STORE_FASTvar_num
Stores TOS into the local co_varnames[var_num].
DELETE_FASTvar_num
Deletes local co_varnames[var_num].
LOAD_CLOSUREi
Pushes a reference to the cell contained in slot i of the
cell and free variable storage. The name of the variable is
co_cellvars[i] if i is less than the length of
co_cellvars. Otherwise it is
co_freevars[i - len(co_cellvars)].
LOAD_DEREFi
Loads the cell contained in slot i of the cell and free variable
storage. Pushes a reference to the object the cell contains on the
stack.
STORE_DEREFi
Stores TOS into the cell contained in slot i of the cell and
free variable storage.
SET_LINENOlineno
This opcode is obsolete.
RAISE_VARARGSargc
Raises an exception. argc indicates the number of parameters
to the raise statement, ranging from 0 to 3. The handler will find
the traceback as TOS2, the parameter as TOS1, and the exception
as TOS.
CALL_FUNCTIONargc
Calls a function. The low byte of argc indicates the number of
positional parameters, the high byte the number of keyword parameters.
On the stack, the opcode finds the keyword parameters first. For each
keyword argument, the value is on top of the key. Below the keyword
parameters, the positional parameters are on the stack, with the
right-most parameter on top. Below the parameters, the function object
to call is on the stack.
MAKE_FUNCTIONargc
Pushes a new function object on the stack. TOS is the code associated
with the function. The function object is defined to have argc
default parameters, which are found below TOS.
MAKE_CLOSUREargc
Creates a new function object, sets its func_closure slot, and
pushes it on the stack. TOS is the code associated with the function.
If the code object has N free variables, the next N items on the stack
are the cells for these variables. The function also has argc
default parameters, where are found before the cells.
BUILD_SLICEargc
Pushes a slice object on the stack. argc must be 2 or 3. If it
is 2, slice(TOS1, TOS) is pushed; if it is 3,
slice(TOS2, TOS1, TOS) is pushed.
See the slice() built-in function for more
information.
EXTENDED_ARGext
Prefixes any opcode which has an argument too big to fit into the
default two bytes. ext holds two additional bytes which, taken
together with the subsequent opcode's argument, comprise a four-byte
argument, ext being the two most-significant bytes.
CALL_FUNCTION_VARargc
Calls a function. argc is interpreted as in CALL_FUNCTION.
The top element on the stack contains the variable argument list, followed
by keyword and positional arguments.
CALL_FUNCTION_KWargc
Calls a function. argc is interpreted as in CALL_FUNCTION.
The top element on the stack contains the keyword arguments dictionary,
followed by explicit keyword and positional arguments.
CALL_FUNCTION_VAR_KWargc
Calls a function. argc is interpreted as in
CALL_FUNCTION. The top element on the stack contains the
keyword arguments dictionary, followed by the variable-arguments
tuple, followed by explicit keyword and positional arguments.
HAVE_ARGUMENT
This is not really an opcode. It identifies the dividing line between
opcodes which don't take arguments < HAVE_ARGUMENT and those which do
>= HAVE_ARGUMENT.