cpython/Include/code.h

/* Definitions for bytecode */

#ifndef Py_LIMITED_API
#ifndef Py_CODE_H
#define Py_CODE_H
#ifdef __cplusplus
extern "C" {
#endif

typedef uint16_t _Py_CODEUNIT;

#ifdef WORDS_BIGENDIAN
#  define _Py_OPCODE(word) ((word) >> 8)
#  define _Py_OPARG(word) ((word) & 255)
#else
#  define _Py_OPCODE(word) ((word) & 255)
#  define _Py_OPARG(word) ((word) >> 8)
#endif

typedef struct _PyOpcache _PyOpcache;

/* Bytecode object */
typedef struct {
    PyObject_HEAD
    int co_argcount;            /* #arguments, except *args */
    int co_posonlyargcount;     /* #positional only arguments */
    int co_kwonlyargcount;      /* #keyword only arguments */
    int co_nlocals;             /* #local variables */
    int co_stacksize;           /* #entries needed for evaluation stack */
    int co_flags;               /* CO_..., see below */
    int co_firstlineno;         /* first source line number */
    PyObject *co_code;          /* instruction opcodes */
    PyObject *co_consts;        /* list (constants used) */
    PyObject *co_names;         /* list of strings (names used) */
    PyObject *co_varnames;      /* tuple of strings (local variable names) */
    PyObject *co_freevars;      /* tuple of strings (free variable names) */
    PyObject *co_cellvars;      /* tuple of strings (cell variable names) */
    /* The rest aren't used in either hash or comparisons, except for co_name,
       used in both. This is done to preserve the name and line number
       for tracebacks and debuggers; otherwise, constant de-duplication
       would collapse identical functions/lambdas defined on different lines.
    */
    Py_ssize_t *co_cell2arg;    /* Maps cell vars which are arguments. */
    PyObject *co_filename;      /* unicode (where it was loaded from) */
    PyObject *co_name;          /* unicode (name, for reference) */
    PyObject *co_lnotab;        /* string (encoding addr<->lineno mapping) See
                                   Objects/lnotab_notes.txt for details. */
    void *co_zombieframe;       /* for optimization only (see frameobject.c) */
    PyObject *co_weakreflist;   /* to support weakrefs to code objects */
    /* Scratch space for extra data relating to the code object.
       Type is a void* to keep the format private in codeobject.c to force
       people to go through the proper APIs. */
    void *co_extra;

    /* Per opcodes just-in-time cache
     *
     * To reduce cache size, we use indirect mapping from opcode index to
     * cache object:
     *   cache = co_opcache[co_opcache_map[next_instr - first_instr] - 1]
     */

    // co_opcache_map is indexed by (next_instr - first_instr).
    //  * 0 means there is no cache for this opcode.
    //  * n > 0 means there is cache in co_opcache[n-1].
    unsigned char *co_opcache_map;
    _PyOpcache *co_opcache;
    int co_opcache_flag;  // used to determine when create a cache.
    unsigned char co_opcache_size;  // length of co_opcache.
} PyCodeObject;

/* Masks for co_flags above */
#define CO_OPTIMIZED    0x0001
#define CO_NEWLOCALS    0x0002
#define CO_VARARGS      0x0004
#define CO_VARKEYWORDS  0x0008
#define CO_NESTED       0x0010
#define CO_GENERATOR    0x0020
/* The CO_NOFREE flag is set if there are no free or cell variables.
   This information is redundant, but it allows a single flag test
   to determine whether there is any extra work to be done when the
   call frame it setup.
*/
#define CO_NOFREE       0x0040

/* The CO_COROUTINE flag is set for coroutine functions (defined with
   ``async def`` keywords) */
#define CO_COROUTINE            0x0080
#define CO_ITERABLE_COROUTINE   0x0100
#define CO_ASYNC_GENERATOR      0x0200

/* bpo-39562: These constant values are changed in Python 3.9
   to prevent collision with compiler flags. CO_FUTURE_ and PyCF_
   constants must be kept unique. PyCF_ constants can use bits from
   0x0100 to 0x10000. CO_FUTURE_ constants use bits starting at 0x20000. */
#define CO_FUTURE_DIVISION      0x20000
#define CO_FUTURE_ABSOLUTE_IMPORT 0x40000 /* do absolute imports by default */
#define CO_FUTURE_WITH_STATEMENT  0x80000
#define CO_FUTURE_PRINT_FUNCTION  0x100000
#define CO_FUTURE_UNICODE_LITERALS 0x200000

#define CO_FUTURE_BARRY_AS_BDFL  0x400000
#define CO_FUTURE_GENERATOR_STOP  0x800000
#define CO_FUTURE_ANNOTATIONS    0x1000000

/* This value is found in the co_cell2arg array when the associated cell
   variable does not correspond to an argument. */
#define CO_CELL_NOT_AN_ARG (-1)

/* This should be defined if a future statement modifies the syntax.
   For example, when a keyword is added.
*/
#define PY_PARSER_REQUIRES_FUTURE_KEYWORD

#define CO_MAXBLOCKS 20 /* Max static block nesting within a function */

PyAPI_DATA(PyTypeObject) PyCode_Type;

#define PyCode_Check(op) Py_IS_TYPE(op, &PyCode_Type)
#define PyCode_GetNumFree(op) (PyTuple_GET_SIZE((op)->co_freevars))

/* Public interface */
PyAPI_FUNC(PyCodeObject *) PyCode_New(
        int, int, int, int, int, PyObject *, PyObject *,
        PyObject *, PyObject *, PyObject *, PyObject *,
        PyObject *, PyObject *, int, PyObject *);

PyAPI_FUNC(PyCodeObject *) PyCode_NewWithPosOnlyArgs(
        int, int, int, int, int, int, PyObject *, PyObject *,
        PyObject *, PyObject *, PyObject *, PyObject *,
        PyObject *, PyObject *, int, PyObject *);
        /* same as struct above */

/* Creates a new empty code object with the specified source location. */
PyAPI_FUNC(PyCodeObject *)
PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno);

/* Return the line number associated with the specified bytecode index
   in this code object.  If you just need the line number of a frame,
   use PyFrame_GetLineNumber() instead. */
PyAPI_FUNC(int) PyCode_Addr2Line(PyCodeObject *, int);

/* for internal use only */
typedef struct _addr_pair {
        int ap_lower;
        int ap_upper;
} PyAddrPair;

#ifndef Py_LIMITED_API
/* Update *bounds to describe the first and one-past-the-last instructions in the
   same line as lasti.  Return the number of that line.
*/
PyAPI_FUNC(int) _PyCode_CheckLineNumber(PyCodeObject* co,
                                        int lasti, PyAddrPair *bounds);

/* Create a comparable key used to compare constants taking in account the
 * object type. It is used to make sure types are not coerced (e.g., float and
 * complex) _and_ to distinguish 0.0 from -0.0 e.g. on IEEE platforms
 *
 * Return (type(obj), obj, ...): a tuple with variable size (at least 2 items)
 * depending on the type and the value. The type is the first item to not
 * compare bytes and str which can raise a BytesWarning exception. */
PyAPI_FUNC(PyObject*) _PyCode_ConstantKey(PyObject *obj);
#endif

PyAPI_FUNC(PyObject*) PyCode_Optimize(PyObject *code, PyObject* consts,
                                      PyObject *names, PyObject *lnotab);


#ifndef Py_LIMITED_API
PyAPI_FUNC(int) _PyCode_GetExtra(PyObject *code, Py_ssize_t index,
                                 void **extra);
PyAPI_FUNC(int) _PyCode_SetExtra(PyObject *code, Py_ssize_t index,
                                 void *extra);
#endif

#ifdef __cplusplus
}
#endif
#endif /* !Py_CODE_H */
#endif /* Py_LIMITED_API */