#include <stdbool.h>

#include "Python.h"

#include "opcode.h"

#include "structmember.h" // PyMemberDef

#include "pycore_code.h" // _PyCodeConstructor

#include "pycore_frame.h" // FRAME_SPECIALS_SIZE

#include "pycore_interp.h" // PyInterpreterState.co_extra_freefuncs

#include "pycore_opcode.h" // _PyOpcode_Deopt

#include "pycore_pystate.h" // _PyInterpreterState_GET()

#include "pycore_tuple.h" // _PyTuple_ITEMS()

#include "clinic/codeobject.c.h"

static int

all_name_chars(PyObject *o)

{

const unsigned char *s, *e;

if (!PyUnicode_IS_ASCII(o))

return 0;

s = PyUnicode_1BYTE_DATA(o);

e = s + PyUnicode_GET_LENGTH(o);

for (; s != e; s++) {

if (!Py_ISALNUM(*s) && *s != '_')

return 0;

}

return 1;

}

static int

intern_strings(PyObject *tuple)

{

Py_ssize_t i;

for (i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {

PyObject *v = PyTuple_GET_ITEM(tuple, i);

if (v == NULL || !PyUnicode_CheckExact(v)) {

PyErr_SetString(PyExc_SystemError,

"non-string found in code slot");

return -1;

}

PyUnicode_InternInPlace(&_PyTuple_ITEMS(tuple)[i]);

}

return 0;

}

static int

intern_string_constants(PyObject *tuple, int *modified)

{

for (Py_ssize_t i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {

PyObject *v = PyTuple_GET_ITEM(tuple, i);

if (PyUnicode_CheckExact(v)) {

if (PyUnicode_READY(v) == -1) {

return -1;

}

if (all_name_chars(v)) {

PyObject *w = v;

PyUnicode_InternInPlace(&v);

if (w != v) {

PyTuple_SET_ITEM(tuple, i, v);

if (modified) {

*modified = 1;

}

}

}

}

else if (PyTuple_CheckExact(v)) {

if (intern_string_constants(v, NULL) < 0) {

return -1;

}

}

else if (PyFrozenSet_CheckExact(v)) {

PyObject *w = v;

PyObject *tmp = PySequence_Tuple(v);

if (tmp == NULL) {

return -1;

}

int tmp_modified = 0;

if (intern_string_constants(tmp, &tmp_modified) < 0) {

Py_DECREF(tmp);

return -1;

}

if (tmp_modified) {

v = PyFrozenSet_New(tmp);

if (v == NULL) {

Py_DECREF(tmp);

return -1;

}

PyTuple_SET_ITEM(tuple, i, v);

Py_DECREF(w);

if (modified) {

*modified = 1;

}

}

Py_DECREF(tmp);

}

}

return 0;

}

static PyObject*

validate_and_copy_tuple(PyObject *tup)

{

PyObject *newtuple;

PyObject *item;

Py_ssize_t i, len;

len = PyTuple_GET_SIZE(tup);

newtuple = PyTuple_New(len);

if (newtuple == NULL)

return NULL;

for (i = 0; i < len; i++) {

item = PyTuple_GET_ITEM(tup, i);

if (PyUnicode_CheckExact(item)) {

Py_INCREF(item);

}

else if (!PyUnicode_Check(item)) {

PyErr_Format(

PyExc_TypeError,

"name tuples must contain only "

"strings, not '%.500s'",

Py_TYPE(item)->tp_name);

Py_DECREF(newtuple);

return NULL;

}

else {

item = _PyUnicode_Copy(item);

if (item == NULL) {

Py_DECREF(newtuple);

return NULL;

}

}

PyTuple_SET_ITEM(newtuple, i, item);

}

return newtuple;

}

static int

init_co_cached(PyCodeObject *self) {

if (self->_co_cached == NULL) {

self->_co_cached = PyMem_New(_PyCoCached, 1);

if (self->_co_cached == NULL) {

PyErr_NoMemory();

return -1;

}

self->_co_cached->_co_code = NULL;

self->_co_cached->_co_cellvars = NULL;

self->_co_cached->_co_freevars = NULL;

self->_co_cached->_co_varnames = NULL;

}

return 0;

}

_Py_set_localsplus_info(int offset, PyObject *name, _PyLocals_Kind kind,

PyObject *names, PyObject *kinds)

{

Py_INCREF(name);

PyTuple_SET_ITEM(names, offset, name);

_PyLocals_SetKind(kinds, offset, kind);

}

static void

get_localsplus_counts(PyObject *names, PyObject *kinds,

int *pnlocals, int *pnplaincellvars, int *pncellvars,

int *pnfreevars)

{

int nlocals = 0;

int nplaincellvars = 0;

int ncellvars = 0;

int nfreevars = 0;

Py_ssize_t nlocalsplus = PyTuple_GET_SIZE(names);

for (int i = 0; i < nlocalsplus; i++) {

_PyLocals_Kind kind = _PyLocals_GetKind(kinds, i);

if (kind & CO_FAST_LOCAL) {

nlocals += 1;

if (kind & CO_FAST_CELL) {

ncellvars += 1;

}

}

else if (kind & CO_FAST_CELL) {

ncellvars += 1;

nplaincellvars += 1;

}

else if (kind & CO_FAST_FREE) {

nfreevars += 1;

}

}

if (pnlocals != NULL) {

*pnlocals = nlocals;

}

if (pnplaincellvars != NULL) {

*pnplaincellvars = nplaincellvars;

}

if (pncellvars != NULL) {

*pncellvars = ncellvars;

}

if (pnfreevars != NULL) {

*pnfreevars = nfreevars;

}

}

static PyObject *

get_localsplus_names(PyCodeObject *co, _PyLocals_Kind kind, int num)

{

PyObject *names = PyTuple_New(num);

if (names == NULL) {

return NULL;

}

int index = 0;

for (int offset = 0; offset < co->co_nlocalsplus; offset++) {

_PyLocals_Kind k = _PyLocals_GetKind(co->co_localspluskinds, offset);

if ((k & kind) == 0) {

continue;

}

assert(index < num);

PyObject *name = PyTuple_GET_ITEM(co->co_localsplusnames, offset);

Py_INCREF(name);

PyTuple_SET_ITEM(names, index, name);

index += 1;

}

assert(index == num);

return names;

}

_PyCode_Validate(struct _PyCodeConstructor *con)

{

/* Check argument types */

if (con->argcount < con->posonlyargcount || con->posonlyargcount < 0 ||

con->kwonlyargcount < 0 ||

con->stacksize < 0 || con->flags < 0 ||

con->code == NULL || !PyBytes_Check(con->code) ||

con->consts == NULL || !PyTuple_Check(con->consts) ||

con->names == NULL || !PyTuple_Check(con->names) ||

con->localsplusnames == NULL || !PyTuple_Check(con->localsplusnames) ||

con->localspluskinds == NULL || !PyBytes_Check(con->localspluskinds) ||

PyTuple_GET_SIZE(con->localsplusnames)

!= PyBytes_GET_SIZE(con->localspluskinds) ||

con->name == NULL || !PyUnicode_Check(con->name) ||

con->qualname == NULL || !PyUnicode_Check(con->qualname) ||

con->filename == NULL || !PyUnicode_Check(con->filename) ||

con->linetable == NULL || !PyBytes_Check(con->linetable) ||

con->exceptiontable == NULL || !PyBytes_Check(con->exceptiontable)

) {

PyErr_BadInternalCall();

return -1;

}

/* Make sure that code is indexable with an int, this is

if (PyBytes_GET_SIZE(con->code) > INT_MAX) {

PyErr_SetString(PyExc_OverflowError,

"code: co_code larger than INT_MAX");

return -1;

}

if (PyBytes_GET_SIZE(con->code) % sizeof(_Py_CODEUNIT) != 0 ||

!_Py_IS_ALIGNED(PyBytes_AS_STRING(con->code), sizeof(_Py_CODEUNIT))

) {

PyErr_SetString(PyExc_ValueError, "code: co_code is malformed");

return -1;

}

/* Ensure that the co_varnames has enough names to cover the arg counts.

int nlocals;

get_localsplus_counts(con->localsplusnames, con->localspluskinds,

&nlocals, NULL, NULL, NULL);

int nplainlocals = nlocals -

con->argcount -

con->kwonlyargcount -

((con->flags & CO_VARARGS) != 0) -

((con->flags & CO_VARKEYWORDS) != 0);

if (nplainlocals < 0) {

PyErr_SetString(PyExc_ValueError, "code: co_varnames is too small");

return -1;

}

return 0;

}

static void

init_code(PyCodeObject *co, struct _PyCodeConstructor *con)

{

int nlocalsplus = (int)PyTuple_GET_SIZE(con->localsplusnames);

int nlocals, nplaincellvars, ncellvars, nfreevars;

get_localsplus_counts(con->localsplusnames, con->localspluskinds,

&nlocals, &nplaincellvars, &ncellvars, &nfreevars);

Py_INCREF(con->filename);

co->co_filename = con->filename;

Py_INCREF(con->name);

co->co_name = con->name;

Py_INCREF(con->qualname);

co->co_qualname = con->qualname;

co->co_flags = con->flags;

co->co_firstlineno = con->firstlineno;

Py_INCREF(con->linetable);

co->co_linetable = con->linetable;

Py_INCREF(con->consts);

co->co_consts = con->consts;

Py_INCREF(con->names);

co->co_names = con->names;

Py_INCREF(con->localsplusnames);

co->co_localsplusnames = con->localsplusnames;

Py_INCREF(con->localspluskinds);

co->co_localspluskinds = con->localspluskinds;

co->co_argcount = con->argcount;

co->co_posonlyargcount = con->posonlyargcount;

co->co_kwonlyargcount = con->kwonlyargcount;

co->co_stacksize = con->stacksize;

Py_INCREF(con->exceptiontable);

co->co_exceptiontable = con->exceptiontable;

/* derived values */

co->co_nlocalsplus = nlocalsplus;

co->co_nlocals = nlocals;

co->co_framesize = nlocalsplus + con->stacksize + FRAME_SPECIALS_SIZE;

co->co_nplaincellvars = nplaincellvars;

co->co_ncellvars = ncellvars;

co->co_nfreevars = nfreevars;

/* not set */

co->co_weakreflist = NULL;

co->co_extra = NULL;

co->_co_cached = NULL;

co->co_warmup = QUICKENING_INITIAL_WARMUP_VALUE;

co->_co_linearray_entry_size = 0;

co->_co_linearray = NULL;

memcpy(_PyCode_CODE(co), PyBytes_AS_STRING(con->code),

PyBytes_GET_SIZE(con->code));

int entry_point = 0;

while (entry_point < Py_SIZE(co) &&

_Py_OPCODE(_PyCode_CODE(co)[entry_point]) != RESUME) {

entry_point++;

}

co->_co_firsttraceable = entry_point;

}

static int

scan_varint(const uint8_t *ptr)

{

unsigned int read = *ptr++;

unsigned int val = read & 63;

unsigned int shift = 0;

while (read & 64) {

read = *ptr++;

shift += 6;

val |= (read & 63) << shift;

}

return val;

}

static int

scan_signed_varint(const uint8_t *ptr)

{

unsigned int uval = scan_varint(ptr);

if (uval & 1) {

return -(int)(uval >> 1);

}

else {

return uval >> 1;

}

}

static int

get_line_delta(const uint8_t *ptr)

{

int code = ((*ptr) >> 3) & 15;

switch (code) {

case PY_CODE_LOCATION_INFO_NONE:

return 0;

case PY_CODE_LOCATION_INFO_NO_COLUMNS:

case PY_CODE_LOCATION_INFO_LONG:

return scan_signed_varint(ptr+1);

case PY_CODE_LOCATION_INFO_ONE_LINE0:

return 0;

case PY_CODE_LOCATION_INFO_ONE_LINE1:

return 1;

case PY_CODE_LOCATION_INFO_ONE_LINE2:

return 2;

default:

/* Same line */

return 0;

}

}

static PyObject *

remove_column_info(PyObject *locations)

{

int offset = 0;

const uint8_t *data = (const uint8_t *)PyBytes_AS_STRING(locations);

PyObject *res = PyBytes_FromStringAndSize(NULL, 32);

if (res == NULL) {

PyErr_NoMemory();

return NULL;

}

uint8_t *output = (uint8_t *)PyBytes_AS_STRING(res);

while (offset < PyBytes_GET_SIZE(locations)) {

Py_ssize_t write_offset = output - (uint8_t *)PyBytes_AS_STRING(res);

if (write_offset + 16 >= PyBytes_GET_SIZE(res)) {

if (_PyBytes_Resize(&res, PyBytes_GET_SIZE(res) * 2) < 0) {

return NULL;

}

output = (uint8_t *)PyBytes_AS_STRING(res) + write_offset;

}

int code = (data[offset] >> 3) & 15;

if (code == PY_CODE_LOCATION_INFO_NONE) {

*output++ = data[offset];

}

else {

int blength = (data[offset] & 7)+1;

output += write_location_entry_start(

output, PY_CODE_LOCATION_INFO_NO_COLUMNS, blength);

int ldelta = get_line_delta(&data[offset]);

output += write_signed_varint(output, ldelta);

}

offset++;

while (offset < PyBytes_GET_SIZE(locations) &&

(data[offset] & 128) == 0) {

offset++;

}

}

Py_ssize_t write_offset = output - (uint8_t *)PyBytes_AS_STRING(res);

if (_PyBytes_Resize(&res, write_offset)) {

return NULL;

}

return res;

}

PyCodeObject *

_PyCode_New(struct _PyCodeConstructor *con)

{

/* Ensure that strings are ready Unicode string */

if (PyUnicode_READY(con->name) < 0) {

return NULL;

}

if (PyUnicode_READY(con->qualname) < 0) {

return NULL;

}

if (PyUnicode_READY(con->filename) < 0) {

return NULL;

}

if (intern_strings(con->names) < 0) {

return NULL;

}

if (intern_string_constants(con->consts, NULL) < 0) {

return NULL;

}

if (intern_strings(con->localsplusnames) < 0) {

return NULL;

}

PyObject *replacement_locations = NULL;

// Compact the linetable if we are opted out of debug

// ranges.

if (!_Py_GetConfig()->code_debug_ranges) {

replacement_locations = remove_column_info(con->linetable);

if (replacement_locations == NULL) {

return NULL;

}

con->linetable = replacement_locations;

}

Py_ssize_t size = PyBytes_GET_SIZE(con->code) / sizeof(_Py_CODEUNIT);

PyCodeObject *co = PyObject_NewVar(PyCodeObject, &PyCode_Type, size);

if (co == NULL) {

Py_XDECREF(replacement_locations);

PyErr_NoMemory();

return NULL;

}

init_code(co, con);

Py_XDECREF(replacement_locations);

return co;

}

PyCodeObject *

PyCode_NewWithPosOnlyArgs(int argcount, int posonlyargcount, int kwonlyargcount,

PyObject *exceptiontable)

{

PyCodeObject *co = NULL;

PyObject *localsplusnames = NULL;

PyObject *localspluskinds = NULL;

if (varnames == NULL || !PyTuple_Check(varnames) ||

cellvars == NULL || !PyTuple_Check(cellvars) ||

freevars == NULL || !PyTuple_Check(freevars)

) {

PyErr_BadInternalCall();

return NULL;

}

// Set the "fast locals plus" info.

int nvarnames = (int)PyTuple_GET_SIZE(varnames);

int ncellvars = (int)PyTuple_GET_SIZE(cellvars);

int nfreevars = (int)PyTuple_GET_SIZE(freevars);

int nlocalsplus = nvarnames + ncellvars + nfreevars;

localsplusnames = PyTuple_New(nlocalsplus);

if (localsplusnames == NULL) {

goto error;

}

localspluskinds = PyBytes_FromStringAndSize(NULL, nlocalsplus);

if (localspluskinds == NULL) {

goto error;

}

int offset = 0;

for (int i = 0; i < nvarnames; i++, offset++) {

PyObject *name = PyTuple_GET_ITEM(varnames, i);

_Py_set_localsplus_info(offset, name, CO_FAST_LOCAL,

localsplusnames, localspluskinds);

}

for (int i = 0; i < ncellvars; i++, offset++) {

PyObject *name = PyTuple_GET_ITEM(cellvars, i);

int argoffset = -1;

for (int j = 0; j < nvarnames; j++) {

int cmp = PyUnicode_Compare(PyTuple_GET_ITEM(varnames, j),

name);

assert(!PyErr_Occurred());

if (cmp == 0) {

argoffset = j;

break;

}

}

if (argoffset >= 0) {

// Merge the localsplus indices.

nlocalsplus -= 1;

offset -= 1;

_PyLocals_Kind kind = _PyLocals_GetKind(localspluskinds, argoffset);

_PyLocals_SetKind(localspluskinds, argoffset, kind | CO_FAST_CELL);

continue;

}

_Py_set_localsplus_info(offset, name, CO_FAST_CELL,

localsplusnames, localspluskinds);

}

for (int i = 0; i < nfreevars; i++, offset++) {

PyObject *name = PyTuple_GET_ITEM(freevars, i);

_Py_set_localsplus_info(offset, name, CO_FAST_FREE,

localsplusnames, localspluskinds);

}

// If any cells were args then nlocalsplus will have shrunk.

if (nlocalsplus != PyTuple_GET_SIZE(localsplusnames)) {

if (_PyTuple_Resize(&localsplusnames, nlocalsplus) < 0

|| _PyBytes_Resize(&localspluskinds, nlocalsplus) < 0) {

goto error;

}

}

struct _PyCodeConstructor con = {

.filename = filename,

.name = name,

.qualname = qualname,

.flags = flags,

.code = code,

.firstlineno = firstlineno,

.linetable = linetable,

.consts = consts,

.names = names,

.localsplusnames = localsplusnames,

.localspluskinds = localspluskinds,

.argcount = argcount,

.posonlyargcount = posonlyargcount,

.kwonlyargcount = kwonlyargcount,

.stacksize = stacksize,

.exceptiontable = exceptiontable,

};

if (_PyCode_Validate(&con) < 0) {

goto error;

}

assert(PyBytes_GET_SIZE(code) % sizeof(_Py_CODEUNIT) == 0);

assert(_Py_IS_ALIGNED(PyBytes_AS_STRING(code), sizeof(_Py_CODEUNIT)));

if (nlocals != PyTuple_GET_SIZE(varnames)) {

PyErr_SetString(PyExc_ValueError,

"code: co_nlocals != len(co_varnames)");

goto error;

}

co = _PyCode_New(&con);

if (co == NULL) {

goto error;

}

error:

Py_XDECREF(localsplusnames);

Py_XDECREF(localspluskinds);

return co;

}

PyCodeObject *

PyCode_New(int argcount, int kwonlyargcount,

PyObject *exceptiontable)

{

return PyCode_NewWithPosOnlyArgs(argcount, 0, kwonlyargcount, nlocals,

stacksize, flags, code, consts, names,

varnames, freevars, cellvars, filename,

name, qualname, firstlineno,

linetable,

exceptiontable);

}

static const uint8_t assert0[6] = {

RESUME, 0,

LOAD_ASSERTION_ERROR, 0,

RAISE_VARARGS, 1

};

static const uint8_t linetable[2] = {

(1 << 7) // New entry.

| (PY_CODE_LOCATION_INFO_NO_COLUMNS << 3)

| (3 - 1), // Three code units.

0, // Offset from co_firstlineno.

};

PyCodeObject *

PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno)

{

PyObject *nulltuple = NULL;

PyObject *filename_ob = NULL;

PyObject *funcname_ob = NULL;

PyObject *code_ob = NULL;

PyObject *linetable_ob = NULL;

PyCodeObject *result = NULL;

nulltuple = PyTuple_New(0);

if (nulltuple == NULL) {

goto failed;

}

funcname_ob = PyUnicode_FromString(funcname);

if (funcname_ob == NULL) {

goto failed;

}

filename_ob = PyUnicode_DecodeFSDefault(filename);

if (filename_ob == NULL) {

goto failed;

}

code_ob = PyBytes_FromStringAndSize((const char *)assert0, 6);

if (code_ob == NULL) {

goto failed;

}

linetable_ob = PyBytes_FromStringAndSize((const char *)linetable, 2);

if (linetable_ob == NULL) {

goto failed;

}

#define emptystring (PyObject *)&_Py_SINGLETON(bytes_empty)

struct _PyCodeConstructor con = {

.filename = filename_ob,

.name = funcname_ob,

.qualname = funcname_ob,

.code = code_ob,

.firstlineno = firstlineno,

.linetable = linetable_ob,

.consts = nulltuple,

.names = nulltuple,

.localsplusnames = nulltuple,

.localspluskinds = emptystring,

.exceptiontable = emptystring,

.stacksize = 1,

};

result = _PyCode_New(&con);

failed:

Py_XDECREF(nulltuple);

Py_XDECREF(funcname_ob);

Py_XDECREF(filename_ob);

Py_XDECREF(code_ob);

Py_XDECREF(linetable_ob);

return result;

}

_PyCode_CreateLineArray(PyCodeObject *co)

{

assert(co->_co_linearray == NULL);

PyCodeAddressRange bounds;

int size;

int max_line = 0;

_PyCode_InitAddressRange(co, &bounds);

while(_PyLineTable_NextAddressRange(&bounds)) {

if (bounds.ar_line > max_line) {

max_line = bounds.ar_line;

}

}

if (max_line < (1 << 15)) {

size = 2;

}

else {

size = 4;

}

co->_co_linearray = PyMem_Malloc(Py_SIZE(co)*size);

if (co->_co_linearray == NULL) {

PyErr_NoMemory();

return -1;

}

co->_co_linearray_entry_size = size;

_PyCode_InitAddressRange(co, &bounds);

while(_PyLineTable_NextAddressRange(&bounds)) {

int start = bounds.ar_start / sizeof(_Py_CODEUNIT);

int end = bounds.ar_end / sizeof(_Py_CODEUNIT);

for (int index = start; index < end; index++) {

assert(index < (int)Py_SIZE(co));

if (size == 2) {

assert(((int16_t)bounds.ar_line) == bounds.ar_line);

((int16_t *)co->_co_linearray)[index] = bounds.ar_line;

}

else {

assert(size == 4);

((int32_t *)co->_co_linearray)[index] = bounds.ar_line;

}

}

}

return 0;

}

PyCode_Addr2Line(PyCodeObject *co, int addrq)

{

if (addrq < 0) {

return co->co_firstlineno;

}

assert(addrq >= 0 && addrq < _PyCode_NBYTES(co));

if (co->_co_linearray) {

return _PyCode_LineNumberFromArray(co, addrq / sizeof(_Py_CODEUNIT));

}

PyCodeAddressRange bounds;

_PyCode_InitAddressRange(co, &bounds);

return _PyCode_CheckLineNumber(addrq, &bounds);

}

_PyLineTable_InitAddressRange(const char *linetable, Py_ssize_t length, int firstlineno, PyCodeAddressRange *range)

{

range->opaque.lo_next = (const uint8_t *)linetable;

range->opaque.limit = range->opaque.lo_next + length;

range->ar_start = -1;

range->ar_end = 0;

range->opaque.computed_line = firstlineno;

range->ar_line = -1;

}

_PyCode_InitAddressRange(PyCodeObject* co, PyCodeAddressRange *bounds)

{

assert(co->co_linetable != NULL);

const char *linetable = PyBytes_AS_STRING(co->co_linetable);

Py_ssize_t length = PyBytes_GET_SIZE(co->co_linetable);

_PyLineTable_InitAddressRange(linetable, length, co->co_firstlineno, bounds);

return bounds->ar_line;

}

_PyCode_CheckLineNumber(int lasti, PyCodeAddressRange *bounds)

{

while (bounds->ar_end <= lasti) {

if (!_PyLineTable_NextAddressRange(bounds)) {

return -1;

}

}

while (bounds->ar_start > lasti) {

if (!_PyLineTable_PreviousAddressRange(bounds)) {

return -1;

}

}

return bounds->ar_line;

}

static int

is_no_line_marker(uint8_t b)

{

return (b >> 3) == 0x1f;

}

#define ASSERT_VALID_BOUNDS(bounds) \

assert(bounds->opaque.lo_next <= bounds->opaque.limit && \

(bounds->ar_line == -1 || bounds->ar_line == bounds->opaque.computed_line) && \

(bounds->opaque.lo_next == bounds->opaque.limit || \

(*bounds->opaque.lo_next) & 128))

static int

next_code_delta(PyCodeAddressRange *bounds)

{

assert((*bounds->opaque.lo_next) & 128);

return (((*bounds->opaque.lo_next) & 7) + 1) * sizeof(_Py_CODEUNIT);

}

static int

previous_code_delta(PyCodeAddressRange *bounds)

{

if (bounds->ar_start == 0) {

// If we looking at the first entry, the

// "previous" entry has an implicit length of 1.

return 1;

}

const uint8_t *ptr = bounds->opaque.lo_next-1;

while (((*ptr) & 128) == 0) {

ptr--;

}

return (((*ptr) & 7) + 1) * sizeof(_Py_CODEUNIT);

}

static int

read_byte(PyCodeAddressRange *bounds)

{

return *bounds->opaque.lo_next++;

}

static int

read_varint(PyCodeAddressRange *bounds)

{

unsigned int read = read_byte(bounds);

unsigned int val = read & 63;

unsigned int shift = 0;

while (read & 64) {

read = read_byte(bounds);

shift += 6;

val |= (read & 63) << shift;

}

return val;

}

static int

read_signed_varint(PyCodeAddressRange *bounds)

{

unsigned int uval = read_varint(bounds);

if (uval & 1) {

return -(int)(uval >> 1);

}

else {

return uval >> 1;

}

}

static void

retreat(PyCodeAddressRange *bounds)

{

ASSERT_VALID_BOUNDS(bounds);

assert(bounds->ar_start >= 0);

do {

bounds->opaque.lo_next--;

} while (((*bounds->opaque.lo_next) & 128) == 0);

bounds->opaque.computed_line -= get_line_delta(bounds->opaque.lo_next);

bounds->ar_end = bounds->ar_start;

bounds->ar_start -= previous_code_delta(bounds);

if (is_no_line_marker(bounds->opaque.lo_next[-1])) {

bounds->ar_line = -1;

}

else {

bounds->ar_line = bounds->opaque.computed_line;

}

ASSERT_VALID_BOUNDS(bounds);

}

static void

advance(PyCodeAddressRange *bounds)

{

ASSERT_VALID_BOUNDS(bounds);

bounds->opaque.computed_line += get_line_delta(bounds->opaque.lo_next);

if (is_no_line_marker(*bounds->opaque.lo_next)) {

bounds->ar_line = -1;

}

else {

bounds->ar_line = bounds->opaque.computed_line;

}

bounds->ar_start = bounds->ar_end;

bounds->ar_end += next_code_delta(bounds);

do {

bounds->opaque.lo_next++;

} while (bounds->opaque.lo_next < bounds->opaque.limit &&

((*bounds->opaque.lo_next) & 128) == 0);

ASSERT_VALID_BOUNDS(bounds);

}

static void

advance_with_locations(PyCodeAddressRange *bounds, int *endline, int *column, int *endcolumn)

{

ASSERT_VALID_BOUNDS(bounds);

int first_byte = read_byte(bounds);

int code = (first_byte >> 3) & 15;

bounds->ar_start = bounds->ar_end;

bounds->ar_end = bounds->ar_start + ((first_byte & 7) + 1) * sizeof(_Py_CODEUNIT);

switch(code) {

case PY_CODE_LOCATION_INFO_NONE:

bounds->ar_line = *endline = -1;

*column = *endcolumn = -1;

break;

case PY_CODE_LOCATION_INFO_LONG:

{

bounds->opaque.computed_line += read_signed_varint(bounds);

bounds->ar_line = bounds->opaque.computed_line;

*endline = bounds->ar_line + read_varint(bounds);

*column = read_varint(bounds)-1;

*endcolumn = read_varint(bounds)-1;

break;

}

case PY_CODE_LOCATION_INFO_NO_COLUMNS:

{

/* No column */

bounds->opaque.computed_line += read_signed_varint(bounds);

*endline = bounds->ar_line = bounds->opaque.computed_line;

*column = *endcolumn = -1;

break;

}

case PY_CODE_LOCATION_INFO_ONE_LINE0:

case PY_CODE_LOCATION_INFO_ONE_LINE1:

case PY_CODE_LOCATION_INFO_ONE_LINE2:

{

/* one line form */

int line_delta = code - 10;

bounds->opaque.computed_line += line_delta;

*endline = bounds->ar_line = bounds->opaque.computed_line;

*column = read_byte(bounds);

*endcolumn = read_byte(bounds);

break;

}

default:

{

/* Short forms */

int second_byte = read_byte(bounds);

assert((second_byte & 128) == 0);

*endline = bounds->ar_line = bounds->opaque.computed_line;

*column = code << 3 | (second_byte >> 4);

*endcolumn = *column + (second_byte & 15);

}

}

ASSERT_VALID_BOUNDS(bounds);

}

PyCode_Addr2Location(PyCodeObject *co, int addrq,

int *start_line, int *start_column,

int *end_line, int *end_column)