cpython/Objects/frameobject.c at master · python-emscripten/cpython · GitHub

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/* Frame object implementation */

#include "Python.h"

#include "pycore_object.h"

#include "pycore_gc.h" // _PyObject_GC_IS_TRACKED()

#include "code.h"

#include "frameobject.h"

#include "opcode.h"

#include "structmember.h" // PyMemberDef

#define OFF(x) offsetof(PyFrameObject, x)

static PyMemberDef frame_memberlist[] = {

{"f_back", T_OBJECT, OFF(f_back), READONLY},

{"f_code", T_OBJECT, OFF(f_code), READONLY},

{"f_builtins", T_OBJECT, OFF(f_builtins), READONLY},

{"f_globals", T_OBJECT, OFF(f_globals), READONLY},

{"f_lasti", T_INT, OFF(f_lasti), READONLY},

{"f_trace_lines", T_BOOL, OFF(f_trace_lines), 0},

{"f_trace_opcodes", T_BOOL, OFF(f_trace_opcodes), 0},

{NULL} /* Sentinel */

};

static PyObject *

frame_getlocals(PyFrameObject *f, void *closure)

{

if (PyFrame_FastToLocalsWithError(f) < 0)

return NULL;

Py_INCREF(f->f_locals);

return f->f_locals;

}

int

PyFrame_GetLineNumber(PyFrameObject *f)

{

assert(f != NULL);

if (f->f_trace) {

return f->f_lineno;

}

else {

return PyCode_Addr2Line(f->f_code, f->f_lasti);

}

static PyObject *

frame_getlineno(PyFrameObject *f, void *closure)

{

return PyLong_FromLong(PyFrame_GetLineNumber(f));

}

/* Given the index of the effective opcode,

scan back to construct the oparg with EXTENDED_ARG */

static unsigned int

get_arg(const _Py_CODEUNIT *codestr, Py_ssize_t i)

{

_Py_CODEUNIT word;

unsigned int oparg = _Py_OPARG(codestr[i]);

if (i >= 1 && _Py_OPCODE(word = codestr[i-1]) == EXTENDED_ARG) {

oparg |= _Py_OPARG(word) << 8;

if (i >= 2 && _Py_OPCODE(word = codestr[i-2]) == EXTENDED_ARG) {

oparg |= _Py_OPARG(word) << 16;

if (i >= 3 && _Py_OPCODE(word = codestr[i-3]) == EXTENDED_ARG) {

oparg |= _Py_OPARG(word) << 24;

}

return oparg;

}

typedef enum kind {

With = 1,

Loop = 2,

Try = 3,

Except = 4,

} Kind;

#define BITS_PER_BLOCK 3

static inline int64_t

push_block(int64_t stack, Kind kind)

{

assert(stack < ((int64_t)1)<<(BITS_PER_BLOCK*CO_MAXBLOCKS));

return (stack << BITS_PER_BLOCK) | kind;

}

static inline int64_t

pop_block(int64_t stack)

{

assert(stack > 0);

return stack >> BITS_PER_BLOCK;

}

static inline Kind

top_block(int64_t stack)

{

return stack & ((1<<BITS_PER_BLOCK)-1);

}

static int64_t *

markblocks(PyCodeObject *code_obj, int len)

{

const _Py_CODEUNIT *code =

(const _Py_CODEUNIT *)PyBytes_AS_STRING(code_obj->co_code);

int64_t *blocks = PyMem_New(int64_t, len+1);

int i, j, opcode;

if (blocks == NULL) {

PyErr_NoMemory();

return NULL;

}

memset(blocks, -1, (len+1)*sizeof(int64_t));

blocks[0] = 0;

int todo = 1;

while (todo) {

todo = 0;

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

int64_t block_stack = blocks[i];

int64_t except_stack;

if (block_stack == -1) {

continue;

}

opcode = _Py_OPCODE(code[i]);

switch (opcode) {

case JUMP_IF_FALSE_OR_POP:

case JUMP_IF_TRUE_OR_POP:

case POP_JUMP_IF_FALSE:

case POP_JUMP_IF_TRUE:

case JUMP_IF_NOT_EXC_MATCH:

j = get_arg(code, i) / sizeof(_Py_CODEUNIT);

assert(j < len);

if (blocks[j] == -1 && j < i) {

todo = 1;

}

assert(blocks[j] == -1 || blocks[j] == block_stack);

blocks[j] = block_stack;

blocks[i+1] = block_stack;

break;

case JUMP_ABSOLUTE:

j = get_arg(code, i) / sizeof(_Py_CODEUNIT);

assert(j < len);

if (blocks[j] == -1 && j < i) {

todo = 1;

}

assert(blocks[j] == -1 || blocks[j] == block_stack);

blocks[j] = block_stack;

break;

case SETUP_FINALLY:

j = get_arg(code, i) / sizeof(_Py_CODEUNIT) + i + 1;

assert(j < len);

except_stack = push_block(block_stack, Except);

assert(blocks[j] == -1 || blocks[j] == except_stack);

blocks[j] = except_stack;

block_stack = push_block(block_stack, Try);

blocks[i+1] = block_stack;

break;

case SETUP_WITH:

case SETUP_ASYNC_WITH:

j = get_arg(code, i) / sizeof(_Py_CODEUNIT) + i + 1;

assert(j < len);

except_stack = push_block(block_stack, Except);

assert(blocks[j] == -1 || blocks[j] == except_stack);

blocks[j] = except_stack;

block_stack = push_block(block_stack, With);

blocks[i+1] = block_stack;

break;

case JUMP_FORWARD:

j = get_arg(code, i) / sizeof(_Py_CODEUNIT) + i + 1;

assert(j < len);

assert(blocks[j] == -1 || blocks[j] == block_stack);

blocks[j] = block_stack;

break;

case GET_ITER:

case GET_AITER:

block_stack = push_block(block_stack, Loop);

blocks[i+1] = block_stack;

break;

case FOR_ITER:

blocks[i+1] = block_stack;

block_stack = pop_block(block_stack);

j = get_arg(code, i) / sizeof(_Py_CODEUNIT) + i + 1;

assert(j < len);

assert(blocks[j] == -1 || blocks[j] == block_stack);

blocks[j] = block_stack;

break;

case POP_BLOCK:

case POP_EXCEPT:

block_stack = pop_block(block_stack);

blocks[i+1] = block_stack;

break;

case END_ASYNC_FOR:

block_stack = pop_block(pop_block(block_stack));

blocks[i+1] = block_stack;

break;

case RETURN_VALUE:

case RAISE_VARARGS:

case RERAISE:

/* End of block */

break;

default:

blocks[i+1] = block_stack;

}

return blocks;

}

static int

compatible_block_stack(int64_t from_stack, int64_t to_stack)

{

if (to_stack < 0) {

return 0;

}

while(from_stack > to_stack) {

from_stack = pop_block(from_stack);

}

return from_stack == to_stack;

}

static const char *

explain_incompatible_block_stack(int64_t to_stack)

{

Kind target_kind = top_block(to_stack);

switch(target_kind) {

case Except:

return "can't jump into an 'except' block as there's no exception";

case Try:

return "can't jump into the body of a try statement";

case With:

return "can't jump into the body of a with statement";

case Loop:

return "can't jump into the body of a for loop";

default:

Py_UNREACHABLE();

}

static int *

marklines(PyCodeObject *code, int len)

{

int *linestarts = PyMem_New(int, len);

if (linestarts == NULL) {

return NULL;

}

Py_ssize_t size = PyBytes_GET_SIZE(code->co_lnotab) / 2;

unsigned char *p = (unsigned char*)PyBytes_AS_STRING(code->co_lnotab);

int line = code->co_firstlineno;

int addr = 0;

int index = 0;

while (--size >= 0) {

addr += *p++;

if (index*2 < addr) {

linestarts[index++] = line;

}

while (index*2 < addr) {

linestarts[index++] = -1;

if (index >= len) {

break;

}

line += (signed char)*p;

p++;

}

if (index < len) {

linestarts[index++] = line;

}

while (index < len) {

linestarts[index++] = -1;

}

assert(index == len);

return linestarts;

}

static int

first_line_not_before(int *lines, int len, int line)

{

int result = INT_MAX;

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

if (lines[i] < result && lines[i] >= line) {

result = lines[i];

}

if (result == INT_MAX) {

return -1;

}

return result;

}

static void

frame_stack_pop(PyFrameObject *f)

{

PyObject *v = (*--f->f_stacktop);

Py_DECREF(v);

}

static void

frame_block_unwind(PyFrameObject *f)

{

assert(f->f_iblock > 0);

f->f_iblock--;

PyTryBlock *b = &f->f_blockstack[f->f_iblock];

intptr_t delta = (f->f_stacktop - f->f_valuestack) - b->b_level;

while (delta > 0) {

frame_stack_pop(f);

delta--;

}

/* Setter for f_lineno - you can set f_lineno from within a trace function in

* order to jump to a given line of code, subject to some restrictions. Most

* lines are OK to jump to because they don't make any assumptions about the

* state of the stack (obvious because you could remove the line and the code

* would still work without any stack errors), but there are some constructs

* that limit jumping:

* o Lines with an 'except' statement on them can't be jumped to, because

* they expect an exception to be on the top of the stack.

* o Lines that live in a 'finally' block can't be jumped from or to, since

* we cannot be sure which state the interpreter was in or would be in

* during execution of the finally block.

* o 'try', 'with' and 'async with' blocks can't be jumped into because

* the blockstack needs to be set up before their code runs.

* o 'for' and 'async for' loops can't be jumped into because the

* iterator needs to be on the stack.

* o Jumps cannot be made from within a trace function invoked with a

* 'return' or 'exception' event since the eval loop has been exited at

* that time.

static int

frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignored))

{

if (p_new_lineno == NULL) {

PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");

return -1;

}

/* f_lineno must be an integer. */

if (!PyLong_CheckExact(p_new_lineno)) {

PyErr_SetString(PyExc_ValueError,

"lineno must be an integer");

return -1;

}

/* Upon the 'call' trace event of a new frame, f->f_lasti is -1 and

* f->f_trace is NULL, check first on the first condition.

* Forbidding jumps from the 'call' event of a new frame is a side effect

* of allowing to set f_lineno only from trace functions. */

if (f->f_lasti == -1) {

PyErr_Format(PyExc_ValueError,

"can't jump from the 'call' trace event of a new frame");

return -1;

}

/* You can only do this from within a trace function, not via

* _getframe or similar hackery. */

if (!f->f_trace) {

PyErr_Format(PyExc_ValueError,

"f_lineno can only be set by a trace function");

return -1;

}

/* Forbid jumps upon a 'return' trace event (except after executing a

* YIELD_VALUE or YIELD_FROM opcode, f_stacktop is not NULL in that case)

* and upon an 'exception' trace event.

* Jumps from 'call' trace events have already been forbidden above for new

* frames, so this check does not change anything for 'call' events. */

if (f->f_stacktop == NULL) {

PyErr_SetString(PyExc_ValueError,

"can only jump from a 'line' trace event");

return -1;

}

int new_lineno;

/* Fail if the line falls outside the code block and

select first line with actual code. */

int overflow;

long l_new_lineno = PyLong_AsLongAndOverflow(p_new_lineno, &overflow);

if (overflow

#if SIZEOF_LONG > SIZEOF_INT

|| l_new_lineno > INT_MAX

|| l_new_lineno < INT_MIN

#endif

) {

PyErr_SetString(PyExc_ValueError,

"lineno out of range");

return -1;

}

new_lineno = (int)l_new_lineno;

if (new_lineno < f->f_code->co_firstlineno) {

PyErr_Format(PyExc_ValueError,

"line %d comes before the current code block",

new_lineno);

return -1;

}

/* PyCode_NewWithPosOnlyArgs limits co_code to be under INT_MAX so this

* should never overflow. */

int len = (int)(PyBytes_GET_SIZE(f->f_code->co_code) / sizeof(_Py_CODEUNIT));

int *lines = marklines(f->f_code, len);

if (lines == NULL) {

return -1;

}

new_lineno = first_line_not_before(lines, len, new_lineno);

if (new_lineno < 0) {

PyErr_Format(PyExc_ValueError,

"line %d comes after the current code block",

(int)l_new_lineno);

PyMem_Free(lines);

return -1;

}

int64_t *blocks = markblocks(f->f_code, len);

if (blocks == NULL) {

PyMem_Free(lines);

return -1;

}

int64_t target_block_stack = -1;

int64_t best_block_stack = -1;

int best_addr = -1;

int64_t start_block_stack = blocks[f->f_lasti/sizeof(_Py_CODEUNIT)];

const char *msg = "cannot find bytecode for specified line";

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

if (lines[i] == new_lineno) {

target_block_stack = blocks[i];

if (compatible_block_stack(start_block_stack, target_block_stack)) {

msg = NULL;

if (target_block_stack > best_block_stack) {

best_block_stack = target_block_stack;

best_addr = i*sizeof(_Py_CODEUNIT);

}

else if (msg) {

if (target_block_stack >= 0) {

msg = explain_incompatible_block_stack(target_block_stack);

}

else {

msg = "code may be unreachable.";

}

PyMem_Free(blocks);

PyMem_Free(lines);

if (msg != NULL) {

PyErr_SetString(PyExc_ValueError, msg);

return -1;

}

/* Unwind block stack. */

while (start_block_stack > best_block_stack) {

Kind kind = top_block(start_block_stack);

switch(kind) {

case Loop:

frame_stack_pop(f);

break;

case Try:

frame_block_unwind(f);

break;

case With:

frame_block_unwind(f);

// Pop the exit function

frame_stack_pop(f);

break;

case Except:

PyErr_SetString(PyExc_ValueError,

"can't jump out of an 'except' block");

return -1;

}

start_block_stack = pop_block(start_block_stack);

}

/* Finally set the new f_lineno and f_lasti and return OK. */

f->f_lineno = new_lineno;

f->f_lasti = best_addr;

return 0;

}

static PyObject *

frame_gettrace(PyFrameObject *f, void *closure)

{

PyObject* trace = f->f_trace;

if (trace == NULL)

trace = Py_None;

Py_INCREF(trace);

return trace;

}

static int

frame_settrace(PyFrameObject *f, PyObject* v, void *closure)

{

/* We rely on f_lineno being accurate when f_trace is set. */

f->f_lineno = PyFrame_GetLineNumber(f);

if (v == Py_None)

v = NULL;

Py_XINCREF(v);

Py_XSETREF(f->f_trace, v);

return 0;

}

static PyGetSetDef frame_getsetlist[] = {

{"f_locals", (getter)frame_getlocals, NULL, NULL},

{"f_lineno", (getter)frame_getlineno,

(setter)frame_setlineno, NULL},

{"f_trace", (getter)frame_gettrace, (setter)frame_settrace, NULL},

{0}

};

/* Stack frames are allocated and deallocated at a considerable rate.

In an attempt to improve the speed of function calls, we:

1. Hold a single "zombie" frame on each code object. This retains

the allocated and initialised frame object from an invocation of

the code object. The zombie is reanimated the next time we need a

frame object for that code object. Doing this saves the malloc/

realloc required when using a free_list frame that isn't the

correct size. It also saves some field initialisation.

In zombie mode, no field of PyFrameObject holds a reference, but

the following fields are still valid:

* ob_type, ob_size, f_code, f_valuestack;

* f_locals, f_trace are NULL;

* f_localsplus does not require re-allocation and

the local variables in f_localsplus are NULL.

2. We also maintain a separate free list of stack frames (just like

floats are allocated in a special way -- see floatobject.c). When

a stack frame is on the free list, only the following members have

a meaning:

ob_type == &Frametype

f_back next item on free list, or NULL

f_stacksize size of value stack

ob_size size of localsplus

Note that the value and block stacks are preserved -- this can save

another malloc() call or two (and two free() calls as well!).

Also note that, unlike for integers, each frame object is a

malloc'ed object in its own right -- it is only the actual calls to

malloc() that we are trying to save here, not the administration.

After all, while a typical program may make millions of calls, a

call depth of more than 20 or 30 is probably already exceptional

unless the program contains run-away recursion. I hope.

Later, PyFrame_MAXFREELIST was added to bound the # of frames saved on

free_list. Else programs creating lots of cyclic trash involving

frames could provoke free_list into growing without bound.

/* max value for numfree */

#define PyFrame_MAXFREELIST 200

static void _Py_HOT_FUNCTION

frame_dealloc(PyFrameObject *f)

{

if (_PyObject_GC_IS_TRACKED(f)) {

_PyObject_GC_UNTRACK(f);

}

Py_TRASHCAN_SAFE_BEGIN(f)

/* Kill all local variables */

PyObject **valuestack = f->f_valuestack;

for (PyObject **p = f->f_localsplus; p < valuestack; p++) {

Py_CLEAR(*p);

}

/* Free stack */

if (f->f_stacktop != NULL) {

for (PyObject **p = valuestack; p < f->f_stacktop; p++) {

Py_XDECREF(*p);

}

Py_XDECREF(f->f_back);

Py_DECREF(f->f_builtins);

Py_DECREF(f->f_globals);

Py_CLEAR(f->f_locals);

Py_CLEAR(f->f_trace);

PyCodeObject *co = f->f_code;

if (co->co_zombieframe == NULL) {

co->co_zombieframe = f;

}

else {

PyInterpreterState *interp = _PyInterpreterState_GET();

struct _Py_frame_state *state = &interp->frame;

#ifdef Py_DEBUG

// frame_dealloc() must not be called after _PyFrame_Fini()

assert(state->numfree != -1);

#endif

if (state->numfree < PyFrame_MAXFREELIST) {

++state->numfree;

f->f_back = state->free_list;

state->free_list = f;

}

else {

PyObject_GC_Del(f);

}

Py_DECREF(co);

Py_TRASHCAN_SAFE_END(f)

}

static inline Py_ssize_t

frame_nslots(PyFrameObject *frame)

{

PyCodeObject *code = frame->f_code;

return (code->co_nlocals

+ PyTuple_GET_SIZE(code->co_cellvars)

+ PyTuple_GET_SIZE(code->co_freevars));

}

static int

frame_traverse(PyFrameObject *f, visitproc visit, void *arg)

{

Py_VISIT(f->f_back);

Py_VISIT(f->f_code);

Py_VISIT(f->f_builtins);

Py_VISIT(f->f_globals);

Py_VISIT(f->f_locals);

Py_VISIT(f->f_trace);

/* locals */

PyObject **fastlocals = f->f_localsplus;

for (Py_ssize_t i = frame_nslots(f); --i >= 0; ++fastlocals) {

Py_VISIT(*fastlocals);

}

/* stack */

if (f->f_stacktop != NULL) {

for (PyObject **p = f->f_valuestack; p < f->f_stacktop; p++) {

Py_VISIT(*p);

}

return 0;

}

static int

frame_tp_clear(PyFrameObject *f)

{

/* Before anything else, make sure that this frame is clearly marked

* as being defunct! Else, e.g., a generator reachable from this

* frame may also point to this frame, believe itself to still be

* active, and try cleaning up this frame again.

PyObject **oldtop = f->f_stacktop;

f->f_stacktop = NULL;

f->f_executing = 0;

Py_CLEAR(f->f_trace);

/* locals */

PyObject **fastlocals = f->f_localsplus;

for (Py_ssize_t i = frame_nslots(f); --i >= 0; ++fastlocals) {

Py_CLEAR(*fastlocals);

}

/* stack */

if (oldtop != NULL) {

for (PyObject **p = f->f_valuestack; p < oldtop; p++) {

Py_CLEAR(*p);

}

return 0;

}

static PyObject *

frame_clear(PyFrameObject *f, PyObject *Py_UNUSED(ignored))

{

if (f->f_executing) {

PyErr_SetString(PyExc_RuntimeError,

"cannot clear an executing frame");

return NULL;

}

if (f->f_gen) {

_PyGen_Finalize(f->f_gen);

assert(f->f_gen == NULL);

}

(void)frame_tp_clear(f);

Py_RETURN_NONE;

}

PyDoc_STRVAR(clear__doc__,

"F.clear(): clear most references held by the frame");

static PyObject *

frame_sizeof(PyFrameObject *f, PyObject *Py_UNUSED(ignored))

{

Py_ssize_t res, extras, ncells, nfrees;

PyCodeObject *code = f->f_code;

ncells = PyTuple_GET_SIZE(code->co_cellvars);

nfrees = PyTuple_GET_SIZE(code->co_freevars);

extras = code->co_stacksize + code->co_nlocals + ncells + nfrees;

/* subtract one as it is already included in PyFrameObject */

res = sizeof(PyFrameObject) + (extras-1) * sizeof(PyObject *);

return PyLong_FromSsize_t(res);

}

PyDoc_STRVAR(sizeof__doc__,

"F.__sizeof__() -> size of F in memory, in bytes");

static PyObject *

frame_repr(PyFrameObject *f)

{

int lineno = PyFrame_GetLineNumber(f);

PyCodeObject *code = f->f_code;

return PyUnicode_FromFormat(

"<frame at %p, file %R, line %d, code %S>",

f, code->co_filename, lineno, code->co_name);

}

static PyMethodDef frame_methods[] = {

{"clear", (PyCFunction)frame_clear, METH_NOARGS,

clear__doc__},

{"__sizeof__", (PyCFunction)frame_sizeof, METH_NOARGS,

sizeof__doc__},

{NULL, NULL} /* sentinel */

};

PyTypeObject PyFrame_Type = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

"frame",

sizeof(PyFrameObject),

sizeof(PyObject *),

(destructor)frame_dealloc, /* tp_dealloc */

0, /* tp_vectorcall_offset */

0, /* tp_getattr */

0, /* tp_setattr */

0, /* tp_as_async */

(reprfunc)frame_repr, /* tp_repr */

0, /* tp_as_number */

0, /* tp_as_sequence */

0, /* tp_as_mapping */

0, /* tp_hash */

0, /* tp_call */

0, /* tp_str */

PyObject_GenericGetAttr, /* tp_getattro */

PyObject_GenericSetAttr, /* tp_setattro */

0, /* tp_as_buffer */

Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */

0, /* tp_doc */

(traverseproc)frame_traverse, /* tp_traverse */

(inquiry)frame_tp_clear, /* tp_clear */

0, /* tp_richcompare */

0, /* tp_weaklistoffset */

0, /* tp_iter */

0, /* tp_iternext */

frame_methods, /* tp_methods */

frame_memberlist, /* tp_members */

frame_getsetlist, /* tp_getset */

0, /* tp_base */

0, /* tp_dict */

};

_Py_IDENTIFIER(__builtins__);

static inline PyFrameObject*

frame_alloc(PyCodeObject *code)

{

PyFrameObject *f;

f = code->co_zombieframe;

if (f != NULL) {

code->co_zombieframe = NULL;

_Py_NewReference((PyObject *)f);

assert(f->f_code == code);

return f;

}

Py_ssize_t ncells = PyTuple_GET_SIZE(code->co_cellvars);

Py_ssize_t nfrees = PyTuple_GET_SIZE(code->co_freevars);

Py_ssize_t extras = code->co_stacksize + code->co_nlocals + ncells + nfrees;

PyInterpreterState *interp = _PyInterpreterState_GET();

struct _Py_frame_state *state = &interp->frame;

if (state->free_list == NULL)

{

f = PyObject_GC_NewVar(PyFrameObject, &PyFrame_Type, extras);

if (f == NULL) {

return NULL;

}

else {

#ifdef Py_DEBUG

// frame_alloc() must not be called after _PyFrame_Fini()

assert(state->numfree != -1);

#endif

assert(state->numfree > 0);

--state->numfree;

f = state->free_list;

state->free_list = state->free_list->f_back;

if (Py_SIZE(f) < extras) {

PyFrameObject *new_f = PyObject_GC_Resize(PyFrameObject, f, extras);

if (new_f == NULL) {

PyObject_GC_Del(f);

return NULL;

}

f = new_f;

}

_Py_NewReference((PyObject *)f);

}

f->f_code = code;

extras = code->co_nlocals + ncells + nfrees;

f->f_valuestack = f->f_localsplus + extras;

for (Py_ssize_t i=0; i<extras; i++) {

f->f_localsplus[i] = NULL;

}

f->f_locals = NULL;

f->f_trace = NULL;

return f;

}

static inline PyObject *

frame_get_builtins(PyFrameObject *back, PyObject *globals)

{

PyObject *builtins;

if (back != NULL && back->f_globals == globals) {

/* If we share the globals, we share the builtins.

Save a lookup and a call. */

builtins = back->f_builtins;

assert(builtins != NULL);

Py_INCREF(builtins);

return builtins;

}

builtins = _PyDict_GetItemIdWithError(globals, &PyId___builtins__);

if (builtins != NULL && PyModule_Check(builtins)) {

builtins = PyModule_GetDict(builtins);

assert(builtins != NULL);

}

if (builtins != NULL) {

Py_INCREF(builtins);

return builtins;

}

if (PyErr_Occurred()) {

return NULL;

}

/* No builtins! Make up a minimal one.

Give them 'None', at least. */

builtins = PyDict_New();

if (builtins == NULL) {

return NULL;

}

if (PyDict_SetItemString(builtins, "None", Py_None) < 0) {

Py_DECREF(builtins);

return NULL;

}

return builtins;

}

PyFrameObject* _Py_HOT_FUNCTION

_PyFrame_New_NoTrack(PyThreadState *tstate, PyCodeObject *code,

PyObject *globals, PyObject *locals)

{

#ifdef Py_DEBUG

if (code == NULL || globals == NULL || !PyDict_Check(globals) ||

(locals != NULL && !PyMapping_Check(locals))) {

PyErr_BadInternalCall();

return NULL;

}

#endif

PyFrameObject *back = tstate->frame;

PyObject *builtins = frame_get_builtins(back, globals);

if (builtins == NULL) {

return NULL;

}

PyFrameObject *f = frame_alloc(code);

if (f == NULL) {

Py_DECREF(builtins);

return NULL;

}

f->f_stacktop = f->f_valuestack;

f->f_builtins = builtins;

Py_XINCREF(back);

f->f_back = back;

Py_INCREF(code);

Py_INCREF(globals);

f->f_globals = globals;

/* Most functions have CO_NEWLOCALS and CO_OPTIMIZED set. */

if ((code->co_flags & (CO_NEWLOCALS | CO_OPTIMIZED)) ==

(CO_NEWLOCALS | CO_OPTIMIZED))

; /* f_locals = NULL; will be set by PyFrame_FastToLocals() */

else if (code->co_flags & CO_NEWLOCALS) {

locals = PyDict_New();

if (locals == NULL) {

Py_DECREF(f);

return NULL;

}

f->f_locals = locals;

}

else {

if (locals == NULL)

locals = globals;

Py_INCREF(locals);

f->f_locals = locals;

}

f->f_lasti = -1;

f->f_lineno = code->co_firstlineno;

f->f_iblock = 0;

f->f_executing = 0;

f->f_gen = NULL;

f->f_trace_opcodes = 0;

f->f_trace_lines = 1;

assert(f->f_code != NULL);

return f;

}

PyFrameObject*

PyFrame_New(PyThreadState *tstate, PyCodeObject *code,

PyObject *globals, PyObject *locals)

{

PyFrameObject *f = _PyFrame_New_NoTrack(tstate, code, globals, locals);

if (f)

_PyObject_GC_TRACK(f);

return f;

}

/* Block management */

void

PyFrame_BlockSetup(PyFrameObject *f, int type, int handler, int level)

{

PyTryBlock *b;

if (f->f_iblock >= CO_MAXBLOCKS) {

Py_FatalError("block stack overflow");

}

b = &f->f_blockstack[f->f_iblock++];

b->b_type = type;

b->b_level = level;

b->b_handler = handler;

}

PyTryBlock *

PyFrame_BlockPop(PyFrameObject *f)

{

PyTryBlock *b;

if (f->f_iblock <= 0) {

Py_FatalError("block stack underflow");

}

b = &f->f_blockstack[--f->f_iblock];

return b;

}

/* Convert between "fast" version of locals and dictionary version.

map and values are input arguments. map is a tuple of strings.

values is an array of PyObject*. At index i, map[i] is the name of

the variable with value values[i]. The function copies the first

nmap variable from map/values into dict. If values[i] is NULL,

the variable is deleted from dict.

If deref is true, then the values being copied are cell variables

and the value is extracted from the cell variable before being put

in dict.

static int

map_to_dict(PyObject *map, Py_ssize_t nmap, PyObject *dict, PyObject **values,

int deref)

{

Py_ssize_t j;

assert(PyTuple_Check(map));

assert(PyDict_Check(dict));

assert(PyTuple_Size(map) >= nmap);

for (j=0; j < nmap; j++) {

PyObject *key = PyTuple_GET_ITEM(map, j);

PyObject *value = values[j];

assert(PyUnicode_Check(key));

if (deref && value != NULL) {

assert(PyCell_Check(value));

value = PyCell_GET(value);

}

if (value == NULL) {

if (PyObject_DelItem(dict, key) != 0) {

View remainder of file in raw view

cpython/Objects/frameobject.c at master · python-emscripten/cpython · GitHub

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