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cpython/Objects/frameobject.c

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/* Frame object implementation */
#include "Python.h"
#include "pycore_ceval.h" // _PyEval_BuiltinsFromGlobals()
#include "pycore_moduleobject.h" // _PyModule_GetDict()
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include "pycore_code.h" // CO_FAST_LOCAL, etc.
#include "frameobject.h" // PyFrameObject
#include "pycore_frame.h"
#include "opcode.h" // EXTENDED_ARG
#include "structmember.h" // PyMemberDef
#define OFF(x) offsetof(PyFrameObject, x)
static PyMemberDef frame_memberlist[] = {
{"f_trace_lines", T_BOOL, OFF(f_trace_lines), 0},
{"f_trace_opcodes", T_BOOL, OFF(f_trace_opcodes), 0},
{NULL} /* Sentinel */
};
static struct _Py_frame_state *
get_frame_state(void)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
return &interp->frame;
}
static PyObject *
frame_getlocals(PyFrameObject *f, void *closure)
{
if (PyFrame_FastToLocalsWithError(f) < 0)
return NULL;
PyObject *locals = f->f_frame->f_locals;
Py_INCREF(locals);
return locals;
}
int
PyFrame_GetLineNumber(PyFrameObject *f)
{
assert(f != NULL);
if (f->f_lineno != 0) {
return f->f_lineno;
}
else {
return PyCode_Addr2Line(f->f_frame->f_code, f->f_frame->f_lasti*sizeof(_Py_CODEUNIT));
}
}
static PyObject *
frame_getlineno(PyFrameObject *f, void *closure)
{
int lineno = PyFrame_GetLineNumber(f);
if (lineno < 0) {
Py_RETURN_NONE;
}
else {
return PyLong_FromLong(lineno);
}
}
static PyObject *
frame_getlasti(PyFrameObject *f, void *closure)
{
if (f->f_frame->f_lasti < 0) {
return PyLong_FromLong(-1);
}
return PyLong_FromLong(f->f_frame->f_lasti*sizeof(_Py_CODEUNIT));
}
static PyObject *
frame_getglobals(PyFrameObject *f, void *closure)
{
PyObject *globals = f->f_frame->f_globals;
if (globals == NULL) {
globals = Py_None;
}
Py_INCREF(globals);
return globals;
}
static PyObject *
frame_getbuiltins(PyFrameObject *f, void *closure)
{
PyObject *builtins = f->f_frame->f_builtins;
if (builtins == NULL) {
builtins = Py_None;
}
Py_INCREF(builtins);
return builtins;
}
static PyObject *
frame_getcode(PyFrameObject *f, void *closure)
{
if (PySys_Audit("object.__getattr__", "Os", f, "f_code") < 0) {
return NULL;
}
return (PyObject *)PyFrame_GetCode(f);
}
static PyObject *
frame_getback(PyFrameObject *f, void *closure)
{
PyObject *res = (PyObject *)PyFrame_GetBack(f);
if (res == NULL) {
Py_RETURN_NONE;
}
return res;
}
/* 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;
}
/* Model the evaluation stack, to determine which jumps
* are safe and how many values needs to be popped.
* The stack is modelled by a 64 integer, treating any
* stack that can't fit into 64 bits as "overflowed".
*/
typedef enum kind {
Iterator = 1,
Except = 2,
Object = 3,
} Kind;
#define BITS_PER_BLOCK 2
#define UNINITIALIZED -2
#define OVERFLOWED -1
#define MAX_STACK_ENTRIES (63/BITS_PER_BLOCK)
#define WILL_OVERFLOW (1ULL<<((MAX_STACK_ENTRIES-1)*BITS_PER_BLOCK))
static inline int64_t
push_value(int64_t stack, Kind kind)
{
if (((uint64_t)stack) >= WILL_OVERFLOW) {
return OVERFLOWED;
}
else {
return (stack << BITS_PER_BLOCK) | kind;
}
}
static inline int64_t
pop_value(int64_t stack)
{
return Py_ARITHMETIC_RIGHT_SHIFT(int64_t, stack, BITS_PER_BLOCK);
}
static inline Kind
top_of_stack(int64_t stack)
{
return stack & ((1<<BITS_PER_BLOCK)-1);
}
static int64_t *
mark_stacks(PyCodeObject *code_obj, int len)
{
const _Py_CODEUNIT *code =
(const _Py_CODEUNIT *)PyBytes_AS_STRING(code_obj->co_code);
int64_t *stacks = PyMem_New(int64_t, len+1);
int i, j, opcode;
if (stacks == NULL) {
PyErr_NoMemory();
return NULL;
}
for (int i = 1; i <= len; i++) {
stacks[i] = UNINITIALIZED;
}
stacks[0] = 0;
int todo = 1;
while (todo) {
todo = 0;
for (i = 0; i < len; i++) {
int64_t next_stack = stacks[i];
if (next_stack == UNINITIALIZED) {
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:
{
int64_t target_stack;
int j = get_arg(code, i);
assert(j < len);
if (stacks[j] == UNINITIALIZED && j < i) {
todo = 1;
}
if (opcode == JUMP_IF_NOT_EXC_MATCH) {
next_stack = pop_value(pop_value(next_stack));
target_stack = next_stack;
}
else if (opcode == JUMP_IF_FALSE_OR_POP ||
opcode == JUMP_IF_TRUE_OR_POP)
{
target_stack = next_stack;
next_stack = pop_value(next_stack);
}
else {
next_stack = pop_value(next_stack);
target_stack = next_stack;
}
assert(stacks[j] == UNINITIALIZED || stacks[j] == target_stack);
stacks[j] = target_stack;
stacks[i+1] = next_stack;
break;
}
case JUMP_ABSOLUTE:
j = get_arg(code, i);
assert(j < len);
if (stacks[j] == UNINITIALIZED && j < i) {
todo = 1;
}
assert(stacks[j] == UNINITIALIZED || stacks[j] == next_stack);
stacks[j] = next_stack;
break;
case POP_EXCEPT:
next_stack = pop_value(pop_value(pop_value(next_stack)));
stacks[i+1] = next_stack;
break;
case JUMP_FORWARD:
j = get_arg(code, i) + i + 1;
assert(j < len);
assert(stacks[j] == UNINITIALIZED || stacks[j] == next_stack);
stacks[j] = next_stack;
break;
case GET_ITER:
case GET_AITER:
next_stack = push_value(pop_value(next_stack), Iterator);
stacks[i+1] = next_stack;
break;
case FOR_ITER:
{
int64_t target_stack = pop_value(next_stack);
stacks[i+1] = push_value(next_stack, Object);
j = get_arg(code, i) + i + 1;
assert(j < len);
assert(stacks[j] == UNINITIALIZED || stacks[j] == target_stack);
stacks[j] = target_stack;
break;
}
case END_ASYNC_FOR:
next_stack = pop_value(pop_value(pop_value(next_stack)));
stacks[i+1] = next_stack;
break;
case PUSH_EXC_INFO:
next_stack = push_value(next_stack, Except);
next_stack = push_value(next_stack, Except);
next_stack = push_value(next_stack, Except);
stacks[i+1] = next_stack;
case RETURN_VALUE:
case RAISE_VARARGS:
case RERAISE:
case POP_EXCEPT_AND_RERAISE:
/* End of block */
break;
case GEN_START:
stacks[i+1] = next_stack;
break;
default:
{
int delta = PyCompile_OpcodeStackEffect(opcode, _Py_OPARG(code[i]));
while (delta < 0) {
next_stack = pop_value(next_stack);
delta++;
}
while (delta > 0) {
next_stack = push_value(next_stack, Object);
delta--;
}
stacks[i+1] = next_stack;
}
}
}
}
return stacks;
}
static int
compatible_kind(Kind from, Kind to) {
if (to == 0) {
return 0;
}
if (to == Object) {
return 1;
}
return from == to;
}
static int
compatible_stack(int64_t from_stack, int64_t to_stack)
{
if (from_stack < 0 || to_stack < 0) {
return 0;
}
while(from_stack > to_stack) {
from_stack = pop_value(from_stack);
}
while(from_stack) {
Kind from_top = top_of_stack(from_stack);
Kind to_top = top_of_stack(to_stack);
if (!compatible_kind(from_top, to_top)) {
return 0;
}
from_stack = pop_value(from_stack);
to_stack = pop_value(to_stack);
}
return to_stack == 0;
}
static const char *
explain_incompatible_stack(int64_t to_stack)
{
assert(to_stack != 0);
if (to_stack == OVERFLOWED) {
return "stack is too deep to analyze";
}
if (to_stack == UNINITIALIZED) {
return "can't jump into an exception handler, or code may be unreachable";
}
Kind target_kind = top_of_stack(to_stack);
switch(target_kind) {
case Except:
return "can't jump into an 'except' block as there's no exception";
case Object:
return "differing stack depth";
case Iterator:
return "can't jump into the body of a for loop";
default:
Py_UNREACHABLE();
}
}
static int *
marklines(PyCodeObject *code, int len)
{
PyCodeAddressRange bounds;
_PyCode_InitAddressRange(code, &bounds);
assert (bounds.ar_end == 0);
int *linestarts = PyMem_New(int, len);
if (linestarts == NULL) {
return NULL;
}
for (int i = 0; i < len; i++) {
linestarts[i] = -1;
}
while (PyLineTable_NextAddressRange(&bounds)) {
assert(bounds.ar_start/(int)sizeof(_Py_CODEUNIT) < len);
linestarts[bounds.ar_start/sizeof(_Py_CODEUNIT)] = bounds.ar_line;
}
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 = _PyFrame_StackPop(f->f_frame);
Py_DECREF(v);
}
/* 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 Any exception handlers.
* 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;
}
/*
* This code preserves the historical restrictions on
* setting the line number of a frame.
* Jumps are forbidden on a 'return' trace event (except after a yield).
* Jumps from 'call' trace events are also forbidden.
* In addition, jumps are forbidden when not tracing,
* as this is a debugging feature.
*/
switch(f->f_frame->f_state) {
case FRAME_CREATED:
PyErr_Format(PyExc_ValueError,
"can't jump from the 'call' trace event of a new frame");
return -1;
case FRAME_RETURNED:
case FRAME_UNWINDING:
case FRAME_RAISED:
case FRAME_CLEARED:
PyErr_SetString(PyExc_ValueError,
"can only jump from a 'line' trace event");
return -1;
case FRAME_EXECUTING:
case FRAME_SUSPENDED:
/* 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;
}
break;
}
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_frame->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_frame->f_code->co_code) / sizeof(_Py_CODEUNIT));
int *lines = marklines(f->f_frame->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 *stacks = mark_stacks(f->f_frame->f_code, len);
if (stacks == NULL) {
PyMem_Free(lines);
return -1;
}
int64_t best_stack = OVERFLOWED;
int best_addr = -1;
int64_t start_stack = stacks[f->f_frame->f_lasti];
int err = -1;
const char *msg = "cannot find bytecode for specified line";
for (int i = 0; i < len; i++) {
if (lines[i] == new_lineno) {
int64_t target_stack = stacks[i];
if (compatible_stack(start_stack, target_stack)) {
err = 0;
if (target_stack > best_stack) {
best_stack = target_stack;
best_addr = i;
}
}
else if (err < 0) {
if (start_stack == OVERFLOWED) {
msg = "stack to deep to analyze";
}
else if (start_stack == UNINITIALIZED) {
msg = "can't jump from within an exception handler";
}
else {
msg = explain_incompatible_stack(target_stack);
err = 1;
}
}
}
}
PyMem_Free(stacks);
PyMem_Free(lines);
if (err) {
PyErr_SetString(PyExc_ValueError, msg);
return -1;
}
/* Unwind block stack. */
if (f->f_frame->f_state == FRAME_SUSPENDED) {
/* Account for value popped by yield */
start_stack = pop_value(start_stack);
}
while (start_stack > best_stack) {
frame_stack_pop(f);
start_stack = pop_value(start_stack);
}
/* Finally set the new lasti and return OK. */
f->f_lineno = 0;
f->f_frame->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)
{
if (v == Py_None) {
v = NULL;
}
Py_XINCREF(v);
Py_XSETREF(f->f_trace, v);
return 0;
}
static PyGetSetDef frame_getsetlist[] = {
{"f_back", (getter)frame_getback, NULL, NULL},
{"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},
{"f_lasti", (getter)frame_getlasti, NULL, NULL},
{"f_globals", (getter)frame_getglobals, NULL, NULL},
{"f_builtins", (getter)frame_getbuiltins, NULL, NULL},
{"f_code", (getter)frame_getcode, NULL, NULL},
{0}
};
/* Stack frames are allocated and deallocated at a considerable rate.
In an attempt to improve the speed of function calls, we 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
*/
/* 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_BEGIN(f, frame_dealloc);
PyCodeObject *co = NULL;
/* Kill all local variables including specials, if we own them */
if (f->f_own_locals_memory) {
f->f_own_locals_memory = 0;
InterpreterFrame *frame = f->f_frame;
/* Don't clear code object until the end */
co = frame->f_code;
frame->f_code = NULL;
Py_CLEAR(frame->f_globals);
Py_CLEAR(frame->f_builtins);
Py_CLEAR(frame->f_locals);
PyObject **locals = _PyFrame_GetLocalsArray(frame);
for (int i = 0; i < frame->stacktop; i++) {
Py_CLEAR(locals[i]);
}
PyMem_Free(frame);
}
Py_CLEAR(f->f_back);
Py_CLEAR(f->f_trace);
struct _Py_frame_state *state = get_frame_state();
#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_XDECREF(co);
Py_TRASHCAN_END;
}
static int
frame_traverse(PyFrameObject *f, visitproc visit, void *arg)
{
Py_VISIT(f->f_back);
Py_VISIT(f->f_trace);
if (f->f_own_locals_memory == 0) {
return 0;
}
assert(f->f_frame->frame_obj == NULL);
return _PyFrame_Traverse(f->f_frame, visit, arg);
}
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.
*/
f->f_frame->f_state = FRAME_CLEARED;
Py_CLEAR(f->f_trace);
/* locals and stack */
PyObject **locals = _PyFrame_GetLocalsArray(f->f_frame);
assert(f->f_frame->stacktop >= 0);
for (int i = 0; i < f->f_frame->stacktop; i++) {
Py_CLEAR(locals[i]);
}
f->f_frame->stacktop = 0;
return 0;
}
static PyObject *
frame_clear(PyFrameObject *f, PyObject *Py_UNUSED(ignored))
{
if (_PyFrame_IsExecuting(f->f_frame)) {
PyErr_SetString(PyExc_RuntimeError,
"cannot clear an executing frame");
return NULL;
}
if (f->f_frame->generator) {
_PyGen_Finalize(f->f_frame->generator);
assert(f->f_frame->generator == 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;
res = sizeof(PyFrameObject);
if (f->f_own_locals_memory) {
PyCodeObject *code = f->f_frame->f_code;
res += (code->co_nlocalsplus+code->co_stacksize) * 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_frame->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 InterpreterFrame *
allocate_heap_frame(PyFrameConstructor *con, PyObject *locals)
{
PyCodeObject *code = (PyCodeObject *)con->fc_code;
int size = code->co_nlocalsplus+code->co_stacksize + FRAME_SPECIALS_SIZE;
PyObject **localsarray = PyMem_Malloc(sizeof(PyObject *)*size);
if (localsarray == NULL) {
PyErr_NoMemory();
return NULL;
}
for (Py_ssize_t i=0; i < code->co_nlocalsplus; i++) {
localsarray[i] = NULL;
}
InterpreterFrame *frame = (InterpreterFrame *)(localsarray + code->co_nlocalsplus);
_PyFrame_InitializeSpecials(frame, con, locals, code->co_nlocalsplus);
return frame;
}
static inline PyFrameObject*
frame_alloc(InterpreterFrame *frame, int owns)
{
PyFrameObject *f;
struct _Py_frame_state *state = get_frame_state();
if (state->free_list == NULL)
{
f = PyObject_GC_New(PyFrameObject, &PyFrame_Type);
if (f == NULL) {
if (owns) {
Py_XDECREF(frame->f_code);
Py_XDECREF(frame->f_builtins);
Py_XDECREF(frame->f_globals);
Py_XDECREF(frame->f_locals);
PyMem_Free(frame);
}
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;
_Py_NewReference((PyObject *)f);
}
f->f_frame = frame;
f->f_own_locals_memory = owns;
return f;
}
PyFrameObject* _Py_HOT_FUNCTION
_PyFrame_New_NoTrack(InterpreterFrame *frame, int owns)
{
PyFrameObject *f = frame_alloc(frame, owns);
if (f == NULL) {
return NULL;
}
f->f_back = NULL;
f->f_trace = NULL;
f->f_trace_lines = 1;
f->f_trace_opcodes = 0;
f->f_lineno = 0;
return f;
}
/* Legacy API */
PyFrameObject*
PyFrame_New(PyThreadState *tstate, PyCodeObject *code,
PyObject *globals, PyObject *locals)
{
PyObject *builtins = _PyEval_BuiltinsFromGlobals(tstate, globals); // borrowed ref
if (builtins == NULL) {
return NULL;
}
PyFrameConstructor desc = {
.fc_globals = globals,
.fc_builtins = builtins,
.fc_name = code->co_name,
.fc_qualname = code->co_name,
.fc_code = (PyObject *)code,
.fc_defaults = NULL,
.fc_kwdefaults = NULL,
.fc_closure = NULL
};
InterpreterFrame *frame = allocate_heap_frame(&desc, locals);
if (frame == NULL) {
return NULL;
}
PyFrameObject *f = _PyFrame_New_NoTrack(frame, 1);
if (f) {
_PyObject_GC_TRACK(f);
}
return f;
}
static int
_PyFrame_OpAlreadyRan(InterpreterFrame *frame, int opcode, int oparg)
{
const _Py_CODEUNIT *code =
(const _Py_CODEUNIT *)PyBytes_AS_STRING(frame->f_code->co_code);
for (int i = 0; i < frame->f_lasti; i++) {
if (_Py_OPCODE(code[i]) == opcode && _Py_OPARG(code[i]) == oparg) {
return 1;
}
}
return 0;
}
int
_PyFrame_FastToLocalsWithError(InterpreterFrame *frame) {
/* Merge fast locals into f->f_locals */
PyObject *locals;
PyObject **fast;
PyCodeObject *co;
locals = frame->f_locals;
if (locals == NULL) {
locals = frame->f_locals = PyDict_New();
if (locals == NULL)
return -1;
}
co = frame->f_code;
fast = _PyFrame_GetLocalsArray(frame);
for (int i = 0; i < co->co_nlocalsplus; i++) {
_PyLocals_Kind kind = _PyLocals_GetKind(co->co_localspluskinds, i);
/* If the namespace is unoptimized, then one of the
following cases applies:
1. It does not contain free variables, because it
uses import * or is a top-level namespace.
2. It is a class namespace.
We don't want to accidentally copy free variables
into the locals dict used by the class.
*/
if (kind & CO_FAST_FREE && !(co->co_flags & CO_OPTIMIZED)) {
continue;
}
PyObject *name = PyTuple_GET_ITEM(co->co_localsplusnames, i);
PyObject *value = fast[i];
if (frame->f_state != FRAME_CLEARED) {
if (kind & CO_FAST_FREE) {
// The cell was set when the frame was created from
// the function's closure.
assert(value != NULL && PyCell_Check(value));
value = PyCell_GET(value);
}
else if (kind & CO_FAST_CELL) {
// Note that no *_DEREF ops can happen before MAKE_CELL
// executes. So there's no need to duplicate the work
// that MAKE_CELL would otherwise do later, if it hasn't
// run yet.
if (value != NULL) {
if (PyCell_Check(value) &&
_PyFrame_OpAlreadyRan(frame, MAKE_CELL, i)) {
// (likely) MAKE_CELL must have executed already.
value = PyCell_GET(value);
}
// (likely) Otherwise it it is an arg (kind & CO_FAST_LOCAL),
// with the initial value set when the frame was created...
// (unlikely) ...or it was set to some initial value by
// an earlier call to PyFrame_LocalsToFast().
}
}
}
else {
assert(value == NULL);
}
if (value == NULL) {
if (PyObject_DelItem(locals, name) != 0) {
if (PyErr_ExceptionMatches(PyExc_KeyError)) {
PyErr_Clear();
}
else {
return -1;
}
}
}
else {
if (PyObject_SetItem(locals, name, value) != 0) {
return -1;
}
}
}
return 0;
}
int
PyFrame_FastToLocalsWithError(PyFrameObject *f)
{
if (f == NULL) {
PyErr_BadInternalCall();
return -1;
}
return _PyFrame_FastToLocalsWithError(f->f_frame);
}
void
PyFrame_FastToLocals(PyFrameObject *f)
{
int res;
assert(!PyErr_Occurred());
res = PyFrame_FastToLocalsWithError(f);
if (res < 0)
PyErr_Clear();
}
void
_PyFrame_LocalsToFast(InterpreterFrame *frame, int clear)
{
/* Merge locals into fast locals */
PyObject *locals;
PyObject **fast;
PyObject *error_type, *error_value, *error_traceback;
PyCodeObject *co;
locals = frame->f_locals;
if (locals == NULL)
return;
fast = _PyFrame_GetLocalsArray(frame);
co = frame->f_code;
PyErr_Fetch(&error_type, &error_value, &error_traceback);
for (int i = 0; i < co->co_nlocalsplus; i++) {
_PyLocals_Kind kind = _PyLocals_GetKind(co->co_localspluskinds, i);
/* Same test as in PyFrame_FastToLocals() above. */
if (kind & CO_FAST_FREE && !(co->co_flags & CO_OPTIMIZED)) {
continue;
}
PyObject *name = PyTuple_GET_ITEM(co->co_localsplusnames, i);
PyObject *value = PyObject_GetItem(locals, name);
/* We only care about NULLs if clear is true. */
if (value == NULL) {
PyErr_Clear();
if (!clear) {
continue;
}
}
PyObject *oldvalue = fast[i];
PyObject *cell = NULL;
if (kind == CO_FAST_FREE) {
// The cell was set when the frame was created from
// the function's closure.
assert(oldvalue != NULL && PyCell_Check(oldvalue));
cell = oldvalue;
}
else if (kind & CO_FAST_CELL && oldvalue != NULL) {
/* Same test as in PyFrame_FastToLocals() above. */
if (PyCell_Check(oldvalue) &&
_PyFrame_OpAlreadyRan(frame, MAKE_CELL, i)) {
// (likely) MAKE_CELL must have executed already.
cell = oldvalue;
}
// (unlikely) Otherwise, it must have been set to some
// initial value by an earlier call to PyFrame_LocalsToFast().
}
if (cell != NULL) {
oldvalue = PyCell_GET(cell);
if (value != oldvalue) {
Py_XDECREF(oldvalue);
Py_XINCREF(value);
PyCell_SET(cell, value);
}
}
else if (value != oldvalue) {
Py_XINCREF(value);
Py_XSETREF(fast[i], value);
}
Py_XDECREF(value);
}
PyErr_Restore(error_type, error_value, error_traceback);
}
void
PyFrame_LocalsToFast(PyFrameObject *f, int clear)
{
if (f == NULL || f->f_frame->f_state == FRAME_CLEARED) {
return;
}
_PyFrame_LocalsToFast(f->f_frame, clear);
}
/* Clear out the free list */
void
_PyFrame_ClearFreeList(PyInterpreterState *interp)
{
struct _Py_frame_state *state = &interp->frame;
while (state->free_list != NULL) {
PyFrameObject *f = state->free_list;
state->free_list = state->free_list->f_back;
PyObject_GC_Del(f);
--state->numfree;
}
assert(state->numfree == 0);
}
void
_PyFrame_Fini(PyInterpreterState *interp)
{
_PyFrame_ClearFreeList(interp);
#ifdef Py_DEBUG
struct _Py_frame_state *state = &interp->frame;
state->numfree = -1;
#endif
}
/* Print summary info about the state of the optimized allocator */
void
_PyFrame_DebugMallocStats(FILE *out)
{
struct _Py_frame_state *state = get_frame_state();
_PyDebugAllocatorStats(out,
"free PyFrameObject",
state->numfree, sizeof(PyFrameObject));
}
PyCodeObject *
PyFrame_GetCode(PyFrameObject *frame)
{
assert(frame != NULL);
PyCodeObject *code = frame->f_frame->f_code;
assert(code != NULL);
Py_INCREF(code);
return code;
}
PyFrameObject*
PyFrame_GetBack(PyFrameObject *frame)
{
assert(frame != NULL);
PyFrameObject *back = frame->f_back;
if (back == NULL && frame->f_frame->previous != NULL) {
back = _PyFrame_GetFrameObject(frame->f_frame->previous);
}
Py_XINCREF(back);
return back;
}
PyObject*
_PyEval_BuiltinsFromGlobals(PyThreadState *tstate, PyObject *globals)
{
PyObject *builtins = _PyDict_GetItemIdWithError(globals, &PyId___builtins__);
if (builtins) {
if (PyModule_Check(builtins)) {
builtins = _PyModule_GetDict(builtins);
assert(builtins != NULL);
}
return builtins;
}
if (PyErr_Occurred()) {
return NULL;
}
return _PyEval_GetBuiltins(tstate);
}
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