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5743 lines (5143 loc) · 178 KB
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/* Execute compiled code */
/* XXX TO DO:
XXX speed up searching for keywords by using a dictionary
XXX document it!
*/
/* enable more aggressive intra-module optimizations, where available */
#define PY_LOCAL_AGGRESSIVE
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_call.h" // _PyObject_FastCallDictTstate()
#include "pycore_ceval.h" // _PyEval_SignalAsyncExc()
#include "pycore_code.h" // _PyCode_InitOpcache()
#include "pycore_initconfig.h" // _PyStatus_OK()
#include "pycore_object.h" // _PyObject_GC_TRACK()
#include "pycore_pyerrors.h" // _PyErr_Fetch()
#include "pycore_pylifecycle.h" // _PyErr_Print()
#include "pycore_pymem.h" // _PyMem_IsPtrFreed()
#include "pycore_pystate.h" // _PyInterpreterState_GET()
#include "pycore_sysmodule.h" // _PySys_Audit()
#include "pycore_tuple.h" // _PyTuple_ITEMS()
#include "code.h"
#include "dictobject.h"
#include "frameobject.h"
#include "opcode.h"
#include "pydtrace.h"
#include "setobject.h"
#include <ctype.h>
#ifdef Py_DEBUG
/* For debugging the interpreter: */
#define LLTRACE 1 /* Low-level trace feature */
#define CHECKEXC 1 /* Double-check exception checking */
#endif
#if !defined(Py_BUILD_CORE)
# error "ceval.c must be build with Py_BUILD_CORE define for best performance"
#endif
_Py_IDENTIFIER(__name__);
/* Forward declarations */
Py_LOCAL_INLINE(PyObject *) call_function(
PyThreadState *tstate, PyObject ***pp_stack,
Py_ssize_t oparg, PyObject *kwnames);
static PyObject * do_call_core(
PyThreadState *tstate, PyObject *func,
PyObject *callargs, PyObject *kwdict);
#ifdef LLTRACE
static int lltrace;
static int prtrace(PyThreadState *, PyObject *, const char *);
#endif
static int call_trace(Py_tracefunc, PyObject *,
PyThreadState *, PyFrameObject *,
int, PyObject *);
static int call_trace_protected(Py_tracefunc, PyObject *,
PyThreadState *, PyFrameObject *,
int, PyObject *);
static void call_exc_trace(Py_tracefunc, PyObject *,
PyThreadState *, PyFrameObject *);
static int maybe_call_line_trace(Py_tracefunc, PyObject *,
PyThreadState *, PyFrameObject *,
int *, int *, int *);
static void maybe_dtrace_line(PyFrameObject *, int *, int *, int *);
static void dtrace_function_entry(PyFrameObject *);
static void dtrace_function_return(PyFrameObject *);
static PyObject * import_name(PyThreadState *, PyFrameObject *,
PyObject *, PyObject *, PyObject *);
static PyObject * import_from(PyThreadState *, PyObject *, PyObject *);
static int import_all_from(PyThreadState *, PyObject *, PyObject *);
static void format_exc_check_arg(PyThreadState *, PyObject *, const char *, PyObject *);
static void format_exc_unbound(PyThreadState *tstate, PyCodeObject *co, int oparg);
static PyObject * unicode_concatenate(PyThreadState *, PyObject *, PyObject *,
PyFrameObject *, const _Py_CODEUNIT *);
static PyObject * special_lookup(PyThreadState *, PyObject *, _Py_Identifier *);
static int check_args_iterable(PyThreadState *, PyObject *func, PyObject *vararg);
static void format_kwargs_error(PyThreadState *, PyObject *func, PyObject *kwargs);
static void format_awaitable_error(PyThreadState *, PyTypeObject *, int, int);
#define NAME_ERROR_MSG \
"name '%.200s' is not defined"
#define UNBOUNDLOCAL_ERROR_MSG \
"local variable '%.200s' referenced before assignment"
#define UNBOUNDFREE_ERROR_MSG \
"free variable '%.200s' referenced before assignment" \
" in enclosing scope"
/* Dynamic execution profile */
#ifdef DYNAMIC_EXECUTION_PROFILE
#ifdef DXPAIRS
static long dxpairs[257][256];
#define dxp dxpairs[256]
#else
static long dxp[256];
#endif
#endif
/* per opcode cache */
#ifdef Py_DEBUG
// --with-pydebug is used to find memory leak. opcache makes it harder.
// So we disable opcache when Py_DEBUG is defined.
// See bpo-37146
#define OPCACHE_MIN_RUNS 0 /* disable opcache */
#else
#define OPCACHE_MIN_RUNS 1024 /* create opcache when code executed this time */
#endif
#define OPCACHE_STATS 0 /* Enable stats */
#if OPCACHE_STATS
static size_t opcache_code_objects = 0;
static size_t opcache_code_objects_extra_mem = 0;
static size_t opcache_global_opts = 0;
static size_t opcache_global_hits = 0;
static size_t opcache_global_misses = 0;
#endif
#ifndef NDEBUG
/* Ensure that tstate is valid: sanity check for PyEval_AcquireThread() and
PyEval_RestoreThread(). Detect if tstate memory was freed. It can happen
when a thread continues to run after Python finalization, especially
daemon threads. */
static int
is_tstate_valid(PyThreadState *tstate)
{
assert(!_PyMem_IsPtrFreed(tstate));
assert(!_PyMem_IsPtrFreed(tstate->interp));
return 1;
}
#endif
/* This can set eval_breaker to 0 even though gil_drop_request became
1. We believe this is all right because the eval loop will release
the GIL eventually anyway. */
static inline void
COMPUTE_EVAL_BREAKER(PyInterpreterState *interp,
struct _ceval_runtime_state *ceval,
struct _ceval_state *ceval2)
{
_Py_atomic_store_relaxed(&ceval2->eval_breaker,
_Py_atomic_load_relaxed(&ceval2->gil_drop_request)
| (_Py_atomic_load_relaxed(&ceval->signals_pending)
&& _Py_ThreadCanHandleSignals(interp))
| (_Py_atomic_load_relaxed(&ceval2->pending.calls_to_do)
&& _Py_ThreadCanHandlePendingCalls())
| ceval2->pending.async_exc);
}
static inline void
SET_GIL_DROP_REQUEST(PyInterpreterState *interp)
{
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval2->gil_drop_request, 1);
_Py_atomic_store_relaxed(&ceval2->eval_breaker, 1);
}
static inline void
RESET_GIL_DROP_REQUEST(PyInterpreterState *interp)
{
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval2->gil_drop_request, 0);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
SIGNAL_PENDING_CALLS(PyInterpreterState *interp)
{
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval2->pending.calls_to_do, 1);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
UNSIGNAL_PENDING_CALLS(PyInterpreterState *interp)
{
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval2->pending.calls_to_do, 0);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
SIGNAL_PENDING_SIGNALS(PyInterpreterState *interp)
{
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval->signals_pending, 1);
/* eval_breaker is not set to 1 if thread_can_handle_signals() is false */
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
UNSIGNAL_PENDING_SIGNALS(PyInterpreterState *interp)
{
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval->signals_pending, 0);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
SIGNAL_ASYNC_EXC(PyInterpreterState *interp)
{
struct _ceval_state *ceval2 = &interp->ceval;
ceval2->pending.async_exc = 1;
_Py_atomic_store_relaxed(&ceval2->eval_breaker, 1);
}
static inline void
UNSIGNAL_ASYNC_EXC(PyInterpreterState *interp)
{
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
ceval2->pending.async_exc = 0;
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include "ceval_gil.h"
void _Py_NO_RETURN
_Py_FatalError_TstateNULL(const char *func)
{
_Py_FatalErrorFunc(func,
"the function must be called with the GIL held, "
"but the GIL is released "
"(the current Python thread state is NULL)");
}
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
int
_PyEval_ThreadsInitialized(PyInterpreterState *interp)
{
return gil_created(&interp->ceval.gil);
}
int
PyEval_ThreadsInitialized(void)
{
// Fatal error if there is no current interpreter
PyInterpreterState *interp = PyInterpreterState_Get();
return _PyEval_ThreadsInitialized(interp);
}
#else
int
_PyEval_ThreadsInitialized(_PyRuntimeState *runtime)
{
return gil_created(&runtime->ceval.gil);
}
int
PyEval_ThreadsInitialized(void)
{
_PyRuntimeState *runtime = &_PyRuntime;
return _PyEval_ThreadsInitialized(runtime);
}
#endif
PyStatus
_PyEval_InitGIL(PyThreadState *tstate)
{
#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
if (!_Py_IsMainInterpreter(tstate)) {
/* Currently, the GIL is shared by all interpreters,
and only the main interpreter is responsible to create
and destroy it. */
return _PyStatus_OK();
}
#endif
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
struct _gil_runtime_state *gil = &tstate->interp->ceval.gil;
#else
struct _gil_runtime_state *gil = &tstate->interp->runtime->ceval.gil;
#endif
assert(!gil_created(gil));
PyThread_init_thread();
create_gil(gil);
take_gil(tstate);
assert(gil_created(gil));
return _PyStatus_OK();
}
void
_PyEval_FiniGIL(PyThreadState *tstate)
{
#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
if (!_Py_IsMainInterpreter(tstate)) {
/* Currently, the GIL is shared by all interpreters,
and only the main interpreter is responsible to create
and destroy it. */
return;
}
#endif
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
struct _gil_runtime_state *gil = &tstate->interp->ceval.gil;
#else
struct _gil_runtime_state *gil = &tstate->interp->runtime->ceval.gil;
#endif
if (!gil_created(gil)) {
/* First Py_InitializeFromConfig() call: the GIL doesn't exist
yet: do nothing. */
return;
}
destroy_gil(gil);
assert(!gil_created(gil));
}
void
PyEval_InitThreads(void)
{
/* Do nothing: kept for backward compatibility */
}
void
_PyEval_Fini(void)
{
#if OPCACHE_STATS
fprintf(stderr, "-- Opcode cache number of objects = %zd\n",
opcache_code_objects);
fprintf(stderr, "-- Opcode cache total extra mem = %zd\n",
opcache_code_objects_extra_mem);
fprintf(stderr, "\n");
fprintf(stderr, "-- Opcode cache LOAD_GLOBAL hits = %zd (%d%%)\n",
opcache_global_hits,
(int) (100.0 * opcache_global_hits /
(opcache_global_hits + opcache_global_misses)));
fprintf(stderr, "-- Opcode cache LOAD_GLOBAL misses = %zd (%d%%)\n",
opcache_global_misses,
(int) (100.0 * opcache_global_misses /
(opcache_global_hits + opcache_global_misses)));
fprintf(stderr, "-- Opcode cache LOAD_GLOBAL opts = %zd\n",
opcache_global_opts);
fprintf(stderr, "\n");
#endif
}
void
PyEval_AcquireLock(void)
{
_PyRuntimeState *runtime = &_PyRuntime;
PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
_Py_EnsureTstateNotNULL(tstate);
take_gil(tstate);
}
void
PyEval_ReleaseLock(void)
{
_PyRuntimeState *runtime = &_PyRuntime;
PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
/* This function must succeed when the current thread state is NULL.
We therefore avoid PyThreadState_Get() which dumps a fatal error
in debug mode. */
struct _ceval_runtime_state *ceval = &runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
drop_gil(ceval, ceval2, tstate);
}
void
_PyEval_ReleaseLock(PyThreadState *tstate)
{
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
drop_gil(ceval, ceval2, tstate);
}
void
PyEval_AcquireThread(PyThreadState *tstate)
{
_Py_EnsureTstateNotNULL(tstate);
take_gil(tstate);
struct _gilstate_runtime_state *gilstate = &tstate->interp->runtime->gilstate;
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
(void)_PyThreadState_Swap(gilstate, tstate);
#else
if (_PyThreadState_Swap(gilstate, tstate) != NULL) {
Py_FatalError("non-NULL old thread state");
}
#endif
}
void
PyEval_ReleaseThread(PyThreadState *tstate)
{
assert(is_tstate_valid(tstate));
_PyRuntimeState *runtime = tstate->interp->runtime;
PyThreadState *new_tstate = _PyThreadState_Swap(&runtime->gilstate, NULL);
if (new_tstate != tstate) {
Py_FatalError("wrong thread state");
}
struct _ceval_runtime_state *ceval = &runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
drop_gil(ceval, ceval2, tstate);
}
#ifdef HAVE_FORK
/* This function is called from PyOS_AfterFork_Child to destroy all threads
which are not running in the child process, and clear internal locks
which might be held by those threads. */
PyStatus
_PyEval_ReInitThreads(PyThreadState *tstate)
{
_PyRuntimeState *runtime = tstate->interp->runtime;
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
struct _gil_runtime_state *gil = &tstate->interp->ceval.gil;
#else
struct _gil_runtime_state *gil = &runtime->ceval.gil;
#endif
if (!gil_created(gil)) {
return _PyStatus_OK();
}
recreate_gil(gil);
take_gil(tstate);
struct _pending_calls *pending = &tstate->interp->ceval.pending;
if (_PyThread_at_fork_reinit(&pending->lock) < 0) {
return _PyStatus_ERR("Can't reinitialize pending calls lock");
}
/* Destroy all threads except the current one */
_PyThreadState_DeleteExcept(runtime, tstate);
return _PyStatus_OK();
}
#endif
/* This function is used to signal that async exceptions are waiting to be
raised. */
void
_PyEval_SignalAsyncExc(PyThreadState *tstate)
{
assert(is_tstate_valid(tstate));
SIGNAL_ASYNC_EXC(tstate->interp);
}
PyThreadState *
PyEval_SaveThread(void)
{
_PyRuntimeState *runtime = &_PyRuntime;
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
PyThreadState *old_tstate = _PyThreadState_GET();
PyThreadState *tstate = _PyThreadState_Swap(&runtime->gilstate, old_tstate);
#else
PyThreadState *tstate = _PyThreadState_Swap(&runtime->gilstate, NULL);
#endif
_Py_EnsureTstateNotNULL(tstate);
struct _ceval_runtime_state *ceval = &runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
assert(gil_created(&ceval2->gil));
#else
assert(gil_created(&ceval->gil));
#endif
drop_gil(ceval, ceval2, tstate);
return tstate;
}
void
PyEval_RestoreThread(PyThreadState *tstate)
{
_Py_EnsureTstateNotNULL(tstate);
take_gil(tstate);
struct _gilstate_runtime_state *gilstate = &tstate->interp->runtime->gilstate;
_PyThreadState_Swap(gilstate, tstate);
}
/* Mechanism whereby asynchronously executing callbacks (e.g. UNIX
signal handlers or Mac I/O completion routines) can schedule calls
to a function to be called synchronously.
The synchronous function is called with one void* argument.
It should return 0 for success or -1 for failure -- failure should
be accompanied by an exception.
If registry succeeds, the registry function returns 0; if it fails
(e.g. due to too many pending calls) it returns -1 (without setting
an exception condition).
Note that because registry may occur from within signal handlers,
or other asynchronous events, calling malloc() is unsafe!
Any thread can schedule pending calls, but only the main thread
will execute them.
There is no facility to schedule calls to a particular thread, but
that should be easy to change, should that ever be required. In
that case, the static variables here should go into the python
threadstate.
*/
void
_PyEval_SignalReceived(PyInterpreterState *interp)
{
/* bpo-30703: Function called when the C signal handler of Python gets a
signal. We cannot queue a callback using _PyEval_AddPendingCall() since
that function is not async-signal-safe. */
SIGNAL_PENDING_SIGNALS(interp);
}
/* Push one item onto the queue while holding the lock. */
static int
_push_pending_call(struct _pending_calls *pending,
int (*func)(void *), void *arg)
{
int i = pending->last;
int j = (i + 1) % NPENDINGCALLS;
if (j == pending->first) {
return -1; /* Queue full */
}
pending->calls[i].func = func;
pending->calls[i].arg = arg;
pending->last = j;
return 0;
}
/* Pop one item off the queue while holding the lock. */
static void
_pop_pending_call(struct _pending_calls *pending,
int (**func)(void *), void **arg)
{
int i = pending->first;
if (i == pending->last) {
return; /* Queue empty */
}
*func = pending->calls[i].func;
*arg = pending->calls[i].arg;
pending->first = (i + 1) % NPENDINGCALLS;
}
/* This implementation is thread-safe. It allows
scheduling to be made from any thread, and even from an executing
callback.
*/
int
_PyEval_AddPendingCall(PyInterpreterState *interp,
int (*func)(void *), void *arg)
{
struct _pending_calls *pending = &interp->ceval.pending;
/* Ensure that _PyEval_InitPendingCalls() was called
and that _PyEval_FiniPendingCalls() is not called yet. */
assert(pending->lock != NULL);
PyThread_acquire_lock(pending->lock, WAIT_LOCK);
int result = _push_pending_call(pending, func, arg);
PyThread_release_lock(pending->lock);
/* signal main loop */
SIGNAL_PENDING_CALLS(interp);
return result;
}
int
Py_AddPendingCall(int (*func)(void *), void *arg)
{
/* Best-effort to support subinterpreters and calls with the GIL released.
First attempt _PyThreadState_GET() since it supports subinterpreters.
If the GIL is released, _PyThreadState_GET() returns NULL . In this
case, use PyGILState_GetThisThreadState() which works even if the GIL
is released.
Sadly, PyGILState_GetThisThreadState() doesn't support subinterpreters:
see bpo-10915 and bpo-15751.
Py_AddPendingCall() doesn't require the caller to hold the GIL. */
PyThreadState *tstate = _PyThreadState_GET();
if (tstate == NULL) {
tstate = PyGILState_GetThisThreadState();
}
PyInterpreterState *interp;
if (tstate != NULL) {
interp = tstate->interp;
}
else {
/* Last resort: use the main interpreter */
interp = _PyRuntime.interpreters.main;
}
return _PyEval_AddPendingCall(interp, func, arg);
}
static int
handle_signals(PyThreadState *tstate)
{
assert(is_tstate_valid(tstate));
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
return 0;
}
UNSIGNAL_PENDING_SIGNALS(tstate->interp);
if (_PyErr_CheckSignalsTstate(tstate) < 0) {
/* On failure, re-schedule a call to handle_signals(). */
SIGNAL_PENDING_SIGNALS(tstate->interp);
return -1;
}
return 0;
}
static int
make_pending_calls(PyThreadState *tstate)
{
assert(is_tstate_valid(tstate));
/* only execute pending calls on main thread */
if (!_Py_ThreadCanHandlePendingCalls()) {
return 0;
}
/* don't perform recursive pending calls */
static int busy = 0;
if (busy) {
return 0;
}
busy = 1;
/* unsignal before starting to call callbacks, so that any callback
added in-between re-signals */
UNSIGNAL_PENDING_CALLS(tstate->interp);
int res = 0;
/* perform a bounded number of calls, in case of recursion */
struct _pending_calls *pending = &tstate->interp->ceval.pending;
for (int i=0; i<NPENDINGCALLS; i++) {
int (*func)(void *) = NULL;
void *arg = NULL;
/* pop one item off the queue while holding the lock */
PyThread_acquire_lock(pending->lock, WAIT_LOCK);
_pop_pending_call(pending, &func, &arg);
PyThread_release_lock(pending->lock);
/* having released the lock, perform the callback */
if (func == NULL) {
break;
}
res = func(arg);
if (res) {
goto error;
}
}
busy = 0;
return res;
error:
busy = 0;
SIGNAL_PENDING_CALLS(tstate->interp);
return res;
}
void
_Py_FinishPendingCalls(PyThreadState *tstate)
{
assert(PyGILState_Check());
struct _pending_calls *pending = &tstate->interp->ceval.pending;
if (!_Py_atomic_load_relaxed(&(pending->calls_to_do))) {
return;
}
if (make_pending_calls(tstate) < 0) {
PyObject *exc, *val, *tb;
_PyErr_Fetch(tstate, &exc, &val, &tb);
PyErr_BadInternalCall();
_PyErr_ChainExceptions(exc, val, tb);
_PyErr_Print(tstate);
}
}
/* Py_MakePendingCalls() is a simple wrapper for the sake
of backward-compatibility. */
int
Py_MakePendingCalls(void)
{
assert(PyGILState_Check());
PyThreadState *tstate = _PyThreadState_GET();
/* Python signal handler doesn't really queue a callback: it only signals
that a signal was received, see _PyEval_SignalReceived(). */
int res = handle_signals(tstate);
if (res != 0) {
return res;
}
res = make_pending_calls(tstate);
if (res != 0) {
return res;
}
return 0;
}
/* The interpreter's recursion limit */
#ifndef Py_DEFAULT_RECURSION_LIMIT
#define Py_DEFAULT_RECURSION_LIMIT 1000
#endif
int _Py_CheckRecursionLimit = Py_DEFAULT_RECURSION_LIMIT;
void
_PyEval_InitRuntimeState(struct _ceval_runtime_state *ceval)
{
_Py_CheckRecursionLimit = Py_DEFAULT_RECURSION_LIMIT;
#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
_gil_initialize(&ceval->gil);
#endif
}
int
_PyEval_InitState(struct _ceval_state *ceval)
{
ceval->recursion_limit = Py_DEFAULT_RECURSION_LIMIT;
struct _pending_calls *pending = &ceval->pending;
assert(pending->lock == NULL);
pending->lock = PyThread_allocate_lock();
if (pending->lock == NULL) {
return -1;
}
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
_gil_initialize(&ceval->gil);
#endif
return 0;
}
void
_PyEval_FiniState(struct _ceval_state *ceval)
{
struct _pending_calls *pending = &ceval->pending;
if (pending->lock != NULL) {
PyThread_free_lock(pending->lock);
pending->lock = NULL;
}
}
int
Py_GetRecursionLimit(void)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
return interp->ceval.recursion_limit;
}
void
Py_SetRecursionLimit(int new_limit)
{
PyThreadState *tstate = _PyThreadState_GET();
tstate->interp->ceval.recursion_limit = new_limit;
if (_Py_IsMainInterpreter(tstate)) {
_Py_CheckRecursionLimit = new_limit;
}
}
/* The function _Py_EnterRecursiveCall() only calls _Py_CheckRecursiveCall()
if the recursion_depth reaches _Py_CheckRecursionLimit.
If USE_STACKCHECK, the macro decrements _Py_CheckRecursionLimit
to guarantee that _Py_CheckRecursiveCall() is regularly called.
Without USE_STACKCHECK, there is no need for this. */
int
_Py_CheckRecursiveCall(PyThreadState *tstate, const char *where)
{
int recursion_limit = tstate->interp->ceval.recursion_limit;
#ifdef USE_STACKCHECK
tstate->stackcheck_counter = 0;
if (PyOS_CheckStack()) {
--tstate->recursion_depth;
_PyErr_SetString(tstate, PyExc_MemoryError, "Stack overflow");
return -1;
}
if (_Py_IsMainInterpreter(tstate)) {
/* Needed for ABI backwards-compatibility (see bpo-31857) */
_Py_CheckRecursionLimit = recursion_limit;
}
#endif
if (tstate->recursion_critical)
/* Somebody asked that we don't check for recursion. */
return 0;
if (tstate->overflowed) {
if (tstate->recursion_depth > recursion_limit + 50) {
/* Overflowing while handling an overflow. Give up. */
Py_FatalError("Cannot recover from stack overflow.");
}
return 0;
}
if (tstate->recursion_depth > recursion_limit) {
--tstate->recursion_depth;
tstate->overflowed = 1;
_PyErr_Format(tstate, PyExc_RecursionError,
"maximum recursion depth exceeded%s",
where);
return -1;
}
return 0;
}
static int do_raise(PyThreadState *tstate, PyObject *exc, PyObject *cause);
static int unpack_iterable(PyThreadState *, PyObject *, int, int, PyObject **);
#define _Py_TracingPossible(ceval) ((ceval)->tracing_possible)
PyObject *
PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals)
{
return PyEval_EvalCodeEx(co,
globals, locals,
(PyObject **)NULL, 0,
(PyObject **)NULL, 0,
(PyObject **)NULL, 0,
NULL, NULL);
}
/* Interpreter main loop */
PyObject *
PyEval_EvalFrame(PyFrameObject *f)
{
/* Function kept for backward compatibility */
PyThreadState *tstate = _PyThreadState_GET();
return _PyEval_EvalFrame(tstate, f, 0);
}
PyObject *
PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
{
PyThreadState *tstate = _PyThreadState_GET();
return _PyEval_EvalFrame(tstate, f, throwflag);
}
/* Handle signals, pending calls, GIL drop request
and asynchronous exception */
static int
eval_frame_handle_pending(PyThreadState *tstate)
{
_PyRuntimeState * const runtime = &_PyRuntime;
struct _ceval_runtime_state *ceval = &runtime->ceval;
/* Pending signals */
if (_Py_atomic_load_relaxed(&ceval->signals_pending)) {
if (handle_signals(tstate) != 0) {
return -1;
}
}
/* Pending calls */
struct _ceval_state *ceval2 = &tstate->interp->ceval;
if (_Py_atomic_load_relaxed(&ceval2->pending.calls_to_do)) {
if (make_pending_calls(tstate) != 0) {
return -1;
}
}
/* GIL drop request */
if (_Py_atomic_load_relaxed(&ceval2->gil_drop_request)) {
/* Give another thread a chance */
if (_PyThreadState_Swap(&runtime->gilstate, NULL) != tstate) {
Py_FatalError("tstate mix-up");
}
drop_gil(ceval, ceval2, tstate);
/* Other threads may run now */
take_gil(tstate);
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
(void)_PyThreadState_Swap(&runtime->gilstate, tstate);
#else
if (_PyThreadState_Swap(&runtime->gilstate, tstate) != NULL) {
Py_FatalError("orphan tstate");
}
#endif
}
/* Check for asynchronous exception. */
if (tstate->async_exc != NULL) {
PyObject *exc = tstate->async_exc;
tstate->async_exc = NULL;
UNSIGNAL_ASYNC_EXC(tstate->interp);
_PyErr_SetNone(tstate, exc);
Py_DECREF(exc);
return -1;
}
return 0;
}
PyObject* _Py_HOT_FUNCTION
_PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
{
_Py_EnsureTstateNotNULL(tstate);
#ifdef DXPAIRS
int lastopcode = 0;
#endif
PyObject **stack_pointer; /* Next free slot in value stack */
const _Py_CODEUNIT *next_instr;
int opcode; /* Current opcode */
int oparg; /* Current opcode argument, if any */
PyObject **fastlocals, **freevars;
PyObject *retval = NULL; /* Return value */
struct _ceval_state * const ceval2 = &tstate->interp->ceval;
_Py_atomic_int * const eval_breaker = &ceval2->eval_breaker;
PyCodeObject *co;
/* when tracing we set things up so that
not (instr_lb <= current_bytecode_offset < instr_ub)
is true when the line being executed has changed. The
initial values are such as to make this false the first
time it is tested. */
int instr_ub = -1, instr_lb = 0, instr_prev = -1;
const _Py_CODEUNIT *first_instr;
PyObject *names;
PyObject *consts;
_PyOpcache *co_opcache;
#ifdef LLTRACE
_Py_IDENTIFIER(__ltrace__);
#endif
/* Computed GOTOs, or
the-optimization-commonly-but-improperly-known-as-"threaded code"
using gcc's labels-as-values extension
(http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html).
The traditional bytecode evaluation loop uses a "switch" statement, which
decent compilers will optimize as a single indirect branch instruction
combined with a lookup table of jump addresses. However, since the
indirect jump instruction is shared by all opcodes, the CPU will have a
hard time making the right prediction for where to jump next (actually,
it will be always wrong except in the uncommon case of a sequence of
several identical opcodes).
"Threaded code" in contrast, uses an explicit jump table and an explicit
indirect jump instruction at the end of each opcode. Since the jump
instruction is at a different address for each opcode, the CPU will make a
separate prediction for each of these instructions, which is equivalent to
predicting the second opcode of each opcode pair. These predictions have
a much better chance to turn out valid, especially in small bytecode loops.
A mispredicted branch on a modern CPU flushes the whole pipeline and
can cost several CPU cycles (depending on the pipeline depth),
and potentially many more instructions (depending on the pipeline width).
A correctly predicted branch, however, is nearly free.
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