void duk_hthread_callstack_unwind(duk_hthread *thr, int new_top) {
int idx; /* FIXME: typing of idx and new_top */
DUK_DDDPRINT("unwind callstack top of thread %p from %d to %d",
(void *) thr,
(thr != NULL ? (int) thr->callstack_top : (int) -1),
(int) new_top);
DUK_ASSERT(thr);
DUK_ASSERT(thr->heap);
DUK_ASSERT(new_top >= 0);
DUK_ASSERT((duk_size_t) new_top <= thr->callstack_top); /* cannot grow */
/*
* The loop below must avoid issues with potential callstack
* reallocations. A resize (and other side effects) may happen
* e.g. due to finalizer/errhandler calls caused by a refzero or
* mark-and-sweep. Arbitrary finalizers may run, because when
* an environment record is refzero'd, it may refer to arbitrary
* values which also become refzero'd.
*
* So, the pointer 'p' is re-looked-up below whenever a side effect
* might have changed it.
*/
idx = thr->callstack_top;
while (idx > new_top) {
duk_activation *p;
#ifdef DUK_USE_REFERENCE_COUNTING
duk_hobject *tmp;
#endif
idx--;
DUK_ASSERT(idx >= 0);
DUK_ASSERT((duk_size_t) idx < thr->callstack_size); /* true, despite side effect resizes */
p = &thr->callstack[idx];
DUK_ASSERT(p->func != NULL);
#ifdef DUK_USE_FUNC_NONSTD_CALLER_PROPERTY
/*
* Restore 'caller' property for non-strict callee functions.
*/
if (!DUK_HOBJECT_HAS_STRICT(p->func)) {
duk_tval *tv_caller;
duk_tval tv_tmp;
duk_hobject *h_tmp;
tv_caller = duk_hobject_find_existing_entry_tval_ptr(p->func, DUK_HTHREAD_STRING_CALLER(thr));
/* The p->prev_caller should only be set if the entry for 'caller'
* exists (as it is only set in that case, and the property is not
* configurable), but handle all the cases anyway.
*/
if (tv_caller) {
DUK_TVAL_SET_TVAL(&tv_tmp, tv_caller);
if (p->prev_caller) {
/* Just transfer the refcount from p->prev_caller to tv_caller,
* so no need for a refcount update. This is the expected case.
*/
DUK_TVAL_SET_OBJECT(tv_caller, p->prev_caller);
p->prev_caller = NULL;
} else {
DUK_TVAL_SET_NULL(tv_caller); /* no incref needed */
DUK_ASSERT(p->prev_caller == NULL);
}
DUK_TVAL_DECREF(thr, &tv_tmp); /* side effects */
} else {
h_tmp = p->prev_caller;
if (h_tmp) {
p->prev_caller = NULL;
DUK_HOBJECT_DECREF(thr, h_tmp); /* side effects */
}
}
p = &thr->callstack[idx]; /* avoid side effects */
DUK_ASSERT(p->prev_caller == NULL);
}
#endif
/*
* Close environment record(s) if they exist.
*
* Only variable environments are closed. If lex_env != var_env, it
* cannot currently contain any register bound declarations.
*
* Only environments created for a NEWENV function are closed. If an
* environment is created for e.g. an eval call, it must not be closed.
*/
if (!DUK_HOBJECT_HAS_NEWENV(p->func)) {
DUK_DDDPRINT("skip closing environments, envs not owned by this activation");
goto skip_env_close;
}
DUK_ASSERT(p->lex_env == p->var_env);
if (p->var_env != NULL) {
DUK_DDDPRINT("closing var_env record %p -> %!O",
(void *) p->var_env, (duk_heaphdr *) p->var_env);
duk_js_close_environment_record(thr, p->var_env, p->func, p->idx_bottom);
p = &thr->callstack[idx]; /* avoid side effect issues */
}
#if 0
if (p->lex_env != NULL) {
if (p->lex_env == p->var_env) {
/* common case, already closed, so skip */
DUK_DDPRINT("lex_env and var_env are the same and lex_env "
"already closed -> skip closing lex_env");
;
} else {
DUK_DDPRINT("closing lex_env record %p -> %!O",
(void *) p->lex_env, (duk_heaphdr *) p->lex_env);
duk_js_close_environment_record(thr, p->lex_env, p->func, p->idx_bottom);
p = &thr->callstack[idx]; /* avoid side effect issues */
}
}
#endif
DUK_ASSERT((p->lex_env == NULL) ||
((duk_hobject_find_existing_entry_tval_ptr(p->lex_env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(p->lex_env, DUK_HTHREAD_STRING_INT_VARMAP(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(p->lex_env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(p->lex_env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL)));
DUK_ASSERT((p->var_env == NULL) ||
((duk_hobject_find_existing_entry_tval_ptr(p->var_env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(p->var_env, DUK_HTHREAD_STRING_INT_VARMAP(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(p->var_env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(p->var_env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL)));
skip_env_close:
/*
* Update preventcount
*/
if (p->flags & DUK_ACT_FLAG_PREVENT_YIELD) {
DUK_ASSERT(thr->callstack_preventcount >= 1);
thr->callstack_preventcount--;
}
/*
* Reference count updates
*
* Note: careful manipulation of refcounts. The top is
* not updated yet, so all the activations are reachable
* for mark-and-sweep (which may be triggered by decref).
* However, the pointers are NULL so this is not an issue.
*/
#ifdef DUK_USE_REFERENCE_COUNTING
tmp = p->var_env;
#endif
p->var_env = NULL;
#ifdef DUK_USE_REFERENCE_COUNTING
DUK_HOBJECT_DECREF(thr, tmp);
p = &thr->callstack[idx]; /* avoid side effect issues */
#endif
#ifdef DUK_USE_REFERENCE_COUNTING
tmp = p->lex_env;
#endif
p->lex_env = NULL;
#ifdef DUK_USE_REFERENCE_COUNTING
DUK_HOBJECT_DECREF(thr, tmp);
p = &thr->callstack[idx]; /* avoid side effect issues */
#endif
/* Note: this may cause a corner case situation where a finalizer
* may see a currently reachable activation whose 'func' is NULL.
*/
#ifdef DUK_USE_REFERENCE_COUNTING
tmp = p->func;
#endif
p->func = NULL;
#ifdef DUK_USE_REFERENCE_COUNTING
DUK_HOBJECT_DECREF(thr, tmp);
p = &thr->callstack[idx]; /* avoid side effect issues */
#endif
}
thr->callstack_top = new_top;
/*
* We could clear the book-keeping variables for the topmost activation,
* but don't do so now.
*/
#if 0
if (thr->callstack_top > 0) {
duk_activation *p = thr->callstack + thr->callstack_top - 1;
p->idx_retval = -1;
}
#endif
/* Note: any entries above the callstack top are garbage and not zeroed.
* Also topmost activation idx_retval is garbage and not zeroed.
*/
}
DUK_INTERNAL void duk_hthread_callstack_unwind(duk_hthread *thr, duk_size_t new_top) {
duk_size_t idx;
DUK_DDD(DUK_DDDPRINT("unwind callstack top of thread %p from %ld to %ld",
(void *) thr,
(thr != NULL ? (long) thr->callstack_top : (long) -1),
(long) new_top));
DUK_ASSERT(thr);
DUK_ASSERT(thr->heap);
DUK_ASSERT_DISABLE(new_top >= 0); /* unsigned */
DUK_ASSERT((duk_size_t) new_top <= thr->callstack_top); /* cannot grow */
/*
* The loop below must avoid issues with potential callstack
* reallocations. A resize (and other side effects) may happen
* e.g. due to finalizer/errhandler calls caused by a refzero or
* mark-and-sweep. Arbitrary finalizers may run, because when
* an environment record is refzero'd, it may refer to arbitrary
* values which also become refzero'd.
*
* So, the pointer 'p' is re-looked-up below whenever a side effect
* might have changed it.
*/
idx = thr->callstack_top;
while (idx > new_top) {
duk_activation *act;
duk_hobject *func;
#ifdef DUK_USE_REFERENCE_COUNTING
duk_hobject *tmp;
#endif
#ifdef DUK_USE_DEBUGGER_SUPPORT
duk_heap *heap;
#endif
idx--;
DUK_ASSERT_DISABLE(idx >= 0); /* unsigned */
DUK_ASSERT((duk_size_t) idx < thr->callstack_size); /* true, despite side effect resizes */
act = thr->callstack + idx;
/* With lightfuncs, act 'func' may be NULL */
#ifdef DUK_USE_NONSTD_FUNC_CALLER_PROPERTY
/*
* Restore 'caller' property for non-strict callee functions.
*/
func = DUK_ACT_GET_FUNC(act);
if (func != NULL && !DUK_HOBJECT_HAS_STRICT(func)) {
duk_tval *tv_caller;
duk_tval tv_tmp;
duk_hobject *h_tmp;
tv_caller = duk_hobject_find_existing_entry_tval_ptr(thr->heap, func, DUK_HTHREAD_STRING_CALLER(thr));
/* The act->prev_caller should only be set if the entry for 'caller'
* exists (as it is only set in that case, and the property is not
* configurable), but handle all the cases anyway.
*/
if (tv_caller) {
DUK_TVAL_SET_TVAL(&tv_tmp, tv_caller);
if (act->prev_caller) {
/* Just transfer the refcount from act->prev_caller to tv_caller,
* so no need for a refcount update. This is the expected case.
*/
DUK_TVAL_SET_OBJECT(tv_caller, act->prev_caller);
act->prev_caller = NULL;
} else {
DUK_TVAL_SET_NULL(tv_caller); /* no incref needed */
DUK_ASSERT(act->prev_caller == NULL);
}
DUK_TVAL_DECREF(thr, &tv_tmp); /* side effects */
} else {
h_tmp = act->prev_caller;
if (h_tmp) {
act->prev_caller = NULL;
DUK_HOBJECT_DECREF(thr, h_tmp); /* side effects */
}
}
act = thr->callstack + idx; /* avoid side effects */
DUK_ASSERT(act->prev_caller == NULL);
}
#endif
/*
* Unwind debugger state. If we unwind while stepping
* (either step over or step into), pause execution.
*/
#if defined(DUK_USE_DEBUGGER_SUPPORT)
heap = thr->heap;
if (heap->dbg_step_thread == thr &&
heap->dbg_step_csindex == idx) {
/* Pause for all step types: step into, step over, step out.
* This is the only place explicitly handling a step out.
*/
DUK_HEAP_SET_PAUSED(heap);
DUK_ASSERT(heap->dbg_step_thread == NULL);
}
#endif
/*
* Close environment record(s) if they exist.
*
* Only variable environments are closed. If lex_env != var_env, it
* cannot currently contain any register bound declarations.
*
* Only environments created for a NEWENV function are closed. If an
* environment is created for e.g. an eval call, it must not be closed.
*/
func = DUK_ACT_GET_FUNC(act);
if (func != NULL && !DUK_HOBJECT_HAS_NEWENV(func)) {
DUK_DDD(DUK_DDDPRINT("skip closing environments, envs not owned by this activation"));
goto skip_env_close;
}
/* func is NULL for lightfunc */
DUK_ASSERT(act->lex_env == act->var_env);
if (act->var_env != NULL) {
DUK_DDD(DUK_DDDPRINT("closing var_env record %p -> %!O",
(void *) act->var_env, (duk_heaphdr *) act->var_env));
duk_js_close_environment_record(thr, act->var_env, func, act->idx_bottom);
act = thr->callstack + idx; /* avoid side effect issues */
}
#if 0
if (act->lex_env != NULL) {
if (act->lex_env == act->var_env) {
/* common case, already closed, so skip */
DUK_DD(DUK_DDPRINT("lex_env and var_env are the same and lex_env "
"already closed -> skip closing lex_env"));
;
} else {
DUK_DD(DUK_DDPRINT("closing lex_env record %p -> %!O",
(void *) act->lex_env, (duk_heaphdr *) act->lex_env));
duk_js_close_environment_record(thr, act->lex_env, DUK_ACT_GET_FUNC(act), act->idx_bottom);
act = thr->callstack + idx; /* avoid side effect issues */
}
}
#endif
DUK_ASSERT((act->lex_env == NULL) ||
((duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_VARMAP(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL)));
DUK_ASSERT((act->var_env == NULL) ||
((duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_VARMAP(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL) &&
(duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL)));
skip_env_close:
/*
* Update preventcount
*/
if (act->flags & DUK_ACT_FLAG_PREVENT_YIELD) {
DUK_ASSERT(thr->callstack_preventcount >= 1);
thr->callstack_preventcount--;
}
/*
* Reference count updates
*
* Note: careful manipulation of refcounts. The top is
* not updated yet, so all the activations are reachable
* for mark-and-sweep (which may be triggered by decref).
* However, the pointers are NULL so this is not an issue.
*/
#ifdef DUK_USE_REFERENCE_COUNTING
tmp = act->var_env;
#endif
act->var_env = NULL;
#ifdef DUK_USE_REFERENCE_COUNTING
DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
act = thr->callstack + idx; /* avoid side effect issues */
#endif
#ifdef DUK_USE_REFERENCE_COUNTING
tmp = act->lex_env;
#endif
act->lex_env = NULL;
#ifdef DUK_USE_REFERENCE_COUNTING
DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
act = thr->callstack + idx; /* avoid side effect issues */
#endif
/* Note: this may cause a corner case situation where a finalizer
* may see a currently reachable activation whose 'func' is NULL.
*/
#ifdef DUK_USE_REFERENCE_COUNTING
tmp = DUK_ACT_GET_FUNC(act);
#endif
act->func = NULL;
#ifdef DUK_USE_REFERENCE_COUNTING
DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
act = thr->callstack + idx; /* avoid side effect issues */
DUK_UNREF(act);
#endif
}
thr->callstack_top = new_top;
/*
* We could clear the book-keeping variables for the topmost activation,
* but don't do so now.
*/
#if 0
if (thr->callstack_top > 0) {
duk_activation *act = thr->callstack + thr->callstack_top - 1;
act->idx_retval = 0;
}
#endif
/* Note: any entries above the callstack top are garbage and not zeroed.
* Also topmost activation idx_retval is garbage (not zeroed), and must
* be ignored.
*/
}