OVMS3/OVMS.V3/components/duktape/src-separate/duk_hthread_stacks.c

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/*
* Thread stack (mainly call stack) primitives: allocation of activations,
* unwinding catchers and activations, etc.
*
* Value stack handling is a part of the API implementation.
*/
#include "duk_internal.h"
/* Unwind the topmost catcher of the current activation (caller must check that
* both exist) without side effects.
*/
DUK_INTERNAL void duk_hthread_catcher_unwind_norz(duk_hthread *thr, duk_activation *act) {
duk_catcher *cat;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(act != NULL);
DUK_ASSERT(act->cat != NULL); /* caller must check */
cat = act->cat;
DUK_ASSERT(cat != NULL);
DUK_DDD(DUK_DDDPRINT("unwinding catch stack entry %p (lexenv check is done)", (void *) cat));
if (DUK_CAT_HAS_LEXENV_ACTIVE(cat)) {
duk_hobject *env;
env = act->lex_env; /* current lex_env of the activation (created for catcher) */
DUK_ASSERT(env != NULL); /* must be, since env was created when catcher was created */
act->lex_env = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, env); /* prototype is lex_env before catcher created */
DUK_HOBJECT_INCREF(thr, act->lex_env);
DUK_HOBJECT_DECREF_NORZ(thr, env);
/* There is no need to decref anything else than 'env': if 'env'
* becomes unreachable, refzero will handle decref'ing its prototype.
*/
}
act->cat = cat->parent;
duk_hthread_catcher_free(thr, cat);
}
/* Same as above, but caller is certain no catcher-related lexenv may exist. */
DUK_INTERNAL void duk_hthread_catcher_unwind_nolexenv_norz(duk_hthread *thr, duk_activation *act) {
duk_catcher *cat;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(act != NULL);
DUK_ASSERT(act->cat != NULL); /* caller must check */
cat = act->cat;
DUK_ASSERT(cat != NULL);
DUK_DDD(DUK_DDDPRINT("unwinding catch stack entry %p (lexenv check is not done)", (void *) cat));
DUK_ASSERT(!DUK_CAT_HAS_LEXENV_ACTIVE(cat));
act->cat = cat->parent;
duk_hthread_catcher_free(thr, cat);
}
DUK_LOCAL
#if defined(DUK_USE_CACHE_CATCHER)
DUK_NOINLINE
#endif
duk_catcher *duk__hthread_catcher_alloc_slow(duk_hthread *thr) {
duk_catcher *cat;
cat = (duk_catcher *) DUK_ALLOC_CHECKED(thr, sizeof(duk_catcher));
DUK_ASSERT(cat != NULL);
return cat;
}
#if defined(DUK_USE_CACHE_CATCHER)
DUK_INTERNAL DUK_INLINE duk_catcher *duk_hthread_catcher_alloc(duk_hthread *thr) {
duk_catcher *cat;
DUK_ASSERT(thr != NULL);
cat = thr->heap->catcher_free;
if (DUK_LIKELY(cat != NULL)) {
thr->heap->catcher_free = cat->parent;
return cat;
}
return duk__hthread_catcher_alloc_slow(thr);
}
#else /* DUK_USE_CACHE_CATCHER */
DUK_INTERNAL duk_catcher *duk_hthread_catcher_alloc(duk_hthread *thr) {
return duk__hthread_catcher_alloc_slow(thr);
}
#endif /* DUK_USE_CACHE_CATCHER */
DUK_INTERNAL void duk_hthread_catcher_free(duk_hthread *thr, duk_catcher *cat) {
DUK_ASSERT(thr != NULL);
DUK_ASSERT(cat != NULL);
#if defined(DUK_USE_CACHE_CATCHER)
/* Unconditional caching for now; freed in mark-and-sweep. */
cat->parent = thr->heap->catcher_free;
thr->heap->catcher_free = cat;
#else
DUK_FREE_CHECKED(thr, (void *) cat);
#endif
}
DUK_LOCAL
#if defined(DUK_USE_CACHE_ACTIVATION)
DUK_NOINLINE
#endif
duk_activation *duk__hthread_activation_alloc_slow(duk_hthread *thr) {
duk_activation *act;
act = (duk_activation *) DUK_ALLOC_CHECKED(thr, sizeof(duk_activation));
DUK_ASSERT(act != NULL);
return act;
}
#if defined(DUK_USE_CACHE_ACTIVATION)
DUK_INTERNAL DUK_INLINE duk_activation *duk_hthread_activation_alloc(duk_hthread *thr) {
duk_activation *act;
DUK_ASSERT(thr != NULL);
act = thr->heap->activation_free;
if (DUK_LIKELY(act != NULL)) {
thr->heap->activation_free = act->parent;
return act;
}
return duk__hthread_activation_alloc_slow(thr);
}
#else /* DUK_USE_CACHE_ACTIVATION */
DUK_INTERNAL duk_activation *duk_hthread_activation_alloc(duk_hthread *thr) {
return duk__hthread_activation_alloc_slow(thr);
}
#endif /* DUK_USE_CACHE_ACTIVATION */
DUK_INTERNAL void duk_hthread_activation_free(duk_hthread *thr, duk_activation *act) {
DUK_ASSERT(thr != NULL);
DUK_ASSERT(act != NULL);
#if defined(DUK_USE_CACHE_ACTIVATION)
/* Unconditional caching for now; freed in mark-and-sweep. */
act->parent = thr->heap->activation_free;
thr->heap->activation_free = act;
#else
DUK_FREE_CHECKED(thr, (void *) act);
#endif
}
/* Internal helper: process the unwind for the topmost activation of a thread,
* but leave the duk_activation in place for possible tailcall reuse.
*/
DUK_LOCAL void duk__activation_unwind_nofree_norz(duk_hthread *thr) {
#if defined(DUK_USE_DEBUGGER_SUPPORT)
duk_heap *heap;
#endif
duk_activation *act;
duk_hobject *func;
duk_hobject *tmp;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(thr->callstack_curr != NULL); /* caller must check */
DUK_ASSERT(thr->callstack_top > 0);
act = thr->callstack_curr;
DUK_ASSERT(act != NULL);
/* With lightfuncs, act 'func' may be NULL. */
/* With duk_activation records allocated separately, 'act' is a stable
* pointer and not affected by side effects.
*/
#if defined(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_entry_tval_ptr_stridx(thr->heap, func, DUK_STRIDX_CALLER);
/* 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_NORZ(thr, &tv_tmp);
} else {
h_tmp = act->prev_caller;
if (h_tmp) {
act->prev_caller = NULL;
DUK_HOBJECT_DECREF_NORZ(thr, h_tmp);
}
}
DUK_ASSERT(act->prev_caller == NULL);
}
#endif
/*
* Unwind debugger state. If we unwind while stepping
* (for any step type), pause execution. This is the
* only place explicitly handling a step out.
*/
#if defined(DUK_USE_DEBUGGER_SUPPORT)
heap = thr->heap;
if (heap->dbg_pause_act == thr->callstack_curr) {
if (heap->dbg_pause_flags & DUK_PAUSE_FLAG_FUNC_EXIT) {
DUK_D(DUK_DPRINT("PAUSE TRIGGERED by function exit"));
duk_debug_set_paused(heap);
} else {
DUK_D(DUK_DPRINT("unwound past dbg_pause_act, set to NULL"));
heap->dbg_pause_act = NULL; /* avoid stale pointers */
}
DUK_ASSERT(heap->dbg_pause_act == NULL);
}
#endif
/*
* Unwind catchers.
*
* Since there are no references in the catcher structure,
* unwinding is quite simple. The only thing we need to
* look out for is popping a possible lexical environment
* established for an active catch clause.
*/
while (act->cat != NULL) {
duk_hthread_catcher_unwind_norz(thr, act);
}
/*
* 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 */
/* Catch sites are required to clean up their environments
* in FINALLY part before propagating, so this should
* always hold here.
*/
DUK_ASSERT(act->lex_env == act->var_env);
/* XXX: Closing the environment record copies values from registers
* into the scope object. It's side effect free as such, but may
* currently run out of memory which causes an error throw. This is
* an actual sandboxing problem for error unwinds, and needs to be
* fixed e.g. by preallocating the scope property slots.
*/
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);
}
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, using NORZ macros so we don't
* need to handle side effects.
*
* duk_activation pointers like act->var_env are intentionally
* left as garbage and not NULLed. Without side effects they
* can't be used when the values are dangling/garbage.
*/
DUK_HOBJECT_DECREF_NORZ_ALLOWNULL(thr, act->var_env);
DUK_HOBJECT_DECREF_NORZ_ALLOWNULL(thr, act->lex_env);
tmp = DUK_ACT_GET_FUNC(act);
DUK_HOBJECT_DECREF_NORZ_ALLOWNULL(thr, tmp);
DUK_UNREF(tmp);
}
/* Unwind topmost duk_activation of a thread, caller must ensure that an
* activation exists. The call is side effect free, except that scope
* closure may currently throw an out-of-memory error.
*/
DUK_INTERNAL void duk_hthread_activation_unwind_norz(duk_hthread *thr) {
duk_activation *act;
duk__activation_unwind_nofree_norz(thr);
DUK_ASSERT(thr->callstack_curr != NULL);
DUK_ASSERT(thr->callstack_top > 0);
act = thr->callstack_curr;
thr->callstack_curr = act->parent;
thr->callstack_top--;
/* Ideally we'd restore value stack reserve here to caller's value.
* This doesn't work for current unwind call sites however, because
* the current (unwound) value stack top may be above the reserve.
* Thus value stack reserve is restored by the call sites.
*/
/* XXX: inline for performance builds? */
duk_hthread_activation_free(thr, act);
/* We could clear the book-keeping variables like retval_byteoff for
* the topmost activation, but don't do so now as it's not necessary.
*/
}
DUK_INTERNAL void duk_hthread_activation_unwind_reuse_norz(duk_hthread *thr) {
duk__activation_unwind_nofree_norz(thr);
}
/* Get duk_activation for given callstack level or NULL if level is invalid
* or deeper than the call stack. Level -1 refers to current activation, -2
* to its caller, etc. Starting from Duktape 2.2 finding the activation is
* a linked list scan which gets more expensive the deeper the lookup is.
*/
DUK_INTERNAL duk_activation *duk_hthread_get_activation_for_level(duk_hthread *thr, duk_int_t level) {
duk_activation *act;
if (level >= 0) {
return NULL;
}
act = thr->callstack_curr;
for (;;) {
if (act == NULL) {
return act;
}
if (level == -1) {
return act;
}
level++;
act = act->parent;
}
/* never here */
}
#if defined(DUK_USE_FINALIZER_TORTURE)
DUK_INTERNAL void duk_hthread_valstack_torture_realloc(duk_hthread *thr) {
duk_size_t alloc_size;
duk_tval *new_ptr;
duk_ptrdiff_t alloc_end_off;
duk_ptrdiff_t end_off;
duk_ptrdiff_t bottom_off;
duk_ptrdiff_t top_off;
if (thr->valstack == NULL) {
DUK_D(DUK_DPRINT("skip valstack torture realloc, valstack is NULL"));
return;
}
alloc_end_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_alloc_end - (duk_uint8_t *) thr->valstack);
end_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_end - (duk_uint8_t *) thr->valstack);
bottom_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_bottom - (duk_uint8_t *) thr->valstack);
top_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_top - (duk_uint8_t *) thr->valstack);
alloc_size = (duk_size_t) alloc_end_off;
if (alloc_size == 0) {
DUK_D(DUK_DPRINT("skip valstack torture realloc, alloc_size is zero"));
return;
}
/* Use DUK_ALLOC_RAW() to avoid side effects. */
new_ptr = (duk_tval *) DUK_ALLOC_RAW(thr->heap, alloc_size);
if (new_ptr != NULL) {
duk_memcpy((void *) new_ptr, (const void *) thr->valstack, alloc_size);
duk_memset((void *) thr->valstack, 0x55, alloc_size);
DUK_FREE_CHECKED(thr, (void *) thr->valstack);
thr->valstack = new_ptr;
thr->valstack_alloc_end = (duk_tval *) ((duk_uint8_t *) new_ptr + alloc_end_off);
thr->valstack_end = (duk_tval *) ((duk_uint8_t *) new_ptr + end_off);
thr->valstack_bottom = (duk_tval *) ((duk_uint8_t *) new_ptr + bottom_off);
thr->valstack_top = (duk_tval *) ((duk_uint8_t *) new_ptr + top_off);
} else {
DUK_D(DUK_DPRINT("failed to realloc valstack for torture, ignore"));
}
}
#endif /* DUK_USE_FINALIZER_TORTURE */