UpVal *luaF_findupval (lua_State *L, StkId level) {
UpVal **pp = &L->openupval;
GCObject *o;
UpVal *p;
UpVal *uv;
lua_assert(isintwups(L) || L->openupval == NULL);
while ((p = *pp) != NULL && uplevel(p) >= level) {
if (uplevel(p) == level && !isdead(G(L), p)) /* corresponding upvalue? */
return p; /* return it */
pp = &p->u.open.next;
}
/* not found: create a new upvalue between 'pp' and 'p' */
o = luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal));
uv = gco2upv(o);
uv->u.open.next = p; /* link it to list of open upvalues */
uv->u.open.previous = pp;
if (p)
p->u.open.previous = &uv->u.open.next;
*pp = uv;
uv->v = s2v(level); /* current value lives in the stack */
if (!isintwups(L)) { /* thread not in list of threads with upvalues? */
L->twups = G(L)->twups; /* link it to the list */
G(L)->twups = L;
}
return uv;
}
static lu_mem traversethread (global_State *g, lua_State *th) {
StkId o = th->stack;
if (o == NULL)
return 1; /* stack not completely built yet */
lua_assert(g->gcstate == GCSinsideatomic ||
th->openupval == NULL || isintwups(th));
for (; o < th->top; o++) /* mark live elements in the stack */
markvalue(g, o);
if (g->gcstate == GCSinsideatomic) { /* final traversal? */
StkId lim = th->stack + th->stacksize; /* real end of stack */
for (; o < lim; o++) /* clear not-marked stack slice */
setnilvalue(o);
/* 'remarkupvals' may have removed thread from 'twups' list */
if (!isintwups(th) && th->openupval != NULL) {
th->twups = g->twups; /* link it back to the list */
g->twups = th;
}
}
else if (g->gckind != KGC_EMERGENCY)
luaD_shrinkstack(th); /* do not change stack in emergency cycle */
return (sizeof(lua_State) + sizeof(TValue) * th->stacksize);
}
UpVal *luaF_findupval (lua_State *L, StkId level) {
UpVal **pp = &L->openupval;
UpVal *p;
UpVal *uv;
lua_assert(isintwups(L) || L->openupval == NULL);
while (*pp != NULL && (p = *pp)->v >= level) {
lua_assert(upisopen(p));
if (p->v == level) /* found a corresponding upvalue? */
return p; /* return it */
pp = &p->u.open.next;
}
/* not found: create a new upvalue */
uv = luaM_new(L, UpVal);
uv->refcount = 0;
uv->u.open.next = *pp; /* link it to list of open upvalues */
uv->u.open.touched = 1;
*pp = uv;
uv->v = level; /* current value lives in the stack */
if (!isintwups(L)) { /* thread not in list of threads with upvalues? */
L->twups = G(L)->twups; /* link it to the list */
G(L)->twups = L;
}
return uv;
}