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ffi/target/release/build/mlua-sys-6a99a2ae50f12319/out/luajit-build/build/src/lj_gc.c  view on Meta::CPAN

    gc_traverse_trace(g, T);
    return ((sizeof(GCtrace)+7)&~7) + (T->nins-T->nk)*sizeof(IRIns) +
	   T->nsnap*sizeof(SnapShot) + T->nsnapmap*sizeof(SnapEntry);
#else
    lj_assertG(0, "bad GC type %d", gct);
    return 0;
#endif
  }
}

/* Propagate all gray objects. */
static size_t gc_propagate_gray(global_State *g)
{
  size_t m = 0;
  while (gcref(g->gc.gray) != NULL)
    m += propagatemark(g);
  return m;
}

/* -- Sweep phase --------------------------------------------------------- */

/* Type of GC free functions. */
typedef void (LJ_FASTCALL *GCFreeFunc)(global_State *g, GCobj *o);

/* GC free functions for LJ_TSTR .. LJ_TUDATA. ORDER LJ_T */
static const GCFreeFunc gc_freefunc[] = {
  (GCFreeFunc)lj_str_free,
  (GCFreeFunc)lj_func_freeuv,
  (GCFreeFunc)lj_state_free,
  (GCFreeFunc)lj_func_freeproto,
  (GCFreeFunc)lj_func_free,
#if LJ_HASJIT
  (GCFreeFunc)lj_trace_free,
#else
  (GCFreeFunc)0,
#endif
#if LJ_HASFFI
  (GCFreeFunc)lj_cdata_free,
#else
  (GCFreeFunc)0,
#endif
  (GCFreeFunc)lj_tab_free,
  (GCFreeFunc)lj_udata_free
};

/* Full sweep of a GC list. */
#define gc_fullsweep(g, p)	gc_sweep(g, (p), ~(uint32_t)0)

/* Partial sweep of a GC list. */
static GCRef *gc_sweep(global_State *g, GCRef *p, uint32_t lim)
{
  /* Mask with other white and LJ_GC_FIXED. Or LJ_GC_SFIXED on shutdown. */
  int ow = otherwhite(g);
  GCobj *o;
  while ((o = gcref(*p)) != NULL && lim-- > 0) {
    if (o->gch.gct == ~LJ_TTHREAD)  /* Need to sweep open upvalues, too. */
      gc_fullsweep(g, &gco2th(o)->openupval);
    if (((o->gch.marked ^ LJ_GC_WHITES) & ow)) {  /* Black or current white? */
      lj_assertG(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED),
		 "sweep of undead object");
      makewhite(g, o);  /* Value is alive, change to the current white. */
      p = &o->gch.nextgc;
    } else {  /* Otherwise value is dead, free it. */
      lj_assertG(isdead(g, o) || ow == LJ_GC_SFIXED,
		 "sweep of unlive object");
      setgcrefr(*p, o->gch.nextgc);
      if (o == gcref(g->gc.root))
	setgcrefr(g->gc.root, o->gch.nextgc);  /* Adjust list anchor. */
      gc_freefunc[o->gch.gct - ~LJ_TSTR](g, o);
    }
  }
  return p;
}

/* Sweep one string interning table chain. Preserves hashalg bit. */
static void gc_sweepstr(global_State *g, GCRef *chain)
{
  /* Mask with other white and LJ_GC_FIXED. Or LJ_GC_SFIXED on shutdown. */
  int ow = otherwhite(g);
  uintptr_t u = gcrefu(*chain);
  GCRef q;
  GCRef *p = &q;
  GCobj *o;
  setgcrefp(q, (u & ~(uintptr_t)1));
  while ((o = gcref(*p)) != NULL) {
    if (((o->gch.marked ^ LJ_GC_WHITES) & ow)) {  /* Black or current white? */
      lj_assertG(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED),
		 "sweep of undead string");
      makewhite(g, o);  /* String is alive, change to the current white. */
      p = &o->gch.nextgc;
    } else {  /* Otherwise string is dead, free it. */
      lj_assertG(isdead(g, o) || ow == LJ_GC_SFIXED,
		 "sweep of unlive string");
      setgcrefr(*p, o->gch.nextgc);
      lj_str_free(g, gco2str(o));
    }
  }
  setgcrefp(*chain, (gcrefu(q) | (u & 1)));
}

/* Check whether we can clear a key or a value slot from a table. */
static int gc_mayclear(cTValue *o, int val)
{
  if (tvisgcv(o)) {  /* Only collectable objects can be weak references. */
    if (tvisstr(o)) {  /* But strings cannot be used as weak references. */
      gc_mark_str(strV(o));  /* And need to be marked. */
      return 0;
    }
    if (iswhite(gcV(o)))
      return 1;  /* Object is about to be collected. */
    if (tvisudata(o) && val && isfinalized(udataV(o)))
      return 1;  /* Finalized userdata is dropped only from values. */
  }
  return 0;  /* Cannot clear. */
}

/* Clear collected entries from weak tables. */
static void gc_clearweak(global_State *g, GCobj *o)
{
  UNUSED(g);
  while (o) {
    GCtab *t = gco2tab(o);
    lj_assertG((t->marked & LJ_GC_WEAK), "clear of non-weak table");
    if ((t->marked & LJ_GC_WEAKVAL)) {
      MSize i, asize = t->asize;
      for (i = 0; i < asize; i++) {
	/* Clear array slot when value is about to be collected. */
	TValue *tv = arrayslot(t, i);
	if (gc_mayclear(tv, 1))
	  setnilV(tv);
      }
    }
    if (t->hmask > 0) {
      Node *node = noderef(t->node);
      MSize i, hmask = t->hmask;
      for (i = 0; i <= hmask; i++) {
	Node *n = &node[i];
	/* Clear hash slot when key or value is about to be collected. */
	if (!tvisnil(&n->val) && (gc_mayclear(&n->key, 0) ||
				  gc_mayclear(&n->val, 1)))
	  setnilV(&n->val);
      }
    }
    o = gcref(t->gclist);
  }
}

/* Call a userdata or cdata finalizer. */
static void gc_call_finalizer(global_State *g, lua_State *L,