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/*
** Garbage collector.
** Copyright (C) 2005-2025 Mike Pall. See Copyright Notice in luajit.h
*/

#ifndef _LJ_GC_H
#define _LJ_GC_H

#include "lj_obj.h"

/* Garbage collector states. Order matters. */
enum {
  GCSpause, GCSpropagate, GCSatomic, GCSsweepstring, GCSsweep, GCSfinalize
};

/* Bitmasks for marked field of GCobj. */
#define LJ_GC_WHITE0	0x01
#define LJ_GC_WHITE1	0x02
#define LJ_GC_BLACK	0x04
#define LJ_GC_FINALIZED	0x08
#define LJ_GC_WEAKKEY	0x08
#define LJ_GC_WEAKVAL	0x10
#define LJ_GC_CDATA_FIN	0x10
#define LJ_GC_FIXED	0x20
#define LJ_GC_SFIXED	0x40

#define LJ_GC_WHITES	(LJ_GC_WHITE0 | LJ_GC_WHITE1)
#define LJ_GC_COLORS	(LJ_GC_WHITES | LJ_GC_BLACK)
#define LJ_GC_WEAK	(LJ_GC_WEAKKEY | LJ_GC_WEAKVAL)

/* Macros to test and set GCobj colors. */
#define iswhite(x)	((x)->gch.marked & LJ_GC_WHITES)
#define isblack(x)	((x)->gch.marked & LJ_GC_BLACK)
#define isgray(x)	(!((x)->gch.marked & (LJ_GC_BLACK|LJ_GC_WHITES)))
#define tviswhite(x)	(tvisgcv(x) && iswhite(gcV(x)))
#define otherwhite(g)	(g->gc.currentwhite ^ LJ_GC_WHITES)
#define isdead(g, v)	((v)->gch.marked & otherwhite(g) & LJ_GC_WHITES)

#define curwhite(g)	((g)->gc.currentwhite & LJ_GC_WHITES)
#define newwhite(g, x)	(obj2gco(x)->gch.marked = (uint8_t)curwhite(g))
#define makewhite(g, x) \
  ((x)->gch.marked = ((x)->gch.marked & (uint8_t)~LJ_GC_COLORS) | curwhite(g))
#define flipwhite(x)	((x)->gch.marked ^= LJ_GC_WHITES)
#define black2gray(x)	((x)->gch.marked &= (uint8_t)~LJ_GC_BLACK)
#define fixstring(s)	((s)->marked |= LJ_GC_FIXED)
#define markfinalized(x)	((x)->gch.marked |= LJ_GC_FINALIZED)

/* Collector. */
LJ_FUNC size_t lj_gc_separateudata(global_State *g, int all);
LJ_FUNC void lj_gc_finalize_udata(lua_State *L);
#if LJ_HASFFI
LJ_FUNC void lj_gc_finalize_cdata(lua_State *L);
#else
#define lj_gc_finalize_cdata(L)		UNUSED(L)
#endif
LJ_FUNC void lj_gc_freeall(global_State *g);
LJ_FUNCA int LJ_FASTCALL lj_gc_step(lua_State *L);
LJ_FUNCA void LJ_FASTCALL lj_gc_step_fixtop(lua_State *L);
#if LJ_HASJIT
LJ_FUNC int LJ_FASTCALL lj_gc_step_jit(global_State *g, MSize steps);
#endif
LJ_FUNC void lj_gc_fullgc(lua_State *L);

/* GC check: drive collector forward if the GC threshold has been reached. */
#define lj_gc_check(L) \
  { if (LJ_UNLIKELY(G(L)->gc.total >= G(L)->gc.threshold)) \
      lj_gc_step(L); }
#define lj_gc_check_fixtop(L) \
  { if (LJ_UNLIKELY(G(L)->gc.total >= G(L)->gc.threshold)) \
      lj_gc_step_fixtop(L); }

/* Write barriers. */
LJ_FUNC void lj_gc_barrierf(global_State *g, GCobj *o, GCobj *v);
LJ_FUNCA void LJ_FASTCALL lj_gc_barrieruv(global_State *g, TValue *tv);
LJ_FUNC void lj_gc_closeuv(global_State *g, GCupval *uv);
#if LJ_HASJIT
LJ_FUNC void lj_gc_barriertrace(global_State *g, uint32_t traceno);
#endif

/* Move the GC propagation frontier back for tables (make it gray again). */
static LJ_AINLINE void lj_gc_barrierback(global_State *g, GCtab *t)
{
  GCobj *o = obj2gco(t);
  lj_assertG(isblack(o) && !isdead(g, o),
	     "bad object states for backward barrier");
  lj_assertG(g->gc.state != GCSfinalize && g->gc.state != GCSpause,
	     "bad GC state");
  black2gray(o);
  setgcrefr(t->gclist, g->gc.grayagain);
  setgcref(g->gc.grayagain, o);
}