1 /*
2 ** Garbage collector.
3 ** Copyright (C) 2005-2021 Mike Pall. See Copyright Notice in luajit.h
4 */
5
6 #ifndef _LJ_GC_H
7 #define _LJ_GC_H
8
9 #include "lj_obj.h"
10
11 /* Garbage collector states. Order matters. */
12 enum {
13 GCSpause, GCSpropagate, GCSatomic, GCSsweepstring, GCSsweep, GCSfinalize
14 };
15
16 /* Bitmasks for marked field of GCobj. */
17 #define LJ_GC_WHITE0 0x01
18 #define LJ_GC_WHITE1 0x02
19 #define LJ_GC_BLACK 0x04
20 #define LJ_GC_FINALIZED 0x08
21 #define LJ_GC_WEAKKEY 0x08
22 #define LJ_GC_WEAKVAL 0x10
23 #define LJ_GC_CDATA_FIN 0x10
24 #define LJ_GC_FIXED 0x20
25 #define LJ_GC_SFIXED 0x40
26
27 #define LJ_GC_WHITES (LJ_GC_WHITE0 | LJ_GC_WHITE1)
28 #define LJ_GC_COLORS (LJ_GC_WHITES | LJ_GC_BLACK)
29 #define LJ_GC_WEAK (LJ_GC_WEAKKEY | LJ_GC_WEAKVAL)
30
31 /* Macros to test and set GCobj colors. */
32 #define iswhite(x) ((x)->gch.marked & LJ_GC_WHITES)
33 #define isblack(x) ((x)->gch.marked & LJ_GC_BLACK)
34 #define isgray(x) (!((x)->gch.marked & (LJ_GC_BLACK|LJ_GC_WHITES)))
35 #define tviswhite(x) (tvisgcv(x) && iswhite(gcV(x)))
36 #define otherwhite(g) (g->gc.currentwhite ^ LJ_GC_WHITES)
37 #define isdead(g, v) ((v)->gch.marked & otherwhite(g) & LJ_GC_WHITES)
38
39 #define curwhite(g) ((g)->gc.currentwhite & LJ_GC_WHITES)
40 #define newwhite(g, x) (obj2gco(x)->gch.marked = (uint8_t)curwhite(g))
41 #define makewhite(g, x) \
42 ((x)->gch.marked = ((x)->gch.marked & (uint8_t)~LJ_GC_COLORS) | curwhite(g))
43 #define flipwhite(x) ((x)->gch.marked ^= LJ_GC_WHITES)
44 #define black2gray(x) ((x)->gch.marked &= (uint8_t)~LJ_GC_BLACK)
45 #define fixstring(s) ((s)->marked |= LJ_GC_FIXED)
46 #define markfinalized(x) ((x)->gch.marked |= LJ_GC_FINALIZED)
47
48 /* Collector. */
49 LJ_FUNC size_t lj_gc_separateudata(global_State *g, int all);
50 LJ_FUNC void lj_gc_finalize_udata(lua_State *L);
51 #if LJ_HASFFI
52 LJ_FUNC void lj_gc_finalize_cdata(lua_State *L);
53 #else
54 #define lj_gc_finalize_cdata(L) UNUSED(L)
55 #endif
56 LJ_FUNC void lj_gc_freeall(global_State *g);
57 LJ_FUNCA int LJ_FASTCALL lj_gc_step(lua_State *L);
58 LJ_FUNCA void LJ_FASTCALL lj_gc_step_fixtop(lua_State *L);
59 #if LJ_HASJIT
60 LJ_FUNC int LJ_FASTCALL lj_gc_step_jit(global_State *g, MSize steps);
61 #endif
62 LJ_FUNC void lj_gc_fullgc(lua_State *L);
63
64 /* GC check: drive collector forward if the GC threshold has been reached. */
65 #define lj_gc_check(L) \
66 { if (LJ_UNLIKELY(G(L)->gc.total >= G(L)->gc.threshold)) \
67 lj_gc_step(L); }
68 #define lj_gc_check_fixtop(L) \
69 { if (LJ_UNLIKELY(G(L)->gc.total >= G(L)->gc.threshold)) \
70 lj_gc_step_fixtop(L); }
71
72 /* Write barriers. */
73 LJ_FUNC void lj_gc_barrierf(global_State *g, GCobj *o, GCobj *v);
74 LJ_FUNCA void LJ_FASTCALL lj_gc_barrieruv(global_State *g, TValue *tv);
75 LJ_FUNC void lj_gc_closeuv(global_State *g, GCupval *uv);
76 #if LJ_HASJIT
77 LJ_FUNC void lj_gc_barriertrace(global_State *g, uint32_t traceno);
78 #endif
79
80 /* Move the GC propagation frontier back for tables (make it gray again). */
lj_gc_barrierback(global_State * g,GCtab * t)81 static LJ_AINLINE void lj_gc_barrierback(global_State *g, GCtab *t)
82 {
83 GCobj *o = obj2gco(t);
84 lj_assertG(isblack(o) && !isdead(g, o),
85 "bad object states for backward barrier");
86 lj_assertG(g->gc.state != GCSfinalize && g->gc.state != GCSpause,
87 "bad GC state");
88 black2gray(o);
89 setgcrefr(t->gclist, g->gc.grayagain);
90 setgcref(g->gc.grayagain, o);
91 }
92
93 /* Barrier for stores to table objects. TValue and GCobj variant. */
94 #define lj_gc_anybarriert(L, t) \
95 { if (LJ_UNLIKELY(isblack(obj2gco(t)))) lj_gc_barrierback(G(L), (t)); }
96 #define lj_gc_barriert(L, t, tv) \
97 { if (tviswhite(tv) && isblack(obj2gco(t))) \
98 lj_gc_barrierback(G(L), (t)); }
99 #define lj_gc_objbarriert(L, t, o) \
100 { if (iswhite(obj2gco(o)) && isblack(obj2gco(t))) \
101 lj_gc_barrierback(G(L), (t)); }
102
103 /* Barrier for stores to any other object. TValue and GCobj variant. */
104 #define lj_gc_barrier(L, p, tv) \
105 { if (tviswhite(tv) && isblack(obj2gco(p))) \
106 lj_gc_barrierf(G(L), obj2gco(p), gcV(tv)); }
107 #define lj_gc_objbarrier(L, p, o) \
108 { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \
109 lj_gc_barrierf(G(L), obj2gco(p), obj2gco(o)); }
110
111 /* Allocator. */
112 LJ_FUNC void *lj_mem_realloc(lua_State *L, void *p, GCSize osz, GCSize nsz);
113 LJ_FUNC void * LJ_FASTCALL lj_mem_newgco(lua_State *L, GCSize size);
114 LJ_FUNC void *lj_mem_grow(lua_State *L, void *p,
115 MSize *szp, MSize lim, MSize esz);
116
117 #define lj_mem_new(L, s) lj_mem_realloc(L, NULL, 0, (s))
118
lj_mem_free(global_State * g,void * p,size_t osize)119 static LJ_AINLINE void lj_mem_free(global_State *g, void *p, size_t osize)
120 {
121 g->gc.total -= (GCSize)osize;
122 g->allocf(g->allocd, p, osize, 0);
123 }
124
125 #define lj_mem_newvec(L, n, t) ((t *)lj_mem_new(L, (GCSize)((n)*sizeof(t))))
126 #define lj_mem_reallocvec(L, p, on, n, t) \
127 ((p) = (t *)lj_mem_realloc(L, p, (on)*sizeof(t), (GCSize)((n)*sizeof(t))))
128 #define lj_mem_growvec(L, p, n, m, t) \
129 ((p) = (t *)lj_mem_grow(L, (p), &(n), (m), (MSize)sizeof(t)))
130 #define lj_mem_freevec(g, p, n, t) lj_mem_free(g, (p), (n)*sizeof(t))
131
132 #define lj_mem_newobj(L, t) ((t *)lj_mem_newgco(L, sizeof(t)))
133 #define lj_mem_newt(L, s, t) ((t *)lj_mem_new(L, (s)))
134 #define lj_mem_freet(g, p) lj_mem_free(g, (p), sizeof(*(p)))
135
136 #endif
137