Remove the IND_OLDGEN and IND_OLDGEN_PERM closure types
[ghc.git] / rts / sm / GCAux.c
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team 1998-2008
4 *
5 * Functions called from outside the GC need to be separate from GC.c,
6 * because GC.c is compiled with register variable(s).
7 *
8 * ---------------------------------------------------------------------------*/
9
10 #include "PosixSource.h"
11 #include "Rts.h"
12
13 #include "GC.h"
14 #include "Storage.h"
15 #include "Compact.h"
16 #include "Task.h"
17 #include "Capability.h"
18 #include "Trace.h"
19 #include "Schedule.h"
20 // DO NOT include "GCThread.h", we don't want the register variable
21
22 /* -----------------------------------------------------------------------------
23 isAlive determines whether the given closure is still alive (after
24 a garbage collection) or not. It returns the new address of the
25 closure if it is alive, or NULL otherwise.
26
27 NOTE: Use it before compaction only!
28 It untags and (if needed) retags pointers to closures.
29 -------------------------------------------------------------------------- */
30
31 StgClosure *
32 isAlive(StgClosure *p)
33 {
34 const StgInfoTable *info;
35 bdescr *bd;
36 StgWord tag;
37 StgClosure *q;
38
39 while (1) {
40 /* The tag and the pointer are split, to be merged later when needed. */
41 tag = GET_CLOSURE_TAG(p);
42 q = UNTAG_CLOSURE(p);
43
44 ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
45
46 // ignore static closures
47 //
48 // ToDo: for static closures, check the static link field.
49 // Problem here is that we sometimes don't set the link field, eg.
50 // for static closures with an empty SRT or CONSTR_STATIC_NOCAFs.
51 //
52 if (!HEAP_ALLOCED_GC(q)) {
53 return p;
54 }
55
56 // ignore closures in generations that we're not collecting.
57 bd = Bdescr((P_)q);
58
59 // if it's a pointer into to-space, then we're done
60 if (bd->flags & BF_EVACUATED) {
61 return p;
62 }
63
64 // large objects use the evacuated flag
65 if (bd->flags & BF_LARGE) {
66 if (get_itbl(q)->type == TSO &&
67 ((StgTSO *)p)->what_next == ThreadRelocated) {
68 p = (StgClosure *)((StgTSO *)p)->_link;
69 continue;
70 }
71 return NULL;
72 }
73
74 // check the mark bit for compacted steps
75 if ((bd->flags & BF_MARKED) && is_marked((P_)q,bd)) {
76 return p;
77 }
78
79 info = q->header.info;
80
81 if (IS_FORWARDING_PTR(info)) {
82 // alive!
83 return (StgClosure*)UN_FORWARDING_PTR(info);
84 }
85
86 info = INFO_PTR_TO_STRUCT(info);
87
88 switch (info->type) {
89
90 case IND:
91 case IND_STATIC:
92 case IND_PERM:
93 // follow indirections
94 p = ((StgInd *)q)->indirectee;
95 continue;
96
97 case TSO:
98 if (((StgTSO *)q)->what_next == ThreadRelocated) {
99 p = (StgClosure *)((StgTSO *)q)->_link;
100 continue;
101 }
102 return NULL;
103
104 default:
105 // dead.
106 return NULL;
107 }
108 }
109 }
110
111 /* -----------------------------------------------------------------------------
112 Reverting CAFs
113 -------------------------------------------------------------------------- */
114
115 void
116 revertCAFs( void )
117 {
118 StgIndStatic *c;
119
120 for (c = (StgIndStatic *)revertible_caf_list;
121 c != (StgIndStatic *)END_OF_STATIC_LIST;
122 c = (StgIndStatic *)c->static_link)
123 {
124 SET_INFO(c, c->saved_info);
125 c->saved_info = NULL;
126 // could, but not necessary: c->static_link = NULL;
127 }
128 revertible_caf_list = END_OF_STATIC_LIST;
129 }
130
131 void
132 markCAFs (evac_fn evac, void *user)
133 {
134 StgIndStatic *c;
135
136 for (c = (StgIndStatic *)caf_list;
137 c != (StgIndStatic*)END_OF_STATIC_LIST;
138 c = (StgIndStatic *)c->static_link)
139 {
140 evac(user, &c->indirectee);
141 }
142 for (c = (StgIndStatic *)revertible_caf_list;
143 c != (StgIndStatic*)END_OF_STATIC_LIST;
144 c = (StgIndStatic *)c->static_link)
145 {
146 evac(user, &c->indirectee);
147 }
148 }