849f99f430c0ab1c4cb5c6273bbc1e2fcab5dbc0
[ghc.git] / includes / rts / storage / Block.h
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team, 1998-1999
4 *
5 * Block structure for the storage manager
6 *
7 * ---------------------------------------------------------------------------*/
8
9 #ifndef RTS_STORAGE_BLOCK_H
10 #define RTS_STORAGE_BLOCK_H
11
12 /* The actual block and megablock-size constants are defined in
13 * includes/Constants.h, all constants here are derived from these.
14 */
15
16 /* Block related constants (BLOCK_SHIFT is defined in Constants.h) */
17
18 #define BLOCK_SIZE (1<<BLOCK_SHIFT)
19 #define BLOCK_SIZE_W (BLOCK_SIZE/sizeof(W_))
20 #define BLOCK_MASK (BLOCK_SIZE-1)
21
22 #define BLOCK_ROUND_UP(p) ((void *) (((W_)(p)+BLOCK_SIZE-1) & ~BLOCK_MASK))
23 #define BLOCK_ROUND_DOWN(p) ((void *) ((W_)(p) & ~BLOCK_MASK))
24
25 /* Megablock related constants (MBLOCK_SHIFT is defined in Constants.h) */
26
27 #define MBLOCK_SIZE (1<<MBLOCK_SHIFT)
28 #define MBLOCK_SIZE_W (MBLOCK_SIZE/sizeof(W_))
29 #define MBLOCK_MASK (MBLOCK_SIZE-1)
30
31 #define MBLOCK_ROUND_UP(p) ((void *)(((W_)(p)+MBLOCK_SIZE-1) & ~MBLOCK_MASK))
32 #define MBLOCK_ROUND_DOWN(p) ((void *)((W_)(p) & ~MBLOCK_MASK ))
33
34 /* The largest size an object can be before we give it a block of its
35 * own and treat it as an immovable object during GC, expressed as a
36 * fraction of BLOCK_SIZE.
37 */
38 #define LARGE_OBJECT_THRESHOLD ((nat)(BLOCK_SIZE * 8 / 10))
39
40 /* -----------------------------------------------------------------------------
41 * Block descriptor. This structure *must* be the right length, so we
42 * can do pointer arithmetic on pointers to it.
43 */
44
45 /* The block descriptor is 64 bytes on a 64-bit machine, and 32-bytes
46 * on a 32-bit machine.
47 */
48
49 #ifndef CMINUSMINUS
50 typedef struct bdescr_ {
51 StgPtr start; /* start addr of memory */
52 StgPtr free; /* first free byte of memory */
53 struct bdescr_ *link; /* used for chaining blocks together */
54 union {
55 struct bdescr_ *back; /* used (occasionally) for doubly-linked lists*/
56 StgWord *bitmap;
57 StgPtr scan; /* scan pointer for copying GC */
58 } u;
59 unsigned int gen_no; /* generation */
60 struct step_ *step; /* step */
61 StgWord32 blocks; /* no. of blocks (if grp head, 0 otherwise) */
62 StgWord32 flags; /* block is in to-space */
63 #if SIZEOF_VOID_P == 8
64 StgWord32 _padding[2];
65 #else
66 StgWord32 _padding[0];
67 #endif
68 } bdescr;
69 #endif
70
71 #if SIZEOF_VOID_P == 8
72 #define BDESCR_SIZE 0x40
73 #define BDESCR_MASK 0x3f
74 #define BDESCR_SHIFT 6
75 #else
76 #define BDESCR_SIZE 0x20
77 #define BDESCR_MASK 0x1f
78 #define BDESCR_SHIFT 5
79 #endif
80
81 /* Block contains objects evacuated during this GC */
82 #define BF_EVACUATED 1
83 /* Block is a large object */
84 #define BF_LARGE 2
85 /* Block is pinned */
86 #define BF_PINNED 4
87 /* Block is to be marked, not copied */
88 #define BF_MARKED 8
89 /* Block is free, and on the free list (TODO: is this used?) */
90 #define BF_FREE 16
91 /* Block is executable */
92 #define BF_EXEC 32
93 /* Block contains only a small amount of live data */
94 #define BF_FRAGMENTED 64
95 /* we know about this block (for finding leaks) */
96 #define BF_KNOWN 128
97
98 /* Finding the block descriptor for a given block -------------------------- */
99
100 #ifdef CMINUSMINUS
101
102 #define Bdescr(p) \
103 ((((p) & MBLOCK_MASK & ~BLOCK_MASK) >> (BLOCK_SHIFT-BDESCR_SHIFT)) \
104 | ((p) & ~MBLOCK_MASK))
105
106 #else
107
108 INLINE_HEADER bdescr *Bdescr(StgPtr p)
109 {
110 return (bdescr *)
111 ((((W_)p & MBLOCK_MASK & ~BLOCK_MASK) >> (BLOCK_SHIFT-BDESCR_SHIFT))
112 | ((W_)p & ~MBLOCK_MASK)
113 );
114 }
115
116 #endif
117
118 /* Useful Macros ------------------------------------------------------------ */
119
120 /* Offset of first real data block in a megablock */
121
122 #define FIRST_BLOCK_OFF \
123 ((W_)BLOCK_ROUND_UP(BDESCR_SIZE * (MBLOCK_SIZE / BLOCK_SIZE)))
124
125 /* First data block in a given megablock */
126
127 #define FIRST_BLOCK(m) ((void *)(FIRST_BLOCK_OFF + (W_)(m)))
128
129 /* Last data block in a given megablock */
130
131 #define LAST_BLOCK(m) ((void *)(MBLOCK_SIZE-BLOCK_SIZE + (W_)(m)))
132
133 /* First real block descriptor in a megablock */
134
135 #define FIRST_BDESCR(m) \
136 ((bdescr *)((FIRST_BLOCK_OFF>>(BLOCK_SHIFT-BDESCR_SHIFT)) + (W_)(m)))
137
138 /* Last real block descriptor in a megablock */
139
140 #define LAST_BDESCR(m) \
141 ((bdescr *)(((MBLOCK_SIZE-BLOCK_SIZE)>>(BLOCK_SHIFT-BDESCR_SHIFT)) + (W_)(m)))
142
143 /* Number of usable blocks in a megablock */
144
145 #define BLOCKS_PER_MBLOCK ((MBLOCK_SIZE - FIRST_BLOCK_OFF) / BLOCK_SIZE)
146
147 /* How many blocks in this megablock group */
148
149 #define MBLOCK_GROUP_BLOCKS(n) \
150 (BLOCKS_PER_MBLOCK + (n-1) * (MBLOCK_SIZE / BLOCK_SIZE))
151
152 /* Compute the required size of a megablock group */
153
154 #define BLOCKS_TO_MBLOCKS(n) \
155 (1 + (W_)MBLOCK_ROUND_UP((n-BLOCKS_PER_MBLOCK) * BLOCK_SIZE) / MBLOCK_SIZE)
156
157
158 #ifndef CMINUSMINUS
159 /* to the end... */
160
161 /* Double-linked block lists: --------------------------------------------- */
162
163 INLINE_HEADER void
164 dbl_link_onto(bdescr *bd, bdescr **list)
165 {
166 bd->link = *list;
167 bd->u.back = NULL;
168 if (*list) {
169 (*list)->u.back = bd; /* double-link the list */
170 }
171 *list = bd;
172 }
173
174 INLINE_HEADER void
175 dbl_link_remove(bdescr *bd, bdescr **list)
176 {
177 if (bd->u.back) {
178 bd->u.back->link = bd->link;
179 } else {
180 *list = bd->link;
181 }
182 if (bd->link) {
183 bd->link->u.back = bd->u.back;
184 }
185 }
186
187 INLINE_HEADER void
188 dbl_link_insert_after(bdescr *bd, bdescr *after)
189 {
190 bd->link = after->link;
191 bd->u.back = after;
192 if (after->link) {
193 after->link->u.back = bd;
194 }
195 after->link = bd;
196 }
197
198 INLINE_HEADER void
199 dbl_link_replace(bdescr *new, bdescr *old, bdescr **list)
200 {
201 new->link = old->link;
202 new->u.back = old->u.back;
203 if (old->link) {
204 old->link->u.back = new;
205 }
206 if (old->u.back) {
207 old->u.back->link = new;
208 } else {
209 *list = new;
210 }
211 }
212
213 /* Initialisation ---------------------------------------------------------- */
214
215 extern void initBlockAllocator(void);
216
217 /* Allocation -------------------------------------------------------------- */
218
219 bdescr *allocGroup(nat n);
220 bdescr *allocBlock(void);
221
222 // versions that take the storage manager lock for you:
223 bdescr *allocGroup_lock(nat n);
224 bdescr *allocBlock_lock(void);
225
226 /* De-Allocation ----------------------------------------------------------- */
227
228 void freeGroup(bdescr *p);
229 void freeChain(bdescr *p);
230
231 // versions that take the storage manager lock for you:
232 void freeGroup_lock(bdescr *p);
233 void freeChain_lock(bdescr *p);
234
235 bdescr * splitBlockGroup (bdescr *bd, nat blocks);
236
237 /* Round a value to megablocks --------------------------------------------- */
238
239 // We want to allocate an object around a given size, round it up or
240 // down to the nearest size that will fit in an mblock group.
241 INLINE_HEADER StgWord
242 round_to_mblocks(StgWord words)
243 {
244 if (words > BLOCKS_PER_MBLOCK * BLOCK_SIZE_W) {
245 // first, ignore the gap at the beginning of the first mblock by
246 // adding it to the total words. Then we can pretend we're
247 // dealing in a uniform unit of megablocks.
248 words += FIRST_BLOCK_OFF/sizeof(W_);
249
250 if ((words % MBLOCK_SIZE_W) < (MBLOCK_SIZE_W / 2)) {
251 words = (words / MBLOCK_SIZE_W) * MBLOCK_SIZE_W;
252 } else {
253 words = ((words / MBLOCK_SIZE_W) + 1) * MBLOCK_SIZE_W;
254 }
255
256 words -= FIRST_BLOCK_OFF/sizeof(W_);
257 }
258 return words;
259 }
260
261 INLINE_HEADER StgWord
262 round_up_to_mblocks(StgWord words)
263 {
264 words += FIRST_BLOCK_OFF/sizeof(W_);
265 words = ((words / MBLOCK_SIZE_W) + 1) * MBLOCK_SIZE_W;
266 words -= FIRST_BLOCK_OFF/sizeof(W_);
267 return words;
268 }
269
270 #endif /* !CMINUSMINUS */
271 #endif /* RTS_STORAGE_BLOCK_H */