1 /* -----------------------------------------------------------------------------
2 * $Id: Block.h,v 1.17 2004/08/13 13:09:09 simonmar Exp $
4 * (c) The GHC Team, 1998-1999
6 * Block structure for the storage manager
8 * ---------------------------------------------------------------------------*/
13 /* The actual block and megablock-size constants are defined in
14 * includes/Constants.h, all constants here are derived from these.
17 /* Block related constants (BLOCK_SHIFT is defined in Constants.h) */
19 #define BLOCK_SIZE (1<<BLOCK_SHIFT)
20 #define BLOCK_SIZE_W (BLOCK_SIZE/sizeof(W_))
21 #define BLOCK_MASK (BLOCK_SIZE-1)
23 #define BLOCK_ROUND_UP(p) ((void *) (((W_)(p)+BLOCK_SIZE-1) & ~BLOCK_MASK))
24 #define BLOCK_ROUND_DOWN(p) ((void *) ((W_)(p) & ~BLOCK_MASK))
26 /* Megablock related constants (MBLOCK_SHIFT is defined in Constants.h) */
28 #define MBLOCK_SIZE (1<<MBLOCK_SHIFT)
29 #define MBLOCK_SIZE_W (MBLOCK_SIZE/sizeof(W_))
30 #define MBLOCK_MASK (MBLOCK_SIZE-1)
32 #define MBLOCK_ROUND_UP(p) ((void *)(((W_)(p)+MBLOCK_SIZE-1) & ~MBLOCK_MASK))
33 #define MBLOCK_ROUND_DOWN(p) ((void *)((W_)(p) & ~MBLOCK_MASK ))
35 /* The largest size an object can be before we give it a block of its
36 * own and treat it as an immovable object during GC, expressed as a
37 * fraction of BLOCK_SIZE.
39 #define LARGE_OBJECT_THRESHOLD ((nat)(BLOCK_SIZE * 8 / 10))
41 /* -----------------------------------------------------------------------------
42 * Block descriptor. This structure *must* be the right length, so we
43 * can do pointer arithmetic on pointers to it.
46 /* The block descriptor is 64 bytes on a 64-bit machine, and 32-bytes
47 * on a 32-bit machine.
51 typedef struct bdescr_ {
52 StgPtr start; /* start addr of memory */
53 StgPtr free; /* first free byte of memory */
54 struct bdescr_ *link; /* used for chaining blocks together */
56 struct bdescr_ *back; /* used (occasionally) for doubly-linked lists*/
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];
66 StgWord32 _padding[0];
71 #if SIZEOF_VOID_P == 8
72 #define BDESCR_SIZE 0x40
73 #define BDESCR_MASK 0x3f
74 #define BDESCR_SHIFT 6
76 #define BDESCR_SIZE 0x20
77 #define BDESCR_MASK 0x1f
78 #define BDESCR_SHIFT 5
81 /* Block contains objects evacuated during this GC */
82 #define BF_EVACUATED 1
83 /* Block is a large object */
87 /* Block is part of a compacted generation */
88 #define BF_COMPACTED 8
90 /* Finding the block descriptor for a given block -------------------------- */
95 ((((p) & MBLOCK_MASK & ~BLOCK_MASK) >> (BLOCK_SHIFT-BDESCR_SHIFT)) \
96 | ((p) & ~MBLOCK_MASK))
100 INLINE_HEADER bdescr *Bdescr(StgPtr p)
103 ((((W_)p & MBLOCK_MASK & ~BLOCK_MASK) >> (BLOCK_SHIFT-BDESCR_SHIFT))
104 | ((W_)p & ~MBLOCK_MASK)
110 /* Useful Macros ------------------------------------------------------------ */
112 /* Offset of first real data block in a megablock */
114 #define FIRST_BLOCK_OFF \
115 ((W_)BLOCK_ROUND_UP(BDESCR_SIZE * (MBLOCK_SIZE / BLOCK_SIZE)))
117 /* First data block in a given megablock */
119 #define FIRST_BLOCK(m) ((void *)(FIRST_BLOCK_OFF + (W_)(m)))
121 /* Last data block in a given megablock */
123 #define LAST_BLOCK(m) ((void *)(MBLOCK_SIZE-BLOCK_SIZE + (W_)(m)))
125 /* First real block descriptor in a megablock */
127 #define FIRST_BDESCR(m) \
128 ((bdescr *)((FIRST_BLOCK_OFF>>(BLOCK_SHIFT-BDESCR_SHIFT)) + (W_)(m)))
130 /* Number of usable blocks in a megablock */
132 #define BLOCKS_PER_MBLOCK ((MBLOCK_SIZE - FIRST_BLOCK_OFF) / BLOCK_SIZE)
134 /* How many blocks in this megablock group */
136 #define MBLOCK_GROUP_BLOCKS(n) \
137 (BLOCKS_PER_MBLOCK + (n-1) * (MBLOCK_SIZE / BLOCK_SIZE))
139 /* Compute the required size of a megablock group */
141 #define BLOCKS_TO_MBLOCKS(n) \
142 (1 + (W_)MBLOCK_ROUND_UP((n-BLOCKS_PER_MBLOCK) * BLOCK_SIZE) / MBLOCK_SIZE)
145 /* Double-linked block lists: --------------------------------------------- */
149 dbl_link_onto(bdescr *bd, bdescr **list)
154 (*list)->u.back = bd; /* double-link the list */