1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
/* Heap checking for the mark-sweep collector */
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#ifdef DEBUG
enum block_kind { RAWDATA = 0, PTRDATA = 1, CLOSURE = 2 };
enum block_color { WHITE = 0, GRAY = 4, BLACK = 0xC };
#define At(p,ty) (*((ty *)(p)))
#define Kind_header(h) ((h) & 3)
#define Color_header(h) ((h) & 0xC)
#define Size_header(h) (((h) >> 2) & 0xFFFFFFFC)
extern char * heap_start, * heap_end, * freelist_head;
char * heap_bitmap = NULL;
static inline void bitmap_set(char * bm, unsigned i)
{
bm[i >> 3] |= 1 << (i & 7);
}
static inline int bitmap_get(char * bm, unsigned i)
{
return bm[i >> 3] & (1 << (i & 7));
}
static void check_block(char * p, unsigned s)
{
char * d;
for (/**/; s > 0; p += 4, s -= 4) {
d = At(p, char *);
if (d != NULL) {
assert(d >= heap_start + 4);
assert(d <= heap_end - 4);
assert(((unsigned) d & 3) == 0);
assert(bitmap_get(heap_bitmap, (d - heap_start) >> 2));
}
}
}
void check_heap(void)
{
char * p, * f, * nextf;
unsigned h, s, bitmap_size;
bitmap_size = ((heap_end - heap_start) + 31) / 32;
/* one bit per word -> one byte per 32 bytes in the heap */
if (heap_bitmap == NULL) {
heap_bitmap = malloc(bitmap_size);
assert (heap_bitmap != NULL);
}
memset(heap_bitmap, 0, bitmap_size);
/* Superficial check and construction of the bitmap */
f = freelist_head;
assert(f >= heap_start + 4);
assert(f <= heap_end - 4);
for (p = heap_start; p < heap_end; /**/) {
h = At(p, unsigned);
s = Size_header(h);
assert(s >= 4);
assert((s & 3) == 0);
p = p + 4;
assert (p + s <= heap_end);
if (p == f) {
/* this is a free list block */
assert((h & 0xF) == 0);
nextf = At(p, char *);
if (nextf != NULL) {
assert(nextf > f);
assert(nextf <= heap_end - 4);
}
f = nextf;
} else {
/* this is an allocated block */
assert(Color_header(h) == WHITE);
bitmap_set(heap_bitmap, (p - heap_start) >> 2);
}
p = p + s;
}
assert (p == heap_end);
assert (f == NULL);
/* Check block contents */
f = freelist_head;
for (p = heap_start; p < heap_end; /**/) {
h = At(p, unsigned);
s = Size_header(h);
p = p + 4;
if (p == f) {
/* Fill free block with garbage */
memset(p + 4, 0xEE, s - 4);
f = At(p, char *);
} else {
/* Check block contents */
switch (Kind_header(h)) {
case RAWDATA:
break;
case PTRDATA:
check_block(p, s); break;
case CLOSURE:
check_block(p + 4, s - 4); break;
default:
assert(0);
}
}
p = p + s;
}
}
#endif
|
