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
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
#define GC_SMALLEST_PAGESIZE 4096
/* #define DEBUG_MREMAP 1 */
/* Used to allocate at the head and tail of an existing allocation */
static void *GC_extendHead (void *base, size_t length);
static void *GC_extendTail (void *base, size_t length);
void *GC_mremap (void *base, size_t oldLength, size_t newLength) {
static void* cacheAddress = 0;
static size_t cacheOldLength = 0;
static size_t cacheNewLength = 0;
static size_t cacheTailSize;
static size_t cacheHeadSize;
void* tail;
void* head;
void* alloc;
size_t growth, bsLow, bsHigh, bsTry;
#ifdef DEBUG_MREMAP
fprintf(stderr, "remap(%08X, %d, %d)\n", (size_t)base, oldLength, newLength);
fflush(stderr);
#endif
if (newLength == oldLength)
return base;
if (newLength < oldLength) {
GC_release((char*)base + newLength, oldLength-newLength);
return base;
}
growth = newLength-oldLength;
if (cacheAddress == base &&
cacheOldLength == oldLength &&
cacheNewLength > newLength) /* cache only during backoff */
goto GC_mremap_cached;
/* Start probing for the available tail length */
bsLow = 0;
bsHigh = (growth+GC_SMALLEST_PAGESIZE-1)/GC_SMALLEST_PAGESIZE;
/* Round bsHigh to a power of two -> allocation works with all page sizes */
for (bsTry = 1; bsTry <= bsHigh; bsTry += bsTry) { }
bsHigh = bsTry;
while (bsHigh - bsLow > 1) {
bsTry = (bsHigh + bsLow)/2;
tail = (char*)base + oldLength;
alloc = GC_extendTail(tail, bsTry*GC_SMALLEST_PAGESIZE);
if (tail == alloc) {
GC_release(alloc, bsTry*GC_SMALLEST_PAGESIZE);
bsLow = bsTry;
} else {
if (alloc != (void*)-1)
GC_release(alloc, bsTry*GC_SMALLEST_PAGESIZE);
bsHigh = bsTry;
}
}
cacheTailSize = bsLow*GC_SMALLEST_PAGESIZE;
/* Start probing for the available head length */
bsLow = 0;
bsHigh = (growth+GC_SMALLEST_PAGESIZE-1)/GC_SMALLEST_PAGESIZE;
/* Round bsHigh to a power of two -> allocation works with all page sizes */
for (bsTry = 1; bsTry <= bsHigh; bsTry += bsTry) { }
bsHigh = bsTry;
while (bsHigh - bsLow > 1) {
bsTry = (bsHigh + bsLow)/2;
head = (char*)base - bsTry*GC_SMALLEST_PAGESIZE;
alloc = GC_extendHead(head, bsTry*GC_SMALLEST_PAGESIZE);
if (head == alloc) {
GC_release(alloc, bsTry*GC_SMALLEST_PAGESIZE);
bsLow = bsTry;
} else {
if (alloc != (void*)-1)
GC_release(alloc, bsTry*GC_SMALLEST_PAGESIZE);
bsHigh = bsTry;
}
}
cacheHeadSize = bsLow*GC_SMALLEST_PAGESIZE;
#ifdef DEBUG_MREMAP
fprintf(stderr, "Expansion detects: %10d/%10d/%10d = %10d\n",
cacheHeadSize, oldLength, cacheTailSize,
cacheHeadSize+ oldLength+ cacheTailSize);
fflush(stderr);
#endif
cacheAddress = base;
cacheOldLength = oldLength;
GC_mremap_cached:
cacheNewLength = newLength;
/* Is there enough free space? */
if (cacheTailSize + cacheHeadSize < growth) {
/* No, there's not. Try to move it instead. */
alloc = GC_mmapAnon(0, newLength);
if (alloc != (void*)-1) {
memcpy(alloc, base, oldLength);
GC_release(base, oldLength);
return alloc;
}
/* Failed even to move it */
return (void*)-1;
}
#ifdef DEBUG_MREMAP
fprintf(stderr, "Expansion attempts %d bytes\n", newLength);
fflush(stderr);
#endif
if (growth <= cacheTailSize) {
tail = (char*)base + oldLength;
alloc = GC_extendTail(tail, growth);
if (alloc != tail) {
/* This shouldn't happen; we tested for the memory! */
if (alloc != (void*)-1)
GC_release(alloc, growth);
return (void*)-1;
}
return base;
}
if (cacheTailSize > 0) {
tail = (char*)base + oldLength;
alloc = GC_extendTail(tail, cacheTailSize);
if (alloc != tail) {
/* This shouldn't happen; we tested for the memory! */
if (alloc != (void*)-1)
GC_release(alloc, cacheTailSize);
return (void*)-1;
}
} else {
tail = 0; /* quell warning */
}
head = (char*)base - (growth-cacheTailSize);
alloc = GC_extendHead(head, growth-cacheTailSize);
if (alloc != head) {
/* This shouldn't happen; we tested for the memory! */
if (alloc != (void*)-1)
GC_release(alloc, growth-cacheTailSize);
if (cacheTailSize > 0)
GC_release(tail, cacheTailSize);
return (void*)-1;
}
memmove(head, base, oldLength);
return head;
}
|
