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
153
154
155
156
157
158
159
160
161
162
163
164
165
|
//===-- sanitizer_bvgraph.h -------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of Sanitizer runtime.
// BVGraph -- a directed graph.
//
//===----------------------------------------------------------------------===//
#ifndef SANITIZER_BVGRAPH_H
#define SANITIZER_BVGRAPH_H
#include "sanitizer_common.h"
#include "sanitizer_bitvector.h"
namespace __sanitizer {
// Directed graph of fixed size implemented as an array of bit vectors.
// Not thread-safe, all accesses should be protected by an external lock.
template<class BV>
class BVGraph {
public:
enum SizeEnum : uptr { kSize = BV::kSize };
uptr size() const { return kSize; }
// No CTOR.
void clear() {
for (uptr i = 0; i < size(); i++)
v[i].clear();
}
bool empty() const {
for (uptr i = 0; i < size(); i++)
if (!v[i].empty())
return false;
return true;
}
// Returns true if a new edge was added.
bool addEdge(uptr from, uptr to) {
check(from, to);
return v[from].setBit(to);
}
// Returns true if at least one new edge was added.
uptr addEdges(const BV &from, uptr to, uptr added_edges[],
uptr max_added_edges) {
uptr res = 0;
t1.copyFrom(from);
while (!t1.empty()) {
uptr node = t1.getAndClearFirstOne();
if (v[node].setBit(to))
if (res < max_added_edges)
added_edges[res++] = node;
}
return res;
}
// *EXPERIMENTAL*
// Returns true if an edge from=>to exist.
// This function does not use any global state except for 'this' itself,
// and thus can be called from different threads w/o locking.
// This would be racy.
// FIXME: investigate how much we can prove about this race being "benign".
bool hasEdge(uptr from, uptr to) { return v[from].getBit(to); }
// Returns true if the edge from=>to was removed.
bool removeEdge(uptr from, uptr to) {
return v[from].clearBit(to);
}
// Returns true if at least one edge *=>to was removed.
bool removeEdgesTo(const BV &to) {
bool res = 0;
for (uptr from = 0; from < size(); from++) {
if (v[from].setDifference(to))
res = true;
}
return res;
}
// Returns true if at least one edge from=>* was removed.
bool removeEdgesFrom(const BV &from) {
bool res = false;
t1.copyFrom(from);
while (!t1.empty()) {
uptr idx = t1.getAndClearFirstOne();
if (!v[idx].empty()) {
v[idx].clear();
res = true;
}
}
return res;
}
void removeEdgesFrom(uptr from) {
return v[from].clear();
}
bool hasEdge(uptr from, uptr to) const {
check(from, to);
return v[from].getBit(to);
}
// Returns true if there is a path from the node 'from'
// to any of the nodes in 'targets'.
bool isReachable(uptr from, const BV &targets) {
BV &to_visit = t1,
&visited = t2;
to_visit.copyFrom(v[from]);
visited.clear();
visited.setBit(from);
while (!to_visit.empty()) {
uptr idx = to_visit.getAndClearFirstOne();
if (visited.setBit(idx))
to_visit.setUnion(v[idx]);
}
return targets.intersectsWith(visited);
}
// Finds a path from 'from' to one of the nodes in 'target',
// stores up to 'path_size' items of the path into 'path',
// returns the path length, or 0 if there is no path of size 'path_size'.
uptr findPath(uptr from, const BV &targets, uptr *path, uptr path_size) {
if (path_size == 0)
return 0;
path[0] = from;
if (targets.getBit(from))
return 1;
// The function is recursive, so we don't want to create BV on stack.
// Instead of a getAndClearFirstOne loop we use the slower iterator.
for (typename BV::Iterator it(v[from]); it.hasNext(); ) {
uptr idx = it.next();
if (uptr res = findPath(idx, targets, path + 1, path_size - 1))
return res + 1;
}
return 0;
}
// Same as findPath, but finds a shortest path.
uptr findShortestPath(uptr from, const BV &targets, uptr *path,
uptr path_size) {
for (uptr p = 1; p <= path_size; p++)
if (findPath(from, targets, path, p) == p)
return p;
return 0;
}
private:
void check(uptr idx1, uptr idx2) const {
CHECK_LT(idx1, size());
CHECK_LT(idx2, size());
}
BV v[kSize];
// Keep temporary vectors here since we can not create large objects on stack.
BV t1, t2;
};
} // namespace __sanitizer
#endif // SANITIZER_BVGRAPH_H
|
