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
166
167
|
// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_COMPILER_LOOP_ANALYSIS_H_
#define V8_COMPILER_LOOP_ANALYSIS_H_
#include "src/base/iterator.h"
#include "src/compiler/graph.h"
#include "src/compiler/node.h"
#include "src/zone-containers.h"
namespace v8 {
namespace internal {
namespace compiler {
// TODO(titzer): don't assume entry edges have a particular index.
static const int kAssumedLoopEntryIndex = 0; // assume loops are entered here.
class LoopFinderImpl;
typedef base::iterator_range<Node**> NodeRange;
// Represents a tree of loops in a graph.
class LoopTree : public ZoneObject {
public:
LoopTree(size_t num_nodes, Zone* zone)
: zone_(zone),
outer_loops_(zone),
all_loops_(zone),
node_to_loop_num_(static_cast<int>(num_nodes), -1, zone),
loop_nodes_(zone) {}
// Represents a loop in the tree of loops, including the header nodes,
// the body, and any nested loops.
class Loop {
public:
Loop* parent() const { return parent_; }
const ZoneVector<Loop*>& children() const { return children_; }
size_t HeaderSize() const { return body_start_ - header_start_; }
size_t BodySize() const { return exits_start_ - body_start_; }
size_t ExitsSize() const { return exits_end_ - exits_start_; }
size_t TotalSize() const { return exits_end_ - header_start_; }
size_t depth() const { return static_cast<size_t>(depth_); }
private:
friend class LoopTree;
friend class LoopFinderImpl;
explicit Loop(Zone* zone)
: parent_(nullptr),
depth_(0),
children_(zone),
header_start_(-1),
body_start_(-1),
exits_start_(-1),
exits_end_(-1) {}
Loop* parent_;
int depth_;
ZoneVector<Loop*> children_;
int header_start_;
int body_start_;
int exits_start_;
int exits_end_;
};
// Return the innermost nested loop, if any, that contains {node}.
Loop* ContainingLoop(Node* node) {
if (node->id() >= node_to_loop_num_.size()) return nullptr;
int num = node_to_loop_num_[node->id()];
return num > 0 ? &all_loops_[num - 1] : nullptr;
}
// Check if the {loop} contains the {node}, either directly or by containing
// a nested loop that contains {node}.
bool Contains(Loop* loop, Node* node) {
for (Loop* c = ContainingLoop(node); c != nullptr; c = c->parent_) {
if (c == loop) return true;
}
return false;
}
// Return the list of outer loops.
const ZoneVector<Loop*>& outer_loops() const { return outer_loops_; }
// Return the unique loop number for a given loop. Loop numbers start at {1}.
int LoopNum(Loop* loop) const {
return 1 + static_cast<int>(loop - &all_loops_[0]);
}
// Return a range which can iterate over the header nodes of {loop}.
NodeRange HeaderNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->header_start_,
&loop_nodes_[0] + loop->body_start_);
}
// Return the header control node for a loop.
Node* HeaderNode(Loop* loop);
// Return a range which can iterate over the body nodes of {loop}.
NodeRange BodyNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->body_start_,
&loop_nodes_[0] + loop->exits_start_);
}
// Return a range which can iterate over the body nodes of {loop}.
NodeRange ExitNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->exits_start_,
&loop_nodes_[0] + loop->exits_end_);
}
// Return a range which can iterate over the nodes of {loop}.
NodeRange LoopNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->header_start_,
&loop_nodes_[0] + loop->exits_end_);
}
// Return the node that represents the control, i.e. the loop node itself.
Node* GetLoopControl(Loop* loop) {
// TODO(turbofan): make the loop control node always first?
for (Node* node : HeaderNodes(loop)) {
if (node->opcode() == IrOpcode::kLoop) return node;
}
UNREACHABLE();
return nullptr;
}
Zone* zone() const { return zone_; }
private:
friend class LoopFinderImpl;
Loop* NewLoop() {
all_loops_.push_back(Loop(zone_));
Loop* result = &all_loops_.back();
return result;
}
void SetParent(Loop* parent, Loop* child) {
if (parent != nullptr) {
parent->children_.push_back(child);
child->parent_ = parent;
child->depth_ = parent->depth_ + 1;
} else {
outer_loops_.push_back(child);
}
}
Zone* zone_;
ZoneVector<Loop*> outer_loops_;
ZoneVector<Loop> all_loops_;
ZoneVector<int> node_to_loop_num_;
ZoneVector<Node*> loop_nodes_;
};
class LoopFinder {
public:
// Build a loop tree for the entire graph.
static LoopTree* BuildLoopTree(Graph* graph, Zone* temp_zone);
};
} // namespace compiler
} // namespace internal
} // namespace v8
#endif // V8_COMPILER_LOOP_ANALYSIS_H_
|
