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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
/*
* Copyright (C) 2013 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef DFGNaturalLoops_h
#define DFGNaturalLoops_h
#if ENABLE(DFG_JIT)
#include "DFGAnalysis.h"
#include "DFGBasicBlock.h"
#include "DFGCommon.h"
namespace JSC { namespace DFG {
class NaturalLoops;
class NaturalLoop {
public:
NaturalLoop()
: m_header(0)
, m_outerLoopIndex(UINT_MAX)
{
}
NaturalLoop(BasicBlock* header, unsigned index)
: m_header(header)
, m_outerLoopIndex(UINT_MAX)
, m_index(index)
{
}
BasicBlock* header() const { return m_header; }
unsigned size() const { return m_body.size(); }
BasicBlock* at(unsigned i) const { return m_body[i]; }
BasicBlock* operator[](unsigned i) const { return at(i); }
// This is the slower, but simpler, way of asking if a block belongs to
// a natural loop. It's faster to call NaturalLoops::belongsTo(), which
// tries to be O(loop depth) rather than O(loop size). Loop depth is
// almost always smaller than loop size. A *lot* smaller.
bool contains(BasicBlock* block) const
{
for (unsigned i = m_body.size(); i--;) {
if (m_body[i] == block)
return true;
}
ASSERT(block != header()); // Header should be contained.
return false;
}
// The index of this loop in NaturalLoops.
unsigned index() const { return m_index; }
bool isOuterMostLoop() const { return m_outerLoopIndex == UINT_MAX; }
void dump(PrintStream&) const;
private:
friend class NaturalLoops;
void addBlock(BasicBlock* block) { m_body.append(block); }
BasicBlock* m_header;
Vector<BasicBlock*, 4> m_body;
unsigned m_outerLoopIndex;
unsigned m_index;
};
class NaturalLoops : public Analysis<NaturalLoops> {
public:
NaturalLoops();
~NaturalLoops();
void computeDependencies(Graph&);
void compute(Graph&);
unsigned numLoops() const
{
ASSERT(isValid());
return m_loops.size();
}
const NaturalLoop& loop(unsigned i) const
{
ASSERT(isValid());
return m_loops[i];
}
// Return either null if the block isn't a loop header, or the
// loop it belongs to.
const NaturalLoop* headerOf(BasicBlock* block) const
{
ASSERT(isValid());
const NaturalLoop* loop = innerMostLoopOf(block);
if (!loop)
return 0;
if (loop->header() == block)
return loop;
if (!ASSERT_DISABLED) {
for (; loop; loop = innerMostOuterLoop(*loop))
ASSERT(loop->header() != block);
}
return 0;
}
const NaturalLoop* innerMostLoopOf(BasicBlock* block) const
{
ASSERT(isValid());
unsigned index = block->innerMostLoopIndices[0];
if (index == UINT_MAX)
return 0;
return &m_loops[index];
}
const NaturalLoop* innerMostOuterLoop(const NaturalLoop& loop) const
{
ASSERT(isValid());
if (loop.m_outerLoopIndex == UINT_MAX)
return 0;
return &m_loops[loop.m_outerLoopIndex];
}
bool belongsTo(BasicBlock* block, const NaturalLoop& candidateLoop) const
{
ASSERT(isValid());
// It's faster to do this test using the loop itself, if it's small.
if (candidateLoop.size() < 4)
return candidateLoop.contains(block);
for (const NaturalLoop* loop = innerMostLoopOf(block); loop; loop = innerMostOuterLoop(*loop)) {
if (loop == &candidateLoop)
return true;
}
return false;
}
unsigned loopDepth(BasicBlock* block) const
{
unsigned depth = 0;
for (const NaturalLoop* loop = innerMostLoopOf(block); loop; loop = innerMostOuterLoop(*loop))
depth++;
return depth;
}
// Return the indices of all loops this belongs to.
Vector<const NaturalLoop*> loopsOf(BasicBlock*) const;
void dump(PrintStream&) const;
private:
// If we ever had a scalability problem in our natural loop finder, we could
// use some HashMap's here. But it just feels a heck of a lot less convenient.
Vector<NaturalLoop, 4> m_loops;
};
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
#endif // DFGNaturalLoops_h
|
