1// Copyright 2015 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_
6#define V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_
7
8#include "src/bit-vector.h"
9#include "src/handles.h"
10
11namespace v8 {
12namespace internal {
13
14class BytecodeArray;
15
16namespace compiler {
17
18// A class for identifying branch targets within a bytecode array.
19// This information can be used to construct the local control flow
20// logic for high-level IR graphs built from bytecode.
21//
22// N.B. If this class is used to determine loop headers, then such a
23// usage relies on the only backwards branches in bytecode being jumps
24// back to loop headers.
25class BytecodeBranchAnalysis BASE_EMBEDDED {
26 public:
27  BytecodeBranchAnalysis(Handle<BytecodeArray> bytecode_array, Zone* zone);
28
29  // Analyze the bytecodes to find the branch sites and their
30  // targets. No other methods in this class return valid information
31  // until this has been called.
32  void Analyze();
33
34  // Returns true if there are any forward branches to the bytecode at
35  // |offset|.
36  bool forward_branches_target(int offset) const {
37    return is_forward_target_.Contains(offset);
38  }
39
40  // Returns true if there are any backward branches to the bytecode
41  // at |offset|.
42  bool backward_branches_target(int offset) const {
43    return is_backward_target_.Contains(offset);
44  }
45
46 private:
47  void AddBranch(int origin_offset, int target_offset);
48
49  Zone* zone() const { return zone_; }
50  Handle<BytecodeArray> bytecode_array() const { return bytecode_array_; }
51
52  Handle<BytecodeArray> bytecode_array_;
53  BitVector is_backward_target_;
54  BitVector is_forward_target_;
55  Zone* zone_;
56
57  DISALLOW_COPY_AND_ASSIGN(BytecodeBranchAnalysis);
58};
59
60
61}  // namespace compiler
62}  // namespace internal
63}  // namespace v8
64
65#endif  // V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_
66