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_DEAD_CODE_ELIMINATION_H_
6#define V8_COMPILER_DEAD_CODE_ELIMINATION_H_
7
8#include "src/base/compiler-specific.h"
9#include "src/compiler/graph-reducer.h"
10#include "src/globals.h"
11
12namespace v8 {
13namespace internal {
14namespace compiler {
15
16// Forward declarations.
17class CommonOperatorBuilder;
18
19
20// Propagates {Dead} control through the graph and thereby removes dead code.
21// Note that this does not include trimming dead uses from the graph, and it
22// also does not include detecting dead code by any other means than seeing a
23// {Dead} control input; that is left to other reducers.
24class V8_EXPORT_PRIVATE DeadCodeElimination final
25    : public NON_EXPORTED_BASE(AdvancedReducer) {
26 public:
27  DeadCodeElimination(Editor* editor, Graph* graph,
28                      CommonOperatorBuilder* common);
29  ~DeadCodeElimination() final {}
30
31  Reduction Reduce(Node* node) final;
32
33 private:
34  Reduction ReduceEnd(Node* node);
35  Reduction ReduceLoopOrMerge(Node* node);
36  Reduction ReduceLoopExit(Node* node);
37  Reduction ReduceNode(Node* node);
38
39  Reduction RemoveLoopExit(Node* node);
40
41  void TrimMergeOrPhi(Node* node, int size);
42
43  Graph* graph() const { return graph_; }
44  CommonOperatorBuilder* common() const { return common_; }
45  Node* dead() const { return dead_; }
46
47  Graph* const graph_;
48  CommonOperatorBuilder* const common_;
49  Node* const dead_;
50
51  DISALLOW_COPY_AND_ASSIGN(DeadCodeElimination);
52};
53
54}  // namespace compiler
55}  // namespace internal
56}  // namespace v8
57
58#endif  // V8_COMPILER_DEAD_CODE_ELIMINATION_H_
59