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_LOOP_PEELING_H_
6#define V8_COMPILER_LOOP_PEELING_H_
7
8#include "src/base/compiler-specific.h"
9#include "src/common/globals.h"
10#include "src/compiler/loop-analysis.h"
11
12namespace v8 {
13namespace internal {
14namespace compiler {
15
16class NodeOriginTable;
17class SourcePositionTable;
18
19// Represents the output of peeling a loop, which is basically the mapping
20// from the body of the loop to the corresponding nodes in the peeled
21// iteration.
22class V8_EXPORT_PRIVATE PeeledIteration : public NON_EXPORTED_BASE(ZoneObject) {
23 public:
24  // Maps {node} to its corresponding copy in the peeled iteration, if
25  // the node was part of the body of the loop. Returns {node} otherwise.
26  Node* map(Node* node);
27
28 protected:
29  PeeledIteration() = default;
30};
31
32class CommonOperatorBuilder;
33
34// Implements loop peeling.
35class V8_EXPORT_PRIVATE LoopPeeler {
36 public:
37  LoopPeeler(Graph* graph, CommonOperatorBuilder* common, LoopTree* loop_tree,
38             Zone* tmp_zone, SourcePositionTable* source_positions,
39             NodeOriginTable* node_origins)
40      : graph_(graph),
41        common_(common),
42        loop_tree_(loop_tree),
43        tmp_zone_(tmp_zone),
44        source_positions_(source_positions),
45        node_origins_(node_origins) {}
46  bool CanPeel(LoopTree::Loop* loop) {
47    return LoopFinder::HasMarkedExits(loop_tree_, loop);
48  }
49  PeeledIteration* Peel(LoopTree::Loop* loop);
50  void PeelInnerLoopsOfTree();
51
52  static void EliminateLoopExits(Graph* graph, Zone* tmp_zone);
53  static void EliminateLoopExit(Node* loop);
54  static const size_t kMaxPeeledNodes = 1000;
55
56 private:
57  Graph* const graph_;
58  CommonOperatorBuilder* const common_;
59  LoopTree* const loop_tree_;
60  Zone* const tmp_zone_;
61  SourcePositionTable* const source_positions_;
62  NodeOriginTable* const node_origins_;
63
64  void PeelInnerLoops(LoopTree::Loop* loop);
65};
66
67
68}  // namespace compiler
69}  // namespace internal
70}  // namespace v8
71
72#endif  // V8_COMPILER_LOOP_PEELING_H_
73