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 
12 namespace v8 {
13 namespace internal {
14 namespace compiler {
15 
16 class NodeOriginTable;
17 class 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.
22 class 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 
32 class CommonOperatorBuilder;
33 
34 // Implements loop peeling.
35 class V8_EXPORT_PRIVATE LoopPeeler {
36  public:
LoopPeeler(Graph* graph, CommonOperatorBuilder* common, LoopTree* loop_tree, Zone* tmp_zone, SourcePositionTable* source_positions, NodeOriginTable* node_origins)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) {}
CanPeel(LoopTree::Loop* loop)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