[turbofan] First version of loop peeling.

src/compiler/loop-peeling.h

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_COMPILER_LOOP_PEELING_H_
+#define V8_COMPILER_LOOP_PEELING_H_
+
+#include "src/compiler/loop-analysis.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+// Represents the output of peeling a loop, which is basically the mapping
+// from the body of the loop to the corresponding nodes in the peeled
+// iteration.
+class PeeledIteration : public ZoneObject {
+ public:
+  // Maps {node} to its corresponding copy in the peeled iteration, if
+  // the node was part of the body of the loop. Returns {node} otherwise.
+  Node* map(Node* node);
+
+ protected:
+  PeeledIteration() {}
+};
+
+class CommonOperatorBuilder;
+
+// Implements loop peeling.
+class LoopPeeler {
+ public:
+  static PeeledIteration* Peel(Graph* graph, CommonOperatorBuilder* common,
+                               LoopTree* loop_tree, LoopTree::Loop* loop,
+                               Zone* tmp_zone);
+};
+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_LOOP_PEELING_H_