[turbofan] Cache for reusing value vector nodes in frame states.

src/compiler/state-values-utils.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_STATE_VALUES_UTILS_H_
+#define V8_COMPILER_STATE_VALUES_UTILS_H_
+
+#include "src/compiler/js-graph.h"
+
+namespace v8 {
+namespace internal {
+
+namespace compiler {
+
+class Graph;
+
+class StateValuesCache {
+ public:
+  explicit StateValuesCache(JSGraph* js_graph);
+
+  Node* GetNodeForValues(Node** values, size_t count);
+
+ private:
+  static const size_t kMaxInputCount = 8;
+
+  struct NodeKey {
+    Node* node;
+
+    explicit NodeKey(Node* node) : node(node) {}
+  };
+
+  struct StateValuesKey : public NodeKey {
+    // ValueArray - array of nodes ({node} has to be nullptr).
+    size_t count;
+    Node** values;
+
+    StateValuesKey(size_t count, Node** values)
+        : NodeKey(nullptr), count(count), values(values) {}
+  };
+
+  class ValueArrayIterator;
+
+  static bool AreKeysEqual(void* key1, void* key2);
+  static bool IsKeysEqualToNode(StateValuesKey* key, Node* node);
+  static bool AreValueKeysEqual(StateValuesKey* key1, StateValuesKey* key2);
+
+  Node* BuildTree(ValueArrayIterator* it, size_t max_height);
+  NodeVector* GetWorkingSpace(size_t level);
+  Node* GetEmptyStateValues();
+  Node* GetValuesNodeFromCache(Node** nodes, size_t count);
+
+  Graph* graph() { return js_graph_->graph(); }
+  CommonOperatorBuilder* common() { return js_graph_->common(); }
+
+  Zone* zone() { return graph()->zone(); }
+
+  JSGraph* js_graph_;
+  ZoneHashMap hash_map_;
+  ZoneVector<NodeVector*> working_space_;  // One working space per level.
+  Node* empty_state_values_;
+};
+
+class StateValuesAccess {
+ public:
+  class iterator {
+   public:
+    // Bare minimum of operators needed for range iteration.
+    bool operator!=(iterator& other);
+    iterator& operator++();
+    Node* operator*();
+
+   private:
+    friend class StateValuesAccess;
+
+    iterator() : current_depth_(-1) {}
+    explicit iterator(Node* node);
+
+    Node* node();
+    bool done();
+    void Advance();
+
+    struct StatePos {
+      Node* node;
+      int index;
+
+      explicit StatePos(Node* node) : node(node), index(0) {}
+      StatePos() {}
+    };
+
+    StatePos* Top();
+    void Push(Node* node);
+    void Pop();
+
+    static const int kMaxInlineDepth = 8;
+    StatePos stack_[kMaxInlineDepth];
+    int current_depth_;
+  };
+
+  explicit StateValuesAccess(Node* node) : node_(node) {}
+
+  size_t size();
+  iterator begin() { return iterator(node_); }
+  iterator end() { return iterator(); }
+
+ private:
+  Node* node_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_STATE_VALUES_UTILS_H_