Merge changes up to V8 version 2.1.3 into the partial snapshots

src/data-flow.h

Index: src/data-flow.h
===================================================================
--- src/data-flow.h	(revision 3964)
+++ src/data-flow.h	(working copy)
@@ -28,12 +28,403 @@
 #ifndef V8_DATAFLOW_H_
 #define V8_DATAFLOW_H_
 
+#include "v8.h"
+
 #include "ast.h"
 #include "compiler.h"
+#include "zone-inl.h"
 
 namespace v8 {
 namespace internal {
 
+class BitVector: public ZoneObject {
+ public:
+  explicit BitVector(int length)
+      : length_(length),
+        data_length_(SizeFor(length)),
+        data_(Zone::NewArray<uint32_t>(data_length_)) {
+    ASSERT(length > 0);
+    Clear();
+  }
+
+  BitVector(const BitVector& other)
+      : length_(other.length()),
+        data_length_(SizeFor(length_)),
+        data_(Zone::NewArray<uint32_t>(data_length_)) {
+    CopyFrom(other);
+  }
+
+  static int SizeFor(int length) {
+    return 1 + ((length - 1) / 32);
+  }
+
+  BitVector& operator=(const BitVector& rhs) {
+    if (this != &rhs) CopyFrom(rhs);
+    return *this;
+  }
+
+  void CopyFrom(const BitVector& other) {
+    ASSERT(other.length() == length());
+    for (int i = 0; i < data_length_; i++) {
+      data_[i] = other.data_[i];
+    }
+  }
+
+  bool Contains(int i) {
+    ASSERT(i >= 0 && i < length());
+    uint32_t block = data_[i / 32];
+    return (block & (1U << (i % 32))) != 0;
+  }
+
+  void Add(int i) {
+    ASSERT(i >= 0 && i < length());
+    data_[i / 32] |= (1U << (i % 32));
+  }
+
+  void Remove(int i) {
+    ASSERT(i >= 0 && i < length());
+    data_[i / 32] &= ~(1U << (i % 32));
+  }
+
+  void Union(const BitVector& other) {
+    ASSERT(other.length() == length());
+    for (int i = 0; i < data_length_; i++) {
+      data_[i] |= other.data_[i];
+    }
+  }
+
+  void Intersect(const BitVector& other) {
+    ASSERT(other.length() == length());
+    for (int i = 0; i < data_length_; i++) {
+      data_[i] &= other.data_[i];
+    }
+  }
+
+  void Clear() {
+    for (int i = 0; i < data_length_; i++) {
+      data_[i] = 0;
+    }
+  }
+
+  bool IsEmpty() const {
+    for (int i = 0; i < data_length_; i++) {
+      if (data_[i] != 0) return false;
+    }
+    return true;
+  }
+
+  int length() const { return length_; }
+
+ private:
+  int length_;
+  int data_length_;
+  uint32_t* data_;
+};
+
+
+// Forward declarations of Node types.
+class Node;
+class BranchNode;
+class JoinNode;
+
+// Flow graphs have a single entry and single exit.  The empty flowgraph is
+// represented by both entry and exit being NULL.
+class FlowGraph BASE_EMBEDDED {
+ public:
+  FlowGraph() : entry_(NULL), exit_(NULL) {}
+
+  static FlowGraph Empty() { return FlowGraph(); }
+
+  bool is_empty() const { return entry_ == NULL; }
+  Node* entry() const { return entry_; }
+  Node* exit() const { return exit_; }
+
+  // Add a single instruction to the end of this flowgraph.
+  void AppendInstruction(AstNode* instruction);
+
+  // Add a single node to the end of this flow graph.
+  void AppendNode(Node* node);
+
+  // Add a flow graph fragment to the end of this one.
+  void AppendGraph(FlowGraph* graph);
+
+  // Concatenate an if-then-else flow-graph to this one.  Control is split
+  // and merged, so the graph remains single-entry, single-exit.
+  void Split(BranchNode* branch,
+             FlowGraph* left,
+             FlowGraph* right,
+             JoinNode* merge);
+
+  // Concatenate a forward loop (e.g., while or for loop) flow-graph to this
+  // one.  Control is split by the condition and merged back from the back
+  // edge at end of the body to the beginning of the condition.  The single
+  // (free) exit of the result graph is the right (false) arm of the branch
+  // node.
+  void Loop(JoinNode* merge,
+            FlowGraph* condition,
+            BranchNode* branch,
+            FlowGraph* body);
+
+#ifdef DEBUG
+  void PrintText(ZoneList<Node*>* postorder);
+#endif
+
+ private:
+  Node* entry_;
+  Node* exit_;
+};
+
+
+// Flow-graph nodes.
+class Node: public ZoneObject {
+ public:
+  Node() : number_(-1), mark_(false) {}
+
+  virtual ~Node() {}
+
+  virtual bool IsBlockNode() { return false; }
+  virtual bool IsJoinNode() { return false; }
+
+  virtual void AddPredecessor(Node* predecessor) = 0;
+  virtual void AddSuccessor(Node* successor) = 0;
+
+  bool IsMarkedWith(bool mark) { return mark_ == mark; }
+  void MarkWith(bool mark) { mark_ = mark; }
+
+  // Perform a depth first search and record preorder and postorder
+  // traversal orders.
+  virtual void Traverse(bool mark,
+                        ZoneList<Node*>* preorder,
+                        ZoneList<Node*>* postorder) = 0;
+
+  int number() { return number_; }
+  void set_number(int number) { number_ = number; }
+
+#ifdef DEBUG
+  virtual void AssignNumbers();
+  virtual void PrintText() = 0;
+#endif
+
+ private:
+  int number_;
+  bool mark_;
+
+  DISALLOW_COPY_AND_ASSIGN(Node);
+};
+
+
+// An entry node has no predecessors and a single successor.
+class EntryNode: public Node {
+ public:
+  EntryNode() : successor_(NULL) {}
+
+  void AddPredecessor(Node* predecessor) { UNREACHABLE(); }
+
+  void AddSuccessor(Node* successor) {
+    ASSERT(successor_ == NULL && successor != NULL);
+    successor_ = successor;
+  }
+
+  void Traverse(bool mark,
+                ZoneList<Node*>* preorder,
+                ZoneList<Node*>* postorder);
+
+#ifdef DEBUG
+  void PrintText();
+#endif
+
+ private:
+  Node* successor_;
+
+  DISALLOW_COPY_AND_ASSIGN(EntryNode);
+};
+
+
+// An exit node has a arbitrarily many predecessors and no successors.
+class ExitNode: public Node {
+ public:
+  ExitNode() : predecessors_(4) {}
+
+  void AddPredecessor(Node* predecessor) {
+    ASSERT(predecessor != NULL);
+    predecessors_.Add(predecessor);
+  }
+
+  void AddSuccessor(Node* successor) { /* Do nothing. */ }
+
+  void Traverse(bool mark,
+                ZoneList<Node*>* preorder,
+                ZoneList<Node*>* postorder);
+
+#ifdef DEBUG
+  void PrintText();
+#endif
+
+ private:
+  ZoneList<Node*> predecessors_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExitNode);
+};
+
+
+// Block nodes have a single successor and predecessor and a list of
+// instructions.
+class BlockNode: public Node {
+ public:
+  BlockNode() : predecessor_(NULL), successor_(NULL), instructions_(4) {}
+
+  static BlockNode* cast(Node* node) {
+    ASSERT(node->IsBlockNode());
+    return reinterpret_cast<BlockNode*>(node);
+  }
+
+  bool IsBlockNode() { return true; }
+
+  void AddPredecessor(Node* predecessor) {
+    ASSERT(predecessor_ == NULL && predecessor != NULL);
+    predecessor_ = predecessor;
+  }
+
+  void AddSuccessor(Node* successor) {
+    ASSERT(successor_ == NULL && successor != NULL);
+    successor_ = successor;
+  }
+
+  void AddInstruction(AstNode* instruction) {
+    instructions_.Add(instruction);
+  }
+
+  void Traverse(bool mark,
+                ZoneList<Node*>* preorder,
+                ZoneList<Node*>* postorder);
+
+#ifdef DEBUG
+  void AssignNumbers();
+  void PrintText();
+#endif
+
+ private:
+  Node* predecessor_;
+  Node* successor_;
+  ZoneList<AstNode*> instructions_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlockNode);
+};
+
+
+// Branch nodes have a single predecessor and a pair of successors.
+class BranchNode: public Node {
+ public:
+  BranchNode() : predecessor_(NULL), successor0_(NULL), successor1_(NULL) {}
+
+  void AddPredecessor(Node* predecessor) {
+    ASSERT(predecessor_ == NULL && predecessor != NULL);
+    predecessor_ = predecessor;
+  }
+
+  void AddSuccessor(Node* successor) {
+    ASSERT(successor1_ == NULL && successor != NULL);
+    if (successor0_ == NULL) {
+      successor0_ = successor;
+    } else {
+      successor1_ = successor;
+    }
+  }
+
+  void Traverse(bool mark,
+                ZoneList<Node*>* preorder,
+                ZoneList<Node*>* postorder);
+
+#ifdef DEBUG
+  void PrintText();
+#endif
+
+ private:
+  Node* predecessor_;
+  Node* successor0_;
+  Node* successor1_;
+
+  DISALLOW_COPY_AND_ASSIGN(BranchNode);
+};
+
+
+// Join nodes have arbitrarily many predecessors and a single successor.
+class JoinNode: public Node {
+ public:
+  JoinNode() : predecessors_(2), successor_(NULL) {}
+
+  static JoinNode* cast(Node* node) {
+    ASSERT(node->IsJoinNode());
+    return reinterpret_cast<JoinNode*>(node);
+  }
+
+  bool IsJoinNode() { return true; }
+
+  void AddPredecessor(Node* predecessor) {
+    ASSERT(predecessor != NULL);
+    predecessors_.Add(predecessor);
+  }
+
+  void AddSuccessor(Node* successor) {
+    ASSERT(successor_ == NULL && successor != NULL);
+    successor_ = successor;
+  }
+
+  void Traverse(bool mark,
+                ZoneList<Node*>* preorder,
+                ZoneList<Node*>* postorder);
+
+#ifdef DEBUG
+  void PrintText();
+#endif
+
+ private:
+  ZoneList<Node*> predecessors_;
+  Node* successor_;
+
+  DISALLOW_COPY_AND_ASSIGN(JoinNode);
+};
+
+
+// Construct a flow graph from a function literal.  Build pre- and postorder
+// traversal orders as a byproduct.
+class FlowGraphBuilder: public AstVisitor {
+ public:
+  FlowGraphBuilder()
+      : global_exit_(NULL),
+        preorder_(4),
+        postorder_(4),
+        definitions_(4) {
+  }
+
+  void Build(FunctionLiteral* lit);
+
+  FlowGraph* graph() { return &graph_; }
+
+  ZoneList<Node*>* postorder() { return &postorder_; }
+
+ private:
+  ExitNode* global_exit() { return global_exit_; }
+
+  // AST node visit functions.
+#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
+
+  FlowGraph graph_;
+  ExitNode* global_exit_;
+  ZoneList<Node*> preorder_;
+  ZoneList<Node*> postorder_;
+
+  // The flow graph builder collects a list of definitions (assignments and
+  // count operations) to stack-allocated variables to use for reaching
+  // definitions analysis.
+  ZoneList<AstNode*> definitions_;
+
+  DISALLOW_COPY_AND_ASSIGN(FlowGraphBuilder);
+};
+
+
 // This class is used to number all expressions in the AST according to
 // their evaluation order (post-order left-to-right traversal).
 class AstLabeler: public AstVisitor {