[Isolates] Merge crankshaft (r5922 from bleeding_edge).

src/data-flow.h

Index: src/data-flow.h
diff --git a/src/data-flow.h b/src/data-flow.h
index e6d2c7357316eb91b3e1edf107f8e71f3db0f715..7e4adf4416f56d7c193b4c07097772979e0f805e 100644
--- a/src/data-flow.h
+++ b/src/data-flow.h
@@ -42,10 +42,57 @@ class Node;
 
 class BitVector: public ZoneObject {
  public:
-  BitVector() : length_(0), data_length_(0), data_(NULL) { }
+  // Iterator for the elements of this BitVector.
+  class Iterator BASE_EMBEDDED {
+   public:
+    explicit Iterator(BitVector* target)
+        : target_(target),
+          current_index_(0),
+          current_value_(target->data_[0]),
+          current_(-1) {
+      ASSERT(target->data_length_ > 0);
+      Advance();
+    }
+    ~Iterator() { }
+
+    bool Done() const { return current_index_ >= target_->data_length_; }
+    void Advance();
+
+    int Current() const {
+      ASSERT(!Done());
+      return current_;
+    }
+
+   private:
+    uint32_t SkipZeroBytes(uint32_t val) {
+      while ((val & 0xFF) == 0) {
+        val >>= 8;
+        current_ += 8;
+      }
+      return val;
+    }
+    uint32_t SkipZeroBits(uint32_t val) {
+      while ((val & 0x1) == 0) {
+        val >>= 1;
+        current_++;
+      }
+      return val;
+    }
 
-  explicit BitVector(int length) {
-    ExpandTo(length);
+    BitVector* target_;
+    int current_index_;
+    uint32_t current_value_;
+    int current_;
+
+    friend class BitVector;
+  };
+
+  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)
@@ -55,12 +102,8 @@ class BitVector: public ZoneObject {
     CopyFrom(other);
   }
 
-  void ExpandTo(int length) {
-    ASSERT(length > 0);
-    length_ = length;
-    data_length_ = SizeFor(length);
-    data_ = ZONE->NewArray<uint32_t>(data_length_);
-    Clear();
+  static int SizeFor(int length) {
+    return 1 + ((length - 1) / 32);
   }
 
   BitVector& operator=(const BitVector& rhs) {
@@ -75,7 +118,7 @@ class BitVector: public ZoneObject {
     }
   }
 
-  bool Contains(int i) {
+  bool Contains(int i) const {
     ASSERT(i >= 0 && i < length());
     uint32_t block = data_[i / 32];
     return (block & (1U << (i % 32))) != 0;
@@ -98,6 +141,17 @@ class BitVector: public ZoneObject {
     }
   }
 
+  bool UnionIsChanged(const BitVector& other) {
+    ASSERT(other.length() == length());
+    bool changed = false;
+    for (int i = 0; i < data_length_; i++) {
+      uint32_t old_data = data_[i];
+      data_[i] |= other.data_[i];
+      if (data_[i] != old_data) changed = true;
+    }
+    return changed;
+  }
+
   void Intersect(const BitVector& other) {
     ASSERT(other.length() == length());
     for (int i = 0; i < data_length_; i++) {
@@ -139,16 +193,102 @@ class BitVector: public ZoneObject {
 #endif
 
  private:
-  static int SizeFor(int length) {
-    return 1 + ((length - 1) / 32);
-  }
-
   int length_;
   int data_length_;
   uint32_t* data_;
 };
 
 
+// An implementation of a sparse set whose elements are drawn from integers
+// in the range [0..universe_size[.  It supports constant-time Contains,
+// destructive Add, and destructuve Remove operations and linear-time (in
+// the number of elements) destructive Union.
+class SparseSet: public ZoneObject {
+ public:
+  // Iterator for sparse set elements.  Elements should not be added or
+  // removed during iteration.
+  class Iterator BASE_EMBEDDED {
+   public:
+    explicit Iterator(SparseSet* target) : target_(target), current_(0) {
+      ASSERT(++target->iterator_count_ > 0);
+    }
+    ~Iterator() {
+      ASSERT(target_->iterator_count_-- > 0);
+    }
+    bool Done() const { return current_ >= target_->dense_.length(); }
+    void Advance() {
+      ASSERT(!Done());
+      ++current_;
+    }
+    int Current() {
+      ASSERT(!Done());
+      return target_->dense_[current_];
+    }
+
+   private:
+    SparseSet* target_;
+    int current_;
+
+    friend class SparseSet;
+  };
+
+  explicit SparseSet(int universe_size)
+      : dense_(4),
+        sparse_(ZONE->NewArray<int>(universe_size)) {
+#ifdef DEBUG
+    size_ = universe_size;
+    iterator_count_ = 0;
+#endif
+  }
+
+  bool Contains(int n) const {
+    ASSERT(0 <= n && n < size_);
+    int dense_index = sparse_[n];
+    return (0 <= dense_index) &&
+        (dense_index < dense_.length()) &&
+        (dense_[dense_index] == n);
+  }
+
+  void Add(int n) {
+    ASSERT(0 <= n && n < size_);
+    ASSERT(iterator_count_ == 0);
+    if (!Contains(n)) {
+      sparse_[n] = dense_.length();
+      dense_.Add(n);
+    }
+  }
+
+  void Remove(int n) {
+    ASSERT(0 <= n && n < size_);
+    ASSERT(iterator_count_ == 0);
+    if (Contains(n)) {
+      int dense_index = sparse_[n];
+      int last = dense_.RemoveLast();
+      if (dense_index < dense_.length()) {
+        dense_[dense_index] = last;
+        sparse_[last] = dense_index;
+      }
+    }
+  }
+
+  void Union(const SparseSet& other) {
+    for (int i = 0; i < other.dense_.length(); ++i) {
+      Add(other.dense_[i]);
+    }
+  }
+
+ private:
+  // The set is implemented as a pair of a growable dense list and an
+  // uninitialized sparse array.
+  ZoneList<int> dense_;
+  int* sparse_;
+#ifdef DEBUG
+  int size_;
+  int iterator_count_;
+#endif
+};
+
+
 // Simple fixed-capacity list-based worklist (managed as a queue) of
 // pointers to T.
 template<typename T>
@@ -198,10 +338,12 @@ class WorkList BASE_EMBEDDED {
 // is guaranteed to be a smi.
 class AssignedVariablesAnalyzer : public AstVisitor {
  public:
-  explicit AssignedVariablesAnalyzer() : info_(NULL) { }
-  bool Analyze(CompilationInfo* info);
+  static bool Analyze(CompilationInfo* info);
 
  private:
+  AssignedVariablesAnalyzer(CompilationInfo* info, int bits);
+  bool Analyze();
+
   Variable* FindSmiLoopVariable(ForStatement* stmt);
 
   int BitIndex(Variable* var);