Various cleanups in check elimination.

src/unique.h

Index: src/unique.h
diff --git a/src/unique.h b/src/unique.h
index 82ed652391355785b9fba49826b353c3211f2b9b..8ed26829012c3980139d1a5d71c6d053e70eebe4 100644
--- a/src/unique.h
+++ b/src/unique.h
@@ -134,6 +134,19 @@ class UniqueSet V8_FINAL : public ZoneObject {
   // Constructor. A new set will be empty.
   UniqueSet() : size_(0), capacity_(0), array_(NULL) { }
 
+  // Capacity constructor. A new set will be empty.
+  UniqueSet(int capacity, Zone* zone)
+      : size_(0), capacity_(capacity),
+        array_(zone->NewArray<Unique<T> >(capacity)) {
+    ASSERT(capacity <= kMaxCapacity);
+  }
+
+  // Singleton constructor.
+  UniqueSet(Unique<T> uniq, Zone* zone)
+      : size_(1), capacity_(1), array_(zone->NewArray<Unique<T> >(1)) {
+    array_[0] = uniq;
+  }
+
   // Add a new element to this unique set. Mutates this set. O(|this|).
   void Add(Unique<T> uniq, Zone* zone) {
     ASSERT(uniq.IsInitialized());
@@ -178,8 +191,11 @@ class UniqueSet V8_FINAL : public ZoneObject {
   // TODO(titzer): use binary search for large sets to make this O(log|this|)
   template <typename U>
   bool Contains(const Unique<U> elem) const {
-    for (int i = 0; i < size_; i++) {
-      if (this->array_[i] == elem) return true;
+    for (int i = 0; i < this->size_; ++i) {
+      Unique<T> cand = this->array_[i];
+      if (cand.raw_address_ >= elem.raw_address_) {
+        return cand.raw_address_ == elem.raw_address_;
+      }
     }
     return false;
   }
@@ -201,11 +217,11 @@ class UniqueSet V8_FINAL : public ZoneObject {
 
   // Returns a new set representing the intersection of this set and the other.
   // O(|this| + |that|).
-  UniqueSet<T>* Intersect(UniqueSet<T>* that, Zone* zone) const {
+  UniqueSet<T>* Intersect(const UniqueSet<T>* that, Zone* zone) const {
     if (that->size_ == 0 || this->size_ == 0) return new(zone) UniqueSet<T>();
 
-    UniqueSet<T>* out = new(zone) UniqueSet<T>();
-    out->Grow(Min(this->size_, that->size_), zone);
+    UniqueSet<T>* out = new(zone) UniqueSet<T>(
+        Min(this->size_, that->size_), zone);
 
     int i = 0, j = 0, k = 0;
     while (i < this->size_ && j < that->size_) {
@@ -228,12 +244,12 @@ class UniqueSet V8_FINAL : public ZoneObject {
 
   // Returns a new set representing the union of this set and the other.
   // O(|this| + |that|).
-  UniqueSet<T>* Union(UniqueSet<T>* that, Zone* zone) const {
+  UniqueSet<T>* Union(const UniqueSet<T>* that, Zone* zone) const {
     if (that->size_ == 0) return this->Copy(zone);
     if (this->size_ == 0) return that->Copy(zone);
 
-    UniqueSet<T>* out = new(zone) UniqueSet<T>();
-    out->Grow(this->size_ + that->size_, zone);
+    UniqueSet<T>* out = new(zone) UniqueSet<T>(
+        this->size_ + that->size_, zone);
 
     int i = 0, j = 0, k = 0;
     while (i < this->size_ && j < that->size_) {
@@ -261,10 +277,8 @@ class UniqueSet V8_FINAL : public ZoneObject {
 
   // Makes an exact copy of this set. O(|this|).
   UniqueSet<T>* Copy(Zone* zone) const {
-    UniqueSet<T>* copy = new(zone) UniqueSet<T>();
+    UniqueSet<T>* copy = new(zone) UniqueSet<T>(this->size_, zone);
     copy->size_ = this->size_;
-    copy->capacity_ = this->size_;
-    copy->array_ = zone->NewArray<Unique<T> >(this->size_);
     memcpy(copy->array_, this->array_, this->size_ * sizeof(Unique<T>));
     return copy;
   }