Handle HCheckInstanceType and HIsStringAndBranch in check elimination.

src/unique.h

 // Copyright 2013 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_HYDROGEN_UNIQUE_H_
 #define V8_HYDROGEN_UNIQUE_H_
 
 #include "handles.h"
 #include "objects.h"
 #include "utils.h"
@@ skipping 257 matching lines @@
       }
     }
 
     while (i < this->size_) out->array_[k++] = this->array_[i++];
     while (j < that->size_) out->array_[k++] = that->array_[j++];
 
     out->size_ = k;
     return out;
   }
 
+  // Returns a new set representing all elements from this set which are not in
+  // that set. O(|this| * |that|).
+  UniqueSet<T>* Subtract(const UniqueSet<T>* that, Zone* zone) const {
+    if (that->size_ == 0) return this->Copy(zone);
+
+    UniqueSet<T>* out = new(zone) UniqueSet<T>(this->size_, zone);
+
+    int i = 0, j = 0;
+    while (i < this->size_) {
+      Unique<T> cand = this->array_[i];
+      if (!that->Contains(cand)) {
+        out->array_[j++] = cand;
+      }
+    }
+
+    out->size_ = j;
+    return out;
+  }
+
   // Makes an exact copy of this set. O(|this|).
   UniqueSet<T>* Copy(Zone* zone) const {
     UniqueSet<T>* copy = new(zone) UniqueSet<T>(this->size_, zone);
     copy->size_ = this->size_;
     memcpy(copy->array_, this->array_, this->size_ * sizeof(Unique<T>));
     return copy;
   }
 
   void Clear() {
     size_ = 0;
@@ skipping 30 matching lines @@
       capacity_ = new_capacity;
       array_ = new_array;
     }
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_UNIQUE_H_