First step to SSA construction: Phi insertion.

vm/bit_vector.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_BIT_VECTOR_H_
 #define VM_BIT_VECTOR_H_
 
 #include "vm/allocation.h"
 #include "vm/isolate.h"
 #include "vm/zone.h"
@@ skipping 45 matching lines @@
 
   static intptr_t SizeFor(intptr_t length) {
     return 1 + ((length - 1) / kBitsPerWord);
   }
 
   void Add(intptr_t i) {
     ASSERT(i >= 0 && i < length());
     data_[i / kBitsPerWord] |= (static_cast<uword>(1) << (i % kBitsPerWord));
   }
 
+  bool Contains(int i) const {
+    ASSERT(i >= 0 && i < length());
+    uword block = data_[i / sizeof(uword)];
+    return (block & (1U << (i % sizeof(uword)))) != 0;

[srdjan, 2012/06/12 17:34:37]

Please add a test

[Florian Schneider, 2012/06/13 10:53:40]

Done. Good point. I fixed a bug here as well.

+  }
+
   void Clear() {
     for (intptr_t i = 0; i < data_length_; i++) {
       data_[i] = 0;
     }
   }
 
   intptr_t length() const { return length_; }
 
  private:
   intptr_t length_;
   intptr_t data_length_;
   uword* data_;
 
   DISALLOW_COPY_AND_ASSIGN(BitVector);
 };
 
 }  // namespace dart
 
 #endif  // VM_BIT_VECTOR_H_