Track side-effect free paths in the graph to allow CSE and LICM for instructions that depend on som…

runtime/vm/hash_map.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_HASH_MAP_H_
 #define VM_HASH_MAP_H_
 
 namespace dart {
 
 template <typename KeyValueTrait>
@@ skipping 10 matching lines @@
   }
 
   DirectChainedHashMap(const DirectChainedHashMap& other);
 
   void Insert(typename KeyValueTrait::Pair kv);
 
   typename KeyValueTrait::Value Lookup(typename KeyValueTrait::Key key) const;
 
   bool IsEmpty() const { return count_ == 0; }
 
- private:
+  void Clear() {
+    if (!IsEmpty()) {
+      count_ = 0;
+      memset(array_, 0, sizeof(HashMapListElement) * array_size_);
+      memset(lists_, 0, sizeof(HashMapListElement) * lists_size_);
+      lists_[0].next = kNil;
+      for (intptr_t i = 1; i < lists_size_; ++i) {
+        lists_[i].next = i - 1;
+      }
+      free_list_head_ = lists_size_ - 1;
+    }
+  }
+
+ protected:
   // A linked list of T values.  Stored in arrays.
   struct HashMapListElement {
     typename KeyValueTrait::Pair kv;
     intptr_t next;  // Index in the array of the next list element.
   };
   static const intptr_t kNil = -1;  // The end of a linked list
 
   // Must be a power of 2.
   static const intptr_t kInitialSize = 16;
 
@@ skipping 179 matching lines @@
   }
 
   static inline bool IsKeyEqual(Pair kv, Key key) {
     return kv->Equals(key);
   }
 };
 
 }  // namespace dart
 
 #endif  // VM_HASH_MAP_H_