Improve constant pool implementation in the assembler.

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 13 matching lines @@
 
   void Insert(typename KeyValueTrait::Pair kv);
 
   typename KeyValueTrait::Value Lookup(typename KeyValueTrait::Key key) const;
 
   bool IsEmpty() const { return count_ == 0; }
 
   void Clear() {
     if (!IsEmpty()) {
       count_ = 0;
-      memset(array_, 0, sizeof(HashMapListElement) * array_size_);
-      memset(lists_, 0, sizeof(HashMapListElement) * lists_size_);
+      InitArray(array_, array_size_);
+      InitArray(lists_, 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 {
+    HashMapListElement() : kv(KeyValueTrait::NoValue()), next(kNil) { }
     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
 
+  static void InitArray(HashMapListElement* array, intptr_t size) {
+    for (intptr_t i = 0; i < size; ++i) {
+      array[i] = HashMapListElement();
+    }
+  }
+
   // Must be a power of 2.
   static const intptr_t kInitialSize = 16;
 
   void Resize(intptr_t new_size);
   void ResizeLists(intptr_t new_size);
   uword Bound(uword value) const { return value & (array_size_ - 1); }
 
   intptr_t array_size_;
   intptr_t lists_size_;
   intptr_t count_;  // The number of values stored in the HashMap.
   HashMapListElement* array_;  // Primary store - contains the first value
   // with a given hash.  Colliding elements are stored in linked lists.
   HashMapListElement* lists_;  // The linked lists containing hash collisions.
   intptr_t free_list_head_;  // Unused elements in lists_ are on the free list.
 };
 
 
 template <typename KeyValueTrait>
 typename KeyValueTrait::Value
     DirectChainedHashMap<KeyValueTrait>::
         Lookup(typename KeyValueTrait::Key key) const {
-  const typename KeyValueTrait::Value kNoValue =
-      static_cast<typename KeyValueTrait::Value>(0);
+  const typename KeyValueTrait::Value kNoValue = KeyValueTrait::NoValue();
 
   uword hash = static_cast<uword>(KeyValueTrait::Hashcode(key));
   uword pos = Bound(hash);
   if (KeyValueTrait::ValueOf(array_[pos].kv) != kNoValue) {
     if (KeyValueTrait::IsKeyEqual(array_[pos].kv, key)) {
       return KeyValueTrait::ValueOf(array_[pos].kv);
     }
 
     intptr_t next = array_[pos].next;
     while (next != kNil) {
@@ skipping 19 matching lines @@
     lists_(Isolate::Current()->current_zone()->
            Alloc<HashMapListElement>(other.lists_size_)),
     free_list_head_(other.free_list_head_) {
   memmove(array_, other.array_, array_size_ * sizeof(HashMapListElement));
   memmove(lists_, other.lists_, lists_size_ * sizeof(HashMapListElement));
 }
 
 
 template <typename KeyValueTrait>
 void DirectChainedHashMap<KeyValueTrait>::Resize(intptr_t new_size) {
-  const typename KeyValueTrait::Value kNoValue =
-      static_cast<typename KeyValueTrait::Value>(0);
+  const typename KeyValueTrait::Value kNoValue = KeyValueTrait::NoValue();
 
   ASSERT(new_size > count_);
   // Hashing the values into the new array has no more collisions than in the
   // old hash map, so we can use the existing lists_ array, if we are careful.
 
   // Make sure we have at least one free element.
   if (free_list_head_ == kNil) {
     ResizeLists(lists_size_ << 1);
   }
 
   HashMapListElement* new_array =
       Isolate::Current()->current_zone()->Alloc<HashMapListElement>(new_size);
-  memset(new_array, 0, sizeof(HashMapListElement) * new_size);
+  InitArray(new_array, new_size);
 
   HashMapListElement* old_array = array_;
   intptr_t old_size = array_size_;
 
   intptr_t old_count = count_;
   count_ = 0;
   array_size_ = new_size;
   array_ = new_array;
 
   if (old_array != NULL) {
@@ skipping 18 matching lines @@
 }
 
 
 template <typename T>
 void DirectChainedHashMap<T>::ResizeLists(intptr_t new_size) {
   ASSERT(new_size > lists_size_);
 
   HashMapListElement* new_lists =
       Isolate::Current()->current_zone()->
       Alloc<HashMapListElement>(new_size);
-  memset(new_lists, 0, sizeof(HashMapListElement) * new_size);
+  InitArray(new_lists, new_size);
 
   HashMapListElement* old_lists = lists_;
   intptr_t old_size = lists_size_;
 
   lists_size_ = new_size;
   lists_ = new_lists;
 
   if (old_lists != NULL) {
     memmove(lists_, old_lists, old_size * sizeof(HashMapListElement));
   }
   for (intptr_t i = old_size; i < lists_size_; ++i) {
     lists_[i].next = free_list_head_;
     free_list_head_ = i;
   }
 }
 
 
 template <typename KeyValueTrait>
 void DirectChainedHashMap<KeyValueTrait>::
     Insert(typename KeyValueTrait::Pair kv) {
-  const typename KeyValueTrait::Value kNoValue =
-      static_cast<typename KeyValueTrait::Value>(0);
+  const typename KeyValueTrait::Value kNoValue = KeyValueTrait::NoValue();
 
   ASSERT(KeyValueTrait::ValueOf(kv) != kNoValue);
   // Resizing when half of the hashtable is filled up.
   if (count_ >= array_size_ >> 1) Resize(array_size_ << 1);
   ASSERT(count_ < array_size_);
   count_++;
   uword pos = Bound(
       static_cast<uword>(KeyValueTrait::Hashcode(KeyValueTrait::KeyOf(kv))));
   if (KeyValueTrait::ValueOf(array_[pos].kv) == kNoValue) {
     array_[pos].kv = kv;
@@ skipping 22 matching lines @@
   typedef T* Pair;
 
   static Key KeyOf(Pair kv) {
     return kv;
   }
 
   static Value ValueOf(Pair kv) {
     return kv;
   }
 
+  static Value NoValue() { return NULL; }
+
   static inline intptr_t Hashcode(Key key) {
     return key->Hashcode();
   }
 
   static inline bool IsKeyEqual(Pair kv, Key key) {
     return kv->Equals(key);
   }
 };
 
 }  // namespace dart
 
 #endif  // VM_HASH_MAP_H_