[10/12] Add helper class for valued-based empty and deleted slots

[Richard Sandiford <richard.sandiford@arm.com>]

part_traits in cfgexpand.c needs to use the value rather than the key to
represent empty and deleted slots.  What it's doing is pretty generic,
so this patch adds a helper class to hash-map-traits.h.


gcc/
	* hash-map-traits.h (unbounded_hashmap_traits): New class.
	(unbounded_int_hashmap_traits): Likewise.
	* cfgexpand.c (part_traits): Use unbounded_int_hashmap_traits.

Index: gcc/hash-map-traits.h
===================================================================
--- gcc/hash-map-traits.h	2015-06-23 15:54:04.515950631 +0100
+++ gcc/hash-map-traits.h	2015-06-23 15:54:04.511950679 +0100
@@ -174,4 +174,84 @@ simple_hashmap_traits <H>::mark_deleted
   H::mark_deleted (entry.m_key);
 }
 
+/* Implement traits for a hash_map with values of type Value for cases
+   in which the key cannot represent empty and deleted slots.  Instead
+   record empty and deleted entries in Value.  Derived classes must
+   implement the hash and equal_keys functions.  */
+
+template <typename Value>
+struct unbounded_hashmap_traits
+{
+  template <typename T> static inline void remove (T &);
+  template <typename T> static inline bool is_empty (const T &);
+  template <typename T> static inline bool is_deleted (const T &);
+  template <typename T> static inline void mark_empty (T &);
+  template <typename T> static inline void mark_deleted (T &);
+};
+
+template <typename Value>
+template <typename T>
+inline void
+unbounded_hashmap_traits <Value>::remove (T &entry)
+{
+  default_hash_traits <Value>::remove (entry.m_value);
+}
+
+template <typename Value>
+template <typename T>
+inline bool
+unbounded_hashmap_traits <Value>::is_empty (const T &entry)
+{
+  return default_hash_traits <Value>::is_empty (entry.m_value);
+}
+
+template <typename Value>
+template <typename T>
+inline bool
+unbounded_hashmap_traits <Value>::is_deleted (const T &entry)
+{
+  return default_hash_traits <Value>::is_deleted (entry.m_value);
+}
+
+template <typename Value>
+template <typename T>
+inline void
+unbounded_hashmap_traits <Value>::mark_empty (T &entry)
+{
+  default_hash_traits <Value>::mark_empty (entry.m_value);
+}
+
+template <typename Value>
+template <typename T>
+inline void
+unbounded_hashmap_traits <Value>::mark_deleted (T &entry)
+{
+  default_hash_traits <Value>::mark_deleted (entry.m_value);
+}
+
+/* Implement traits for a hash_map from integer type Key to Value in
+   cases where Key has no spare values for recording empty and deleted
+   slots.  */
+
+template <typename Key, typename Value>
+struct unbounded_int_hashmap_traits : unbounded_hashmap_traits <Value>
+{
+  static inline hashval_t hash (Key);
+  static inline bool equal_keys (Key, Key);
+};
+
+template <typename Key, typename Value>
+inline hashval_t
+unbounded_int_hashmap_traits <Key, Value>::hash (Key k)
+{
+  return k;
+}
+
+template <typename Key, typename Value>
+inline bool
+unbounded_int_hashmap_traits <Key, Value>::equal_keys (Key k1, Key k2)
+{
+  return k1 == k2;
+}
+
 #endif // HASH_MAP_TRAITS_H
Index: gcc/cfgexpand.c
===================================================================
--- gcc/cfgexpand.c	2015-06-23 15:54:04.515950631 +0100
+++ gcc/cfgexpand.c	2015-06-23 15:54:04.511950679 +0100
@@ -612,25 +612,7 @@ stack_var_cmp (const void *a, const void
   return 0;
 }
 
-struct part_traits : default_hashmap_traits
-{
-  template<typename T>
-    static bool
-    is_deleted (T &e)
-    { return e.m_value == reinterpret_cast<void *> (1); }
-
-  template<typename T> static bool is_empty (T &e) { return e.m_value == NULL; }
-  template<typename T>
-    static void
-    mark_deleted (T &e)
-    { e.m_value = reinterpret_cast<T> (1); }
-
-  template<typename T>
-    static void
-    mark_empty (T &e)
-      { e.m_value = NULL; }
-};
-
+struct part_traits : unbounded_int_hashmap_traits <size_t, bitmap> {};
 typedef hash_map<size_t, bitmap, part_traits> part_hashmap;
 
 /* If the points-to solution *PI points to variables that are in a partition