Reduce memory consumption of property names.

Property names were always required a string reference which consumed
a large amount of memory for arrays. This patch reduces this consumption
by directly storing the value part of certain strings.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

Author: zherczeg

jerry-core/ecma/base/ecma-gc.c

@@ -384,14 +384,7 @@ ecma_gc_sweep (ecma_object_t *object_p) /**< object to free */
       {
         if (prop_iter_p->types[i] != ECMA_PROPERTY_TYPE_DELETED)
         {
-          ecma_string_t *name_p = ECMA_GET_POINTER (ecma_string_t, prop_pair_p->names_cp[i]);
-
-          ecma_free_property (object_p, name_p, prop_iter_p->types + i);
-
-          if (name_p != NULL)
-          {
-            ecma_deref_ecma_string (name_p);
-          }
+          ecma_free_property (object_p, prop_pair_p->names_cp[i], prop_iter_p->types + i);
         }
       }
 

jerry-core/ecma/base/ecma-globals.h

@@ -329,6 +329,16 @@ typedef enum
  */
 #define ECMA_PROPERTY_FIXED 0
 
+/**
+ * Shift for property name part.
+ */
+#define ECMA_PROPERTY_NAME_TYPE_SHIFT (ECMA_PROPERTY_FLAG_SHIFT + 4)
+
+/**
+ * Property name is a generic string.
+ */
+#define ECMA_PROPERTY_NAME_TYPE_STRING 3
+
 /**
  * Abstract property representation.
  *
@@ -411,13 +421,25 @@ typedef struct
 #define ECMA_PROPERTY_GET_TYPE(property) \
   ((ecma_property_types_t) ((property) & ECMA_PROPERTY_TYPE_MASK))
 
+/**
+ * Get property name type.
+ */
+#define ECMA_PROPERTY_GET_NAME_TYPE(property) \
+  ((property) >> ECMA_PROPERTY_NAME_TYPE_SHIFT)
+
 /**
  * Returns true if the property pointer is a property pair.
  */
 #define ECMA_PROPERTY_IS_PROPERTY_PAIR(property_header_p) \
   (ECMA_PROPERTY_GET_TYPE ((property_header_p)->types[0]) != ECMA_PROPERTY_TYPE_VIRTUAL \
    && (property_header_p)->types[0] != ECMA_PROPERTY_TYPE_HASHMAP)
 
+/**
+ * Returns true if the property is named property.
+ */
+#define ECMA_PROPERTY_IS_NAMED_PROPERTY(property) \
+  (ECMA_PROPERTY_GET_TYPE (property) != ECMA_PROPERTY_TYPE_SPECIAL)
+
 /**
  * Returns the internal property type
  */
@@ -909,14 +931,14 @@ typedef struct
  */
 typedef enum
 {
-  ECMA_STRING_CONTAINER_HEAP_UTF8_STRING, /**< actual data is on the heap as an utf-8 (cesu8) string
-                                           *   maximum size is 2^16. */
-  ECMA_STRING_CONTAINER_HEAP_LONG_UTF8_STRING, /**< actual data is on the heap as an utf-8 (cesu8) string
-                                                *   maximum size is 2^32. */
   ECMA_STRING_CONTAINER_UINT32_IN_DESC, /**< actual data is UInt32-represeneted Number
                                              stored locally in the string's descriptor */
   ECMA_STRING_CONTAINER_MAGIC_STRING, /**< the ecma-string is equal to one of ECMA magic strings */
   ECMA_STRING_CONTAINER_MAGIC_STRING_EX, /**< the ecma-string is equal to one of external magic strings */
+  ECMA_STRING_CONTAINER_HEAP_UTF8_STRING, /**< actual data is on the heap as an utf-8 (cesu8) string
+                                           *   maximum size is 2^16. */
+  ECMA_STRING_CONTAINER_HEAP_LONG_UTF8_STRING, /**< actual data is on the heap as an utf-8 (cesu8) string
+                                                *   maximum size is 2^32. */
 
   ECMA_STRING_LITERAL_NUMBER, /**< a literal number which is used solely by the literal storage
                                *   so no string processing function supports this type except
@@ -985,10 +1007,10 @@ typedef struct
 
     lit_utf8_size_t long_utf8_string_size; /**< size of this long utf-8 string in bytes */
     uint32_t uint32_number; /**< uint32-represented number placed locally in the descriptor */
-    lit_magic_string_id_t magic_string_id; /**< identifier of a magic string */
-    lit_magic_string_ex_id_t magic_string_ex_id; /**< identifier of an external magic string */
+    uint32_t magic_string_id; /**< identifier of a magic string */
+    uint32_t magic_string_ex_id; /**< identifier of an external magic string */
     ecma_value_t lit_number; /**< literal number (note: not a regular string type) */
-    uint32_t common_field; /**< for zeroing and comparison in some cases */
+    uint32_t common_uint32_field; /**< for zeroing and comparison in some cases */
   } u;
 } ecma_string_t;