Optimize Promise data structures. (#3768)

This patch reworks several structures:

- Fulfill and reject reactions are combined into one collection. The values in this collection
are compressed: a capability followed by an optional fulfill and reject functions.
- Fulfill and reject reactions are directly stored, no need to allocate an object for them.
- The job queue directly stores its items, this saves a pointer to the value, and the
callback is replaced by an uint8 type.
- Promise status and already resolved is stored in extra_info.

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

Author: zherczeg

jerry-core/api/jerry.c

@@ -76,9 +76,8 @@ JERRY_STATIC_ASSERT ((int) RE_FLAG_GLOBAL == (int) JERRY_REGEXP_FLAG_GLOBAL
 
 #if ENABLED (JERRY_ES2015_BUILTIN_PROMISE)
 /* The internal ECMA_PROMISE_STATE_* values are "one byte away" from the API values */
-JERRY_STATIC_ASSERT (((ECMA_PROMISE_STATE_PENDING + 1) == JERRY_PROMISE_STATE_PENDING)
-                     && ((ECMA_PROMISE_STATE_FULFILLED + 1) == JERRY_PROMISE_STATE_FULFILLED)
-                     && ((ECMA_PROMISE_STATE_REJECTED + 1) == JERRY_PROMISE_STATE_REJECTED),
+JERRY_STATIC_ASSERT ((int) ECMA_PROMISE_IS_PENDING == (int) JERRY_PROMISE_STATE_PENDING
+                     && (int) ECMA_PROMISE_IS_FULFILLED == (int) JERRY_PROMISE_STATE_FULFILLED,
                      promise_internal_state_matches_external);
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_PROMISE) */
 
@@ -1616,14 +1615,14 @@ jerry_create_promise (void)
   jerry_assert_api_available ();
 
 #if ENABLED (JERRY_ES2015_BUILTIN_PROMISE)
-  ecma_object_t * old_new_target_p = JERRY_CONTEXT (current_new_target);
+  ecma_object_t *old_new_target_p = JERRY_CONTEXT (current_new_target);
 
   if (old_new_target_p == NULL)
   {
     JERRY_CONTEXT (current_new_target) = ecma_builtin_get (ECMA_BUILTIN_ID_PROMISE);
   }
 
-  ecma_value_t promise_value =  ecma_op_create_promise_object (ECMA_VALUE_EMPTY, ECMA_PROMISE_EXECUTOR_EMPTY);
+  ecma_value_t promise_value = ecma_op_create_promise_object (ECMA_VALUE_EMPTY, ECMA_PROMISE_EXECUTOR_EMPTY);
 
   JERRY_CONTEXT (current_new_target) = old_new_target_p;
   return promise_value;
@@ -3331,12 +3330,10 @@ jerry_get_promise_state (const jerry_value_t promise) /**< promise object to get
     return JERRY_PROMISE_STATE_NONE;
   }
 
-  uint8_t state = ecma_promise_get_state (ecma_get_object_from_value (promise));
-
-  JERRY_ASSERT (state < ECMA_PROMISE_STATE__COUNT);
+  uint16_t flags = ecma_promise_get_flags (ecma_get_object_from_value (promise));
+  flags &= (ECMA_PROMISE_IS_PENDING | ECMA_PROMISE_IS_FULFILLED);
 
-  /* Static assert above guarantees the mapping from internal type to external type. */
-  return (jerry_promise_state_t) (state + 1);
+  return (flags ? flags : JERRY_PROMISE_STATE_REJECTED);
 #else /* !ENABLED (JERRY_ES2015_BUILTIN_PROMISE) */
   JERRY_UNUSED (promise);
   return JERRY_PROMISE_STATE_NONE;

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

@@ -268,27 +268,28 @@ ecma_gc_mark_promise_object (ecma_extended_object_t *ext_object_p) /**< extended
 
   /* Mark all reactions. */
   ecma_promise_object_t *promise_object_p = (ecma_promise_object_t *) ext_object_p;
-  ecma_collection_t *collection_p = promise_object_p->fulfill_reactions;
+  ecma_collection_t *collection_p = promise_object_p->reactions;
 
   if (collection_p != NULL)
   {
     ecma_value_t *buffer_p = collection_p->buffer_p;
+    ecma_value_t *buffer_end_p = buffer_p + collection_p->item_count;
 
-    for (uint32_t i = 0; i < collection_p->item_count; i++)
+    while (buffer_p < buffer_end_p)
     {
-      ecma_gc_set_object_visited (ecma_get_object_from_value (buffer_p[i]));
-    }
-  }
+      ecma_value_t value = *buffer_p++;
 
-  collection_p = promise_object_p->reject_reactions;
+      ecma_gc_set_object_visited (ECMA_GET_NON_NULL_POINTER_FROM_POINTER_TAG (ecma_object_t, value));
 
-  if (collection_p != NULL)
-  {
-    ecma_value_t *buffer_p = collection_p->buffer_p;
+      if (JMEM_CP_GET_FIRST_BIT_FROM_POINTER_TAG (value))
+      {
+        ecma_gc_set_object_visited (ecma_get_object_from_value (*buffer_p++));
+      }
 
-    for (uint32_t i = 0; i < collection_p->item_count; i++)
-    {
-      ecma_gc_set_object_visited (ecma_get_object_from_value (buffer_p[i]));
+      if (JMEM_CP_GET_SECOND_BIT_FROM_POINTER_TAG (value))
+      {
+        ecma_gc_set_object_visited (ecma_get_object_from_value (*buffer_p++));
+      }
     }
   }
 } /* ecma_gc_mark_promise_object */
@@ -1145,8 +1146,10 @@ ecma_gc_free_object (ecma_object_t *object_p) /**< object to free */
         case LIT_MAGIC_STRING_PROMISE_UL:
         {
           ecma_free_value_if_not_object (ext_object_p->u.class_prop.u.value);
-          ecma_collection_free_if_not_object (((ecma_promise_object_t *) object_p)->fulfill_reactions);
-          ecma_collection_free_if_not_object (((ecma_promise_object_t *) object_p)->reject_reactions);
+
+          /* Reactions only contains objects. */
+          ecma_collection_destroy (((ecma_promise_object_t *) object_p)->reactions);
+
           ext_object_size = sizeof (ecma_promise_object_t);
           break;
         }