From 9c3aa4a003e7dca97b54560ef1efc3dcb80454f4 Mon Sep 17 00:00:00 2001
From: Ruben Ayrapetyan <r.ayrapetyan@samsung.com>
Date: Fri, 30 Oct 2015 18:44:49 +0300
Subject: [PATCH] Improve performance of item 3.l of arrays'
 [[DefineOwnProperty]] (ecma_op_array_object_define_own_property).

JerryScript-DCO-1.0-Signed-off-by: Ruben Ayrapetyan r.ayrapetyan@samsung.com
---
 .../ecma/operations/ecma-array-object.cpp     | 61 +++++++++++++++----
 jerry-core/ecma/operations/ecma-objects.cpp   |  2 +-
 2 files changed, 49 insertions(+), 14 deletions(-)

diff --git a/jerry-core/ecma/operations/ecma-array-object.cpp b/jerry-core/ecma/operations/ecma-array-object.cpp
index 354f59efc..135a7564c 100644
--- a/jerry-core/ecma/operations/ecma-array-object.cpp
+++ b/jerry-core/ecma/operations/ecma-array-object.cpp
@@ -291,29 +291,60 @@ ecma_op_array_object_define_own_property (ecma_object_t *obj_p, /**< the array o
             // l
             JERRY_ASSERT (new_len_uint32 < old_len_uint32);
 
-            bool reduce_succeeded = true;
+            /*
+             * Item i. is replaced with faster iteration: only indices that actually exist in the array, are iterated
+             */
+            bool is_reduce_succeeded = true;
 
-            while (new_len_uint32 < old_len_uint32)
+            ecma_collection_header_t *array_index_props_p = ecma_op_object_get_property_names (obj_p,
+                                                                                               true,
+                                                                                               false,
+                                                                                               false);
+
+            ecma_length_t array_index_props_num = array_index_props_p->unit_number;
+
+            MEM_DEFINE_LOCAL_ARRAY (array_index_values_p, array_index_props_num, uint32_t);
+
+            ecma_collection_iterator_t iter;
+            ecma_collection_iterator_init (&iter, array_index_props_p);
+
+            uint32_t array_index_values_pos = 0;
+
+            while (ecma_collection_iterator_next (&iter))
             {
-              // i
-              old_len_uint32--;
+              ecma_string_t *property_name_p = ecma_get_string_from_value (*iter.current_value_p);
 
-              // ii
-              ecma_string_t *old_length_string_p = ecma_new_ecma_string_from_uint32 (old_len_uint32);
+              uint32_t index;
+              bool is_index = ecma_string_get_array_index (property_name_p, &index);
+              JERRY_ASSERT (is_index);
+              JERRY_ASSERT (index < old_len_uint32);
+
+              array_index_values_p[array_index_values_pos++] = index;
+            }
+
+            JERRY_ASSERT (array_index_values_pos == array_index_props_num);
+
+            while (array_index_values_pos != 0
+                   && array_index_values_p[--array_index_values_pos] >= new_len_uint32)
+            {
+              uint32_t index = array_index_values_p[array_index_values_pos];
+
+              // ii.
+              ecma_string_t *index_string_p = ecma_new_ecma_string_from_uint32 (index);
               ecma_completion_value_t delete_succeeded = ecma_op_object_delete (obj_p,
-                                                                                old_length_string_p,
+                                                                                index_string_p,
                                                                                 false);
-              ecma_deref_ecma_string (old_length_string_p);
+              ecma_deref_ecma_string (index_string_p);
 
-              // iii
               if (ecma_is_completion_value_normal_false (delete_succeeded))
               {
-                JERRY_ASSERT (ecma_is_value_number (new_len_property_desc.value));
+                // iii.
+                new_len_uint32 = (index + 1u);
 
                 ecma_number_t *new_len_num_p = ecma_get_number_from_value (new_len_property_desc.value);
 
                 // 1.
-                *new_len_num_p = ecma_uint32_to_number (old_len_uint32 + 1);
+                *new_len_num_p = ecma_uint32_to_number (index + 1u);
 
                 // 2.
                 if (!new_writable)
@@ -333,13 +364,17 @@ ecma_op_array_object_define_own_property (ecma_object_t *obj_p, /**< the array o
                 JERRY_ASSERT (ecma_is_completion_value_normal_true (completion)
                               || ecma_is_completion_value_normal_false (completion));
 
-                reduce_succeeded = false;
+                is_reduce_succeeded = false;
 
                 break;
               }
             }
 
-            if (!reduce_succeeded)
+            MEM_FINALIZE_LOCAL_ARRAY (array_index_values_p);
+
+            ecma_free_values_collection (array_index_props_p, true);
+
+            if (!is_reduce_succeeded)
             {
               ret_value = ecma_reject (is_throw);
             }
diff --git a/jerry-core/ecma/operations/ecma-objects.cpp b/jerry-core/ecma/operations/ecma-objects.cpp
index 11e759f67..2c5c159b4 100644
--- a/jerry-core/ecma/operations/ecma-objects.cpp
+++ b/jerry-core/ecma/operations/ecma-objects.cpp
@@ -656,7 +656,7 @@ ecma_op_object_get_property_names (ecma_object_t *obj_p, /**< object */
             else
             {
               JERRY_ASSERT (insertion_pos < array_index_name_pos);
-              JERRY_ASSERT (index < array_index_names_p[insertion_pos]);
+              JERRY_ASSERT (index >= array_index_names_p[insertion_pos]);
 
               uint32_t move_pos = ++array_index_name_pos;