Implement efficient element copying in ElementsAccessors.

src/builtins.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 292 matching lines @@
 
 
 BUILTIN(ArrayCodeGeneric) {
   return ArrayCodeGenericCommon(
       &args,
       isolate,
       isolate->context()->global_context()->array_function());
 }
 
 
-static void CopyElements(Heap* heap,
-                         AssertNoAllocation* no_gc,
-                         FixedArray* dst,
-                         int dst_index,
-                         FixedArray* src,
-                         int src_index,
-                         int len) {
-  if (len == 0) return;
-  ASSERT(dst != src);  // Use MoveElements instead.
-  ASSERT(dst->map() != HEAP->fixed_cow_array_map());
-  ASSERT(len > 0);
-  CopyWords(dst->data_start() + dst_index,
-            src->data_start() + src_index,
-            len);
-  WriteBarrierMode mode = dst->GetWriteBarrierMode(*no_gc);
-  if (mode == UPDATE_WRITE_BARRIER) {
-    heap->RecordWrites(dst->address(), dst->OffsetOfElementAt(dst_index), len);
-  }
-  heap->incremental_marking()->RecordWrites(dst);
-}
-
-
 static void MoveElements(Heap* heap,
                          AssertNoAllocation* no_gc,
                          FixedArray* dst,
                          int dst_index,
                          FixedArray* src,
                          int src_index,
                          int len) {
   if (len == 0) return;
   ASSERT(dst->map() != HEAP->fixed_cow_array_map());
   memmove(dst->data_start() + dst_index,
@@ skipping 179 matching lines @@
   if (new_length > elms->length()) {
     // New backing storage is needed.
     int capacity = new_length + (new_length >> 1) + 16;
     Object* obj;
     { MaybeObject* maybe_obj = heap->AllocateUninitializedFixedArray(capacity);
       if (!maybe_obj->ToObject(&obj)) return maybe_obj;
     }
     FixedArray* new_elms = FixedArray::cast(obj);
 
     AssertNoAllocation no_gc;
-    CopyElements(heap, &no_gc, new_elms, 0, elms, 0, len);
+    CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS, 0,
+                               new_elms, FAST_ELEMENTS, 0, len);
     FillWithHoles(heap, new_elms, new_length, capacity);
 
     elms = new_elms;
   }
 
   // Add the provided values.
   AssertNoAllocation no_gc;
   WriteBarrierMode mode = elms->GetWriteBarrierMode(no_gc);
   for (int index = 0; index < to_add; index++) {
     elms->set(index + len, args[index + 1], mode);
@@ skipping 115 matching lines @@
 
   if (new_length > elms->length()) {
     // New backing storage is needed.
     int capacity = new_length + (new_length >> 1) + 16;
     Object* obj;
     { MaybeObject* maybe_obj = heap->AllocateUninitializedFixedArray(capacity);
       if (!maybe_obj->ToObject(&obj)) return maybe_obj;
     }
     FixedArray* new_elms = FixedArray::cast(obj);
     AssertNoAllocation no_gc;
-    CopyElements(heap, &no_gc, new_elms, to_add, elms, 0, len);
+    CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS, 0,
+                               new_elms, FAST_ELEMENTS, to_add, len);
     FillWithHoles(heap, new_elms, new_length, capacity);
     elms = new_elms;
     array->set_elements(elms);
   } else {
     AssertNoAllocation no_gc;
     MoveElements(heap, &no_gc, elms, to_add, elms, 0, len);
   }
 
   // Add the provided values.
   AssertNoAllocation no_gc;
@@ skipping 90 matching lines @@
   int result_len = Max(final - k, 0);
 
   MaybeObject* maybe_array =
       heap->AllocateJSArrayAndStorage(elements_kind,
                                       result_len,
                                       result_len);
   JSArray* result_array;
   if (!maybe_array->To(&result_array)) return maybe_array;
 
   AssertNoAllocation no_gc;
-  CopyElements(heap, &no_gc, FixedArray::cast(result_array->elements()), 0,
-               elms, k, result_len);
+  CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS, k,
+                             FixedArray::cast(result_array->elements()),
+                             FAST_ELEMENTS, 0, result_len);
 
   return result_array;
 }
 
 
 BUILTIN(ArraySplice) {
   Heap* heap = isolate->heap();
   Object* receiver = *args.receiver();
   Object* elms_obj;
   { MaybeObject* maybe_elms_obj =
@@ skipping 52 matching lines @@
       JSObject::cast(receiver)->GetElementsKind();
   MaybeObject* maybe_array =
       heap->AllocateJSArrayAndStorage(elements_kind,
                                       actual_delete_count,
                                       actual_delete_count);
   if (!maybe_array->To(&result_array)) return maybe_array;
 
   {
     AssertNoAllocation no_gc;
     // Fill newly created array.
-    CopyElements(heap,
-                 &no_gc,
-                 FixedArray::cast(result_array->elements()), 0,
-                 elms, actual_start,
-                 actual_delete_count);
+    CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS, actual_start,
+                               FixedArray::cast(result_array->elements()),
+                               FAST_ELEMENTS, 0, actual_delete_count);
   }
 
   int item_count = (n_arguments > 1) ? (n_arguments - 2) : 0;
   int new_length = len - actual_delete_count + item_count;
 
   bool elms_changed = false;
   if (item_count < actual_delete_count) {
     // Shrink the array.
     const bool trim_array = !heap->lo_space()->Contains(elms) &&
       ((actual_start + item_count) <
@@ skipping 29 matching lines @@
       Object* obj;
       { MaybeObject* maybe_obj =
             heap->AllocateUninitializedFixedArray(capacity);
         if (!maybe_obj->ToObject(&obj)) return maybe_obj;
       }
       FixedArray* new_elms = FixedArray::cast(obj);
 
       {
         AssertNoAllocation no_gc;
         // Copy the part before actual_start as is.
-        CopyElements(heap, &no_gc, new_elms, 0, elms, 0, actual_start);
+        CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS, 0,
+                                   new_elms, FAST_ELEMENTS, 0, actual_start);
         const int to_copy = len - actual_delete_count - actual_start;
-        CopyElements(heap, &no_gc,
-                     new_elms, actual_start + item_count,
-                     elms, actual_start + actual_delete_count,
-                     to_copy);
+        CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS,
+                                   actual_start + actual_delete_count,
+                                   new_elms, FAST_ELEMENTS,
+                                   actual_start + item_count, to_copy);
       }
 
       FillWithHoles(heap, new_elms, new_length, capacity);
 
       elms = new_elms;
       elms_changed = true;
     } else {
       AssertNoAllocation no_gc;
       MoveElements(heap, &no_gc,
                    elms, actual_start + item_count,
@@ skipping 68 matching lines @@
   if (result_len == 0) return result_array;
 
   // Copy data.
   AssertNoAllocation no_gc;
   int start_pos = 0;
   FixedArray* result_elms(FixedArray::cast(result_array->elements()));
   for (int i = 0; i < n_arguments; i++) {
     JSArray* array = JSArray::cast(args[i]);
     int len = Smi::cast(array->length())->value();
     FixedArray* elms = FixedArray::cast(array->elements());
-    CopyElements(heap, &no_gc, result_elms, start_pos, elms, 0, len);
+    CopyObjectToObjectElements(&no_gc, elms, FAST_ELEMENTS, 0,
+                               result_elms, FAST_ELEMENTS,
+                               start_pos, len);
     start_pos += len;
   }
   ASSERT(start_pos == result_len);
 
   return result_array;
 }
 
 
 // -----------------------------------------------------------------------------
 // Strict mode poison pills
@@ skipping 742 matching lines @@
   return Handle<Code>(code_address);                        \
 }
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 } }  // namespace v8::internal