Preallocate transitioned maps for TypedArrays.

src/runtime.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 777 matching lines @@
 RUNTIME_FUNCTION(MaybeObject*, Runtime_TypedArrayInitialize) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 5);
   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
   CONVERT_SMI_ARG_CHECKED(arrayId, 1);
   CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, buffer, 2);
   CONVERT_ARG_HANDLE_CHECKED(Object, byte_offset_object, 3);
   CONVERT_ARG_HANDLE_CHECKED(Object, byte_length_object, 4);
 
   ExternalArrayType arrayType;
-  ElementsKind elementsKind;
   size_t elementSize;
   switch (arrayId) {
     case ARRAY_ID_UINT8:
-      elementsKind = EXTERNAL_UNSIGNED_BYTE_ELEMENTS;
       arrayType = kExternalUnsignedByteArray;
       elementSize = 1;
       break;
     case ARRAY_ID_INT8:
-      elementsKind = EXTERNAL_BYTE_ELEMENTS;
       arrayType = kExternalByteArray;
       elementSize = 1;
       break;
     case ARRAY_ID_UINT16:
-      elementsKind = EXTERNAL_UNSIGNED_SHORT_ELEMENTS;
       arrayType = kExternalUnsignedShortArray;
       elementSize = 2;
       break;
     case ARRAY_ID_INT16:
-      elementsKind = EXTERNAL_SHORT_ELEMENTS;
       arrayType = kExternalShortArray;
       elementSize = 2;
       break;
     case ARRAY_ID_UINT32:
-      elementsKind = EXTERNAL_UNSIGNED_INT_ELEMENTS;
       arrayType = kExternalUnsignedIntArray;
       elementSize = 4;
       break;
     case ARRAY_ID_INT32:
-      elementsKind = EXTERNAL_INT_ELEMENTS;
       arrayType = kExternalIntArray;
       elementSize = 4;
       break;
     case ARRAY_ID_FLOAT32:
-      elementsKind = EXTERNAL_FLOAT_ELEMENTS;
       arrayType = kExternalFloatArray;
       elementSize = 4;
       break;
     case ARRAY_ID_FLOAT64:
-      elementsKind = EXTERNAL_DOUBLE_ELEMENTS;
       arrayType = kExternalDoubleArray;
       elementSize = 8;
       break;
     case ARRAY_ID_UINT8C:
-      elementsKind = EXTERNAL_PIXEL_ELEMENTS;
       arrayType = kExternalPixelArray;
       elementSize = 1;
       break;
     default:
       UNREACHABLE();
       return NULL;
   }
 
   holder->set_buffer(*buffer);
   holder->set_byte_offset(*byte_offset_object);
   holder->set_byte_length(*byte_length_object);
 
   size_t byte_offset = NumberToSize(isolate, *byte_offset_object);
   size_t byte_length = NumberToSize(isolate, *byte_length_object);
   ASSERT(byte_length % elementSize == 0);
   size_t length = byte_length / elementSize;
 
   Handle<Object> length_obj = isolate->factory()->NewNumberFromSize(length);
   holder->set_length(*length_obj);
 
   Handle<ExternalArray> elements =
       isolate->factory()->NewExternalArray(
           static_cast<int>(length), arrayType,
           static_cast<uint8_t*>(buffer->backing_store()) + byte_offset);
-  Handle<Map> map =
-      isolate->factory()->GetElementsTransitionMap(holder, elementsKind);
-  holder->set_map(*map);
   holder->set_elements(*elements);
   return isolate->heap()->undefined_value();
 }
 
 
 #define TYPED_ARRAY_GETTER(getter, accessor) \
   RUNTIME_FUNCTION(MaybeObject*, Runtime_TypedArrayGet##getter) {             \
     HandleScope scope(isolate);                                               \
     ASSERT(args.length() == 1);                                               \
     CONVERT_ARG_HANDLE_CHECKED(Object, holder, 0);                            \
@@ skipping 12628 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal