Implement unaligned allocate and allocate heap numbers in runtime double unaligned.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 2794 matching lines @@
 WriteBarrierMode HeapObject::GetWriteBarrierMode(
     const DisallowHeapAllocation& promise) {
   Heap* heap = GetHeap();
   if (heap->incremental_marking()->IsMarking()) return UPDATE_WRITE_BARRIER;
   if (heap->InNewSpace(this)) return SKIP_WRITE_BARRIER;
   return UPDATE_WRITE_BARRIER;
 }
 
 
 bool HeapObject::NeedsToEnsureDoubleAlignment() {
-#ifndef V8_HOST_ARCH_64_BIT
+#ifdef V8_HOST_ARCH_32_BIT
   return (IsFixedFloat64Array() || IsFixedDoubleArray() ||
           IsConstantPoolArray()) &&
          FixedArrayBase::cast(this)->length() != 0;
 #else
   return false;
-#endif  // V8_HOST_ARCH_64_BIT
+#endif  // V8_HOST_ARCH_32_BIT
 }
 
 
+bool HeapObject::NeedsToEnsureDoubleUnalignment() {
+#ifdef V8_HOST_ARCH_32_BIT
+  return IsHeapNumber();
+#else
+  return false;
+#endif  // V8_HOST_ARCH_32_BIT
+}
+
+
 void FixedArray::set(int index,
                      Object* value,
                      WriteBarrierMode mode) {
   DCHECK(map() != GetHeap()->fixed_cow_array_map());
   DCHECK(index >= 0 && index < this->length());
   int offset = kHeaderSize + index * kPointerSize;
   WRITE_FIELD(this, offset, value);
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, offset, value, mode);
 }
 
@@ skipping 4763 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_