Use movw/movt on ARM to load constant roots

src/heap.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 2821 matching lines @@
   // Initialize descriptor cache.
   isolate_->descriptor_lookup_cache()->Clear();
 
   // Initialize compilation cache.
   isolate_->compilation_cache()->Clear();
 
   return true;
 }
 
 
+bool Heap::RootCanBeWrittenAfterInitialization(Heap::RootListIndex root_index) {
+  RootListIndex writable_roots[] = {
+    kStoreBufferTopRootIndex,
+    kStackLimitRootIndex,
+    kInstanceofCacheFunctionRootIndex,
+    kInstanceofCacheMapRootIndex,
+    kInstanceofCacheAnswerRootIndex,
+    kCodeStubsRootIndex,
+    kNonMonomorphicCacheRootIndex,
+    kPolymorphicCodeCacheRootIndex,
+    kLastScriptIdRootIndex,
+    kEmptyScriptRootIndex,
+    kRealStackLimitRootIndex,
+    kArgumentsAdaptorDeoptPCOffsetRootIndex,
+    kConstructStubDeoptPCOffsetRootIndex,
+    kGetterStubDeoptPCOffsetRootIndex,
+    kSetterStubDeoptPCOffsetRootIndex,
+    kSymbolTableRootIndex,
+  };
+
+  for (unsigned int i = 0; i < ARRAY_SIZE(writable_roots); i++) {
+    if (root_index == writable_roots[i])
+      return true;
+  }
+  return false;
+}
+
+
 Object* RegExpResultsCache::Lookup(Heap* heap,
                                    String* key_string,
                                    Object* key_pattern,
                                    ResultsCacheType type) {
   FixedArray* cache;
   if (!key_string->IsSymbol()) return Smi::FromInt(0);
   if (type == STRING_SPLIT_SUBSTRINGS) {
     ASSERT(key_pattern->IsString());
     if (!key_pattern->IsSymbol()) return Smi::FromInt(0);
     cache = heap->string_split_cache();
@@ skipping 4515 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   memcpy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   memcpy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal