Convert constant numbers at compile time.

src/hydrogen.cc

 // Copyright 2013 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 1523 matching lines @@
 
   return BuildUncheckedDictionaryElementLoadHelper(elements, key,
                                                    hash, mask, 0);
 }
 
 
 HValue* HGraphBuilder::BuildNumberToString(HValue* object,
                                            Handle<Type> type) {
   NoObservableSideEffectsScope scope(this);
 
+  // Convert constant numbers at compile time.
+  if (object->IsConstant() && HConstant::cast(object)->HasNumberValue()) {
+    Handle<Object> number = HConstant::cast(object)->handle(isolate());
+    Handle<String> result = isolate()->factory()->NumberToString(number);
+    return Add<HConstant>(result);
+  }
+
   // Create a joinable continuation.
   HIfContinuation found(graph()->CreateBasicBlock(),
                         graph()->CreateBasicBlock());
 
   // Load the number string cache.
   HValue* number_string_cache =
       Add<HLoadRoot>(Heap::kNumberStringCacheRootIndex);
 
   // Make the hash mask from the length of the number string cache. It
   // contains two elements (number and string) for each cache entry.
@@ skipping 9079 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal