Inline String.fromCharCode in hydrogen.

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 2399 matching lines @@
   generator->set_context(isolate->heap()->undefined_value());
   generator->set_continuation(0);
   generator->set_operand_stack(isolate->heap()->empty_fixed_array());
 
   return generator;
 }
 
 
 MUST_USE_RESULT static MaybeObject* CharFromCode(Isolate* isolate,
                                                  Object* char_code) {
-  uint32_t code;
-  if (char_code->ToArrayIndex(&code)) {
-    if (code <= 0xffff) {
-      return isolate->heap()->LookupSingleCharacterStringFromCode(code);
-    }
+  if (char_code->IsNumber()) {
+    return isolate->heap()->LookupSingleCharacterStringFromCode(
+        NumberToUint32(char_code) & 0xffff);
   }
   return isolate->heap()->empty_string();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_StringCharCodeAt) {
   NoHandleAllocation ha(isolate);
   ASSERT(args.length() == 2);
 
   CONVERT_ARG_CHECKED(String, subject, 0);
@@ skipping 10772 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