Add a fast case to Array.join when all the elements and the separator are fla...

src/arm/codegen-arm.cc

 // Copyright 2010 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 5798 matching lines @@
   ASSERT(args->length() == 1);
   Load(args->at(0));
   Register value = frame_->PopToRegister();
 
   __ ldr(value, FieldMemOperand(value, String::kHashFieldOffset));
   __ IndexFromHash(value, value);
   frame_->EmitPush(value);
 }
 
 
+void CodeGenerator::GenerateFastAsciiArrayJoin(ZoneList<Expression*>* args) {
+  ASSERT(args->length() == 2);
+  Load(args->at(0));
+  Register value = frame_->PopToRegister();
+  __ LoadRoot(value, Heap::kUndefinedValueRootIndex);
+  frame_->EmitPush(value);
+}
+
+
 void CodeGenerator::VisitCallRuntime(CallRuntime* node) {
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   if (CheckForInlineRuntimeCall(node)) {
     ASSERT((has_cc() && frame_->height() == original_height) ||
            (!has_cc() && frame_->height() == original_height + 1));
     return;
   }
 
@@ skipping 1436 matching lines @@
                BinaryOpIC::GetName(runtime_operands_type_));
   return name_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM