Copy-on-write arrays.

src/x64/full-codegen-x64.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 1312 matching lines @@
 void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
   Comment cmnt(masm_, "[ ArrayLiteral");
 
   ZoneList<Expression*>* subexprs = expr->values();
   int length = subexprs->length();
 
   __ movq(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
   __ push(FieldOperand(rbx, JSFunction::kLiteralsOffset));
   __ Push(Smi::FromInt(expr->literal_index()));
   __ Push(expr->constant_elements());
-  if (expr->depth() > 1) {
+  if (expr->constant_elements()->map() == Heap::fixed_cow_array_map()) {
+    FastCloneShallowArrayStub stub(
+        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS, length);
+    __ CallStub(&stub);
+  } else if (expr->depth() > 1) {
     __ CallRuntime(Runtime::kCreateArrayLiteral, 3);
-  } else if (length > FastCloneShallowArrayStub::kMaximumLength) {
+  } else if (length > FastCloneShallowArrayStub::kMaximumClonedLength) {
     __ CallRuntime(Runtime::kCreateArrayLiteralShallow, 3);
   } else {
-    FastCloneShallowArrayStub stub(length);
+    FastCloneShallowArrayStub stub(
+        FastCloneShallowArrayStub::CLONE_ELEMENTS, length);
     __ CallStub(&stub);
   }
 
   bool result_saved = false;  // Is the result saved to the stack?
 
   // Emit code to evaluate all the non-constant subexpressions and to store
   // them into the newly cloned array.
   for (int i = 0; i < length; i++) {
     Expression* subexpr = subexprs->at(i);
     // If the subexpression is a literal or a simple materialized literal it
@@ skipping 1995 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64