Ensure that InternalArrays remain InternalArrays regardless of how they are constructed.

src/x64/builtins-x64.cc

 // Copyright 2011 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 1309 matching lines @@
   // esp[0]: return address
   // esp[8]: last argument
   __ pop(rcx);
   __ lea(rsp, Operand(rsp, rax, times_pointer_size, 1 * kPointerSize));
   __ push(rcx);
   __ movq(rax, rbx);
   __ ret(0);
 }
 
 
+void Builtins::Generate_InternalArrayCode(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- rax : argc
+  //  -- rsp[0] : return address
+  //  -- rsp[8] : last argument
+  // -----------------------------------
+  Label generic_array_code;
+
+  // Get the InternalArray function.
+  __ LoadGlobalFunction(Context::INTERNAL_ARRAY_FUNCTION_INDEX, rdi);
+
+  if (FLAG_debug_code) {
+    // Initial map for the builtin InternalArray functions should be maps.
+    __ movq(rbx, FieldOperand(rdi, JSFunction::kPrototypeOrInitialMapOffset));
+    // Will both indicate a NULL and a Smi.
+    STATIC_ASSERT(kSmiTag == 0);
+    Condition not_smi = NegateCondition(masm->CheckSmi(rbx));
+    __ Check(not_smi, "Unexpected initial map for InternalArray function");
+    __ CmpObjectType(rbx, MAP_TYPE, rcx);
+    __ Check(equal, "Unexpected initial map for InternalArray function");
+  }
+
+  // Run the native code for the InternalArray function called as a normal
+  // function.
+  ArrayNativeCode(masm, &generic_array_code);
+
+  // Jump to the generic array code in case the specialized code cannot handle
+  // the construction.
+  __ bind(&generic_array_code);
+  Handle<Code> array_code =
+      masm->isolate()->builtins()->ArrayCodeGeneric();
+  __ Jump(array_code, RelocInfo::CODE_TARGET);
+}
+
+
 void Builtins::Generate_ArrayCode(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax : argc
   //  -- rsp[0] : return address
   //  -- rsp[8] : last argument
   // -----------------------------------
   Label generic_array_code;
 
   // Get the Array function.
   __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, rdi);
@@ skipping 236 matching lines @@
   Deoptimizer::EntryGenerator generator(masm, Deoptimizer::OSR);
   generator.Generate();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64