Array() in optimized code can create with wrong ElementsKind in corner cases.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 4045 matching lines @@
   CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
 }
 
 
 void LCodeGen::DoCallNewArray(LCallNewArray* instr) {
   DCHECK(ToRegister(instr->context()).is(rsi));
   DCHECK(ToRegister(instr->constructor()).is(rdi));
   DCHECK(ToRegister(instr->result()).is(rax));
 
   __ Set(rax, instr->arity());
-  __ LoadRoot(rbx, Heap::kUndefinedValueRootIndex);
+  if (instr->arity() == 1) {
+    // We only need the allocation site for the case we have a length argument.
+    // The case may bail out to the runtime, which will determine the correct
+    // elements kind with the site.
+    __ Move(rbx, instr->hydrogen()->site());
+  } else {
+    __ LoadRoot(rbx, Heap::kUndefinedValueRootIndex);
+  }
+
   ElementsKind kind = instr->hydrogen()->elements_kind();
   AllocationSiteOverrideMode override_mode =
       (AllocationSite::GetMode(kind) == TRACK_ALLOCATION_SITE)
           ? DISABLE_ALLOCATION_SITES
           : DONT_OVERRIDE;
 
   if (instr->arity() == 0) {
     ArrayNoArgumentConstructorStub stub(isolate(), kind, override_mode);
     CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
   } else if (instr->arity() == 1) {
@@ skipping 1834 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64