X87: Array() in optimized code can create with wrong ElementsKind in corner cases

src/x87/lithium-codegen-x87.cc

 // Copyright 2012 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_X87
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 4361 matching lines @@
   CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
 }
 
 
 void LCodeGen::DoCallNewArray(LCallNewArray* instr) {
   DCHECK(ToRegister(instr->context()).is(esi));
   DCHECK(ToRegister(instr->constructor()).is(edi));
   DCHECK(ToRegister(instr->result()).is(eax));
 
   __ Move(eax, Immediate(instr->arity()));
-  __ mov(ebx, isolate()->factory()->undefined_value());
+  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.
+    __ mov(ebx, instr->hydrogen()->site());
+  } else {
+    __ mov(ebx, isolate()->factory()->undefined_value());
+  }
+
   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 1951 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X87