Revert r20974: Unify and simplify the FastCloneShallowArrayStub

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index b76af2465a03f4f5bbe8980be3903cb5fb9febd7..cffab77e3aa4dd9abdc376003deaeb6b9a4a749e 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -1821,12 +1821,33 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
   __ ldr(r3, FieldMemOperand(r3, JSFunction::kLiteralsOffset));
   __ mov(r2, Operand(Smi::FromInt(expr->literal_index())));
   __ mov(r1, Operand(constant_elements));
-  if (expr->depth() > 1) {
+  if (has_fast_elements && constant_elements_values->map() ==
+      isolate()->heap()->fixed_cow_array_map()) {
+    FastCloneShallowArrayStub stub(
+        isolate(),
+        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
+        allocation_site_mode,
+        length);
+    __ CallStub(&stub);
+    __ IncrementCounter(
+        isolate()->counters()->cow_arrays_created_stub(), 1, r1, r2);
+  } else if (expr->depth() > 1 || Serializer::enabled() ||
+             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
     __ mov(r0, Operand(Smi::FromInt(flags)));
     __ Push(r3, r2, r1, r0);
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
+    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
+           FLAG_smi_only_arrays);
+    FastCloneShallowArrayStub::Mode mode =
+        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
+
+    if (has_fast_elements) {
+      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
+    }
+
+    FastCloneShallowArrayStub stub(isolate(), mode, allocation_site_mode,
+                                   length);
     __ CallStub(&stub);
   }