Reland r20974: Unify and simplify the FastCloneShallowArrayStub

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 54007737e2474f4a38089c7f4da12d9bf4224038..1f03fbf9df0597f910d5cdf91ce7566139037485 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -1766,24 +1766,7 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     allocation_site_mode = DONT_TRACK_ALLOCATION_SITE;
   }
 
-  Heap* heap = isolate()->heap();
-  if (has_constant_fast_elements &&
-      constant_elements_values->map() == heap->fixed_cow_array_map()) {
-    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
-    // change, so it's possible to specialize the stub in advance.
-    __ IncrementCounter(isolate()->counters()->cow_arrays_created_stub(), 1);
-    __ movp(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
-    __ movp(rax, FieldOperand(rbx, JSFunction::kLiteralsOffset));
-    __ Move(rbx, Smi::FromInt(expr->literal_index()));
-    __ Move(rcx, constant_elements);
-    FastCloneShallowArrayStub stub(
-        isolate(),
-        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
-        allocation_site_mode,
-        length);
-    __ CallStub(&stub);
-  } else if (expr->depth() > 1 || Serializer::enabled(isolate()) ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+  if (expr->depth() > 1) {
     __ movp(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
     __ Push(FieldOperand(rbx, JSFunction::kLiteralsOffset));
     __ Push(Smi::FromInt(expr->literal_index()));
@@ -1791,24 +1774,11 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     __ Push(Smi::FromInt(flags));
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
-           FLAG_smi_only_arrays);
-    FastCloneShallowArrayStub::Mode mode =
-        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
-
-    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
-    // change, so it's possible to specialize the stub in advance.
-    if (has_constant_fast_elements) {
-      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
-    }
-
     __ movp(rbx, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
     __ movp(rax, FieldOperand(rbx, JSFunction::kLiteralsOffset));
     __ Move(rbx, Smi::FromInt(expr->literal_index()));
     __ Move(rcx, constant_elements);
-    FastCloneShallowArrayStub stub(isolate(),
-                                   mode,
-                                   allocation_site_mode, length);
+    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
     __ CallStub(&stub);
   }