Fix usage of literal cloning for large double arrays.

src/ast/ast.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/ast/ast.h"
 
 #include <cmath>  // For isfinite.
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/prettyprinter.h"
@@ skipping 556 matching lines @@
   constant_properties_ = constant_properties;
   bit_field_ = FastElementsField::update(
       bit_field_,
       (max_element_index <= 32) || ((2 * elements) >= max_element_index));
   bit_field_ = HasElementsField::update(bit_field_, elements > 0);
 
   set_is_simple(is_simple);
   set_depth(depth_acc);
 }
 
+bool ObjectLiteral::IsFastCloningSupported() const {
+  // FastCloneShallowObjectStub doesn't copy elements, and object literals don't
+  // support copy-on-write (COW) elements for now.
+  // TODO(mvstanton): make object literals support COW elements.
+  return fast_elements() && has_shallow_properties() &&
+         properties_count() <=
+             FastCloneShallowObjectStub::kMaximumClonedProperties;
+}
 
 void ArrayLiteral::BuildConstantElements(Isolate* isolate) {
   DCHECK_LT(first_spread_index_, 0);
 
   if (!constant_elements_.is_null()) return;
 
   int constants_length = values()->length();
   ElementsKind kind = FIRST_FAST_ELEMENTS_KIND;
   Handle<FixedArray> fixed_array =
       isolate->factory()->NewFixedArrayWithHoles(constants_length);
@@ skipping 54 matching lines @@
   // in a 2-element FixedArray.
   Handle<FixedArray> literals = isolate->factory()->NewFixedArray(2, TENURED);
   literals->set(0, Smi::FromInt(kind));
   literals->set(1, *elements);
 
   constant_elements_ = literals;
   set_is_simple(is_simple);
   set_depth(depth_acc);
 }
 
+bool ArrayLiteral::IsFastCloningSupported() const {
+  return depth() <= 1 &&
+         values()->length() <=
+             FastCloneShallowArrayStub::kMaximumClonedElements;
+}
 
 void ArrayLiteral::AssignFeedbackVectorSlots(Isolate* isolate,
                                              FeedbackVectorSpec* spec,
                                              FeedbackVectorSlotCache* cache) {
   // This logic that computes the number of slots needed for vector store
   // ics must mirror FullCodeGenerator::VisitArrayLiteral.
   for (int array_index = 0; array_index < values()->length(); array_index++) {
     Expression* subexpr = values()->at(array_index);
     DCHECK(!subexpr->IsSpread());
     if (CompileTimeValue::IsCompileTimeValue(subexpr)) continue;
@@ skipping 286 matching lines @@
 // static
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && x->AsString() == y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 }  // namespace internal
 }  // namespace v8