Reland: track global accesses to constant types

src/property-details.h

 // 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.
 
 #ifndef V8_PROPERTY_DETAILS_H_
 #define V8_PROPERTY_DETAILS_H_
 
 #include "include/v8.h"
 #include "src/allocation.h"
 #include "src/utils.h"
@@ skipping 168 matching lines @@
 static const int kDescriptorIndexBitCount = 10;
 // The maximum number of descriptors we want in a descriptor array (should
 // fit in a page).
 static const int kMaxNumberOfDescriptors =
     (1 << kDescriptorIndexBitCount) - 2;
 static const int kInvalidEnumCacheSentinel =
     (1 << kDescriptorIndexBitCount) - 1;
 
 
 enum class PropertyCellType {
-  kUninitialized,        // Cell is deleted or not yet defined.
-  kUndefined,            // The PREMONOMORPHIC of property cells.
-  kConstant,             // Cell has been assigned only once.
-  kMutable,              // Cell will no longer be tracked as constant.
-  kDeleted = kConstant,  // like kUninitialized, but for cells already deleted.
-  kInvalid = kMutable,   // For dictionaries not holding cells.
+  // Meaningful when a property cell does not contain the hole.
+  kUndefined,     // The PREMONOMORPHIC of property cells.
+  kConstant,      // Cell has been assigned only once.
+  kConstantType,  // Cell has been assigned only one type.
+  kMutable,       // Cell will no longer be tracked as constant.
+
+  // Meaningful when a property cell contains the hole.
+  kUninitialized = kUndefined,  // Cell has never been initialized.
+  kInvalidated = kConstant,     // Cell has been deleted or invalidated.
+
+  // For dictionaries not holding cells.
+  kNoCell = kMutable,
 };
 
 
+enum class PropertyCellConstantType {
+  kSmi,
+  kStableMap,
+};
+
+
 // PropertyDetails captures type and attributes for a property.
 // They are used both in property dictionaries and instance descriptors.
 class PropertyDetails BASE_EMBEDDED {
  public:
   PropertyDetails(PropertyAttributes attributes, PropertyType type, int index,
                   PropertyCellType cell_type) {
     value_ = TypeField::encode(type) | AttributesField::encode(attributes) |
              DictionaryStorageField::encode(index) |
              PropertyCellTypeField::encode(cell_type);
 
@@ skipping 14 matching lines @@
   PropertyDetails(PropertyAttributes attributes, PropertyKind kind,
                   PropertyLocation location, Representation representation,
                   int field_index = 0) {
     value_ = KindField::encode(kind) | LocationField::encode(location) |
              AttributesField::encode(attributes) |
              RepresentationField::encode(EncodeRepresentation(representation)) |
              FieldIndexField::encode(field_index);
   }
 
   static PropertyDetails Empty() {
-    return PropertyDetails(NONE, DATA, 0, PropertyCellType::kInvalid);
+    return PropertyDetails(NONE, DATA, 0, PropertyCellType::kNoCell);
   }
 
   int pointer() const { return DescriptorPointer::decode(value_); }
 
   PropertyDetails set_pointer(int i) const {
     return PropertyDetails(value_, i);
   }
 
   PropertyDetails set_cell_type(PropertyCellType type) const {
     PropertyDetails details = *this;
@@ skipping 110 matching lines @@
   uint32_t value_;
 };
 
 
 std::ostream& operator<<(std::ostream& os,
                          const PropertyAttributes& attributes);
 std::ostream& operator<<(std::ostream& os, const PropertyDetails& details);
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_