Imported v8 version 3.7.3 from https://github.com/v8/v8.git

Change-Id: I152648081e46f599c2bb88eaaf67034fa5daac3a

1 files changed, 352 insertions, 0 deletions

diff --git a/src/3rdparty/v8/src/objects-visiting.h b/src/3rdparty/v8/src/objects-visiting.h
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+++ b/src/3rdparty/v8/src/objects-visiting.h
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+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_OBJECTS_VISITING_H_
+#define V8_OBJECTS_VISITING_H_
+
+#include "allocation.h"
+
+// This file provides base classes and auxiliary methods for defining
+// static object visitors used during GC.
+// Visiting HeapObject body with a normal ObjectVisitor requires performing
+// two switches on object's instance type to determine object size and layout
+// and one or more virtual method calls on visitor itself.
+// Static visitor is different: it provides a dispatch table which contains
+// pointers to specialized visit functions. Each map has the visitor_id
+// field which contains an index of specialized visitor to use.
+
+namespace v8 {
+namespace internal {
+
+
+// Base class for all static visitors.
+class StaticVisitorBase : public AllStatic {
+ public:
+  enum VisitorId {
+    kVisitSeqAsciiString = 0,
+    kVisitSeqTwoByteString,
+    kVisitShortcutCandidate,
+    kVisitByteArray,
+    kVisitFreeSpace,
+    kVisitFixedArray,
+    kVisitFixedDoubleArray,
+    kVisitGlobalContext,
+
+    // For data objects, JS objects and structs along with generic visitor which
+    // can visit object of any size we provide visitors specialized by
+    // object size in words.
+    // Ids of specialized visitors are declared in a linear order (without
+    // holes) starting from the id of visitor specialized for 2 words objects
+    // (base visitor id) and ending with the id of generic visitor.
+    // Method GetVisitorIdForSize depends on this ordering to calculate visitor
+    // id of specialized visitor from given instance size, base visitor id and
+    // generic visitor's id.
+
+    kVisitDataObject,
+    kVisitDataObject2 = kVisitDataObject,
+    kVisitDataObject3,
+    kVisitDataObject4,
+    kVisitDataObject5,
+    kVisitDataObject6,
+    kVisitDataObject7,
+    kVisitDataObject8,
+    kVisitDataObject9,
+    kVisitDataObjectGeneric,
+
+    kVisitJSObject,
+    kVisitJSObject2 = kVisitJSObject,
+    kVisitJSObject3,
+    kVisitJSObject4,
+    kVisitJSObject5,
+    kVisitJSObject6,
+    kVisitJSObject7,
+    kVisitJSObject8,
+    kVisitJSObject9,
+    kVisitJSObjectGeneric,
+
+    kVisitStruct,
+    kVisitStruct2 = kVisitStruct,
+    kVisitStruct3,
+    kVisitStruct4,
+    kVisitStruct5,
+    kVisitStruct6,
+    kVisitStruct7,
+    kVisitStruct8,
+    kVisitStruct9,
+    kVisitStructGeneric,
+
+    kVisitConsString,
+    kVisitSlicedString,
+    kVisitOddball,
+    kVisitCode,
+    kVisitMap,
+    kVisitPropertyCell,
+    kVisitSharedFunctionInfo,
+    kVisitJSFunction,
+    kVisitJSWeakMap,
+    kVisitJSRegExp,
+
+    kVisitorIdCount,
+    kMinObjectSizeInWords = 2
+  };
+
+  // Visitor ID should fit in one byte.
+  STATIC_ASSERT(kVisitorIdCount <= 256);
+
+  // Determine which specialized visitor should be used for given instance type
+  // and instance type.
+  static VisitorId GetVisitorId(int instance_type, int instance_size);
+
+  static VisitorId GetVisitorId(Map* map) {
+    return GetVisitorId(map->instance_type(), map->instance_size());
+  }
+
+  // For visitors that allow specialization by size calculate VisitorId based
+  // on size, base visitor id and generic visitor id.
+  static VisitorId GetVisitorIdForSize(VisitorId base,
+                                       VisitorId generic,
+                                       int object_size) {
+    ASSERT((base == kVisitDataObject) ||
+           (base == kVisitStruct) ||
+           (base == kVisitJSObject));
+    ASSERT(IsAligned(object_size, kPointerSize));
+    ASSERT(kMinObjectSizeInWords * kPointerSize <= object_size);
+    ASSERT(object_size < Page::kMaxHeapObjectSize);
+
+    const VisitorId specialization = static_cast<VisitorId>(
+        base + (object_size >> kPointerSizeLog2) - kMinObjectSizeInWords);
+
+    return Min(specialization, generic);
+  }
+};
+
+
+template<typename Callback>
+class VisitorDispatchTable {
+ public:
+  void CopyFrom(VisitorDispatchTable* other) {
+    // We are not using memcpy to guarantee that during update
+    // every element of callbacks_ array will remain correct
+    // pointer (memcpy might be implemented as a byte copying loop).
+    for (int i = 0; i < StaticVisitorBase::kVisitorIdCount; i++) {
+      NoBarrier_Store(&callbacks_[i], other->callbacks_[i]);
+    }
+  }
+
+  inline Callback GetVisitorById(StaticVisitorBase::VisitorId id) {
+    return reinterpret_cast<Callback>(callbacks_[id]);
+  }
+
+  inline Callback GetVisitor(Map* map) {
+    return reinterpret_cast<Callback>(callbacks_[map->visitor_id()]);
+  }
+
+  void Register(StaticVisitorBase::VisitorId id, Callback callback) {
+    ASSERT(id < StaticVisitorBase::kVisitorIdCount);  // id is unsigned.
+    callbacks_[id] = reinterpret_cast<AtomicWord>(callback);
+  }
+
+  template<typename Visitor,
+           StaticVisitorBase::VisitorId base,
+           StaticVisitorBase::VisitorId generic,
+           int object_size_in_words>
+  void RegisterSpecialization() {
+    static const int size = object_size_in_words * kPointerSize;
+    Register(StaticVisitorBase::GetVisitorIdForSize(base, generic, size),
+             &Visitor::template VisitSpecialized<size>);
+  }
+
+
+  template<typename Visitor,
+           StaticVisitorBase::VisitorId base,
+           StaticVisitorBase::VisitorId generic>
+  void RegisterSpecializations() {
+    STATIC_ASSERT(
+        (generic - base + StaticVisitorBase::kMinObjectSizeInWords) == 10);
+    RegisterSpecialization<Visitor, base, generic, 2>();
+    RegisterSpecialization<Visitor, base, generic, 3>();
+    RegisterSpecialization<Visitor, base, generic, 4>();
+    RegisterSpecialization<Visitor, base, generic, 5>();
+    RegisterSpecialization<Visitor, base, generic, 6>();
+    RegisterSpecialization<Visitor, base, generic, 7>();
+    RegisterSpecialization<Visitor, base, generic, 8>();
+    RegisterSpecialization<Visitor, base, generic, 9>();
+    Register(generic, &Visitor::Visit);
+  }
+
+ private:
+  AtomicWord callbacks_[StaticVisitorBase::kVisitorIdCount];
+};
+
+
+template<typename StaticVisitor>
+class BodyVisitorBase : public AllStatic {
+ public:
+  INLINE(static void IteratePointers(Heap* heap,
+                                     HeapObject* object,
+                                     int start_offset,
+                                     int end_offset)) {
+    Object** start_slot = reinterpret_cast<Object**>(object->address() +
+                                                     start_offset);
+    Object** end_slot = reinterpret_cast<Object**>(object->address() +
+                                                   end_offset);
+    StaticVisitor::VisitPointers(heap, start_slot, end_slot);
+  }
+};
+
+
+template<typename StaticVisitor, typename BodyDescriptor, typename ReturnType>
+class FlexibleBodyVisitor : public BodyVisitorBase<StaticVisitor> {
+ public:
+  static inline ReturnType Visit(Map* map, HeapObject* object) {
+    int object_size = BodyDescriptor::SizeOf(map, object);
+    BodyVisitorBase<StaticVisitor>::IteratePointers(
+        map->GetHeap(),
+        object,
+        BodyDescriptor::kStartOffset,
+        object_size);
+    return static_cast<ReturnType>(object_size);
+  }
+
+  template<int object_size>
+  static inline ReturnType VisitSpecialized(Map* map, HeapObject* object) {
+    ASSERT(BodyDescriptor::SizeOf(map, object) == object_size);
+    BodyVisitorBase<StaticVisitor>::IteratePointers(
+        map->GetHeap(),
+        object,
+        BodyDescriptor::kStartOffset,
+        object_size);
+    return static_cast<ReturnType>(object_size);
+  }
+};
+
+
+template<typename StaticVisitor, typename BodyDescriptor, typename ReturnType>
+class FixedBodyVisitor : public BodyVisitorBase<StaticVisitor> {
+ public:
+  static inline ReturnType Visit(Map* map, HeapObject* object) {
+    BodyVisitorBase<StaticVisitor>::IteratePointers(
+        map->GetHeap(),
+        object,
+        BodyDescriptor::kStartOffset,
+        BodyDescriptor::kEndOffset);
+    return static_cast<ReturnType>(BodyDescriptor::kSize);
+  }
+};
+
+
+// Base class for visitors used for a linear new space iteration.
+// IterateBody returns size of visited object.
+// Certain types of objects (i.e. Code objects) are not handled
+// by dispatch table of this visitor because they cannot appear
+// in the new space.
+//
+// This class is intended to be used in the following way:
+//
+//   class SomeVisitor : public StaticNewSpaceVisitor<SomeVisitor> {
+//     ...
+//   }
+//
+// This is an example of Curiously recurring template pattern
+// (see http://en.wikipedia.org/wiki/Curiously_recurring_template_pattern).
+// We use CRTP to guarantee aggressive compile time optimizations (i.e.
+// inlining and specialization of StaticVisitor::VisitPointers methods).
+template<typename StaticVisitor>
+class StaticNewSpaceVisitor : public StaticVisitorBase {
+ public:
+  static void Initialize();
+
+  static inline int IterateBody(Map* map, HeapObject* obj) {
+    return table_.GetVisitor(map)(map, obj);
+  }
+
+  static inline void VisitPointers(Heap* heap, Object** start, Object** end) {
+    for (Object** p = start; p < end; p++) StaticVisitor::VisitPointer(heap, p);
+  }
+
+ private:
+  static inline int VisitByteArray(Map* map, HeapObject* object) {
+    return reinterpret_cast<ByteArray*>(object)->ByteArraySize();
+  }
+
+  static inline int VisitFixedDoubleArray(Map* map, HeapObject* object) {
+    int length = reinterpret_cast<FixedDoubleArray*>(object)->length();
+    return FixedDoubleArray::SizeFor(length);
+  }
+
+  static inline int VisitJSObject(Map* map, HeapObject* object) {
+    return JSObjectVisitor::Visit(map, object);
+  }
+
+  static inline int VisitSeqAsciiString(Map* map, HeapObject* object) {
+    return SeqAsciiString::cast(object)->
+        SeqAsciiStringSize(map->instance_type());
+  }
+
+  static inline int VisitSeqTwoByteString(Map* map, HeapObject* object) {
+    return SeqTwoByteString::cast(object)->
+        SeqTwoByteStringSize(map->instance_type());
+  }
+
+  static inline int VisitFreeSpace(Map* map, HeapObject* object) {
+    return FreeSpace::cast(object)->Size();
+  }
+
+  class DataObjectVisitor {
+   public:
+    template<int object_size>
+    static inline int VisitSpecialized(Map* map, HeapObject* object) {
+      return object_size;
+    }
+
+    static inline int Visit(Map* map, HeapObject* object) {
+      return map->instance_size();
+    }
+  };
+
+  typedef FlexibleBodyVisitor<StaticVisitor,
+                              StructBodyDescriptor,
+                              int> StructVisitor;
+
+  typedef FlexibleBodyVisitor<StaticVisitor,
+                              JSObject::BodyDescriptor,
+                              int> JSObjectVisitor;
+
+  typedef int (*Callback)(Map* map, HeapObject* object);
+
+  static VisitorDispatchTable<Callback> table_;
+};
+
+
+template<typename StaticVisitor>
+VisitorDispatchTable<typename StaticNewSpaceVisitor<StaticVisitor>::Callback>
+  StaticNewSpaceVisitor<StaticVisitor>::table_;
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_OBJECTS_VISITING_H_