Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/src/google/protobuf/generated_message_reflection.cc

Index: third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
diff --git a/third_party/protobuf/src/google/protobuf/generated_message_reflection.cc b/third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
index 08742232237ef2e8994b58c6ea48936b40aad1a5..2313181cc995220fe39ce23236e365b467e05276 100644
--- a/third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
+++ b/third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
@@ -44,7 +44,6 @@
 #include <google/protobuf/generated_message_util.h>
 #include <google/protobuf/map_field.h>
 #include <google/protobuf/repeated_field.h>
-// #include "google/protobuf/bridge/compatibility_mode_support.h"
 
 
 #define GOOGLE_PROTOBUF_HAS_ONEOF
@@ -85,22 +84,6 @@ inline bool SupportsArenas(const Descriptor* descriptor) {
 
 namespace {
 
-template <class To>
-To* GetPointerAtOffset(Message* message, uint32 offset) {
-  return reinterpret_cast<To*>(reinterpret_cast<char*>(message) + offset);
-}
-
-template <class To>
-const To* GetConstPointerAtOffset(const Message* message, uint32 offset) {
-  return reinterpret_cast<const To*>(reinterpret_cast<const char*>(message) +
-                                     offset);
-}
-
-template <class To>
-const To& GetConstRefAtOffset(const Message& message, uint32 offset) {
-  return *GetConstPointerAtOffset<To>(&message, offset);
-}
-
 void ReportReflectionUsageError(
     const Descriptor* descriptor, const FieldDescriptor* field,
     const char* method, const char* description) {
@@ -190,24 +173,61 @@ static void ReportReflectionUsageEnumTypeError(
 // ===================================================================
 
 GeneratedMessageReflection::GeneratedMessageReflection(
-    const Descriptor* descriptor, const ReflectionSchema& schema,
-    const DescriptorPool* pool, MessageFactory* factory)
-    : descriptor_(descriptor),
-      schema_(schema),
-      descriptor_pool_((pool == NULL) ? DescriptorPool::generated_pool()
-                                      : pool),
-      message_factory_(factory),
-      // TODO(haberman) remove this when upb is using our table driven.
-      default_instance_(schema_.default_instance_),
-      default_oneof_instance_(schema_.default_oneof_instance_),
-      offsets_(schema_.offsets_),
-      has_bits_indices_(schema_.has_bit_indices_),
-      has_bits_offset_(schema_.has_bits_offset_),
-      oneof_case_offset_(schema_.oneof_case_offset_),
-      unknown_fields_offset_(-1),
-      extensions_offset_(schema_.extensions_offset_),
-      arena_offset_(schema_.metadata_offset_),
-      object_size_(schema_.object_size_) {
+    const Descriptor* descriptor,
+    const Message* default_instance,
+    const int offsets[],
+    int has_bits_offset,
+    int unknown_fields_offset,
+    int extensions_offset,
+    const DescriptorPool* descriptor_pool,
+    MessageFactory* factory,
+    int object_size,
+    int arena_offset,
+    int is_default_instance_offset)
+  : descriptor_       (descriptor),
+    default_instance_ (default_instance),
+    offsets_          (offsets),
+    has_bits_offset_  (has_bits_offset),
+    unknown_fields_offset_(unknown_fields_offset),
+    extensions_offset_(extensions_offset),
+    arena_offset_     (arena_offset),
+    is_default_instance_offset_(is_default_instance_offset),
+    object_size_      (object_size),
+    descriptor_pool_  ((descriptor_pool == NULL) ?
+                         DescriptorPool::generated_pool() :
+                         descriptor_pool),
+    message_factory_  (factory) {
+}
+
+GeneratedMessageReflection::GeneratedMessageReflection(
+    const Descriptor* descriptor,
+    const Message* default_instance,
+    const int offsets[],
+    int has_bits_offset,
+    int unknown_fields_offset,
+    int extensions_offset,
+    const void* default_oneof_instance,
+    int oneof_case_offset,
+    const DescriptorPool* descriptor_pool,
+    MessageFactory* factory,
+    int object_size,
+    int arena_offset,
+    int is_default_instance_offset)
+  : descriptor_       (descriptor),
+    default_instance_ (default_instance),
+    default_oneof_instance_ (default_oneof_instance),
+    offsets_          (offsets),
+    has_bits_offset_  (has_bits_offset),
+    oneof_case_offset_(oneof_case_offset),
+    unknown_fields_offset_(unknown_fields_offset),
+    extensions_offset_(extensions_offset),
+    arena_offset_     (arena_offset),
+    is_default_instance_offset_(is_default_instance_offset),
+    object_size_      (object_size),
+    descriptor_pool_  ((descriptor_pool == NULL) ?
+                         DescriptorPool::generated_pool() :
+                         descriptor_pool),
+    message_factory_  (factory) {
 }
 
 GeneratedMessageReflection::~GeneratedMessageReflection() {}
@@ -235,33 +255,39 @@ const UnknownFieldSet& GetEmptyUnknownFieldSet() {
 const UnknownFieldSet& GeneratedMessageReflection::GetUnknownFields(
     const Message& message) const {
   if (descriptor_->file()->syntax() == FileDescriptor::SYNTAX_PROTO3) {
-    // We have to ensure that any mutations made to the return value of
-    // MutableUnknownFields() are not reflected here.
     return GetEmptyUnknownFieldSet();
-  } else {
+  }
+  if (unknown_fields_offset_ == kUnknownFieldSetInMetadata) {
     return GetInternalMetadataWithArena(message).unknown_fields();
   }
+  const void* ptr = reinterpret_cast<const uint8*>(&message) +
+                    unknown_fields_offset_;
+  return *reinterpret_cast<const UnknownFieldSet*>(ptr);
 }
 
 UnknownFieldSet* GeneratedMessageReflection::MutableUnknownFields(
     Message* message) const {
-  return MutableInternalMetadataWithArena(message)->mutable_unknown_fields();
+  if (unknown_fields_offset_ == kUnknownFieldSetInMetadata) {
+    return MutableInternalMetadataWithArena(message)->
+        mutable_unknown_fields();
+  }
+  void* ptr = reinterpret_cast<uint8*>(message) + unknown_fields_offset_;
+  return reinterpret_cast<UnknownFieldSet*>(ptr);
 }
 
 int GeneratedMessageReflection::SpaceUsed(const Message& message) const {
   // object_size_ already includes the in-memory representation of each field
   // in the message, so we only need to account for additional memory used by
   // the fields.
-  int total_size = schema_.GetObjectSize();
+  int total_size = object_size_;
 
   total_size += GetUnknownFields(message).SpaceUsedExcludingSelf();
 
-  if (schema_.HasExtensionSet()) {
+  if (extensions_offset_ != -1) {
     total_size += GetExtensionSet(message).SpaceUsedExcludingSelf();
   }
 
-  const int field_count = descriptor_->field_count();
-  for (int i = 0; i < field_count; i++) {
+  for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
 
     if (field->is_repeated()) {
@@ -330,9 +356,9 @@ int GeneratedMessageReflection::SpaceUsed(const Message& message) const {
               // the prototype. Only count the string if it has been changed
               // from the default value.
               const string* default_ptr =
-                  &DefaultRaw<ArenaStringPtr>(field).Get();
+                  &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
               const string* ptr =
-                  &GetField<ArenaStringPtr>(message, field).Get();
+                  &GetField<ArenaStringPtr>(message, field).Get(default_ptr);
 
               if (ptr != default_ptr) {
                 // string fields are represented by just a pointer, so also
@@ -346,7 +372,7 @@ int GeneratedMessageReflection::SpaceUsed(const Message& message) const {
         }
 
         case FieldDescriptor::CPPTYPE_MESSAGE:
-          if (schema_.IsDefaultInstance(message)) {
+          if (&message == default_instance_) {
             // For singular fields, the prototype just stores a pointer to the
             // external type's prototype, so there is no extra memory usage.
           } else {
@@ -468,9 +494,9 @@ void GeneratedMessageReflection::SwapField(
                 string1->Swap(string2);
               } else {
                 const string* default_ptr =
-                    &DefaultRaw<ArenaStringPtr>(field).Get();
-                const string temp = string1->Get();
-                string1->Set(default_ptr, string2->Get(), arena1);
+                    &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
+                const string temp = string1->Get(default_ptr);
+                string1->Set(default_ptr, string2->Get(default_ptr), arena1);
                 string2->Set(default_ptr, temp, arena2);
               }
             }
@@ -631,16 +657,16 @@ void GeneratedMessageReflection::Swap(
     // Slow copy path.
     // Use our arena as temp space, if available.
     Message* temp = message1->New(GetArena(message1));
-    temp->MergeFrom(*message2);
-    message2->CopyFrom(*message1);
-    Swap(message1, temp);
+    temp->MergeFrom(*message1);
+    message1->CopyFrom(*message2);
+    message2->CopyFrom(*temp);
     if (GetArena(message1) == NULL) {
       delete temp;
     }
     return;
   }
 
-  if (schema_.HasHasbits()) {
+  if (has_bits_offset_ != -1) {
     uint32* has_bits1 = MutableHasBits(message1);
     uint32* has_bits2 = MutableHasBits(message2);
     int has_bits_size = (descriptor_->field_count() + 31) / 32;
@@ -650,20 +676,18 @@ void GeneratedMessageReflection::Swap(
     }
   }
 
-  const int field_count = descriptor_->field_count();
-  for (int i = 0; i < field_count; i++) {
+  for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
     if (!field->containing_oneof()) {
       SwapField(message1, message2, field);
     }
   }
 
-  const int oneof_decl_count = descriptor_->oneof_decl_count();
-  for (int i = 0; i < oneof_decl_count; i++) {
+  for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
     SwapOneofField(message1, message2, descriptor_->oneof_decl(i));
   }
 
-  if (schema_.HasExtensionSet()) {
+  if (extensions_offset_ != -1) {
     MutableExtensionSet(message1)->Swap(MutableExtensionSet(message2));
   }
 
@@ -673,7 +697,7 @@ void GeneratedMessageReflection::Swap(
 void GeneratedMessageReflection::SwapFields(
     Message* message1,
     Message* message2,
-    const std::vector<const FieldDescriptor*>& fields) const {
+    const vector<const FieldDescriptor*>& fields) const {
   if (message1 == message2) return;
 
   // TODO(kenton):  Other Reflection methods should probably check this too.
@@ -694,8 +718,7 @@ void GeneratedMessageReflection::SwapFields(
 
   std::set<int> swapped_oneof;
 
-  const int fields_size = static_cast<int>(fields.size());
-  for (int i = 0; i < fields_size; i++) {
+  for (int i = 0; i < fields.size(); i++) {
     const FieldDescriptor* field = fields[i];
     if (field->is_extension()) {
       MutableExtensionSet(message1)->SwapExtension(
@@ -817,9 +840,9 @@ void GeneratedMessageReflection::ClearField(
             default:  // TODO(kenton):  Support other string reps.
             case FieldOptions::STRING: {
               const string* default_ptr =
-                  &DefaultRaw<ArenaStringPtr>(field).Get();
-              MutableRaw<ArenaStringPtr>(message, field)->SetAllocated(
-                  default_ptr, NULL, GetArena(message));
+                  &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
+              MutableRaw<ArenaStringPtr>(message, field)->Destroy(default_ptr,
+                  GetArena(message));
               break;
             }
           }
@@ -827,7 +850,7 @@ void GeneratedMessageReflection::ClearField(
         }
 
         case FieldDescriptor::CPPTYPE_MESSAGE:
-          if (!schema_.HasHasbits()) {
+          if (has_bits_offset_ == -1) {
             // Proto3 does not have has-bits and we need to set a message field
             // to NULL in order to indicate its un-presence.
             if (GetArena(message) == NULL) {
@@ -1003,60 +1026,35 @@ struct FieldNumberSorter {
     return left->number() < right->number();
   }
 };
-
-inline bool IsIndexInHasBitSet(
-    const uint32* has_bit_set, uint32 has_bit_index) {
-  return ((has_bit_set[has_bit_index / 32] >> (has_bit_index % 32)) &
-          static_cast<uint32>(1)) != 0;
-}
 }  // namespace
 
 void GeneratedMessageReflection::ListFields(
     const Message& message,
-    std::vector<const FieldDescriptor*>* output) const {
+    vector<const FieldDescriptor*>* output) const {
   output->clear();
 
   // Optimization:  The default instance never has any fields set.
-  if (schema_.IsDefaultInstance(message)) return;
-
-  // Optimization: Avoid calling GetHasBits() and HasOneofField() many times
-  // within the field loop.  We allow this violation of ReflectionSchema
-  // encapsulation because this function takes a noticable about of CPU
-  // fleetwide and properly allowing this optimization through public interfaces
-  // seems more trouble than it is worth.
-  const uint32* const has_bits =
-      schema_.HasHasbits() ? GetHasBits(message) : NULL;
-  const uint32* const has_bits_indices = schema_.has_bit_indices_;
-  const uint32* const oneof_case_array =
-      &GetConstRefAtOffset<uint32>(message, schema_.oneof_case_offset_);
-
-  const int field_count = descriptor_->field_count();
-  output->reserve(field_count);
-  for (int i = 0; i < field_count; i++) {
+  if (&message == default_instance_) return;
+
+  output->reserve(descriptor_->field_count());
+  for (int i = 0; i < descriptor_->field_count(); i++) {
     const FieldDescriptor* field = descriptor_->field(i);
     if (field->is_repeated()) {
       if (FieldSize(message, field) > 0) {
         output->push_back(field);
       }
     } else {
-      const OneofDescriptor* containing_oneof = field->containing_oneof();
-      if (containing_oneof) {
-        // Equivalent to: HasOneofField(message, field)
-        if (oneof_case_array[containing_oneof->index()] == field->number()) {
-          output->push_back(field);
-        }
-      } else if (has_bits) {
-        // Equivalent to: HasBit(message, field)
-        if (IsIndexInHasBitSet(has_bits, has_bits_indices[i])) {
+      if (field->containing_oneof()) {
+        if (HasOneofField(message, field)) {
           output->push_back(field);
         }
-      } else if (HasBit(message, field)) {  // Fall back on proto3-style HasBit.
+      } else if (HasBit(message, field)) {
         output->push_back(field);
       }
     }
   }
 
-  if (schema_.HasExtensionSet()) {
+  if (extensions_offset_ != -1) {
     GetExtensionSet(message).AppendToList(descriptor_, descriptor_pool_,
                                           output);
   }
@@ -1150,7 +1148,9 @@ string GeneratedMessageReflection::GetString(
     switch (field->options().ctype()) {
       default:  // TODO(kenton):  Support other string reps.
       case FieldOptions::STRING: {
-        return GetField<ArenaStringPtr>(message, field).Get();
+        const string* default_ptr =
+            &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
+        return GetField<ArenaStringPtr>(message, field).Get(default_ptr);
       }
     }
 
@@ -1170,7 +1170,9 @@ const string& GeneratedMessageReflection::GetStringReference(
     switch (field->options().ctype()) {
       default:  // TODO(kenton):  Support other string reps.
       case FieldOptions::STRING: {
-        return GetField<ArenaStringPtr>(message, field).Get();
+        const string* default_ptr =
+            &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
+        return GetField<ArenaStringPtr>(message, field).Get(default_ptr);
       }
     }
 
@@ -1191,7 +1193,8 @@ void GeneratedMessageReflection::SetString(
     switch (field->options().ctype()) {
       default:  // TODO(kenton):  Support other string reps.
       case FieldOptions::STRING: {
-        const string* default_ptr = &DefaultRaw<ArenaStringPtr>(field).Get();
+        const string* default_ptr =
+            &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
         if (field->containing_oneof() && !HasOneofField(*message, field)) {
           ClearOneof(message, field->containing_oneof());
           MutableField<ArenaStringPtr>(message, field)->UnsafeSetDefault(
@@ -1576,8 +1579,7 @@ Message* GeneratedMessageReflection::UnsafeArenaReleaseMessage(
 
   if (field->is_extension()) {
     return static_cast<Message*>(
-        MutableExtensionSet(message)->UnsafeArenaReleaseMessage(field,
-                                                                factory));
+        MutableExtensionSet(message)->ReleaseMessage(field, factory));
   } else {
     ClearBit(message, field);
     if (field->containing_oneof()) {
@@ -1725,10 +1727,11 @@ void* GeneratedMessageReflection::MutableRawRepeatedField(
   } else {
     // Trigger transform for MapField
     if (IsMapFieldInApi(field)) {
-      return MutableRawNonOneof<MapFieldBase>(message, field)
+      return reinterpret_cast<MapFieldBase*>(reinterpret_cast<uint8*>(message) +
+                                             offsets_[field->index()])
           ->MutableRepeatedField();
     }
-    return MutableRawNonOneof<void>(message, field);
+    return reinterpret_cast<uint8*>(message) + offsets_[field->index()];
   }
 }
 
@@ -1755,9 +1758,11 @@ const void* GeneratedMessageReflection::GetRawRepeatedField(
   } else {
     // Trigger transform for MapField
     if (IsMapFieldInApi(field)) {
-      return &(GetRawNonOneof<MapFieldBase>(message, field).GetRepeatedField());
+      return &(reinterpret_cast<const MapFieldBase*>(
+          reinterpret_cast<const uint8*>(&message) +
+          offsets_[field->index()])->GetRepeatedField());
     }
-    return &GetRawNonOneof<char>(message, field);
+    return reinterpret_cast<const uint8*>(&message) + offsets_[field->index()];
   }
 }
 
@@ -1839,7 +1844,7 @@ int GeneratedMessageReflection::MapSize(
 
 const FieldDescriptor* GeneratedMessageReflection::FindKnownExtensionByName(
     const string& name) const {
-  if (!schema_.HasExtensionSet()) return NULL;
+  if (extensions_offset_ == -1) return NULL;
 
   const FieldDescriptor* result = descriptor_pool_->FindExtensionByName(name);
   if (result != NULL && result->containing_type() == descriptor_) {
@@ -1851,8 +1856,7 @@ const FieldDescriptor* GeneratedMessageReflection::FindKnownExtensionByName(
     const Descriptor* type = descriptor_pool_->FindMessageTypeByName(name);
     if (type != NULL) {
       // Look for a matching extension in the foreign type's scope.
-      const int type_extension_count = type->extension_count();
-      for (int i = 0; i < type_extension_count; i++) {
+      for (int i = 0; i < type->extension_count(); i++) {
         const FieldDescriptor* extension = type->extension(i);
         if (extension->containing_type() == descriptor_ &&
             extension->type() == FieldDescriptor::TYPE_MESSAGE &&
@@ -1870,7 +1874,7 @@ const FieldDescriptor* GeneratedMessageReflection::FindKnownExtensionByName(
 
 const FieldDescriptor* GeneratedMessageReflection::FindKnownExtensionByNumber(
     int number) const {
-  if (!schema_.HasExtensionSet()) return NULL;
+  if (extensions_offset_ == -1) return NULL;
   return descriptor_pool_->FindExtensionByNumber(descriptor_, number);
 }
 
@@ -1883,176 +1887,204 @@ bool GeneratedMessageReflection::SupportsUnknownEnumValues() const {
 
 // These simple template accessors obtain pointers (or references) to
 // the given field.
-
-template <class Type>
-const Type& GeneratedMessageReflection::GetRawNonOneof(
-    const Message& message, const FieldDescriptor* field) const {
-  return GetConstRefAtOffset<Type>(message,
-                                   schema_.GetFieldOffsetNonOneof(field));
-}
-
-template <class Type>
-Type* GeneratedMessageReflection::MutableRawNonOneof(
-    Message* message, const FieldDescriptor* field) const {
-  return GetPointerAtOffset<Type>(message,
-                                  schema_.GetFieldOffsetNonOneof(field));
-}
-
 template <typename Type>
-const Type& GeneratedMessageReflection::GetRaw(
+inline const Type& GeneratedMessageReflection::GetRaw(
     const Message& message, const FieldDescriptor* field) const {
   if (field->containing_oneof() && !HasOneofField(message, field)) {
     return DefaultRaw<Type>(field);
   }
-  return GetConstRefAtOffset<Type>(message, schema_.GetFieldOffset(field));
+  int index = field->containing_oneof() ?
+      descriptor_->field_count() + field->containing_oneof()->index() :
+      field->index();
+  const void* ptr = reinterpret_cast<const uint8*>(&message) +
+      offsets_[index];
+  return *reinterpret_cast<const Type*>(ptr);
 }
 
 template <typename Type>
-Type* GeneratedMessageReflection::MutableRaw(Message* message,
-                                   const FieldDescriptor* field) const {
-  return GetPointerAtOffset<Type>(message, schema_.GetFieldOffset(field));
+inline Type* GeneratedMessageReflection::MutableRaw(
+    Message* message, const FieldDescriptor* field) const {
+  int index = field->containing_oneof() ?
+      descriptor_->field_count() + field->containing_oneof()->index() :
+      field->index();
+  void* ptr = reinterpret_cast<uint8*>(message) + offsets_[index];
+  return reinterpret_cast<Type*>(ptr);
 }
 
+template <typename Type>
+inline const Type& GeneratedMessageReflection::DefaultRaw(
+    const FieldDescriptor* field) const {
+  const void* ptr = field->containing_oneof() ?
+      reinterpret_cast<const uint8*>(default_oneof_instance_) +
+      offsets_[field->index()] :
+      reinterpret_cast<const uint8*>(default_instance_) +
+      offsets_[field->index()];
+  return *reinterpret_cast<const Type*>(ptr);
+}
 
 inline const uint32* GeneratedMessageReflection::GetHasBits(
     const Message& message) const {
-  GOOGLE_DCHECK(schema_.HasHasbits());
-  return &GetConstRefAtOffset<uint32>(message, schema_.HasBitsOffset());
+  if (has_bits_offset_ == -1) {  // proto3 with no has-bits.
+    return NULL;
+  }
+  const void* ptr = reinterpret_cast<const uint8*>(&message) + has_bits_offset_;
+  return reinterpret_cast<const uint32*>(ptr);
 }
-
 inline uint32* GeneratedMessageReflection::MutableHasBits(
     Message* message) const {
-  GOOGLE_DCHECK(schema_.HasHasbits());
-  return GetPointerAtOffset<uint32>(message, schema_.HasBitsOffset());
+  if (has_bits_offset_ == -1) {
+    return NULL;
+  }
+  void* ptr = reinterpret_cast<uint8*>(message) + has_bits_offset_;
+  return reinterpret_cast<uint32*>(ptr);
 }
 
 inline uint32 GeneratedMessageReflection::GetOneofCase(
-    const Message& message, const OneofDescriptor* oneof_descriptor) const {
-  return GetConstRefAtOffset<uint32>(
-      message, schema_.GetOneofCaseOffset(oneof_descriptor));
+    const Message& message,
+    const OneofDescriptor* oneof_descriptor) const {
+  const void* ptr = reinterpret_cast<const uint8*>(&message)
+      + oneof_case_offset_;
+  return reinterpret_cast<const uint32*>(ptr)[oneof_descriptor->index()];
 }
 
 inline uint32* GeneratedMessageReflection::MutableOneofCase(
-    Message* message, const OneofDescriptor* oneof_descriptor) const {
-  return GetPointerAtOffset<uint32>(
-      message, schema_.GetOneofCaseOffset(oneof_descriptor));
+    Message* message,
+    const OneofDescriptor* oneof_descriptor) const {
+  void* ptr = reinterpret_cast<uint8*>(message) + oneof_case_offset_;
+  return &(reinterpret_cast<uint32*>(ptr)[oneof_descriptor->index()]);
 }
 
 inline const ExtensionSet& GeneratedMessageReflection::GetExtensionSet(
     const Message& message) const {
-  return GetConstRefAtOffset<ExtensionSet>(message,
-                                           schema_.GetExtensionSetOffset());
+  GOOGLE_DCHECK_NE(extensions_offset_, -1);
+  const void* ptr = reinterpret_cast<const uint8*>(&message) +
+                    extensions_offset_;
+  return *reinterpret_cast<const ExtensionSet*>(ptr);
 }
-
 inline ExtensionSet* GeneratedMessageReflection::MutableExtensionSet(
     Message* message) const {
-  return GetPointerAtOffset<ExtensionSet>(message,
-                                          schema_.GetExtensionSetOffset());
+  GOOGLE_DCHECK_NE(extensions_offset_, -1);
+  void* ptr = reinterpret_cast<uint8*>(message) + extensions_offset_;
+  return reinterpret_cast<ExtensionSet*>(ptr);
 }
 
 inline Arena* GeneratedMessageReflection::GetArena(Message* message) const {
-  return GetInternalMetadataWithArena(*message).arena();
+  if (arena_offset_ == kNoArenaPointer) {
+    return NULL;
+  }
+
+  if (unknown_fields_offset_ == kUnknownFieldSetInMetadata) {
+    // zero-overhead arena pointer overloading UnknownFields
+    return GetInternalMetadataWithArena(*message).arena();
+  }
+
+  // Baseline case: message class has a dedicated arena pointer.
+  void* ptr = reinterpret_cast<uint8*>(message) + arena_offset_;
+  return *reinterpret_cast<Arena**>(ptr);
 }
 
 inline const InternalMetadataWithArena&
 GeneratedMessageReflection::GetInternalMetadataWithArena(
     const Message& message) const {
-  return GetConstRefAtOffset<InternalMetadataWithArena>(
-      message, schema_.GetMetadataOffset());
+  const void* ptr = reinterpret_cast<const uint8*>(&message) + arena_offset_;
+  return *reinterpret_cast<const InternalMetadataWithArena*>(ptr);
 }
 
 inline InternalMetadataWithArena*
 GeneratedMessageReflection::MutableInternalMetadataWithArena(
     Message* message) const {
-  return GetPointerAtOffset<InternalMetadataWithArena>(
-      message, schema_.GetMetadataOffset());
+  void* ptr = reinterpret_cast<uint8*>(message) + arena_offset_;
+  return reinterpret_cast<InternalMetadataWithArena*>(ptr);
 }
 
-template <typename Type>
-inline const Type& GeneratedMessageReflection::DefaultRaw(
-    const FieldDescriptor* field) const {
-  return *reinterpret_cast<const Type*>(schema_.GetFieldDefault(field));
+inline bool
+GeneratedMessageReflection::GetIsDefaultInstance(
+    const Message& message) const {
+  if (is_default_instance_offset_ == kHasNoDefaultInstanceField) {
+    return false;
+  }
+  const void* ptr = reinterpret_cast<const uint8*>(&message) +
+      is_default_instance_offset_;
+  return *reinterpret_cast<const bool*>(ptr);
 }
 
 // Simple accessors for manipulating has_bits_.
 inline bool GeneratedMessageReflection::HasBit(
     const Message& message, const FieldDescriptor* field) const {
-  if (schema_.HasHasbits()) {
-    return IsIndexInHasBitSet(GetHasBits(message), schema_.HasBitIndex(field));
-  }
-
-  // proto3: no has-bits. All fields present except messages, which are
-  // present only if their message-field pointer is non-NULL.
-  if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
-    return !schema_.IsDefaultInstance(message) &&
-        GetRaw<const Message*>(message, field) != NULL;
-  } else {
-    // Non-message field (and non-oneof, since that was handled in HasField()
-    // before calling us), and singular (again, checked in HasField). So, this
-    // field must be a scalar.
-
-    // Scalar primitive (numeric or string/bytes) fields are present if
-    // their value is non-zero (numeric) or non-empty (string/bytes).  N.B.:
-    // we must use this definition here, rather than the "scalar fields
-    // always present" in the proto3 docs, because MergeFrom() semantics
-    // require presence as "present on wire", and reflection-based merge
-    // (which uses HasField()) needs to be consistent with this.
-    switch (field->cpp_type()) {
-      case FieldDescriptor::CPPTYPE_STRING:
-        switch (field->options().ctype()) {
-          default: {
-            return GetField<ArenaStringPtr>(message, field).Get().size() > 0;
+  if (has_bits_offset_ == -1) {
+    // proto3: no has-bits. All fields present except messages, which are
+    // present only if their message-field pointer is non-NULL.
+    if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+      return !GetIsDefaultInstance(message) &&
+          GetRaw<const Message*>(message, field) != NULL;
+    } else {
+      // Non-message field (and non-oneof, since that was handled in HasField()
+      // before calling us), and singular (again, checked in HasField). So, this
+      // field must be a scalar.
+
+      // Scalar primitive (numeric or string/bytes) fields are present if
+      // their value is non-zero (numeric) or non-empty (string/bytes).  N.B.:
+      // we must use this definition here, rather than the "scalar fields
+      // always present" in the proto3 docs, because MergeFrom() semantics
+      // require presence as "present on wire", and reflection-based merge
+      // (which uses HasField()) needs to be consistent with this.
+      switch (field->cpp_type()) {
+        case FieldDescriptor::CPPTYPE_STRING:
+          switch (field->options().ctype()) {
+            default: {
+              const string* default_ptr =
+                  &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
+              return GetField<ArenaStringPtr>(message, field).Get(
+                  default_ptr).size() > 0;
+            }
           }
-        }
-        return false;
-      case FieldDescriptor::CPPTYPE_BOOL:
-        return GetRaw<bool>(message, field) != false;
-      case FieldDescriptor::CPPTYPE_INT32:
-        return GetRaw<int32>(message, field) != 0;
-      case FieldDescriptor::CPPTYPE_INT64:
-        return GetRaw<int64>(message, field) != 0;
-      case FieldDescriptor::CPPTYPE_UINT32:
-        return GetRaw<uint32>(message, field) != 0;
-      case FieldDescriptor::CPPTYPE_UINT64:
-        return GetRaw<uint64>(message, field) != 0;
-      case FieldDescriptor::CPPTYPE_FLOAT:
-        return GetRaw<float>(message, field) != 0.0;
-      case FieldDescriptor::CPPTYPE_DOUBLE:
-        return GetRaw<double>(message, field) != 0.0;
-      case FieldDescriptor::CPPTYPE_ENUM:
-        return GetRaw<int>(message, field) != 0;
-      case FieldDescriptor::CPPTYPE_MESSAGE:
-        // handled above; avoid warning
-        break;
+          return false;
+        case FieldDescriptor::CPPTYPE_BOOL:
+          return GetRaw<bool>(message, field) != false;
+        case FieldDescriptor::CPPTYPE_INT32:
+          return GetRaw<int32>(message, field) != 0;
+        case FieldDescriptor::CPPTYPE_INT64:
+          return GetRaw<int64>(message, field) != 0;
+        case FieldDescriptor::CPPTYPE_UINT32:
+          return GetRaw<uint32>(message, field) != 0;
+        case FieldDescriptor::CPPTYPE_UINT64:
+          return GetRaw<uint64>(message, field) != 0;
+        case FieldDescriptor::CPPTYPE_FLOAT:
+          return GetRaw<float>(message, field) != 0.0;
+        case FieldDescriptor::CPPTYPE_DOUBLE:
+          return GetRaw<double>(message, field) != 0.0;
+        case FieldDescriptor::CPPTYPE_ENUM:
+          return GetRaw<int>(message, field) != 0;
+        case FieldDescriptor::CPPTYPE_MESSAGE:
+          // handled above; avoid warning
+          GOOGLE_LOG(FATAL) << "Reached impossible case in HasBit().";
+          break;
+      }
     }
-    GOOGLE_LOG(FATAL) << "Reached impossible case in HasBit().";
-    return false;
   }
+  return GetHasBits(message)[field->index() / 32] &
+    (1 << (field->index() % 32));
 }
 
 inline void GeneratedMessageReflection::SetBit(
     Message* message, const FieldDescriptor* field) const {
-  if (!schema_.HasHasbits()) {
+  if (has_bits_offset_ == -1) {
     return;
   }
-  const uint32 index = schema_.HasBitIndex(field);
-  MutableHasBits(message)[index / 32] |=
-      (static_cast<uint32>(1) << (index % 32));
+  MutableHasBits(message)[field->index() / 32] |= (1 << (field->index() % 32));
 }
 
 inline void GeneratedMessageReflection::ClearBit(
     Message* message, const FieldDescriptor* field) const {
-  if (!schema_.HasHasbits()) {
+  if (has_bits_offset_ == -1) {
     return;
   }
-  const uint32 index = schema_.HasBitIndex(field);
-  MutableHasBits(message)[index / 32] &=
-      ~(static_cast<uint32>(1) << (index % 32));
+  MutableHasBits(message)[field->index() / 32] &= ~(1 << (field->index() % 32));
 }
 
 inline void GeneratedMessageReflection::SwapBit(
     Message* message1, Message* message2, const FieldDescriptor* field) const {
-  if (!schema_.HasHasbits()) {
+  if (has_bits_offset_ == -1) {
     return;
   }
   bool temp_has_bit = HasBit(*message1, field);
@@ -2093,7 +2125,7 @@ inline void GeneratedMessageReflection::ClearOneofField(
 inline void GeneratedMessageReflection::ClearOneof(
     Message* message, const OneofDescriptor* oneof_descriptor) const {
   // TODO(jieluo): Consider to cache the unused object instead of deleting
-  // it. It will be much faster if an application switches a lot from
+  // it. It will be much faster if an aplication switches a lot from
   // a few oneof fields.  Time/space tradeoff
   uint32 oneof_case = GetOneofCase(*message, oneof_descriptor);
   if (oneof_case > 0) {
@@ -2105,7 +2137,7 @@ inline void GeneratedMessageReflection::ClearOneof(
             default:  // TODO(kenton):  Support other string reps.
             case FieldOptions::STRING: {
               const string* default_ptr =
-                  &DefaultRaw<ArenaStringPtr>(field).Get();
+                  &DefaultRaw<ArenaStringPtr>(field).Get(NULL);
               MutableField<ArenaStringPtr>(message, field)->
                   Destroy(default_ptr, GetArena(message));
               break;
@@ -2217,7 +2249,7 @@ void* GeneratedMessageReflection::RepeatedFieldData(
     return MutableExtensionSet(message)->MutableRawRepeatedField(
         field->number(), field->type(), field->is_packed(), field);
   } else {
-    return MutableRawNonOneof<char>(message, field);
+    return reinterpret_cast<uint8*>(message) + offsets_[field->index()];
   }
 }
 
@@ -2229,165 +2261,56 @@ MapFieldBase* GeneratedMessageReflection::MapData(
   return MutableRaw<MapFieldBase>(message, field);
 }
 
-namespace {
-
-// Helper function to transform migration schema into reflection schema.
-ReflectionSchema MigrationToReflectionSchema(
-    const DefaultInstanceData* default_instance_data, const uint32* offsets,
-    MigrationSchema migration_schema) {
-  ReflectionSchema result;
-  result.default_instance_ = default_instance_data->default_instance;
-  // First 5 offsets are offsets to the special fields. The following offsets
-  // are the proto fields.
-  result.offsets_ = offsets + migration_schema.offsets_index + 4;
-  result.has_bit_indices_ = offsets + migration_schema.has_bit_indices_index;
-  result.has_bits_offset_ = offsets[migration_schema.offsets_index + 0];
-  result.metadata_offset_ = offsets[migration_schema.offsets_index + 1];
-  result.extensions_offset_ = offsets[migration_schema.offsets_index + 2];
-  result.default_oneof_instance_ = default_instance_data->default_oneof_instance;
-  result.oneof_case_offset_ = offsets[migration_schema.offsets_index + 3];
-  result.object_size_ = migration_schema.object_size;
-  return result;
-}
-
-ReflectionSchema MigrationToReflectionSchema(
-    const DefaultInstanceData* default_instance_data, const uint32* offsets,
-    ReflectionSchema schema) {
-  return schema;
-}
-
-template<typename Schema>
-class AssignDescriptorsHelper {
- public:
-  AssignDescriptorsHelper(MessageFactory* factory,
-                          Metadata* file_level_metadata,
-                          const EnumDescriptor** file_level_enum_descriptors,
-                          const Schema* schemas,
-                          const DefaultInstanceData* default_instance_data,
-                          const uint32* offsets)
-      : factory_(factory),
-        file_level_metadata_(file_level_metadata),
-        file_level_enum_descriptors_(file_level_enum_descriptors),
-        schemas_(schemas),
-        default_instance_data_(default_instance_data),
-        offsets_(offsets) {}
-
-  void AssignMessageDescriptor(const Descriptor* descriptor) {
-    for (int i = 0; i < descriptor->nested_type_count(); i++) {
-      AssignMessageDescriptor(descriptor->nested_type(i));
-    }
-
-    file_level_metadata_->descriptor = descriptor;
-
-    if (!descriptor->options().map_entry()) {
-      // Only set reflection for non map types.
-      file_level_metadata_->reflection = new GeneratedMessageReflection(
-          descriptor, MigrationToReflectionSchema(default_instance_data_++,
-                                                  offsets_, *schemas_),
-          ::google::protobuf::DescriptorPool::generated_pool(), factory_);
-      for (int i = 0; i < descriptor->enum_type_count(); i++) {
-        AssignEnumDescriptor(descriptor->enum_type(i));
-      }
-      schemas_++;
-    }
-    file_level_metadata_++;
-  }
-
-  void AssignEnumDescriptor(const EnumDescriptor* descriptor) {
-    *file_level_enum_descriptors_ = descriptor;
-    file_level_enum_descriptors_++;
-  }
-
- private:
-  MessageFactory* factory_;
-  Metadata* file_level_metadata_;
-  const EnumDescriptor** file_level_enum_descriptors_;
-  const Schema* schemas_;
-  const DefaultInstanceData* default_instance_data_;
-  const uint32* offsets_;
-};
-
-}  // namespace
-
-void AssignDescriptors(
-    const string& filename, const MigrationSchema* schemas,
-    const DefaultInstanceData* default_instance_data, const uint32* offsets,
-    MessageFactory* factory,
-    // update the following descriptor arrays.
-    Metadata* file_level_metadata,
-    const EnumDescriptor** file_level_enum_descriptors,
-    const ServiceDescriptor** file_level_service_descriptors) {
-  const ::google::protobuf::FileDescriptor* file =
-      ::google::protobuf::DescriptorPool::generated_pool()->FindFileByName(filename);
-  GOOGLE_CHECK(file != NULL);
-
-  if (!factory) factory = MessageFactory::generated_factory();
-
-  AssignDescriptorsHelper<MigrationSchema> helper(factory, file_level_metadata,
-                                 file_level_enum_descriptors, schemas,
-                                 default_instance_data, offsets);
-
-  for (int i = 0; i < file->message_type_count(); i++) {
-    helper.AssignMessageDescriptor(file->message_type(i));
-  }
-
-  for (int i = 0; i < file->enum_type_count(); i++) {
-    helper.AssignEnumDescriptor(file->enum_type(i));
-  }
-  if (file->options().cc_generic_services()) {
-    for (int i = 0; i < file->service_count(); i++) {
-      file_level_service_descriptors[i] = file->service(i);
-    }
-  }
-}
-
-void AssignDescriptors(
-    const string& filename, const ReflectionSchema* schemas,
-    MessageFactory* factory,
-    // update the following descriptor arrays.
-    Metadata* file_level_metadata,
-    const EnumDescriptor** file_level_enum_descriptors,
-    const ServiceDescriptor** file_level_service_descriptors) {
-  const ::google::protobuf::FileDescriptor* file =
-      ::google::protobuf::DescriptorPool::generated_pool()->FindFileByName(filename);
-  GOOGLE_CHECK(file != NULL);
-
-  if (!factory) factory = MessageFactory::generated_factory();
-
-  AssignDescriptorsHelper<ReflectionSchema> helper(factory, file_level_metadata,
-                                 file_level_enum_descriptors, schemas,
-                                 NULL, NULL);
-
-  for (int i = 0; i < file->message_type_count(); i++) {
-    helper.AssignMessageDescriptor(file->message_type(i));
-  }
-
-  for (int i = 0; i < file->enum_type_count(); i++) {
-    helper.AssignEnumDescriptor(file->enum_type(i));
-  }
-  if (file->options().cc_generic_services()) {
-    for (int i = 0; i < file->service_count(); i++) {
-      file_level_service_descriptors[i] = file->service(i);
-    }
-  }
-}
-
-void RegisterAllTypesInternal(const Metadata* file_level_metadata, int size) {
-  for (int i = 0; i < size; i++) {
-    const GeneratedMessageReflection* reflection =
-        static_cast<const GeneratedMessageReflection*>(
-           file_level_metadata[i].reflection);
-    if (reflection) {
-      // It's not a map type
-      ::google::protobuf::MessageFactory::InternalRegisterGeneratedMessage(
-          file_level_metadata[i].descriptor,
-          reflection->schema_.default_instance_);
-    }
-  }
-}
-
-void RegisterAllTypes(const Metadata* file_level_metadata, int size) {
-  RegisterAllTypesInternal(file_level_metadata, size);
+GeneratedMessageReflection*
+GeneratedMessageReflection::NewGeneratedMessageReflection(
+    const Descriptor* descriptor,
+    const Message* default_instance,
+    const int offsets[],
+    int has_bits_offset,
+    int unknown_fields_offset,
+    int extensions_offset,
+    const void* default_oneof_instance,
+    int oneof_case_offset,
+    int object_size,
+    int arena_offset,
+    int is_default_instance_offset) {
+  return new GeneratedMessageReflection(descriptor,
+                                        default_instance,
+                                        offsets,
+                                        has_bits_offset,
+                                        unknown_fields_offset,
+                                        extensions_offset,
+                                        default_oneof_instance,
+                                        oneof_case_offset,
+                                        DescriptorPool::generated_pool(),
+                                        MessageFactory::generated_factory(),
+                                        object_size,
+                                        arena_offset,
+                                        is_default_instance_offset);
+}
+
+GeneratedMessageReflection*
+GeneratedMessageReflection::NewGeneratedMessageReflection(
+    const Descriptor* descriptor,
+    const Message* default_instance,
+    const int offsets[],
+    int has_bits_offset,
+    int unknown_fields_offset,
+    int extensions_offset,
+    int object_size,
+    int arena_offset,
+    int is_default_instance_offset) {
+  return new GeneratedMessageReflection(descriptor,
+                                        default_instance,
+                                        offsets,
+                                        has_bits_offset,
+                                        unknown_fields_offset,
+                                        extensions_offset,
+                                        DescriptorPool::generated_pool(),
+                                        MessageFactory::generated_factory(),
+                                        object_size,
+                                        arena_offset,
+                                        is_default_instance_offset);
 }
 
 }  // namespace internal