Shrink ObjC overhead (generated size and some runtime sizes)

NOTE: This is a binary breaking change as structure sizes have changed size
and/or order.

- Drop capturing field options, no other options were captured and other mobile
  targeted languages don't try to capture this sort information (saved 8
  bytes for every field defined (in static data and again in field descriptor
  instance size data).
- No longer generate/compile in the messages/enums in descriptor.proto. If
  developers need it, they should generate it and compile it in. Reduced the
  overhead of the core library.
- Compute the number of has_bits actually needs to avoid over reserving.
- Let the boolean single fields store via a has_bit to avoid storage, makes
  the common cases of the instance size smaller.
- Reorder some flags and down size the enums to contain the bits needed.
- Reorder the items in the structures to manually ensure they are are packed
  better (especially when generating 64bit code - 8 bytes for every field,
  16 bytes for every extension, instance sizes 8 bytes also).
- Split off the structure initialization so when the default is zero, the
  generated static storage doesn't need to reserve the space. This is batched
  at the message level, so all the fields for the message have to have zero
  defaults to get the saves. By definition all proto3 syntax  files fall into
  this case but it also saves space for the proto2 that use the standard
  defaults. (saves 8 bytes of static data for every field that had a zero
  default)
- Don't track the enums defined by a message. Nothing in the runtime needs it
  and it was just generation and runtime overhead. (saves 8 bytes per enum)
- Ensure EnumDescriptors are started up threadsafe in all cases.
- Split some of the Descriptor initialization into multiple methods so the
  generated code isn't padded with lots of zero/nil args.
- Change how oneof info is feed to the runtime enabling us to generate less
  static data (8 bytes saved per oneof for 64bit).
- Change how enum value informat is capture to pack the data and only decode
  it if it ends up being needed. Avoids padding issues causing bloat of 64bit,
  and removes the needs for extra pointers in addition to the data (just the
  data and one pointer now).

16 files changed, 357 insertions, 276 deletions

diff --git a/src/google/protobuf/compiler/objectivec/objectivec_enum.cc b/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
index 857d24a4..3f81dcb8 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
@@ -122,16 +122,6 @@ void EnumGenerator::GenerateSource(io::Printer* printer) {
       "\n",
       "name", name_);
 
-  printer->Print(
-      "GPBEnumDescriptor *$name$_EnumDescriptor(void) {\n"
-      "  static GPBEnumDescriptor *descriptor = NULL;\n"
-      "  if (!descriptor) {\n"
-      "    static GPBMessageEnumValueDescription values[] = {\n",
-      "name", name_);
-  printer->Indent();
-  printer->Indent();
-  printer->Indent();
-
   // Note: For the TextFormat decode info, we can't use the enum value as
   // the key because protocol buffer enums have 'allow_alias', which lets
   // a value be used more than once. Instead, the index into the list of
@@ -139,41 +129,66 @@ void EnumGenerator::GenerateSource(io::Printer* printer) {
   // will be zero.
   TextFormatDecodeData text_format_decode_data;
   int enum_value_description_key = -1;
+  string text_blob;
 
   for (int i = 0; i < all_values_.size(); i++) {
     ++enum_value_description_key;
     string short_name(EnumValueShortName(all_values_[i]));
-    printer->Print("{ .name = \"$short_name$\", .number = $name$ },\n",
-                   "short_name", short_name,
-                   "name", EnumValueName(all_values_[i]));
+    text_blob += short_name + '\0';
     if (UnCamelCaseEnumShortName(short_name) != all_values_[i]->name()) {
       text_format_decode_data.AddString(enum_value_description_key, short_name,
                                         all_values_[i]->name());
     }
   }
-  printer->Outdent();
-  printer->Outdent();
-  printer->Outdent();
+
+  printer->Print(
+      "GPBEnumDescriptor *$name$_EnumDescriptor(void) {\n"
+      "  static GPBEnumDescriptor *descriptor = NULL;\n"
+      "  if (!descriptor) {\n",
+      "name", name_);
+
+  static const int kBytesPerLine = 40;  // allow for escaping
+  printer->Print(
+      "    static const char *valueNames =");
+  for (int i = 0; i < text_blob.size(); i += kBytesPerLine) {
+    printer->Print(
+        "\n        \"$data$\"",
+        "data", EscapeTrigraphs(CEscape(text_blob.substr(i, kBytesPerLine))));
+  }
+  printer->Print(
+      ";\n"
+      "    static const int32_t values[] = {\n");
+  for (int i = 0; i < all_values_.size(); i++) {
+    printer->Print("        $name$,\n",  "name", EnumValueName(all_values_[i]));
+  }
   printer->Print("    };\n");
+
   if (text_format_decode_data.num_entries() == 0) {
     printer->Print(
-        "    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
-        "                                                   values:values\n"
-        "                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)\n"
-        "                                             enumVerifier:$name$_IsValidValue];\n",
+        "    GPBEnumDescriptor *worker =\n"
+        "        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
+        "                                       valueNames:valueNames\n"
+        "                                           values:values\n"
+        "                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))\n"
+        "                                     enumVerifier:$name$_IsValidValue];\n",
         "name", name_);
     } else {
       printer->Print(
         "    static const char *extraTextFormatInfo = \"$extraTextFormatInfo$\";\n"
-        "    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
-        "                                                   values:values\n"
-        "                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)\n"
-        "                                             enumVerifier:$name$_IsValidValue\n"
-        "                                      extraTextFormatInfo:extraTextFormatInfo];\n",
+        "    GPBEnumDescriptor *worker =\n"
+        "        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
+        "                                       valueNames:valueNames\n"
+        "                                           values:values\n"
+        "                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))\n"
+        "                                     enumVerifier:$name$_IsValidValue\n"
+        "                              extraTextFormatInfo:extraTextFormatInfo];\n",
         "name", name_,
         "extraTextFormatInfo", CEscape(text_format_decode_data.Data()));
     }
     printer->Print(
+      "    if (!OSAtomicCompareAndSwapPtrBarrier(nil, worker, (void * volatile *)&descriptor)) {\n"
+      "      [worker release];\n"
+      "    }\n"
       "  }\n"
       "  return descriptor;\n"
       "}\n\n");
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc b/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
index cfbb8c52..b63bc0de 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
@@ -59,6 +59,9 @@ void SetEnumVariables(const FieldDescriptor* descriptor,
   (*variables)["enum_verifier"] = type + "_IsValidValue";
   (*variables)["enum_desc_func"] = type + "_EnumDescriptor";
 
+  (*variables)["dataTypeSpecific_name"] = "enumDescFunc";
+  (*variables)["dataTypeSpecific_value"] = (*variables)["enum_desc_func"];
+
   const Descriptor* msg_descriptor = descriptor->containing_type();
   (*variables)["owning_message_class"] = ClassName(msg_descriptor);
 }
@@ -72,13 +75,6 @@ EnumFieldGenerator::EnumFieldGenerator(const FieldDescriptor* descriptor,
 
 EnumFieldGenerator::~EnumFieldGenerator() {}
 
-void EnumFieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "  .dataTypeSpecific.enumDescFunc = $enum_desc_func$,\n");
-}
-
 void EnumFieldGenerator::GenerateCFunctionDeclarations(
     io::Printer* printer) const {
   if (!HasPreservingUnknownEnumSemantics(descriptor_->file())) {
@@ -145,13 +141,6 @@ void RepeatedEnumFieldGenerator::FinishInitialization(void) {
       "// |" + variables_["name"] + "| contains |" + variables_["storage_type"] + "|\n";
 }
 
-void RepeatedEnumFieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "  .dataTypeSpecific.enumDescFunc = $enum_desc_func$,\n");
-}
-
 }  // namespace objectivec
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_enum_field.h b/src/google/protobuf/compiler/objectivec/objectivec_enum_field.h
index ae2f57e3..946faa81 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_enum_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_enum_field.h
@@ -45,7 +45,6 @@ class EnumFieldGenerator : public SingleFieldGenerator {
                                               const Options& options);
 
  public:
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;
   virtual void GenerateCFunctionDeclarations(io::Printer* printer) const;
   virtual void GenerateCFunctionImplementations(io::Printer* printer) const;
   virtual void DetermineForwardDeclarations(set<string>* fwd_decls) const;
@@ -64,7 +63,6 @@ class RepeatedEnumFieldGenerator : public RepeatedFieldGenerator {
 
  public:
   virtual void FinishInitialization();
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;
 
  protected:
   RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor,
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_extension.cc b/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
index 4e348393..3f7ab9d3 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
@@ -114,14 +114,14 @@ void ExtensionGenerator::GenerateStaticVariablesInitialization(
 
   printer->Print(vars,
                  "{\n"
+                 "  .defaultValue.$default_name$ = $default$,\n"
                  "  .singletonName = GPBStringifySymbol($root_class_and_method_name$),\n"
-                 "  .dataType = $extension_type$,\n"
                  "  .extendedClass = GPBStringifySymbol($extended_type$),\n"
-                 "  .fieldNumber = $number$,\n"
-                 "  .defaultValue.$default_name$ = $default$,\n"
                  "  .messageOrGroupClassName = $type$,\n"
-                 "  .options = $options$,\n"
                  "  .enumDescriptorFunc = $enum_desc_func_name$,\n"
+                 "  .fieldNumber = $number$,\n"
+                 "  .dataType = $extension_type$,\n"
+                 "  .options = $options$,\n"
                  "},\n");
 }
 
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_field.cc b/src/google/protobuf/compiler/objectivec/objectivec_field.cc
index 8697e225..7bb9837d 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_field.cc
@@ -28,6 +28,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include <iostream>
+
 #include <google/protobuf/compiler/objectivec/objectivec_field.h>
 #include <google/protobuf/compiler/objectivec/objectivec_helpers.h>
 #include <google/protobuf/compiler/objectivec/objectivec_enum_field.h>
@@ -75,7 +77,6 @@ void SetCommonFieldVariables(const FieldDescriptor* descriptor,
   (*variables)["field_number_name"] =
       classname + "_FieldNumber_" + capitalized_name;
   (*variables)["field_number"] = SimpleItoa(descriptor->number());
-  (*variables)["has_index"] = SimpleItoa(descriptor->index());
   (*variables)["field_type"] = GetCapitalizedType(descriptor);
   std::vector<string> field_flags;
   if (descriptor->is_repeated()) field_flags.push_back("GPBFieldRepeated");
@@ -99,18 +100,9 @@ void SetCommonFieldVariables(const FieldDescriptor* descriptor,
   (*variables)["dataTypeSpecific_name"] = "className";
   (*variables)["dataTypeSpecific_value"] = "NULL";
 
-  string field_options = descriptor->options().SerializeAsString();
-  // Must convert to a standard byte order for packing length into
-  // a cstring.
-  uint32 length = ghtonl(field_options.length());
-  if (length > 0) {
-    string bytes((const char*)&length, sizeof(length));
-    bytes.append(field_options);
-    string options_str = "\"" + CEscape(bytes) + "\"";
-    (*variables)["fieldoptions"] = "\"" + CEscape(bytes) + "\"";
-  } else {
-    (*variables)["fieldoptions"] = "";
-  }
+  (*variables)["storage_offset_value"] =
+      "(uint32_t)offsetof(" + classname + "__storage_, " + camel_case_name + ")";
+  (*variables)["storage_offset_comment"] = "";
 
   // Clear some common things so they can be set just when needed.
   (*variables)["storage_attribute"] = "";
@@ -190,52 +182,54 @@ void FieldGenerator::DetermineForwardDeclarations(
 }
 
 void FieldGenerator::GenerateFieldDescription(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "{\n"
-      "  .name = \"$name$\",\n"
-      "  .number = $field_number_name$,\n"
-      "  .hasIndex = $has_index$,\n"
-      "  .flags = $fieldflags$,\n"
-      "  .dataType = GPBDataType$field_type$,\n"
-      "  .offset = offsetof($classname$__storage_, $name$),\n"
-      "  .defaultValue.$default_name$ = $default$,\n");
-
-  // TODO(thomasvl): It might be useful to add a CPP wrapper to support
-  // compiling away the EnumDescriptors.  To do that, we'd need a #if here
-  // to control setting the descriptor vs. the validator, and above in
-  // SetCommonFieldVariables() we'd want to wrap how we add
-  // GPBFieldHasDefaultValue to the flags.
-
-  // "  .dataTypeSpecific.value* = [something],"
-  GenerateFieldDescriptionTypeSpecific(printer);
-
-  const string& field_options(variables_.find("fieldoptions")->second);
-  if (field_options.empty()) {
-    printer->Print("  .fieldOptions = NULL,\n");
+    io::Printer* printer, bool include_default) const {
+  // Printed in the same order as the structure decl.
+  if (include_default) {
+    printer->Print(
+        variables_,
+        "{\n"
+        "  .defaultValue.$default_name$ = $default$,\n"
+        "  .core.name = \"$name$\",\n"
+        "  .core.dataTypeSpecific.$dataTypeSpecific_name$ = $dataTypeSpecific_value$,\n"
+        "  .core.number = $field_number_name$,\n"
+        "  .core.hasIndex = $has_index$,\n"
+        "  .core.offset = $storage_offset_value$,$storage_offset_comment$\n"
+        "  .core.flags = $fieldflags$,\n"
+        "  .core.dataType = GPBDataType$field_type$,\n"
+        "},\n");
   } else {
-    // Can't use PrintRaw() here to get the #if/#else/#endif lines completely
-    // outdented because the need for indent captured on the previous
-    // printing of a \n and there is no way to get the current indent level
-    // to call the right number of Outdent()/Indents() to maintain state.
     printer->Print(
         variables_,
-        "#if GPBOBJC_INCLUDE_FIELD_OPTIONS\n"
-        "  .fieldOptions = $fieldoptions$,\n"
-        "#else\n"
-        "  .fieldOptions = NULL,\n"
-        "#endif  // GPBOBJC_INCLUDE_FIELD_OPTIONS\n");
+        "{\n"
+        "  .name = \"$name$\",\n"
+        "  .dataTypeSpecific.$dataTypeSpecific_name$ = $dataTypeSpecific_value$,\n"
+        "  .number = $field_number_name$,\n"
+        "  .hasIndex = $has_index$,\n"
+        "  .offset = $storage_offset_value$,$storage_offset_comment$\n"
+        "  .flags = $fieldflags$,\n"
+        "  .dataType = GPBDataType$field_type$,\n"
+        "},\n");
   }
+}
 
-  printer->Print("},\n");
+void FieldGenerator::SetRuntimeHasBit(int has_index) {
+  variables_["has_index"] = SimpleItoa(has_index);
 }
 
-void FieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "  .dataTypeSpecific.$dataTypeSpecific_name$ = $dataTypeSpecific_value$,\n");
+void FieldGenerator::SetNoHasBit(void) {
+  variables_["has_index"] = "GPBNoHasBit";
+}
+
+int FieldGenerator::ExtraRuntimeHasBitsNeeded(void) const {
+  return 0;
+}
+
+void FieldGenerator::SetExtraRuntimeHasBitsBase(int index_base) {
+  // NOTE: src/google/protobuf/compiler/plugin.cc makes use of cerr for some
+  // error cases, so it seems to be ok to use as a back door for errors.
+  cerr << "Error: should have overriden SetExtraRuntimeHasBitsBase()." << endl;
+  cerr.flush();
+  abort();
 }
 
 void FieldGenerator::SetOneofIndexBase(int index_base) {
@@ -302,6 +296,14 @@ bool SingleFieldGenerator::WantsHasProperty(void) const {
   return false;
 }
 
+bool SingleFieldGenerator::RuntimeUsesHasBit(void) const {
+  if (descriptor_->containing_oneof() != NULL) {
+    // The oneof tracks what is set instead.
+    return false;
+  }
+  return true;
+}
+
 ObjCObjFieldGenerator::ObjCObjFieldGenerator(const FieldDescriptor* descriptor,
                                              const Options& options)
     : SingleFieldGenerator(descriptor, options) {
@@ -347,8 +349,6 @@ void ObjCObjFieldGenerator::GeneratePropertyDeclaration(
 RepeatedFieldGenerator::RepeatedFieldGenerator(
     const FieldDescriptor* descriptor, const Options& options)
     : ObjCObjFieldGenerator(descriptor, options) {
-  // Repeated fields don't use the has index.
-  variables_["has_index"] = "GPBNoHasBit";
   // Default to no comment and let the cases needing it fill it in.
   variables_["array_comment"] = "";
 }
@@ -402,6 +402,10 @@ bool RepeatedFieldGenerator::WantsHasProperty(void) const {
   return false;
 }
 
+bool RepeatedFieldGenerator::RuntimeUsesHasBit(void) const {
+  return false;  // The array having anything is what is used.
+}
+
 FieldGeneratorMap::FieldGeneratorMap(const Descriptor* descriptor,
                                      const Options& options)
     : descriptor_(descriptor),
@@ -432,12 +436,40 @@ const FieldGenerator& FieldGeneratorMap::get_extension(int index) const {
   return *extension_generators_[index];
 }
 
+int FieldGeneratorMap::CalculateHasBits(void) {
+  int total_bits = 0;
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    if (field_generators_[i]->RuntimeUsesHasBit()) {
+      field_generators_[i]->SetRuntimeHasBit(total_bits);
+      ++total_bits;
+    } else {
+      field_generators_[i]->SetNoHasBit();
+    }
+    int extra_bits = field_generators_[i]->ExtraRuntimeHasBitsNeeded();
+    if (extra_bits) {
+      field_generators_[i]->SetExtraRuntimeHasBitsBase(total_bits);
+      total_bits += extra_bits;
+    }
+  }
+  return total_bits;
+}
+
 void FieldGeneratorMap::SetOneofIndexBase(int index_base) {
   for (int i = 0; i < descriptor_->field_count(); i++) {
     field_generators_[i]->SetOneofIndexBase(index_base);
   }
 }
 
+bool FieldGeneratorMap::DoesAnyFieldHaveNonZeroDefault(void) const {
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    if (HasNonZeroDefaultValue(descriptor_->field(i))) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 }  // namespace objectivec
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_field.h b/src/google/protobuf/compiler/objectivec/objectivec_field.h
index e8a20a72..a3a4b1b6 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_field.h
@@ -61,7 +61,6 @@ class FieldGenerator {
 
   // Called by GenerateFieldDescription, exposed for classes that need custom
   // generation.
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;
 
   // Exposed for subclasses to extend, base does nothing.
   virtual void GenerateCFunctionDeclarations(io::Printer* printer) const;
@@ -71,9 +70,16 @@ class FieldGenerator {
   virtual void DetermineForwardDeclarations(set<string>* fwd_decls) const;
 
   // Used during generation, not intended to be extended by subclasses.
-  void GenerateFieldDescription(io::Printer* printer) const;
+  void GenerateFieldDescription(
+      io::Printer* printer, bool include_default) const;
   void GenerateFieldNumberConstant(io::Printer* printer) const;
 
+  // Exposed to get and set the has bits information.
+  virtual bool RuntimeUsesHasBit(void) const = 0;
+  void SetRuntimeHasBit(int has_index);
+  void SetNoHasBit(void);
+  virtual int ExtraRuntimeHasBitsNeeded(void) const;
+  virtual void SetExtraRuntimeHasBitsBase(int index_base);
   void SetOneofIndexBase(int index_base);
 
   string variable(const char* key) const {
@@ -109,6 +115,8 @@ class SingleFieldGenerator : public FieldGenerator {
 
   virtual void GeneratePropertyImplementation(io::Printer* printer) const;
 
+  virtual bool RuntimeUsesHasBit(void) const;
+
  protected:
   SingleFieldGenerator(const FieldDescriptor* descriptor,
                        const Options& options);
@@ -143,6 +151,8 @@ class RepeatedFieldGenerator : public ObjCObjFieldGenerator {
 
   virtual void GeneratePropertyImplementation(io::Printer* printer) const;
 
+  virtual bool RuntimeUsesHasBit(void) const;
+
  protected:
   RepeatedFieldGenerator(const FieldDescriptor* descriptor,
                          const Options& options);
@@ -162,8 +172,14 @@ class FieldGeneratorMap {
   const FieldGenerator& get(const FieldDescriptor* field) const;
   const FieldGenerator& get_extension(int index) const;
 
+  // Assigns the has bits and returns the number of bits needed.
+  int CalculateHasBits(void);
+
   void SetOneofIndexBase(int index_base);
 
+  // Check if any field of this message has a non zero default.
+  bool DoesAnyFieldHaveNonZeroDefault(void) const;
+
  private:
   const Descriptor* descriptor_;
   scoped_array<scoped_ptr<FieldGenerator> > field_generators_;
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_file.cc b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
index 16199884..c58e7530 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_file.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
@@ -45,7 +45,7 @@ namespace protobuf {
 // This is also found in GPBBootstrap.h, and needs to be kept in sync.  It
 // is the version check done to ensure generated code works with the current
 // runtime being used.
-const int32 GOOGLE_PROTOBUF_OBJC_GEN_VERSION = 30000;
+const int32 GOOGLE_PROTOBUF_OBJC_GEN_VERSION = 30001;
 
 namespace compiler {
 namespace objectivec {
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc b/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
index b912ea67..fda51807 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
@@ -220,11 +220,6 @@ string NameFromFieldDescriptor(const FieldDescriptor* field) {
   }
 }
 
-// Escape C++ trigraphs by escaping question marks to \?
-string EscapeTrigraphs(const string& to_escape) {
-  return StringReplace(to_escape, "?", "\\?", true);
-}
-
 void PathSplit(const string& path, string* directory, string* basename) {
   string::size_type last_slash = path.rfind('/');
   if (last_slash == string::npos) {
@@ -264,6 +259,11 @@ bool IsSpecialName(const string& name, const string* special_names,
 
 }  // namespace
 
+// Escape C++ trigraphs by escaping question marks to \?
+string EscapeTrigraphs(const string& to_escape) {
+  return StringReplace(to_escape, "?", "\\?", true);
+}
+
 string StripProto(const string& filename) {
   if (HasSuffixString(filename, ".protodevel")) {
     return StripSuffixString(filename, ".protodevel");
@@ -734,7 +734,7 @@ string DefaultValue(const FieldDescriptor* field) {
         uint32 length = ghtonl(default_string.length());
         string bytes((const char*)&length, sizeof(length));
         bytes.append(default_string);
-        return "(NSData*)\"" + CEscape(bytes) + "\"";
+        return "(NSData*)\"" + EscapeTrigraphs(CEscape(bytes)) + "\"";
       } else {
         return "@\"" + EscapeTrigraphs(CEscape(default_string)) + "\"";
       }
@@ -751,6 +751,50 @@ string DefaultValue(const FieldDescriptor* field) {
   return NULL;
 }
 
+bool HasNonZeroDefaultValue(const FieldDescriptor* field) {
+  // Repeated fields don't have defaults.
+  if (field->is_repeated()) {
+    return false;
+  }
+
+  if (!field->has_default_value()) {
+    // No custom default set in the proto file.
+    return false;
+  }
+
+  // Some proto file set the default to the zero value, so make sure the value
+  // isn't the zero case.
+  switch (field->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32:
+      return field->default_value_int32() != 0;
+    case FieldDescriptor::CPPTYPE_UINT32:
+      return field->default_value_uint32() != 0U;
+    case FieldDescriptor::CPPTYPE_INT64:
+      return field->default_value_int64() != 0LL;
+    case FieldDescriptor::CPPTYPE_UINT64:
+      return field->default_value_uint64() != 0ULL;
+    case FieldDescriptor::CPPTYPE_DOUBLE:
+      return field->default_value_double() != 0.0;
+    case FieldDescriptor::CPPTYPE_FLOAT:
+      return field->default_value_float() != 0.0f;
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return field->default_value_bool();
+    case FieldDescriptor::CPPTYPE_STRING: {
+      const string& default_string = field->default_value_string();
+      return default_string.length() != 0;
+    }
+    case FieldDescriptor::CPPTYPE_ENUM:
+      return field->default_value_enum()->number() != 0;
+    case FieldDescriptor::CPPTYPE_MESSAGE:
+      return false;
+  }
+
+  // Some compilers report reaching end of function even though all cases of
+  // the enum are handed in the switch.
+  GOOGLE_LOG(FATAL) << "Can't get here.";
+  return false;
+}
+
 string BuildFlagsString(const vector<string>& strings) {
   if (strings.size() == 0) {
     return "0";
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_helpers.h b/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
index a301493e..0db9de94 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
@@ -48,6 +48,9 @@ struct Options {
   string expected_prefixes_path;
 };
 
+// Escape C++ trigraphs by escaping question marks to "\?".
+string EscapeTrigraphs(const string& to_escape);
+
 // Strips ".proto" or ".protodevel" from the end of a filename.
 string StripProto(const string& filename);
 
@@ -143,6 +146,7 @@ bool IsReferenceType(const FieldDescriptor* field);
 
 string GPBGenericValueFieldName(const FieldDescriptor* field);
 string DefaultValue(const FieldDescriptor* field);
+bool HasNonZeroDefaultValue(const FieldDescriptor* field);
 
 string BuildFlagsString(const vector<string>& strings);
 
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_map_field.cc b/src/google/protobuf/compiler/objectivec/objectivec_map_field.cc
index 2751e936..ac5d8aea 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_map_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_map_field.cc
@@ -140,13 +140,18 @@ MapFieldGenerator::MapFieldGenerator(const FieldDescriptor* descriptor,
           value_field_generator_->variable("storage_type") + "*>";
     }
   }
+
+  variables_["dataTypeSpecific_name"] =
+      value_field_generator_->variable("dataTypeSpecific_name");
+  variables_["dataTypeSpecific_value"] =
+      value_field_generator_->variable("dataTypeSpecific_value");
 }
 
 MapFieldGenerator::~MapFieldGenerator() {}
 
 void MapFieldGenerator::FinishInitialization(void) {
   RepeatedFieldGenerator::FinishInitialization();
-  // Use the array_comment suport in RepeatedFieldGenerator to output what the
+  // Use the array_comment support in RepeatedFieldGenerator to output what the
   // values in the map are.
   const FieldDescriptor* value_descriptor =
       descriptor_->message_type()->FindFieldByName("value");
@@ -156,13 +161,6 @@ void MapFieldGenerator::FinishInitialization(void) {
   }
 }
 
-void MapFieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  // Relay it to the value generator to provide enum validator, message
-  // class, etc.
-  value_field_generator_->GenerateFieldDescriptionTypeSpecific(printer);
-}
-
 void MapFieldGenerator::DetermineForwardDeclarations(
     set<string>* fwd_decls) const {
   RepeatedFieldGenerator::DetermineForwardDeclarations(fwd_decls);
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_map_field.h b/src/google/protobuf/compiler/objectivec/objectivec_map_field.h
index 7351ea05..bc68a682 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_map_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_map_field.h
@@ -46,7 +46,6 @@ class MapFieldGenerator : public RepeatedFieldGenerator {
 
  public:
   virtual void FinishInitialization(void);
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;
 
  protected:
   MapFieldGenerator(const FieldDescriptor* descriptor, const Options& options);
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_message.cc b/src/google/protobuf/compiler/objectivec/objectivec_message.cc
index e0ea8bd2..3ebeeade 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_message.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_message.cc
@@ -66,11 +66,12 @@ int OrderGroupForFieldDescriptor(const FieldDescriptor* descriptor) {
   // The first item in the object structure is our uint32[] for has bits.
   // We then want to order things to make the instances as small as
   // possible. So we follow the has bits with:
-  //   1. Bools (1 byte)
-  //   2. Anything always 4 bytes - float, *32, enums
-  //   3. Anything that is always a pointer (they will be 8 bytes on 64 bit
+  //   1. Anything always 4 bytes - float, *32, enums
+  //   2. Anything that is always a pointer (they will be 8 bytes on 64 bit
   //      builds and 4 bytes on 32bit builds.
-  //   4. Anything always 8 bytes - double, *64
+  //   3. Anything always 8 bytes - double, *64
+  //
+  // NOTE: Bools aren't listed, they were stored in the has bits.
   //
   // Why? Using 64bit builds as an example, this means worse case, we have
   // enough bools that we overflow 1 byte from 4 byte alignment, so 3 bytes
@@ -115,9 +116,9 @@ int OrderGroupForFieldDescriptor(const FieldDescriptor* descriptor) {
     case FieldDescriptor::TYPE_ENUM:
       return 2;
 
-    // 1 byte.
+    // 0 bytes. Stored in the has bits.
     case FieldDescriptor::TYPE_BOOL:
-      return 1;
+      return 99;  // End of the list (doesn't really matter).
   }
 
   // Some compilers report reaching end of function even though all cases of
@@ -404,32 +405,28 @@ void MessageGenerator::GenerateSource(io::Printer* printer) {
     sort(sorted_extensions.begin(), sorted_extensions.end(),
          ExtensionRangeOrdering());
 
-    // TODO(thomasvl): Finish optimizing has bit. The current behavior is as
-    // follows:
-    // 1. objectivec_field.cc's SetCommonFieldVariables() defaults the has_index
-    //    to the field's index in the list of fields.
-    // 2. RepeatedFieldGenerator::RepeatedFieldGenerator() sets has_index to
-    //    GPBNoHasBit because repeated fields & map<> fields don't use the has
-    //    bit.
-    // 3. FieldGenerator::SetOneofIndexBase() overrides has_bit with a negative
-    //    index that groups all the elements on of the oneof.
-    // So in has_storage, we need enough bits for the single fields that aren't
-    // in any oneof, and then one int32 for each oneof (to store the field
-    // number).  So we could save a little space by not using the field's index
-    // and instead make a second pass only assigning indexes for the fields
-    // that would need it.  The only savings would come when messages have over
-    // a multiple of 32 fields with some number being repeated or in oneofs to
-    // drop the count below that 32 multiple; so it hasn't seemed worth doing
-    // at the moment.
-    size_t num_has_bits = descriptor_->field_count();
+    // Assign has bits:
+    // 1. FieldGeneratorMap::CalculateHasBits() loops through the fields seeing
+    //    who needs has bits and assigning them.
+    // 2. FieldGenerator::SetOneofIndexBase() overrides has_bit with a negative
+    //    index that groups all the elements in the oneof.
+    size_t num_has_bits = field_generators_.CalculateHasBits();
     size_t sizeof_has_storage = (num_has_bits + 31) / 32;
+    if (sizeof_has_storage == 0) {
+      // In the case where no field needs has bits, don't let the _has_storage_
+      // end up as zero length (zero length arrays are sort of a grey area
+      // since it has to be at the start of the struct). This also ensures a
+      // field with only oneofs keeps the required negative indices they need.
+      sizeof_has_storage = 1;
+    }
     // Tell all the fields the oneof base.
     for (vector<OneofGenerator*>::iterator iter = oneof_generators_.begin();
          iter != oneof_generators_.end(); ++iter) {
       (*iter)->SetOneofIndexBase(sizeof_has_storage);
     }
     field_generators_.SetOneofIndexBase(sizeof_has_storage);
-    // Add an int32 for each oneof to store which is set.
+    // sizeof_has_storage needs enough bits for the single fields that aren't in
+    // any oneof, and then one int32 for each oneof (to store the field number).
     sizeof_has_storage += descriptor_->oneof_decl_count();
 
     printer->Print(
@@ -456,47 +453,26 @@ void MessageGenerator::GenerateSource(io::Printer* printer) {
         "  static GPBDescriptor *descriptor = nil;\n"
         "  if (!descriptor) {\n");
 
-    bool has_oneofs = oneof_generators_.size();
-    if (has_oneofs) {
-      printer->Print(
-          "    static GPBMessageOneofDescription oneofs[] = {\n");
-      printer->Indent();
-      printer->Indent();
-      printer->Indent();
-      for (vector<OneofGenerator*>::iterator iter = oneof_generators_.begin();
-           iter != oneof_generators_.end(); ++iter) {
-        (*iter)->GenerateDescription(printer);
-      }
-      printer->Outdent();
-      printer->Outdent();
-      printer->Outdent();
-      printer->Print(
-          "    };\n");
-    }
-
     TextFormatDecodeData text_format_decode_data;
     bool has_fields = descriptor_->field_count() > 0;
+    bool need_defaults = field_generators_.DoesAnyFieldHaveNonZeroDefault();
+    string field_description_type;
+    if (need_defaults) {
+      field_description_type = "GPBMessageFieldDescriptionWithDefault";
+    } else {
+      field_description_type = "GPBMessageFieldDescription";
+    }
     if (has_fields) {
-      // TODO(thomasvl): The plugin's FieldGenerator::GenerateFieldDescription()
-      // wraps the fieldOptions's value of this structure in an CPP gate so
-      // they can be compiled away; but that still results in a const char* in
-      // the structure for a NULL pointer for every message field.  If the
-      // fieldOptions are moved to a separate payload like the TextFormat extra
-      // data is, then it would shrink that static data shrinking the binaries
-      // a little more.
-      // TODO(thomasvl): proto3 syntax doens't need a defaultValue in the
-      // structure because primitive types are always zero.  If we add a second
-      // structure and a different initializer, we can avoid the wasted static
-      // storage for every field in a proto3 message.
       printer->Print(
-          "    static GPBMessageFieldDescription fields[] = {\n");
+          "    static $field_description_type$ fields[] = {\n",
+          "field_description_type", field_description_type);
       printer->Indent();
       printer->Indent();
       printer->Indent();
       for (int i = 0; i < descriptor_->field_count(); ++i) {
         const FieldGenerator& field_generator =
             field_generators_.get(sorted_fields[i]);
-        field_generator.GenerateFieldDescription(printer);
+        field_generator.GenerateFieldDescription(printer, need_defaults);
         if (field_generator.needs_textformat_name_support()) {
           text_format_decode_data.AddString(sorted_fields[i]->number(),
                                             field_generator.generated_objc_name(),
@@ -510,111 +486,89 @@ void MessageGenerator::GenerateSource(io::Printer* printer) {
           "    };\n");
     }
 
-    bool has_enums = enum_generators_.size();
-    if (has_enums) {
+    map<string, string> vars;
+    vars["classname"] = class_name_;
+    vars["rootclassname"] = root_classname_;
+    vars["fields"] = has_fields ? "fields" : "NULL";
+    if (has_fields) {
+      vars["fields_count"] =
+          "(uint32_t)(sizeof(fields) / sizeof(" + field_description_type + "))";
+    } else {
+      vars["fields_count"] = "0";
+    }
+
+    std::vector<string> init_flags;
+    if (need_defaults) {
+      init_flags.push_back("GPBDescriptorInitializationFlag_FieldsWithDefault");
+    }
+    if (descriptor_->options().message_set_wire_format()) {
+      init_flags.push_back("GPBDescriptorInitializationFlag_WireFormat");
+    }
+    vars["init_flags"] = BuildFlagsString(init_flags);
+
+    printer->Print(
+        vars,
+        "    GPBDescriptor *localDescriptor =\n"
+        "        [GPBDescriptor allocDescriptorForClass:[$classname$ class]\n"
+        "                                     rootClass:[$rootclassname$ class]\n"
+        "                                          file:$rootclassname$_FileDescriptor()\n"
+        "                                        fields:$fields$\n"
+        "                                    fieldCount:$fields_count$\n"
+        "                                   storageSize:sizeof($classname$__storage_)\n"
+        "                                         flags:$init_flags$];\n");
+    if (oneof_generators_.size() != 0) {
       printer->Print(
-          "    static GPBMessageEnumDescription enums[] = {\n");
-      printer->Indent();
-      printer->Indent();
-      printer->Indent();
-      for (vector<EnumGenerator*>::iterator iter = enum_generators_.begin();
-           iter != enum_generators_.end(); ++iter) {
-        printer->Print("{ .enumDescriptorFunc = $name$_EnumDescriptor },\n",
-                       "name", (*iter)->name());
+          "    static const char *oneofs[] = {\n");
+      for (vector<OneofGenerator*>::iterator iter = oneof_generators_.begin();
+           iter != oneof_generators_.end(); ++iter) {
+        printer->Print(
+            "      \"$name$\",\n",
+            "name", (*iter)->DescriptorName());
       }
-      printer->Outdent();
-      printer->Outdent();
-      printer->Outdent();
       printer->Print(
-          "    };\n");
+          "    };\n"
+          "    [localDescriptor setupOneofs:oneofs\n"
+          "                           count:(uint32_t)(sizeof(oneofs) / sizeof(char*))\n"
+          "                   firstHasIndex:$first_has_index$];\n",
+          "first_has_index", oneof_generators_[0]->HasIndexAsString());
     }
-
-    bool has_extensions = sorted_extensions.size();
-    if (has_extensions) {
+    if (text_format_decode_data.num_entries() != 0) {
+      const string text_format_data_str(text_format_decode_data.Data());
       printer->Print(
-          "    static GPBExtensionRange ranges[] = {\n");
-      printer->Indent();
-      printer->Indent();
-      printer->Indent();
-      for (int i = 0; i < sorted_extensions.size(); i++) {
-        printer->Print("{ .start = $start$, .end = $end$ },\n",
-                       "start", SimpleItoa(sorted_extensions[i]->start),
-                       "end", SimpleItoa(sorted_extensions[i]->end));
+          "#if !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n"
+          "    static const char *extraTextFormatInfo =");
+      static const int kBytesPerLine = 40;  // allow for escaping
+      for (int i = 0; i < text_format_data_str.size(); i += kBytesPerLine) {
+        printer->Print(
+            "\n        \"$data$\"",
+            "data", EscapeTrigraphs(
+                CEscape(text_format_data_str.substr(i, kBytesPerLine))));
       }
-      printer->Outdent();
-      printer->Outdent();
-      printer->Outdent();
       printer->Print(
-          "    };\n");
+          ";\n"
+          "    [localDescriptor setupExtraTextInfo:extraTextFormatInfo];\n"
+          "#endif  // !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n");
     }
-
-    map<string, string> vars;
-    vars["classname"] = class_name_;
-    vars["rootclassname"] = root_classname_;
-    vars["fields"] = has_fields ? "fields" : "NULL";
-    vars["fields_count"] =
-        has_fields ? "sizeof(fields) / sizeof(GPBMessageFieldDescription)" : "0";
-    vars["oneofs"] = has_oneofs ? "oneofs" : "NULL";
-    vars["oneof_count"] =
-        has_oneofs ? "sizeof(oneofs) / sizeof(GPBMessageOneofDescription)" : "0";
-    vars["enums"] = has_enums ? "enums" : "NULL";
-    vars["enum_count"] =
-        has_enums ? "sizeof(enums) / sizeof(GPBMessageEnumDescription)" : "0";
-    vars["ranges"] = has_extensions ? "ranges" : "NULL";
-    vars["range_count"] =
-        has_extensions ? "sizeof(ranges) / sizeof(GPBExtensionRange)" : "0";
-    vars["wireformat"] =
-        descriptor_->options().message_set_wire_format() ? "YES" : "NO";
-
-    if (text_format_decode_data.num_entries() == 0) {
+    if (sorted_extensions.size() != 0) {
       printer->Print(
-          vars,
-          "    GPBDescriptor *localDescriptor =\n"
-          "        [GPBDescriptor allocDescriptorForClass:[$classname$ class]\n"
-          "                                     rootClass:[$rootclassname$ class]\n"
-          "                                          file:$rootclassname$_FileDescriptor()\n"
-          "                                        fields:$fields$\n"
-          "                                    fieldCount:$fields_count$\n"
-          "                                        oneofs:$oneofs$\n"
-          "                                    oneofCount:$oneof_count$\n"
-          "                                         enums:$enums$\n"
-          "                                     enumCount:$enum_count$\n"
-          "                                        ranges:$ranges$\n"
-          "                                    rangeCount:$range_count$\n"
-          "                                   storageSize:sizeof($classname$__storage_)\n"
-          "                                    wireFormat:$wireformat$];\n");
-    } else {
-      vars["extraTextFormatInfo"] = CEscape(text_format_decode_data.Data());
-      printer->Print(
-          vars,
-          "#if GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n"
-          "    const char *extraTextFormatInfo = NULL;\n"
-          "#else\n"
-          "    static const char *extraTextFormatInfo = \"$extraTextFormatInfo$\";\n"
-          "#endif  // GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n"
-          "    GPBDescriptor *localDescriptor =\n"
-          "        [GPBDescriptor allocDescriptorForClass:[$classname$ class]\n"
-          "                                     rootClass:[$rootclassname$ class]\n"
-          "                                          file:$rootclassname$_FileDescriptor()\n"
-          "                                        fields:$fields$\n"
-          "                                    fieldCount:$fields_count$\n"
-          "                                        oneofs:$oneofs$\n"
-          "                                    oneofCount:$oneof_count$\n"
-          "                                         enums:$enums$\n"
-          "                                     enumCount:$enum_count$\n"
-          "                                        ranges:$ranges$\n"
-          "                                    rangeCount:$range_count$\n"
-          "                                   storageSize:sizeof($classname$__storage_)\n"
-          "                                    wireFormat:$wireformat$\n"
-          "                           extraTextFormatInfo:extraTextFormatInfo];\n");
+          "    static const GPBExtensionRange ranges[] = {\n");
+      for (int i = 0; i < sorted_extensions.size(); i++) {
+        printer->Print("      { .start = $start$, .end = $end$ },\n",
+                       "start", SimpleItoa(sorted_extensions[i]->start),
+                       "end", SimpleItoa(sorted_extensions[i]->end));
       }
       printer->Print(
-          "    NSAssert(descriptor == nil, @\"Startup recursed!\");\n"
-          "    descriptor = localDescriptor;\n"
-          "  }\n"
-          "  return descriptor;\n"
-          "}\n\n"
-          "@end\n\n");
+          "    };\n"
+          "    [localDescriptor setupExtensionRanges:ranges\n"
+          "                                    count:(uint32_t)(sizeof(ranges) / sizeof(GPBExtensionRange))];\n");
+    }
+    printer->Print(
+        "    NSAssert(descriptor == nil, @\"Startup recursed!\");\n"
+        "    descriptor = localDescriptor;\n"
+        "  }\n"
+        "  return descriptor;\n"
+        "}\n\n"
+        "@end\n\n");
 
     for (int i = 0; i < descriptor_->field_count(); i++) {
       field_generators_.get(descriptor_->field(i))
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc b/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc
index 24e6df07..44bafd7f 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc
@@ -120,17 +120,16 @@ void OneofGenerator::GenerateClearFunctionImplementation(io::Printer* printer) {
       "void $owning_message_class$_Clear$capitalized_name$OneOfCase($owning_message_class$ *message) {\n"
       "  GPBDescriptor *descriptor = [message descriptor];\n"
       "  GPBOneofDescriptor *oneof = descriptor->oneofs_[$raw_index$];\n"
-      "  GPBMaybeClearOneof(message, oneof, 0);\n"
+      "  GPBMaybeClearOneof(message, oneof, $index$, 0);\n"
       "}\n");
 }
 
-void OneofGenerator::GenerateDescription(io::Printer* printer) {
-  printer->Print(
-      variables_,
-      "{\n"
-      "  .name = \"$name$\",\n"
-      "  .index = $index$,\n"
-      "},\n");
+string OneofGenerator::DescriptorName(void) const {
+  return variables_.find("name")->second;
+}
+
+string OneofGenerator::HasIndexAsString(void) const {
+  return variables_.find("index")->second;
 }
 
 }  // namespace objectivec
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_oneof.h b/src/google/protobuf/compiler/objectivec/objectivec_oneof.h
index bcba82da..3d9df4db 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_oneof.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_oneof.h
@@ -61,7 +61,9 @@ class OneofGenerator {
 
   void GeneratePropertyImplementation(io::Printer* printer);
   void GenerateClearFunctionImplementation(io::Printer* printer);
-  void GenerateDescription(io::Printer* printer);
+
+  string DescriptorName(void) const;
+  string HasIndexAsString(void) const;
 
  private:
   const OneofDescriptor* descriptor_;
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc b/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc
index ea7f1b91..d49350f4 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc
@@ -134,6 +134,32 @@ PrimitiveFieldGenerator::PrimitiveFieldGenerator(
 
 PrimitiveFieldGenerator::~PrimitiveFieldGenerator() {}
 
+void PrimitiveFieldGenerator::GenerateFieldStorageDeclaration(
+    io::Printer* printer) const {
+  if (GetObjectiveCType(descriptor_) == OBJECTIVECTYPE_BOOLEAN) {
+    // Nothing, BOOLs are stored in the has bits.
+  } else {
+    SingleFieldGenerator::GenerateFieldStorageDeclaration(printer);
+  }
+}
+
+int PrimitiveFieldGenerator::ExtraRuntimeHasBitsNeeded(void) const {
+  if (GetObjectiveCType(descriptor_) == OBJECTIVECTYPE_BOOLEAN) {
+    // Reserve a bit for the storage of the boolean.
+    return 1;
+  }
+  return 0;
+}
+
+void PrimitiveFieldGenerator::SetExtraRuntimeHasBitsBase(int has_base) {
+  if (GetObjectiveCType(descriptor_) == OBJECTIVECTYPE_BOOLEAN) {
+    // Set into the offset the has bit to use for the actual value.
+    variables_["storage_offset_value"] = SimpleItoa(has_base);
+    variables_["storage_offset_comment"] =
+        "  // Stored in _has_storage_ to save space.";
+  }
+}
+
 PrimitiveObjFieldGenerator::PrimitiveObjFieldGenerator(
     const FieldDescriptor* descriptor, const Options& options)
     : ObjCObjFieldGenerator(descriptor, options) {
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.h b/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.h
index 87139afb..69bb1fdd 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.h
@@ -49,6 +49,11 @@ class PrimitiveFieldGenerator : public SingleFieldGenerator {
                           const Options& options);
   virtual ~PrimitiveFieldGenerator();
 
+  virtual void GenerateFieldStorageDeclaration(io::Printer* printer) const;
+
+  virtual int ExtraRuntimeHasBitsNeeded(void) const;
+  virtual void SetExtraRuntimeHasBitsBase(int index_base);
+
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(PrimitiveFieldGenerator);
 };