Merge abi diffs, improve linking performance.

Bug: 38325544

Test:
As shown by out/build.trace.gz when using built header-abi-linker to
link .sdump files produced by header-abi-linker.

Without fix:
Time taken to produce libc.so.lsdump by header-abi-linker => ~51 sec
With fix:
Time taken to produce libc.so.lsdump by header-abi-linker => ~3 sec

Bug: 38325929

Test: merged abiff reports of libjpeg, libc.

Change-Id: Iae54f4754d8b0407fabdb8bc8550a7f7b3479f8f

vndk/tools/header-checker/Android.bp

@@ -212,6 +212,38 @@ cc_binary_host {
     },
 }
 
+cc_binary_host {
+    name: "merge-abi-diff",
+
+    defaults: [
+        "header-checker-defaults",
+        "header-abi-linker-lib-defaults",
+    ],
+
+    srcs: [
+        "merge-abi-diff/src/*.cpp",
+    ],
+
+    static_libs: [
+        "libheader-checker-proto",
+    ],
+
+    target: {
+        linux: {
+            host_ldlibs: [
+                "-ldl",
+                "-lpthread",
+            ],
+        },
+        darwin: {
+            host_ldlibs: [
+                "-ldl",
+                "-lpthread",
+            ],
+        },
+    },
+}
+
 cc_library_static {
     name: "libheader-abi-util",
     defaults: [

vndk/tools/header-checker/header-abi-diff/src/abi_diff.cpp

@@ -27,7 +27,7 @@
 
 #include <stdlib.h>
 
-Status HeaderAbiDiff::GenerateCompatibilityReport() {
+CompatibilityStatus HeaderAbiDiff::GenerateCompatibilityReport() {
   abi_dump::TranslationUnit old_tu;
   abi_dump::TranslationUnit new_tu;
   std::ifstream old_input(old_dump_);
@@ -37,41 +37,51 @@ Status HeaderAbiDiff::GenerateCompatibilityReport() {
 
   if (!google::protobuf::TextFormat::Parse(&text_iso, &old_tu) ||
       !google::protobuf::TextFormat::Parse(&text_isn, &new_tu)) {
-    llvm::errs() << "Failed to Parse Input\n";
+    llvm::errs() << "Failed to generate compatibility report\n";
     ::exit(1);
   }
-   return CompareTUs(old_tu, new_tu);
+  return CompareTUs(old_tu, new_tu);
 }
 
-Status HeaderAbiDiff::CompareTUs(const abi_dump::TranslationUnit &old_tu,
-                                 const abi_dump::TranslationUnit &new_tu) {
+CompatibilityStatus HeaderAbiDiff::CompareTUs(
+    const abi_dump::TranslationUnit &old_tu,
+    const abi_dump::TranslationUnit &new_tu) {
   std::unique_ptr<abi_diff::TranslationUnitDiff> diff_tu(
       new abi_diff::TranslationUnitDiff);
-
-  Status record_status = Collect<abi_dump::RecordDecl>(
+  CompatibilityStatus record_status = Collect<abi_dump::RecordDecl>(
       diff_tu->mutable_records_added(), diff_tu->mutable_records_removed(),
       diff_tu->mutable_records_diff(), old_tu.records(), new_tu.records(),
       ignored_symbols_);
 
-  Status function_status = Collect<abi_dump::FunctionDecl>(
+  CompatibilityStatus function_status = Collect<abi_dump::FunctionDecl>(
       diff_tu->mutable_functions_added(), diff_tu->mutable_functions_removed(),
       diff_tu->mutable_functions_diff(), old_tu.functions(),
       new_tu.functions(), ignored_symbols_);
 
-  Status enum_status = Collect<abi_dump::EnumDecl>(
+  CompatibilityStatus enum_status = Collect<abi_dump::EnumDecl>(
       diff_tu->mutable_enums_added(), diff_tu->mutable_enums_removed(),
       diff_tu->mutable_enums_diff(), old_tu.enums(), new_tu.enums(),
       ignored_symbols_);
 
-  Status global_var_status = Collect<abi_dump::GlobalVarDecl>(
+  CompatibilityStatus global_var_status = Collect<abi_dump::GlobalVarDecl>(
       diff_tu->mutable_global_vars_added(),
       diff_tu->mutable_global_vars_removed(),
       diff_tu->mutable_global_vars_diff(), old_tu.global_vars(),
       new_tu.global_vars(), ignored_symbols_);
 
-  Status combined_status =
+  CompatibilityStatus combined_status =
       record_status | function_status | enum_status | global_var_status;
 
+  if (combined_status & CompatibilityStatus::INCOMPATIBLE) {
+    combined_status = CompatibilityStatus::INCOMPATIBLE;
+  } else if (combined_status & CompatibilityStatus::EXTENSION) {
+    combined_status = CompatibilityStatus::EXTENSION;
+  } else {
+    combined_status = CompatibilityStatus::COMPATIBLE;
+  }
+  diff_tu->set_compatibility_status(combined_status);
+  diff_tu->set_lib_name(lib_name_);
+  diff_tu->set_arch(arch_);
   std::ofstream text_output(cr_);
   google::protobuf::io::OstreamOutputStream text_os(&text_output);
 
@@ -79,17 +89,11 @@ Status HeaderAbiDiff::CompareTUs(const abi_dump::TranslationUnit &old_tu,
     llvm::errs() << "Unable to dump report\n";
     ::exit(1);
   }
-  if (combined_status & INCOMPATIBLE) {
-    return INCOMPATIBLE;
-  }
-  if (combined_status & EXTENSION) {
-    return EXTENSION;
-  }
-  return COMPATIBLE;
+  return combined_status;
 }
 
 template <typename T, typename TDiff>
-Status HeaderAbiDiff::Collect(
+abi_diff::CompatibilityStatus HeaderAbiDiff::Collect(
     google::protobuf::RepeatedPtrField<T> *elements_added,
     google::protobuf::RepeatedPtrField<T> *elements_removed,
     google::protobuf::RepeatedPtrField<TDiff> *elements_diff,
@@ -115,12 +119,12 @@ Status HeaderAbiDiff::Collect(
     ::exit(1);
   }
   if (elements_diff->size() || elements_removed->size()) {
-    return INCOMPATIBLE;
+    return CompatibilityStatus::INCOMPATIBLE;
   }
   if (elements_added->size()) {
-    return EXTENSION;
+    return CompatibilityStatus::EXTENSION;
   }
-  return COMPATIBLE;
+  return CompatibilityStatus::COMPATIBLE;
 }
 
 template <typename T>

vndk/tools/header-checker/header-abi-diff/src/abi_diff.h

@@ -28,29 +28,26 @@
 #include <vector>
 
 
+typedef abi_diff::CompatibilityStatus CompatibilityStatus;
+
 class HeaderAbiDiff {
  public:
-  enum Status {
-    COMPATIBLE = 1 << 0,
-    EXTENSION = 1 << 1,
-    INCOMPATIBLE = 1 << 2,
-  };
-
-
-  HeaderAbiDiff(const std::string &old_dump, const std::string &new_dump,
+  HeaderAbiDiff(const std::string &lib_name, const std::string &arch,
+                const std::string &old_dump, const std::string &new_dump,
                 const std::string &compatibility_report,
                 const std::set<std::string> &ignored_symbols)
-      : old_dump_(old_dump), new_dump_(new_dump), cr_(compatibility_report),
-        ignored_symbols_(ignored_symbols) { }
+      : lib_name_(lib_name), arch_(arch), old_dump_(old_dump),
+        new_dump_(new_dump), cr_(compatibility_report),
+      ignored_symbols_(ignored_symbols) { }
 
-  Status GenerateCompatibilityReport();
+  CompatibilityStatus GenerateCompatibilityReport();
 
  private:
-  Status CompareTUs(const abi_dump::TranslationUnit &old_tu,
-                    const abi_dump::TranslationUnit &new_tu);
+  CompatibilityStatus CompareTUs(const abi_dump::TranslationUnit &old_tu,
+                                 const abi_dump::TranslationUnit &new_tu);
   // Collect* methods fill in the diff_tu.
   template <typename T, typename TDiff>
-  static Status Collect(
+  static CompatibilityStatus Collect(
       google::protobuf::RepeatedPtrField<T> *elements_added,
       google::protobuf::RepeatedPtrField<T> *elements_removed,
       google::protobuf::RepeatedPtrField<TDiff> *elements_diff,
@@ -88,14 +85,14 @@ class HeaderAbiDiff {
                                const std::set<std::string> &ignored_symbols);
 
  private:
+  const std::string &lib_name_;
+  const std::string &arch_;
   const std::string &old_dump_;
   const std::string &new_dump_;
   const std::string &cr_;
   const std::set<std::string> &ignored_symbols_;
 };
 
-typedef HeaderAbiDiff::Status Status;
-
 template <typename T>
 inline void HeaderAbiDiff::AddToMap(
     std::map<std::string, const T *> *dst,
@@ -105,14 +102,16 @@ inline void HeaderAbiDiff::AddToMap(
   }
 }
 
-static inline Status operator|(Status f, Status s) {
-  return static_cast<Status>(
-      static_cast<std::underlying_type<Status>::type>(f) |
-      static_cast<std::underlying_type<Status>::type>(s));
+static inline CompatibilityStatus operator|(CompatibilityStatus f,
+                                            CompatibilityStatus s) {
+  return static_cast<CompatibilityStatus>(
+      static_cast<std::underlying_type<CompatibilityStatus>::type>(f) |
+      static_cast<std::underlying_type<CompatibilityStatus>::type>(s));
 }
 
-static inline Status operator&(Status f, Status s) {
-  return static_cast<Status>(
-      static_cast<std::underlying_type<Status>::type>(f) &
-      static_cast<std::underlying_type<Status>::type>(s));
+static inline CompatibilityStatus operator&(
+    CompatibilityStatus f, CompatibilityStatus s) {
+  return static_cast<CompatibilityStatus>(
+      static_cast<std::underlying_type<CompatibilityStatus>::type>(f) &
+      static_cast<std::underlying_type<CompatibilityStatus>::type>(s));
 }

vndk/tools/header-checker/header-abi-diff/src/abi_diff_wrappers.cpp

@@ -276,6 +276,7 @@ DiffWrapper<EnumDecl, EnumDeclDiff>::Get() {
   google::protobuf::RepeatedPtrField<EnumFieldDeclDiff> *fdiffs =
       enum_diff->mutable_field_diffs();
   assert(fdiffs != nullptr);
+  enum_diff->set_name(oldp_->basic_abi().name());
   if (GetElementDiffs(fdiffs, oldp_->enum_fields(), newp_->enum_fields()) ||
       DiffBasicNamedAndTypedDecl(
           enum_diff->mutable_type_diff()->mutable_old(),

vndk/tools/header-checker/header-abi-diff/src/header_abi_diff.cpp

@@ -25,6 +25,14 @@ static llvm::cl::opt<std::string> compatibility_report(
     "o", llvm::cl::desc("<compatibility report>"), llvm::cl::Required,
     llvm::cl::cat(header_checker_category));
 
+static llvm::cl::opt<std::string> lib_name(
+    "lib", llvm::cl::desc("<lib name>"), llvm::cl::Required,
+    llvm::cl::cat(header_checker_category));
+
+static llvm::cl::opt<std::string> arch(
+    "arch", llvm::cl::desc("<arch>"), llvm::cl::Required,
+    llvm::cl::cat(header_checker_category));
+
 static llvm::cl::opt<std::string> new_dump(
     "new", llvm::cl::desc("<new dump>"), llvm::cl::Required,
     llvm::cl::cat(header_checker_category));
@@ -33,13 +41,18 @@ static llvm::cl::opt<std::string> old_dump(
     "old", llvm::cl::desc("<old dump>"), llvm::cl::Required,
     llvm::cl::cat(header_checker_category));
 
+static llvm::cl::opt<std::string> ignore_symbol_list(
+    "ignore-symbols", llvm::cl::desc("ignore symbols"), llvm::cl::Optional,
+    llvm::cl::cat(header_checker_category));
+
 static llvm::cl::opt<bool> advice_only(
     "advice-only", llvm::cl::desc("Advisory mode only"), llvm::cl::Optional,
     llvm::cl::cat(header_checker_category));
 
-static llvm::cl::opt<std::string> ignore_symbol_list(
-    "ignore-symbols", llvm::cl::desc("ignore symbols"), llvm::cl::Optional,
-    llvm::cl::cat(header_checker_category));
+static llvm::cl::opt<bool> allow_extensions(
+    "allow-extensions",
+    llvm::cl::desc("Do not return a non zero status on extensions"),
+    llvm::cl::Optional, llvm::cl::cat(header_checker_category));
 
 static std::set<std::string> LoadIgnoredSymbols(std::string &symbol_list_path) {
   std::ifstream symbol_ifstream(symbol_list_path);
@@ -58,32 +71,21 @@ static std::set<std::string> LoadIgnoredSymbols(std::string &symbol_list_path) {
 int main(int argc, const char **argv) {
   GOOGLE_PROTOBUF_VERIFY_VERSION;
   llvm::cl::ParseCommandLineOptions(argc, argv, "header-checker");
-  uint8_t extension_or_incompatible = 0;
   std::set<std::string> ignored_symbols;
   if (llvm::sys::fs::exists(ignore_symbol_list)) {
     ignored_symbols = LoadIgnoredSymbols(ignore_symbol_list);
   }
-  HeaderAbiDiff judge(old_dump, new_dump, compatibility_report,
+  HeaderAbiDiff judge(lib_name, arch, old_dump, new_dump, compatibility_report,
                       ignored_symbols);
-  switch (judge.GenerateCompatibilityReport()) {
-    case HeaderAbiDiff::COMPATIBLE:
-      break;
-    case HeaderAbiDiff::EXTENSION:
-      extension_or_incompatible = 1;
-      break;
-    default:
-      extension_or_incompatible = 2;
-      break;
+
+  CompatibilityStatus status  = judge.GenerateCompatibilityReport();
+
+  if (advice_only) {
+    return CompatibilityStatus::COMPATIBLE;
   }
-  if (extension_or_incompatible) {
-    llvm::errs() << "******************************************************\n"
-                 << "VNDK Abi Compliance breakage:"
-                 << " Please check compatiblity report at : "
-                 << compatibility_report << "\n"
-                 << "*****************************************************\n";
-    if (!advice_only) {
-      return extension_or_incompatible;
-    }
+
+  if (allow_extensions && status == CompatibilityStatus::EXTENSION) {
+    return CompatibilityStatus::COMPATIBLE;
   }
-  return 0;
+  return status;
 }

vndk/tools/header-checker/header-abi-linker/src/header_abi_linker.cpp

@@ -92,6 +92,8 @@ class HeaderAbiLinker {
   template <typename T>
   inline bool LinkDecl(google::protobuf::RepeatedPtrField<T> *dst,
                        std::set<std::string> *link_set,
+                       std::set<std::string> *regex_matched_link_set,
+                       const std::regex *vs_regex,
                        const google::protobuf::RepeatedPtrField<T> &src,
                        bool use_version_script);
 
@@ -104,13 +106,18 @@ class HeaderAbiLinker {
   const std::string &out_dump_name_;
   const std::string &arch_;
   const std::string &api_;
+  // TODO: Add to a map of std::sets instead.
   std::set<std::string> exported_headers_;
   std::set<std::string> record_decl_set_;
   std::set<std::string> function_decl_set_;
   std::set<std::string> enum_decl_set_;
   std::set<std::string> globvar_decl_set_;
-  // Version Script regex matched link set.
-  std::set<std::string> vs_regex_matched_link_set_;
+  // Version Script Regex Matching.
+  std::set<std::string> functions_regex_matched_set;
+  std::regex functions_vs_regex_;
+  // Version Script Regex Matching.
+  std::set<std::string> globvars_regex_matched_set;
+  std::regex globvars_vs_regex_;
 };
 
 bool HeaderAbiLinker::LinkAndDump() {
@@ -164,32 +171,44 @@ static std::string GetSymbol(const abi_dump::GlobalVarDecl &element) {
 }
 
 static bool QueryRegexMatches(std::set<std::string> *regex_matched_link_set,
-                              const std::set<std::string> &link_set,
+                              const std::regex *vs_regex,
                               const std::string &symbol) {
+  assert(regex_matched_link_set != nullptr);
+  assert(vs_regex != nullptr);
   if (regex_matched_link_set->find(symbol) != regex_matched_link_set->end()) {
     return false;
   }
-  // Go through each element in link_set, if there is a regex match, add the
-  // symbol to regex_matched_link_set and return true;
-  for (auto &&regex_match_str : link_set) {
-    std::smatch matcher;
-    std::string regex_match_str_find_glob =
-        abi_util::FindAndReplace(regex_match_str, "\\*", ".*");
-    std::regex match_clause("\\b" + regex_match_str_find_glob + "\\b");
-    if (std::regex_search(symbol, matcher, match_clause)) {
-      regex_matched_link_set->insert(symbol);
-      return true;
-    }
+  if (std::regex_search(symbol, *vs_regex)) {
+    regex_matched_link_set->insert(symbol);
+    return true;
   }
   return false;
 }
 
+static std::regex CreateRegexMatchExprFromSet(
+    const std::set<std::string> &link_set) {
+  std::string all_regex_match_str = "";
+  std::set<std::string>::iterator it = link_set.begin();
+  while (it != link_set.end()) {
+    std::string regex_match_str_find_glob =
+      abi_util::FindAndReplace(*it, "\\*", ".*");
+    all_regex_match_str += "(\\b" + regex_match_str_find_glob + "\\b)";
+    if (++it != link_set.end()) {
+      all_regex_match_str += "|";
+    }
+  }
+  if (all_regex_match_str == "") {
+    return std::regex();
+  }
+  return std::regex(all_regex_match_str);
+}
+
 template <typename T>
 inline bool HeaderAbiLinker::LinkDecl(
     google::protobuf::RepeatedPtrField<T> *dst,
     std::set<std::string> *link_set,
-    const google::protobuf::RepeatedPtrField<T> &src,
-    bool use_version_script) {
+    std::set<std::string> *regex_matched_link_set, const std::regex *vs_regex,
+    const google::protobuf::RepeatedPtrField<T> &src, bool use_version_script) {
   assert(dst != nullptr);
   assert(link_set != nullptr);
   for (auto &&element : src) {
@@ -210,8 +229,7 @@ inline bool HeaderAbiLinker::LinkDecl(
       std::set<std::string>::iterator it =
           link_set->find(element_str);
       if (it == link_set->end()) {
-        if (!QueryRegexMatches(&vs_regex_matched_link_set_, *link_set,
-                               element_str)) {
+        if (!QueryRegexMatches(regex_matched_link_set, vs_regex, element_str)) {
           continue;
         }
       } else {
@@ -234,14 +252,15 @@ bool HeaderAbiLinker::LinkRecords(const abi_dump::TranslationUnit &dump_tu,
   assert(linked_tu != nullptr);
   // Even if version scripts are available we take in records, since the symbols
   // in the version script might reference a record exposed by the library.
-  return LinkDecl(linked_tu->mutable_records(), &record_decl_set_,
-                  dump_tu.records(), false);
+  return LinkDecl(linked_tu->mutable_records(), &record_decl_set_, nullptr,
+                  nullptr, dump_tu.records(), false);
 }
 
 bool HeaderAbiLinker::LinkFunctions(const abi_dump::TranslationUnit &dump_tu,
                                     abi_dump::TranslationUnit *linked_tu) {
   assert(linked_tu != nullptr);
   return LinkDecl(linked_tu->mutable_functions(), &function_decl_set_,
+                  &functions_regex_matched_set, &functions_vs_regex_,
                   dump_tu.functions(), (!version_script_.empty()));
 }
 
@@ -250,14 +269,15 @@ bool HeaderAbiLinker::LinkEnums(const abi_dump::TranslationUnit &dump_tu,
   assert(linked_tu != nullptr);
   // Even if version scripts are available we take in records, since the symbols
   // in the version script might reference an enum exposed by the library.
-  return LinkDecl(linked_tu->mutable_enums(), &enum_decl_set_,
-                  dump_tu.enums(), false);
+  return LinkDecl(linked_tu->mutable_enums(), &enum_decl_set_, nullptr,
+                  nullptr, dump_tu.enums(), false);
 }
 
 bool HeaderAbiLinker::LinkGlobalVars(const abi_dump::TranslationUnit &dump_tu,
                                      abi_dump::TranslationUnit *linked_tu) {
   assert(linked_tu != nullptr);
   return LinkDecl(linked_tu->mutable_global_vars(), &globvar_decl_set_,
+                  &globvars_regex_matched_set, &globvars_vs_regex_,
                   dump_tu.global_vars(), (!version_script.empty()));
 }
 
@@ -269,6 +289,12 @@ bool HeaderAbiLinker::ParseVersionScriptFiles() {
   }
   function_decl_set_ = version_script_parser.GetFunctions();
   globvar_decl_set_ = version_script_parser.GetGlobVars();
+  std::set<std::string> function_regexs =
+      version_script_parser.GetFunctionRegexs();
+  std::set<std::string> globvar_regexs =
+      version_script_parser.GetGlobVarRegexs();
+  functions_vs_regex_ = CreateRegexMatchExprFromSet(function_regexs);
+  globvars_vs_regex_ = CreateRegexMatchExprFromSet(globvar_regexs);
   return true;
 }
 

vndk/tools/header-checker/header-abi-util/include/header_abi_util.h

@@ -21,6 +21,7 @@ namespace abi_util {
 
 std::set<std::string> CollectAllExportedHeaders(
     const std::vector<std::string> &exported_header_dirs);
+
 class VersionScriptParser {
  public:
 
@@ -38,6 +39,10 @@ class VersionScriptParser {
 
   const std::set<std::string> &GetGlobVars();
 
+  const std::set<std::string> &GetFunctionRegexs();
+
+  const std::set<std::string> &GetGlobVarRegexs();
+
  private:
 
   bool ParseInnerBlock(std::ifstream &symbol_ifstream);
@@ -54,11 +59,18 @@ class VersionScriptParser {
 
   int ApiStrToInt(const std::string &api);
 
+  void AddToVars(std::string &symbol);
+
+  void AddToFunctions(std::string &symbol);
+
  private:
   const std::string &version_script_;
   const std::string &arch_;
   std::set<std::string> functions_;
   std::set<std::string> globvars_;
+  // Added to speed up version script parsing and linking.
+  std::set<std::string> function_regexs_;
+  std::set<std::string> globvar_regexs_;
   int api_;
 };
 

vndk/tools/header-checker/header-abi-util/src/version_script_parser.cpp

@@ -102,6 +102,22 @@ bool VersionScriptParser::SymbolExported(const std::string &line,
   return false;
 }
 
+void VersionScriptParser::AddToVars(std::string &symbol) {
+  if (symbol.find("*") != std::string::npos) {
+    globvar_regexs_.insert(symbol);
+  } else {
+    globvars_.insert(symbol);
+  }
+}
+
+void VersionScriptParser::AddToFunctions(std::string &symbol) {
+  if (symbol.find("*") != std::string::npos) {
+    function_regexs_.insert(symbol);
+  } else {
+    functions_.insert(symbol);
+  }
+}
+
 bool VersionScriptParser::ParseSymbolLine(const std::string &line) {
   //The symbol lies before the ; and the tags are after ;
   std::string::size_type pos = line.find(";");
@@ -115,9 +131,9 @@ bool VersionScriptParser::ParseSymbolLine(const std::string &line) {
   std::string tags = line.substr(pos + 1);
   if (SymbolExported(tags, arch_, api_)) {
     if (StringContains(tags, "var")) {
-      globvars_.insert(symbol);
+      AddToVars(symbol);
     } else {
-      functions_.insert(symbol);
+      AddToFunctions(symbol);
     }
   }
   return true;
@@ -161,6 +177,14 @@ const std::set<std::string> &VersionScriptParser::GetGlobVars() {
   return globvars_;
 }
 
+const std::set<std::string> &VersionScriptParser::GetFunctionRegexs() {
+  return function_regexs_;
+}
+
+const std::set<std::string> &VersionScriptParser::GetGlobVarRegexs() {
+  return globvar_regexs_;
+}
+
 bool VersionScriptParser::Parse() {
   std::ifstream symbol_ifstream(version_script_);
   if (!symbol_ifstream.is_open()) {

vndk/tools/header-checker/merge-abi-diff/src/merge_abi_diff.cpp

@@ -0,0 +1,156 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-parameter"
+#pragma clang diagnostic ignored "-Wnested-anon-types"
+#include "proto/abi_dump.pb.h"
+#include "proto/abi_diff.pb.h"
+#pragma clang diagnostic pop
+
+#include <header_abi_util.h>
+
+#include <llvm/Support/CommandLine.h>
+#include <llvm/Support/raw_ostream.h>
+
+#include <google/protobuf/text_format.h>
+#include <google/protobuf/io/zero_copy_stream_impl.h>
+
+#include <memory>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include <stdlib.h>
+
+static llvm::cl::OptionCategory merge_abi_diff_category(
+    "merge-abi-diff options");
+
+static llvm::cl::list<std::string> diff_report_list(
+    llvm::cl::Positional, llvm::cl::desc("<diff-reports>"), llvm::cl::Required,
+    llvm::cl::cat(merge_abi_diff_category), llvm::cl::OneOrMore);
+
+static llvm::cl::opt<std::string> merged_diff_report(
+    "o", llvm::cl::desc("<merged-diff-report>"), llvm::cl::Required,
+    llvm::cl::cat(merge_abi_diff_category));
+
+static llvm::cl::opt<bool> advice_only(
+    "advice-only", llvm::cl::desc("Advisory mode only"), llvm::cl::Optional,
+    llvm::cl::cat(merge_abi_diff_category));
+
+static llvm::cl::opt<bool> do_not_break_on_extensions(
+    "allow-extensions",
+    llvm::cl::desc("Do not return a non zero status on extensions"),
+    llvm::cl::Optional, llvm::cl::cat(merge_abi_diff_category));
+
+typedef abi_diff::CompatibilityStatus CompatibilityStatus;
+
+static bool IsStatusDowngraded(const CompatibilityStatus &old_status,
+                               const CompatibilityStatus &new_status) {
+  bool status_downgraded = false;
+  switch (old_status) {
+    case CompatibilityStatus::EXTENSION:
+      if (new_status == CompatibilityStatus::INCOMPATIBLE) {
+        status_downgraded = true;
+      }
+      break;
+    case CompatibilityStatus::COMPATIBLE:
+      if (new_status != CompatibilityStatus::COMPATIBLE) {
+        status_downgraded = true;
+      }
+      break;
+    default:
+      break;
+  }
+  return status_downgraded;
+}
+
+static CompatibilityStatus MergeDiffReports(
+    const std::vector<std::string> &diff_reports,
+    const std::string &merged_diff_report) {
+
+  abi_diff::MergedTranslationUnitDiff merged_tu_diff;
+  std::ofstream text_output(merged_diff_report);
+  google::protobuf::io::OstreamOutputStream text_os(&text_output);
+  CompatibilityStatus status = CompatibilityStatus::COMPATIBLE;
+
+  for (auto &&i : diff_reports) {
+    abi_diff::TranslationUnitDiff diff_tu;
+    std::ifstream input(i);
+    google::protobuf::io::IstreamInputStream text_is(&input);
+    if (!google::protobuf::TextFormat::Parse(&text_is, &diff_tu)) {
+      llvm::errs() << "Failed to parse diff report\n";
+      ::exit(1);
+    }
+    abi_diff::ConciseDiffReportInformation *added_tu_diff =
+        merged_tu_diff.add_diff_reports();
+    if (!added_tu_diff) {
+      llvm::errs() << "Failed to add diff report to merged report\n";
+      ::exit(1);
+    }
+    CompatibilityStatus new_status = diff_tu.compatibility_status();
+    added_tu_diff->set_lib_name(diff_tu.lib_name());
+    added_tu_diff->set_arch(diff_tu.arch());
+    added_tu_diff->set_diff_report_path(i);
+    added_tu_diff->set_compatibility_status(new_status);
+    // Only, if the status is downgraded, change it.
+    if (IsStatusDowngraded(status, new_status)) {
+      status = new_status;
+    }
+  }
+
+  if (!google::protobuf::TextFormat::Print(merged_tu_diff, &text_os)) {
+    llvm::errs() << "Serialization to ostream failed\n";
+    ::exit(1);
+  }
+  return status;
+}
+
+int main(int argc, const char **argv) {
+  GOOGLE_PROTOBUF_VERIFY_VERSION;
+  llvm::cl::ParseCommandLineOptions(argc, argv, "merge-abi-diff");
+  CompatibilityStatus extension_or_incompatible =
+      MergeDiffReports(diff_report_list, merged_diff_report);
+  std::string status_str = "";
+  switch (extension_or_incompatible) {
+    case CompatibilityStatus::INCOMPATIBLE:
+      status_str = "broken";
+      break;
+    case CompatibilityStatus::EXTENSION:
+      status_str = "extended";
+      break;
+    default:
+      break;
+  }
+  if (extension_or_incompatible) {
+    llvm::errs() << "******************************************************\n"
+                 << "VNDK Abi "
+                 << status_str
+                 << ":"
+                 << " Please check compatiblity report at : "
+                 << merged_diff_report << "\n"
+                 << "*****************************************************\n";
+  }
+
+  if (do_not_break_on_extensions &&
+      extension_or_incompatible == CompatibilityStatus::EXTENSION) {
+      extension_or_incompatible = CompatibilityStatus::COMPATIBLE;
+  }
+
+  if (!advice_only) {
+    return extension_or_incompatible;
+  }
+  return CompatibilityStatus::COMPATIBLE;
+}

vndk/tools/header-checker/proto/abi_diff.proto

@@ -59,7 +59,7 @@ message ParamDeclDiff {
 }
 
 message FunctionDeclDiff {
-  required ReturnTypeDiff return_type_diffs = 1;
+  optional ReturnTypeDiff return_type_diffs = 1;
   repeated ParamDeclDiff param_diffs = 2;
 }
 
@@ -67,20 +67,43 @@ message GlobalVarDeclDiff {
   optional BasicNamedAndTypedDeclDiff type_diff = 1;
 }
 
-message TranslationUnitDiff {
-  // Differing Elements.
-  repeated RecordDeclDiff records_diff = 1;
-  repeated EnumDeclDiff enums_diff = 2;
-  repeated FunctionDeclDiff functions_diff = 3;
-  repeated GlobalVarDeclDiff global_vars_diff = 4;
-  // Removed Elements.
-  repeated abi_dump.RecordDecl records_removed = 5;
-  repeated abi_dump.FunctionDecl functions_removed = 6;
-  repeated abi_dump.EnumDecl enums_removed = 7;
-  repeated abi_dump.GlobalVarDecl global_vars_removed = 8;
-  // Added Elements.
-  repeated abi_dump.RecordDecl records_added = 9;
-  repeated abi_dump.FunctionDecl functions_added = 10;
-  repeated abi_dump.EnumDecl enums_added = 11;
-  repeated abi_dump.GlobalVarDecl global_vars_added = 12;
+enum CompatibilityStatus {
+  COMPATIBLE = 0;
+  EXTENSION = 1;
+  INCOMPATIBLE = 4;
+}
+
+message TranslationUnitDiff {
+  // Library Name
+  optional string lib_name = 1;
+  optional string arch = 2;
+  // Differing Elements.
+  repeated RecordDeclDiff records_diff = 3;
+  repeated EnumDeclDiff enums_diff = 4;
+  repeated FunctionDeclDiff functions_diff = 5;
+  repeated GlobalVarDeclDiff global_vars_diff = 6;
+  // Removed Elements.
+  repeated abi_dump.RecordDecl records_removed = 7;
+  repeated abi_dump.FunctionDecl functions_removed = 8;
+  repeated abi_dump.EnumDecl enums_removed = 9;
+  repeated abi_dump.GlobalVarDecl global_vars_removed = 10;
+  // Added Elements.
+  repeated abi_dump.RecordDecl records_added = 11;
+  repeated abi_dump.FunctionDecl functions_added = 12;
+  repeated abi_dump.EnumDecl enums_added = 13;
+  repeated abi_dump.GlobalVarDecl global_vars_added = 14;
+  // Compatiblity Status
+  optional CompatibilityStatus compatibility_status = 15;
+}
+
+// Not merged with TranslationUnitDiff to allow future extensions.
+message ConciseDiffReportInformation {
+  optional string lib_name = 1;
+  optional string arch = 2;
+  optional string diff_report_path = 3;
+  optional CompatibilityStatus compatibility_status = 4;
+}
+
+message MergedTranslationUnitDiff {
+  repeated ConciseDiffReportInformation diff_reports = 1;
 }