1 files changed, 55 insertions, 4 deletions

diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
index 38674d20717..719c5db050a 100644
--- a/llvm/tools/gold/gold-plugin.cpp
+++ b/llvm/tools/gold/gold-plugin.cpp
@@ -164,6 +164,12 @@ namespace options {
   // corresponding bitcode file, will use a path formed by replacing the
   // bitcode file's path prefix matching oldprefix with newprefix.
   static std::string thinlto_prefix_replace;
+  // Option to control the name of modules encoded in the individual index
+  // files for a distributed backend. This enables the use of minimized
+  // bitcode files for the thin link, assuming the name of the full bitcode
+  // file used in the backend differs just in some part of the file suffix.
+  // If specified, expects a string of the form "oldsuffix:newsuffix".
+  static std::string thinlto_object_suffix_replace;
   // Optional path to a directory for caching ThinLTO objects.
   static std::string cache_dir;
   // Additional options to pass into the code generator.
@@ -206,6 +212,12 @@ namespace options {
       thinlto_prefix_replace = opt.substr(strlen("thinlto-prefix-replace="));
       if (thinlto_prefix_replace.find(';') == std::string::npos)
         message(LDPL_FATAL, "thinlto-prefix-replace expects 'old;new' format");
+    } else if (opt.startswith("thinlto-object-suffix-replace=")) {
+      thinlto_object_suffix_replace =
+          opt.substr(strlen("thinlto-object-suffix-replace="));
+      if (thinlto_object_suffix_replace.find(';') == std::string::npos)
+        message(LDPL_FATAL,
+                "thinlto-object-suffix-replace expects 'old;new' format");
     } else if (opt.startswith("cache-dir=")) {
       cache_dir = opt.substr(strlen("cache-dir="));
     } else if (opt.size() == 2 && opt[0] == 'O') {
@@ -566,8 +578,35 @@ static const void *getSymbolsAndView(claimed_file &F) {
   return View;
 }
 
-static void addModule(LTO &Lto, claimed_file &F, const void *View) {
-  MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize), F.name);
+/// Parse the thinlto-object-suffix-replace option into the \p OldSuffix and
+/// \p NewSuffix strings, if it was specified.
+static void getThinLTOOldAndNewSuffix(std::string &OldSuffix,
+                                      std::string &NewSuffix) {
+  assert(options::thinlto_object_suffix_replace.empty() ||
+         options::thinlto_object_suffix_replace.find(";") != StringRef::npos);
+  StringRef SuffixReplace = options::thinlto_object_suffix_replace;
+  std::pair<StringRef, StringRef> Split = SuffixReplace.split(";");
+  OldSuffix = Split.first.str();
+  NewSuffix = Split.second.str();
+}
+
+/// Given the original \p Path to an output file, replace any filename
+/// suffix matching \p OldSuffix with \p NewSuffix.
+static std::string getThinLTOObjectFileName(const std::string Path,
+                                            const std::string &OldSuffix,
+                                            const std::string &NewSuffix) {
+  if (OldSuffix.empty() && NewSuffix.empty())
+    return Path;
+  StringRef NewPath = Path;
+  NewPath.consume_back(OldSuffix);
+  std::string NewNewPath = NewPath.str() + NewSuffix;
+  return NewPath.str() + NewSuffix;
+}
+
+static void addModule(LTO &Lto, claimed_file &F, const void *View,
+                      StringRef Filename) {
+  MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize),
+                            Filename);
   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
 
   if (!ObjOrErr)
@@ -789,19 +828,31 @@ static ld_plugin_status allSymbolsReadHook() {
   if (options::thinlto_index_only)
     getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
 
+  std::string OldSuffix, NewSuffix;
+  getThinLTOOldAndNewSuffix(OldSuffix, NewSuffix);
+  // Set for owning string objects used as buffer identifiers.
+  StringSet<> ObjectFilenames;
+
   for (claimed_file &F : Modules) {
     if (options::thinlto && !HandleToInputFile.count(F.leader_handle))
       HandleToInputFile.insert(std::make_pair(
           F.leader_handle, llvm::make_unique<PluginInputFile>(F.handle)));
     const void *View = getSymbolsAndView(F);
+    // In case we are thin linking with a minimized bitcode file, ensure
+    // the module paths encoded in the index reflect where the backends
+    // will locate the full bitcode files for compiling/importing.
+    std::string Identifier =
+        getThinLTOObjectFileName(F.name, OldSuffix, NewSuffix);
+    auto ObjFilename = ObjectFilenames.insert(Identifier);
+    assert(ObjFilename.second);
     if (!View) {
       if (options::thinlto_index_only)
         // Write empty output files that may be expected by the distributed
         // build system.
-        writeEmptyDistributedBuildOutputs(F.name, OldPrefix, NewPrefix);
+        writeEmptyDistributedBuildOutputs(Identifier, OldPrefix, NewPrefix);
       continue;
     }
-    addModule(*Lto, F, View);
+    addModule(*Lto, F, View, ObjFilename.first->first());
   }
 
   SmallString<128> Filename;