2 files changed, 25 insertions, 10 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index fc8b5523520..384800e9510 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -1025,16 +1025,22 @@ Expected<BitcodeModule> clang::FindThinLTOModule(MemoryBufferRef MBRef) {
 
   // The bitcode file may contain multiple modules, we want the one that is
   // marked as being the ThinLTO module.
-  for (BitcodeModule &BM : *BMsOrErr) {
-    Expected<BitcodeLTOInfo> LTOInfo = BM.getLTOInfo();
-    if (LTOInfo && LTOInfo->IsThinLTO)
-      return BM;
-  }
+  if (const BitcodeModule *Bm = FindThinLTOModule(*BMsOrErr))
+    return *Bm;
 
   return make_error<StringError>("Could not find module summary",
                                  inconvertibleErrorCode());
 }
 
+BitcodeModule *clang::FindThinLTOModule(MutableArrayRef<BitcodeModule> BMs) {
+  for (BitcodeModule &BM : BMs) {
+    Expected<BitcodeLTOInfo> LTOInfo = BM.getLTOInfo();
+    if (LTOInfo && LTOInfo->IsThinLTO)
+      return &BM;
+  }
+  return nullptr;
+}
+
 static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
                               const HeaderSearchOptions &HeaderOpts,
                               const CodeGenOptions &CGOpts,
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 6ca69d63cdc..13fa4a83308 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -947,12 +947,21 @@ std::unique_ptr<llvm::Module> CodeGenAction::loadModule(MemoryBufferRef MBRef) {
       return {};
     };
 
-    Expected<llvm::BitcodeModule> BMOrErr = FindThinLTOModule(MBRef);
-    if (!BMOrErr)
-      return DiagErrors(BMOrErr.takeError());
-
+    Expected<std::vector<BitcodeModule>> BMsOrErr = getBitcodeModuleList(MBRef);
+    if (!BMsOrErr)
+      return DiagErrors(BMsOrErr.takeError());
+    BitcodeModule *Bm = FindThinLTOModule(*BMsOrErr);
+    // We have nothing to do if the file contains no ThinLTO module. This is
+    // possible if ThinLTO compilation was not able to split module. Content of
+    // the file was already processed by indexing and will be passed to the
+    // linker using merged object file.
+    if (!Bm) {
+      auto M = llvm::make_unique<llvm::Module>("empty", *VMContext);
+      M->setTargetTriple(CI.getTargetOpts().Triple);
+      return M;
+    }
     Expected<std::unique_ptr<llvm::Module>> MOrErr =
-        BMOrErr->parseModule(*VMContext);
+        Bm->parseModule(*VMContext);
     if (!MOrErr)
       return DiagErrors(MOrErr.takeError());
     return std::move(*MOrErr);