1 files changed, 22 insertions, 0 deletions
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index e8ca0804090..03a2c229d0b 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -116,6 +116,16 @@ void CompilerInstance::setModuleManager(IntrusiveRefCntPtr<ASTReader> Reader) {
   ModuleManager = Reader;
 }
 
+std::shared_ptr<ModuleDependencyCollector>
+CompilerInstance::getModuleDepCollector() const {
+  return ModuleDepCollector;
+}
+
+void CompilerInstance::setModuleDepCollector(
+    std::shared_ptr<ModuleDependencyCollector> Collector) {
+  ModuleDepCollector = Collector;
+}
+
 // Diagnostics
 static void SetUpDiagnosticLog(DiagnosticOptions *DiagOpts,
                                const CodeGenOptions *CodeGenOpts,
@@ -278,6 +288,11 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
     AttachDependencyGraphGen(*PP, DepOpts.DOTOutputFile,
                              getHeaderSearchOpts().Sysroot);
 
+  // If we don't have a collector, but we are collecting module dependencies,
+  // then we're the top level compiler instance and need to create one.
+  if (!ModuleDepCollector && !DepOpts.ModuleDependencyOutputDir.empty())
+    ModuleDepCollector = std::make_shared<ModuleDependencyCollector>(
+        DepOpts.ModuleDependencyOutputDir);
 
   // Handle generating header include information, if requested.
   if (DepOpts.ShowHeaderIncludes)
@@ -851,6 +866,10 @@ static void compileModuleImpl(CompilerInstance &ImportingInstance,
   SourceMgr.pushModuleBuildStack(Module->getTopLevelModuleName(),
     FullSourceLoc(ImportLoc, ImportingInstance.getSourceManager()));
 
+  // If we're collecting module dependencies, we need to share a collector
+  // between all of the module CompilerInstances.
+  Instance.setModuleDepCollector(ImportingInstance.getModuleDepCollector());
+
   // Get or create the module map that we'll use to build this module.
   std::string InferredModuleMapContent;
   if (const FileEntry *ModuleMapFile =
@@ -1211,6 +1230,9 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
     if (TheDependencyFileGenerator)
       TheDependencyFileGenerator->AttachToASTReader(*ModuleManager);
 
+    if (ModuleDepCollector)
+      ModuleDepCollector->attachToASTReader(*ModuleManager);
+
     // Try to load the module file.
     unsigned ARRFlags = ASTReader::ARR_OutOfDate | ASTReader::ARR_Missing;
     switch (ModuleManager->ReadAST(ModuleFileName, serialization::MK_Module,