[Modules] Don't compute a modules cache path if we're not using modules!

Notably, this prevents us from doing *tons* of work to compute the
modules hash, including trying to read a darwin specific plist file off
of the system. There is a lot that needs cleaning up below this layer
too.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@233462 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index 1c5b322230456e55c82f56398d19448f039e9f3b..3492bf184d3b1fe1759ef48ed64bf9139fe81387 100644 (file)
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -329,7 +329,8 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
 
   PP->setPreprocessedOutput(getPreprocessorOutputOpts().ShowCPP);
 
-  PP->getHeaderSearchInfo().setModuleCachePath(getSpecificModuleCachePath());
+  if (PP->getLangOpts().Modules)
+    PP->getHeaderSearchInfo().setModuleCachePath(getSpecificModuleCachePath());
 
   // Handle generating dependencies, if requested.
   const DependencyOutputOptions &DepOpts = getDependencyOutputOpts();