<rdar://problem/13509689> Introduce -module-file-info option that provides information about a particular module file.

This option can be useful for end users who want to know why they
ended up with a ton of different variants of the "std" module in their
module cache. This problem should go away over time, as we reduce the
need for module variants, but it will never go away entirely.

llvm-svn: 178148

clang/lib/Frontend/CompilerInvocation.cpp

@@ -644,6 +644,8 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
       Opts.ProgramAction = frontend::InitOnly; break;
     case OPT_fsyntax_only:
       Opts.ProgramAction = frontend::ParseSyntaxOnly; break;
+    case OPT_module_file_info:
+      Opts.ProgramAction = frontend::ModuleFileInfo; break;
     case OPT_print_decl_contexts:
       Opts.ProgramAction = frontend::PrintDeclContext; break;
     case OPT_print_preamble:
@@ -779,7 +781,7 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
       .Case("objective-c-header", IK_ObjC)
       .Case("c++-header", IK_CXX)
       .Case("objective-c++-header", IK_ObjCXX)
-      .Case("ast", IK_AST)
+      .Cases("ast", "pcm", IK_AST)
       .Case("ir", IK_LLVM_IR)
       .Default(IK_None);
     if (DashX == IK_None)
@@ -1465,6 +1467,7 @@ static void ParsePreprocessorOutputArgs(PreprocessorOutputOptions &Opts,
   case frontend::GeneratePCH:
   case frontend::GeneratePTH:
   case frontend::ParseSyntaxOnly:
+  case frontend::ModuleFileInfo:
   case frontend::PluginAction:
   case frontend::PrintDeclContext:
   case frontend::RewriteObjC:
@@ -1627,6 +1630,8 @@ llvm::APInt ModuleSignature::getAsInteger() const {
 }
 
 std::string CompilerInvocation::getModuleHash() const {
+  // Note: For QoI reasons, the things we use as a hash here should all be
+  // dumped via the -module-info flag.
   using llvm::hash_code;
   using llvm::hash_value;
   using llvm::hash_combine;