Driver/Frontend: Add support for -mllvm, which forwards options to the LLVM option parser.

- Note that this is a behavior change, previously -mllvm at the driver level forwarded to clang -cc1. The driver does a little magic to make sure that '-mllvm -disable-llvm-optzns' works correctly, but other users will need to be updated to use -Xclang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101354 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/CC1Options.td

@@ -324,6 +324,11 @@ def ftime_report : Flag<"-ftime-report">,
 def fdump_record_layouts : Flag<"-fdump-record-layouts">,
   HelpText<"Dump record layout information">;
 
+// Generic forwarding to LLVM options. This should only be used for debugging
+// and experimental features.
+def mllvm : Separate<"-mllvm">,
+  HelpText<"Additional arguments to forward to LLVM's option processing">;
+
 //===----------------------------------------------------------------------===//
 // Language Options
 //===----------------------------------------------------------------------===//

include/clang/Frontend/FrontendOptions.h

@@ -110,6 +110,10 @@ public:
   /// \brief The list of AST files to merge.
   std::vector<std::string> ASTMergeFiles;
 
+  /// \brief A list of arguments to forward to LLVM's option processing; this
+  /// should only be used for debugging and experimental features.
+  std::vector<std::string> LLVMArgs;
+
 public:
   FrontendOptions() {
     DebugCodeCompletionPrinter = 1;

lib/Driver/Tools.cpp

@@ -1325,8 +1325,18 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddLastArg(CmdArgs, options::OPT_dM);
   Args.AddLastArg(CmdArgs, options::OPT_dD);
 
+  // Forward -Xclang arguments to -cc1, and -mllvm arguments to the LLVM option
+  // parser.
   Args.AddAllArgValues(CmdArgs, options::OPT_Xclang);
-  Args.AddAllArgValues(CmdArgs, options::OPT_mllvm);
+  for (arg_iterator it = Args.filtered_begin(options::OPT_mllvm),
+         ie = Args.filtered_end(); it != ie; ++it) {
+    // We translate this by hand to the -cc1 argument, since nightly test uses
+    // it and developers have been trained to spell it with -mllvm.
+    if (llvm::StringRef(it->getValue(Args, 0)) == "-disable-llvm-optzns")
+      CmdArgs.push_back("-disable-llvm-optzns");
+    else
+      it->render(Args, CmdArgs);
+  }
 
   if (Output.getType() == types::TY_Dependencies) {
     // Handled with other dependency code.

lib/Frontend/CompilerInvocation.cpp

@@ -383,6 +383,10 @@ static void FrontendOptsToArgs(const FrontendOptions &Opts,
     Res.push_back("-ast-merge");
     Res.push_back(Opts.ASTMergeFiles[i]);
   }
+  for (unsigned i = 0, e = Opts.LLVMArgs.size(); i != e; ++i) {
+    Res.push_back("-mllvm");
+    Res.push_back(Opts.LLVMArgs[i]);
+  }
 }
 
 static void HeaderSearchOptsToArgs(const HeaderSearchOptions &Opts,
@@ -955,6 +959,7 @@ ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args, Diagnostic &Diags) {
   Opts.ShowVersion = Args.hasArg(OPT_version);
   Opts.ViewClassInheritance = getLastArgValue(Args, OPT_cxx_inheritance_view);
   Opts.ASTMergeFiles = getAllArgValues(Args, OPT_ast_merge);
+  Opts.LLVMArgs = getAllArgValues(Args, OPT_mllvm);
 
   FrontendOptions::InputKind DashX = FrontendOptions::IK_None;
   if (const Arg *A = Args.getLastArg(OPT_x)) {

tools/driver/cc1_main.cpp

@@ -241,6 +241,19 @@ int cc1_main(const char **ArgBegin, const char **ArgEnd,
     return 0;
   }
 
+  // Honor -mllvm.
+  //
+  // FIXME: Remove this, one day.
+  if (!Clang->getFrontendOpts().LLVMArgs.empty()) {
+    unsigned NumArgs = Clang->getFrontendOpts().LLVMArgs.size();
+    const char **Args = new const char*[NumArgs + 2];
+    Args[0] = "clang (LLVM option parsing)";
+    for (unsigned i = 0; i != NumArgs; ++i)
+      Args[i + 1] = Clang->getFrontendOpts().LLVMArgs[i].c_str();
+    Args[NumArgs + 1] = 0;
+    llvm::cl::ParseCommandLineOptions(NumArgs + 1, (char**) Args);
+  }
+
   // Create the actual diagnostics engine.
   Clang->createDiagnostics(ArgEnd - ArgBegin, const_cast<char**>(ArgBegin));
   if (!Clang->hasDiagnostics())