Enabling new pass manager in LTO (and thinLTO) link step via -fexperimental-new-pass-manager option

[gyiu]

Summary

Modifications to driver and gold plugin code to get the new pass manager path enabled in LTO (and thinLTO).

[tejohnson]

Thanks for adding this. Please add a test like the one for -ffunction-sections (tools/clang/test/Driver/gold-lto-sections.c).

[gyiu]

Add new testcase to make sure plugin-opt is passed to gold linker to enable new pass manager.

[tejohnson]

LGTM
thanks!

lib/Driver/ToolChains/CommonArgs.cpp

#endif
   if (Arg *A = getLastProfileSampleUseArg(Args)) {
     StringRef FName = A->getValue();
     if (!llvm::sys::fs::exists(FName))
       D.Diag(diag::err_drv_no_such_file) << FName;
     else
       CmdArgs.push_back(
           Args.MakeArgString(Twine("-plugin-opt=sample-profile=") + FName));
   }
+
+  // Need this flag to turn on new pass manager via Gold plugin.
+  if (Args.hasFlag(options::OPT_fexperimental_new_pass_manager,
+                   options::OPT_fno_experimental_new_pass_manager,
+                   /* Default */ false)) {
+    CmdArgs.push_back("-plugin-opt=new-pass-manager");
+  }
+
 }
 
 void tools::addArchSpecificRPath(const ToolChain &TC, const ArgList &Args,
                                  ArgStringList &CmdArgs) {
   std::string CandidateRPath = TC.getArchSpecificLibPath();
   if (TC.getVFS().exists(CandidateRPath)) {
     CmdArgs.push_back("-rpath");
     CmdArgs.push_back(Args.MakeArgString(CandidateRPath.c_str()));

test/Driver/gold-lto-new-pass-man.c

+// RUN: touch %t.o
+//
+// RUN: %clang -target ppc64le-unknown-linux -### %t.o -flto 2>&1 \
+// RUN:     -Wl,-plugin-opt=foo -O3 \
+// RUN:     -fexperimental-new-pass-manager \
+// RUN:     | FileCheck %s
+// CHECK: "-plugin-opt=new-pass-manager"

tools/gold/gold-plugin.cpp

#endif
   // Optional pruning policy for ThinLTO caches.
   static std::string cache_policy;
   // Additional options to pass into the code generator.
   // Note: This array will contain all plugin options which are not claimed
   // as plugin exclusive to pass to the code generator.
   static std::vector<const char *> extra;
   // Sample profile file path
   static std::string sample_profile;
+  // New pass manager
+  static bool new_pass_manager = false;
 
   static void process_plugin_option(const char *opt_)
   {
     if (opt_ == nullptr)
       return;
     llvm::StringRef opt = opt_;
 
     if (opt.startswith("mcpu=")) {
static void process_plugin_option(const char *opt_)
     } else if (opt.startswith("lto-partitions=")) {
       if (opt.substr(strlen("lto-partitions="))
               .getAsInteger(10, ParallelCodeGenParallelismLevel))
         message(LDPL_FATAL, "Invalid codegen partition level: %s", opt_ + 5);
     } else if (opt == "disable-verify") {
       DisableVerify = true;
     } else if (opt.startswith("sample-profile=")) {
       sample_profile= opt.substr(strlen("sample-profile="));
+    } else if (opt == "new-pass-manager") {
+      new_pass_manager = true;
     } else {
       // Save this option to pass to the code generator.
       // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
       // add that.
       if (extra.empty())
         extra.push_back("LLVMgold");
 
       extra.push_back(opt_);
case options::OT_SAVE_TEMPS:
     check(Conf.addSaveTemps(output_name + ".",
                             /* UseInputModulePath */ true));
     break;
   }
 
   if (!options::sample_profile.empty())
     Conf.SampleProfile = options::sample_profile;
 
+  // Use new pass manager if set in driver
+  Conf.UseNewPM = options::new_pass_manager;
+
   return llvm::make_unique<LTO>(std::move(Conf), Backend,
                                 options::ParallelCodeGenParallelismLevel);
 }
 
 // Write empty files that may be expected by a distributed build
 // system when invoked with thinlto_index_only. This is invoked when
 // the linker has decided not to include the given module in the
 // final link. Frequently the distributed build system will want to