[MachO] Enable new passmanager plugin support for LTO

Author: jamesmth

lld/MachO/Config.h

@@ -214,6 +214,9 @@ struct Configuration {
   bool pgoWarnMismatch;
   bool warnThinArchiveMissingMembers;
 
+  llvm::SmallVector<llvm::StringRef, 0> passPlugins;
+  llvm::StringRef ltoNewPmPasses;
+
   bool callGraphProfileSort = false;
   llvm::StringRef printSymbolOrder;
 

lld/MachO/Driver.cpp

@@ -1750,6 +1750,9 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
                    OPT_no_warn_thin_archive_missing_members, true);
   config->generateUuid = !args.hasArg(OPT_no_uuid);
 
+  config->passPlugins = args::getStrings(args, OPT_load_pass_plugins);
+  config->ltoNewPmPasses = args.getLastArgValue(OPT_lto_newpm_passes);
+
   for (const Arg *arg : args.filtered(OPT_alias)) {
     config->aliasedSymbols.push_back(
         std::make_pair(arg->getValue(0), arg->getValue(1)));

lld/MachO/LTO.cpp

@@ -62,6 +62,13 @@ static lto::Config createConfig() {
   c.PGOWarnMismatch = config->pgoWarnMismatch;
   c.OptLevel = config->ltoo;
   c.CGOptLevel = config->ltoCgo;
+
+  for (StringRef pluginFn : config->passPlugins)
+    c.PassPlugins.push_back(std::string(pluginFn));
+
+  // Set up a custom pipeline if we've been asked to.
+  c.OptPipeline = std::string(config->ltoNewPmPasses);
+
   if (config->saveTemps)
     checkError(c.addSaveTemps(config->outputFile.str() + ".",
                               /*UseInputModulePath=*/true));

lld/MachO/Options.td

@@ -156,6 +156,12 @@ defm pgo_warn_mismatch: BB<"pgo-warn-mismatch",
 defm warn_thin_archive_missing_members : BB<"warn-thin-archive-missing-members",
   "Warn on missing object files referenced by thin archives (default)",
   "Do not warn on missing object files referenced by thin archives">, Group<grp_lld>;
+def load_pass_plugins: Flag<["--"], "load-pass-plugin=">,
+    HelpText<"Load passes from plugin library">,
+    Group<grp_lld>;
+def lto_newpm_passes: Flag<["--"], "lto-newpm-passes=">,
+    HelpText<"Passes to run during LTO">,
+    Group<grp_lld>;
 
 // This is a complete Options.td compiled from Apple's ld(1) manpage
 // dated 2018-03-07 and cross checked with ld64 source code in repo