[lld-macho] Addressed additional post-commit comments from D126046

[oontvoo]

Summary

• fixed newlines
• renamed helper function for clarity
• added additional comment

[int3]

Thank you!

lld/MachO/Driver.cpp

if (glob.match(symbolName))
       return true;
   return false;
 }
 
 bool SymbolPatterns::match(StringRef symbolName) const {
   return matchLiteral(symbolName) || matchGlob(symbolName);
 }
 
-static void handleSymbolPatternsListHelper(const Arg *arg,
-                                           SymbolPatterns &symbolPatterns) {
+static void parseSymbolPatternsFile(const Arg *arg,
   StringRef path = arg->getValue();
   Optional<MemoryBufferRef> buffer = readFile(path);
   if (!buffer) {
     error("Could not read symbol file: " + path);
     return;
   }
   MemoryBufferRef mbref = *buffer;
   for (StringRef line : args::getLines(mbref)) {
     line = line.take_until([](char c) { return c == '#'; }).trim();
     if (!line.empty())
       symbolPatterns.insert(line);
   }
 }
+
 static void handleSymbolPatterns(InputArgList &args,
                                  SymbolPatterns &symbolPatterns,
                                  unsigned singleOptionCode,
                                  unsigned listFileOptionCode) {
   for (const Arg *arg : args.filtered(singleOptionCode))
     symbolPatterns.insert(arg->getValue());
   for (const Arg *arg : args.filtered(listFileOptionCode))
-    handleSymbolPatternsListHelper(arg, symbolPatterns);
+    parseSymbolPatternsFile(arg, symbolPatterns);
 }
 
 static void createFiles(const InputArgList &args) {
   TimeTraceScope timeScope("Load input files");
   // This loop should be reserved for options whose exact ordering matters.
   // Other options should be handled via filtered() and/or getLastArg().
   bool isLazy = false;
   for (const Arg *arg : args) {
// together for a more straightforward behaviour)
     bool includeLocal = false;
     bool excludeLocal = false;
     for (const Arg *arg :
          args.filtered(OPT_x, OPT_non_global_symbols_no_strip_list,
                        OPT_non_global_symbols_strip_list)) {
       switch (arg->getOption().getID()) {
       case OPT_x:
         config->localSymbolsPresence = SymtabPresence::None;
-
         break;
       case OPT_non_global_symbols_no_strip_list:
         if (excludeLocal) {
           error("cannot use both -non_global_symbols_no_strip_list and "
                 "-non_global_symbols_strip_list");
         } else {
           includeLocal = true;
           config->localSymbolsPresence = SymtabPresence::SelectivelyIncluded;
-          handleSymbolPatternsListHelper(arg, config->localSymbolPatterns);
+          parseSymbolPatternsFile(arg, config->localSymbolPatterns);
         }
         break;
       case OPT_non_global_symbols_strip_list:
         if (includeLocal) {
           error("cannot use both -non_global_symbols_no_strip_list and "
                 "-non_global_symbols_strip_list");
         } else {
           excludeLocal = true;
           config->localSymbolsPresence = SymtabPresence::SelectivelyExcluded;
-          handleSymbolPatternsListHelper(arg, config->localSymbolPatterns);
+          parseSymbolPatternsFile(arg, config->localSymbolPatterns);
         }
         break;
       default:
         llvm_unreachable("unexpected option");
       }
     }
   }
   // Explicitly-exported literal symbols must be defined, but might

lld/MachO/SyntheticSections.cpp

localSymbolsHandler = [&](Symbol *sym) {
       if (!config->localSymbolPatterns.match(sym->getName()))
         addSymbol(localSymbols, sym);
     };
     break;
   }
 
   // Local symbols aren't in the SymbolTable, so we walk the list of object
   // files to gather them.
-  // But if `-x` is set, then we don't need to.
+  // But if `-x` is set, then we don't need to. localSymbolsHandler() will do
+  // the right thing regardless, but this check is a perf optimization because
+  // iterating through all the input files and their symbols is expensive.
   if (config->localSymbolsPresence != SymtabPresence::None) {
     for (const InputFile *file : inputFiles) {
       if (auto *objFile = dyn_cast<ObjFile>(file)) {
         for (Symbol *sym : objFile->symbols) {
           if (auto *defined = dyn_cast_or_null<Defined>(sym)) {
             if (defined->isExternal() || !defined->isLive() ||
                 !defined->includeInSymtab)
               continue;