Use getLastArgValue instead of getString

[yamaguchi]

Summary

I found that getString defined in the LLD's Driver.cpp is exactly the same as Arg::getLastArgValue defined in llvm/Option/ArgLIst.h.
This patch removes that local function and use the function that the Arg class provides.

[ruiu]

LGTM

Thank you for doing this! I didn't know that Arg class provides that function, that's why I implemented our own getString() function.

lld/ELF/Driver.cpp

if (Config->GcSections)
       error("-r and --gc-sections may not be used together");
     if (Config->ICF)
       error("-r and --icf may not be used together");
     if (Config->Pie)
       error("-r and -pie may not be used together");
   }
 }
 
-static StringRef getString(opt::InputArgList &Args, unsigned Key,
-                           StringRef Default = "") {
-  if (auto *Arg = Args.getLastArg(Key))
-    return Arg->getValue();
-  return Default;
-}
-
 static int getInteger(opt::InputArgList &Args, unsigned Key, int Default) {
   int V = Default;
   if (auto *Arg = Args.getLastArg(Key)) {
     StringRef S = Arg->getValue();
     if (!to_integer(S, V, 10))
       error(Arg->getSpelling() + ": number expected, but got " + S);
   }
   return V;
static UnresolvedPolicy getUnresolvedSymbolPolicy(opt::InputArgList &Args) {
   // -shared implies -unresolved-symbols=ignore-all because missing
   // symbols are likely to be resolved at runtime using other DSOs.
   if (Config->Shared)
     return UnresolvedPolicy::Ignore;
   return ErrorOrWarn;
 }
 
 static Target2Policy getTarget2(opt::InputArgList &Args) {
-  StringRef S = getString(Args, OPT_target2, "got-rel");
+  StringRef S = Args.getLastArgValue(OPT_target2, "got-rel");
   if (S == "rel")
     return Target2Policy::Rel;
   if (S == "abs")
     return Target2Policy::Abs;
   if (S == "got-rel")
     return Target2Policy::GotRel;
   error("unknown --target2 option: " + S);
   return Target2Policy::GotRel;
static StringMap<uint64_t> getSectionStartMap(opt::InputArgList &Args) {
   if (auto *Arg = Args.getLastArg(OPT_Tdata))
     Ret[".data"] = parseSectionAddress(Arg->getValue(), Arg);
   if (auto *Arg = Args.getLastArg(OPT_Tbss))
     Ret[".bss"] = parseSectionAddress(Arg->getValue(), Arg);
   return Ret;
 }
 
 static SortSectionPolicy getSortSection(opt::InputArgList &Args) {
-  StringRef S = getString(Args, OPT_sort_section);
+  StringRef S = Args.getLastArgValue(OPT_sort_section);
   if (S == "alignment")
     return SortSectionPolicy::Alignment;
   if (S == "name")
     return SortSectionPolicy::Name;
   if (!S.empty())
     error("unknown --sort-section rule: " + S);
   return SortSectionPolicy::Default;
 }
 
 static std::pair<bool, bool> getHashStyle(opt::InputArgList &Args) {
-  StringRef S = getString(Args, OPT_hash_style, "sysv");
+  StringRef S = Args.getLastArgValue(OPT_hash_style, "sysv");
   if (S == "sysv")
     return {true, false};
   if (S == "gnu")
     return {false, true};
   if (S != "both")
     error("unknown -hash-style: " + S);
   return {true, true};
 }
for (StringRef S : Arr) {
     S = S.trim();
     if (!S.empty())
       Ret.push_back(S);
   }
   return Ret;
 }
 
 static bool getCompressDebugSections(opt::InputArgList &Args) {
-  StringRef S = getString(Args, OPT_compress_debug_sections, "none");
+  StringRef S = Args.getLastArgValue(OPT_compress_debug_sections, "none");
   if (S == "none")
     return false;
   if (S != "zlib")
     error("unknown --compress-debug-sections value: " + S);
   if (!zlib::isAvailable())
     error("--compress-debug-sections: zlib is not available");
   return true;
 }
Config->DefineCommon = getArg(Args, OPT_define_common, OPT_no_define_common,
                                 !Args.hasArg(OPT_relocatable));
   Config->Demangle = getArg(Args, OPT_demangle, OPT_no_demangle, true);
   Config->DisableVerify = Args.hasArg(OPT_disable_verify);
   Config->Discard = getDiscard(Args);
   Config->DynamicLinker = getDynamicLinker(Args);
   Config->EhFrameHdr = Args.hasArg(OPT_eh_frame_hdr);
   Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
   Config->EnableNewDtags = !Args.hasArg(OPT_disable_new_dtags);
-  Config->Entry = getString(Args, OPT_entry);
+  Config->Entry = Args.getLastArgValue(OPT_entry);
   Config->ExportDynamic =
       getArg(Args, OPT_export_dynamic, OPT_no_export_dynamic, false);
   Config->FatalWarnings =
       getArg(Args, OPT_fatal_warnings, OPT_no_fatal_warnings, false);
-  Config->Fini = getString(Args, OPT_fini, "_fini");
+  Config->Fini = Args.getLastArgValue(OPT_fini, "_fini");
   Config->GcSections = getArg(Args, OPT_gc_sections, OPT_no_gc_sections, false);
   Config->GdbIndex = Args.hasArg(OPT_gdb_index);
   Config->ICF = Args.hasArg(OPT_icf);
-  Config->Init = getString(Args, OPT_init, "_init");
-  Config->LTOAAPipeline = getString(Args, OPT_lto_aa_pipeline);
-  Config->LTONewPmPasses = getString(Args, OPT_lto_newpm_passes);
+  Config->Init = Args.getLastArgValue(OPT_init, "_init");
+  Config->LTOAAPipeline = Args.getLastArgValue(OPT_lto_aa_pipeline);
+  Config->LTONewPmPasses = Args.getLastArgValue(OPT_lto_newpm_passes);
   Config->LTOO = getInteger(Args, OPT_lto_O, 2);
   Config->LTOPartitions = getInteger(Args, OPT_lto_partitions, 1);
-  Config->MapFile = getString(Args, OPT_Map);
+  Config->MapFile = Args.getLastArgValue(OPT_Map);
   Config->NoGnuUnique = Args.hasArg(OPT_no_gnu_unique);
   Config->NoUndefinedVersion = Args.hasArg(OPT_no_undefined_version);
   Config->Nostdlib = Args.hasArg(OPT_nostdlib);
   Config->OFormatBinary = isOutputFormatBinary(Args);
   Config->Omagic = Args.hasArg(OPT_omagic);
-  Config->OptRemarksFilename = getString(Args, OPT_opt_remarks_filename);
+  Config->OptRemarksFilename = Args.getLastArgValue(OPT_opt_remarks_filename);
   Config->OptRemarksWithHotness = Args.hasArg(OPT_opt_remarks_with_hotness);
   Config->Optimize = getInteger(Args, OPT_O, 1);
-  Config->OutputFile = getString(Args, OPT_o);
+  Config->OutputFile = Args.getLastArgValue(OPT_o);
   Config->Pie = getArg(Args, OPT_pie, OPT_nopie, false);
   Config->PrintGcSections = Args.hasArg(OPT_print_gc_sections);
   Config->Rpath = getRpath(Args);
   Config->Relocatable = Args.hasArg(OPT_relocatable);
   Config->SaveTemps = Args.hasArg(OPT_save_temps);
   Config->SearchPaths = getArgs(Args, OPT_L);
   Config->SectionStartMap = getSectionStartMap(Args);
   Config->Shared = Args.hasArg(OPT_shared);
   Config->SingleRoRx = Args.hasArg(OPT_no_rosegment);
-  Config->SoName = getString(Args, OPT_soname);
+  Config->SoName = Args.getLastArgValue(OPT_soname);
   Config->SortSection = getSortSection(Args);
   Config->Strip = getStrip(Args);
-  Config->Sysroot = getString(Args, OPT_sysroot);
+  Config->Sysroot = Args.getLastArgValue(OPT_sysroot);
   Config->Target1Rel = getArg(Args, OPT_target1_rel, OPT_target1_abs, false);
   Config->Target2 = getTarget2(Args);
-  Config->ThinLTOCacheDir = getString(Args, OPT_thinlto_cache_dir);
-  Config->ThinLTOCachePolicy =
-      check(parseCachePruningPolicy(getString(Args, OPT_thinlto_cache_policy)),
-            "--thinlto-cache-policy: invalid cache policy");
+  Config->ThinLTOCacheDir = Args.getLastArgValue(OPT_thinlto_cache_dir);
+  Config->ThinLTOCachePolicy = check(
+      parseCachePruningPolicy(Args.getLastArgValue(OPT_thinlto_cache_policy)),
   Config->ThinLTOJobs = getInteger(Args, OPT_thinlto_jobs, -1u);
   Config->Threads = getArg(Args, OPT_threads, OPT_no_threads, true);
   Config->Trace = Args.hasArg(OPT_trace);
   Config->Undefined = getArgs(Args, OPT_undefined);
   Config->UnresolvedSymbols = getUnresolvedSymbolPolicy(Args);
   Config->Verbose = Args.hasArg(OPT_verbose);
   Config->WarnCommon = Args.hasArg(OPT_warn_common);
   Config->ZCombreloc = !hasZOption(Args, "nocombreloc");
   Config->ZExecstack = hasZOption(Args, "execstack");
   Config->ZNocopyreloc = hasZOption(Args, "nocopyreloc");
   Config->ZNodelete = hasZOption(Args, "nodelete");
   Config->ZNodlopen = hasZOption(Args, "nodlopen");
   Config->ZNow = hasZOption(Args, "now");
   Config->ZOrigin = hasZOption(Args, "origin");
   Config->ZRelro = !hasZOption(Args, "norelro");
   Config->ZRodynamic = hasZOption(Args, "rodynamic");
   Config->ZStackSize = getZOptionValue(Args, "stack-size", 0);
   Config->ZText = !hasZOption(Args, "notext");
   Config->ZWxneeded = hasZOption(Args, "wxneeded");
 
   if (Config->LTOO > 3)
-    error("invalid optimization level for LTO: " + getString(Args, OPT_lto_O));
+    error("invalid optimization level for LTO: " +
+          Args.getLastArgValue(OPT_lto_O));
   if (Config->LTOPartitions == 0)
     error("--lto-partitions: number of threads must be > 0");
   if (Config->ThinLTOJobs == 0)
     error("--thinlto-jobs: number of threads must be > 0");
 
   if (auto *Arg = Args.getLastArg(OPT_m)) {
     // Parse ELF{32,64}{LE,BE} and CPU type.
     StringRef S = Arg->getValue();