[AArch64][GCS] Convert -zgcs-report processing to use an Enum

To enable easier processing of inheritance for the -zgcs-report-dynamic
option, the -zgcs-report option has been converted to use an Enum value
to define its setting rather than a StringRef value.

This adds the Enum class for defining the three options, None, Warning
and Error, along with the appropirate methods for processing the users
input. To enable the error messages, a new lambda function has been
added. This processes the Enum value and passes the appropriate string
into the `report` lambda function for the error message. Error messages
have been updated where required.

Author: Stylie777

lld/ELF/Driver.cpp

@@ -574,6 +574,27 @@ static GcsPolicy getZGcs(Ctx &ctx, opt::InputArgList &args) {
   return ret;
 }
 
+static ReportPolicy getZGcsReport(Ctx &ctx, opt::InputArgList &args) {
+  ReportPolicy ret = ReportPolicy::None;
+
+  for (auto *arg : args.filtered(OPT_z)) {
+    std::pair<StringRef, StringRef> kv = StringRef(arg->getValue()).split('=');
+    if (kv.first == "gcs-report") {
+      arg->claim();
+      if (kv.second == "none")
+        ret = ReportPolicy::None;
+      else if (kv.second == "warning")
+        ret = ReportPolicy::Warning;
+      else if (kv.second == "error")
+        ret = ReportPolicy::Error;
+      else
+        ErrAlways(ctx) << "unknown -z gcs-report= value: " << kv.second;
+    }
+  }
+
+  return ret;
+}
+
 // Report a warning for an unknown -z option.
 static void checkZOptions(Ctx &ctx, opt::InputArgList &args) {
   // This function is called before getTarget(), when certain options are not
@@ -1548,6 +1569,7 @@ static void readConfigs(Ctx &ctx, opt::InputArgList &args) {
   ctx.arg.zForceBti = hasZOption(args, "force-bti");
   ctx.arg.zForceIbt = hasZOption(args, "force-ibt");
   ctx.arg.zGcs = getZGcs(ctx, args);
+  ctx.arg.zGcsReport = getZGcsReport(ctx, args);
   ctx.arg.zGlobal = hasZOption(args, "global");
   ctx.arg.zGnustack = getZGnuStack(args);
   ctx.arg.zHazardplt = hasZOption(args, "hazardplt");
@@ -1620,12 +1642,10 @@ static void readConfigs(Ctx &ctx, opt::InputArgList &args) {
       ErrAlways(ctx) << errPrefix << pat.takeError() << ": " << kv.first;
   }
 
-  auto reports = {
-      std::make_pair("bti-report", &ctx.arg.zBtiReport),
-      std::make_pair("cet-report", &ctx.arg.zCetReport),
-      std::make_pair("execute-only-report", &ctx.arg.zExecuteOnlyReport),
-      std::make_pair("gcs-report", &ctx.arg.zGcsReport),
-      std::make_pair("pauth-report", &ctx.arg.zPauthReport)};
+  auto reports = {std::make_pair("bti-report", &ctx.arg.zBtiReport),
+                  std::make_pair("cet-report", &ctx.arg.zCetReport),
+                  std::make_pair("execute-only-report", &ctx.arg.zExecuteOnlyReport),
+                  std::make_pair("pauth-report", &ctx.arg.zPauthReport)};
   for (opt::Arg *arg : args.filtered(OPT_z)) {
     std::pair<StringRef, StringRef> option =
         StringRef(arg->getValue()).split('=');

lld/test/ELF/aarch64-feature-gcs.s

@@ -54,6 +54,11 @@
 
 # INVALID: error: unknown -z gcs= value: nonsense
 
+## An invalid gcs option should give an error
+# RUN: not ld.lld func1-gcs.o func2-gcs.o func3-gcs.o -z gcs-report=nonsense 2>&1 | FileCheck --check-prefix=INVALID-GCS-REPORT %s
+
+# INVALID-GCS-REPORT: error: unknown -z gcs-report= value: nonsense
+
 #--- func1-gcs.s
 .section ".note.gnu.property", "a"
 .long 4