[NFC][ELF][CHERI] Swap CapRelocsMode enum for bool

All we care about is whether we're using caprelocs or relative
relocations. Note the option name remains the same as it's implemented
downstream in Morello LLD and actually passed by CheriBSD.

Author: jrtc27

lld/ELF/Arch/Cheri.cpp

@@ -952,7 +952,7 @@ void addCapabilityRelocation(
   // For local symbols we can also emit the untagged capability bits and
   // instruct csu/rtld to run CBuildCap
   if ((!sym || !sym->isPreemptible) && !needTrampoline) {
-    assert(ctx.arg.localCapRelocsMode == CapRelocsMode::Legacy &&
+    assert(!ctx.arg.useRelativeCheriRelocs &&
            "relative ELF capability relocations not currently implemented");
     ctx.in.capRelocs->addCapReloc({sec, offset}, {symOrSec, 0u}, addend);
     return;

lld/ELF/Config.h

@@ -100,8 +100,6 @@ enum class BuildIdKind { None, Fast, Md5, Sha1, Hexstring, Uuid };
 // For --call-graph-profile-sort={none,hfsort,cdsort}.
 enum class CGProfileSortKind { None, Hfsort, Cdsort };
 
-enum class CapRelocsMode { Legacy, ElfReloc };
-
 enum class CapTableScopePolicy { All, File, Function };
 
 // For --discard-{all,locals,none}.
@@ -459,8 +457,7 @@ struct Config {
   UnresolvedPolicy unresolvedSymbolsInShlib;
   Target2Policy target2;
   GcsPolicy zGcs;
-  // Method used for capability relocations for non-preemptible symbols
-  CapRelocsMode localCapRelocsMode;
+  bool useRelativeCheriRelocs;
   CapTableScopePolicy capTableScope;
 
   bool power10Stubs;

lld/ELF/Driver.cpp

@@ -481,7 +481,7 @@ static void checkOptions(Ctx &ctx) {
       ErrAlways(ctx) << "-r and -z nosectionheader may not be used together";
   }
 
-  if (ctx.arg.localCapRelocsMode == CapRelocsMode::ElfReloc)
+  if (ctx.arg.useRelativeCheriRelocs)
     error("local-cap-relocs=elf is not implemented yet");
 
   if (ctx.arg.executeOnly) {
@@ -863,19 +863,6 @@ static CapTableScopePolicy getCapTableScope(opt::InputArgList &args) {
   llvm_unreachable("Invalid arg");
 }
 
-static CapRelocsMode getLocalCapRelocsMode(opt::InputArgList &args) {
-  auto *arg =
-      args.getLastArg(OPT_local_caprelocs_legacy, OPT_local_caprelocs_elf);
-  if (!arg) // TODO: change default to ElfReloc
-    return CapRelocsMode::Legacy;
-  if (arg->getOption().getID() == OPT_local_caprelocs_legacy) {
-    return CapRelocsMode::Legacy;
-  } else if (arg->getOption().getID() == OPT_local_caprelocs_elf) {
-    return CapRelocsMode::ElfReloc;
-  }
-  llvm_unreachable("Invalid arg");
-}
-
 static StringRef getDynamicLinker(Ctx &ctx, opt::InputArgList &args) {
   auto *arg = args.getLastArg(OPT_dynamic_linker, OPT_no_dynamic_linker);
   if (!arg)
@@ -1485,7 +1472,9 @@ static void readConfigs(Ctx &ctx, opt::InputArgList &args) {
   ctx.arg.ignoreFunctionAddressEquality =
       args.hasArg(OPT_ignore_function_address_equality);
   ctx.arg.init = args.getLastArgValue(OPT_init, "_init");
-  ctx.arg.localCapRelocsMode = getLocalCapRelocsMode(args);
+  // TODO: change default to true
+  ctx.arg.useRelativeCheriRelocs =
+      args.hasFlag(OPT_local_caprelocs_elf, OPT_local_caprelocs_legacy, false);
   ctx.arg.ltoAAPipeline = args.getLastArgValue(OPT_lto_aa_pipeline);
   ctx.arg.ltoCSProfileGenerate = args.hasArg(OPT_lto_cs_profile_generate);
   ctx.arg.ltoCSProfileFile = args.getLastArgValue(OPT_lto_cs_profile_file);