[clang] [clang-tools-extra] [lld] [llvm] [llvm] Add subcommand support for OptTable (PR #155026)

[via llvm-commits]

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@@ -323,6 +345,39 @@ static void emitOptionParser(const RecordKeeper &Records, raw_ostream &OS) {
   OS << "\n};\n";
   OS << "#endif // OPTTABLE_PREFIXES_TABLE_CODE\n\n";
 
+  // Dump command IDs.
+  OS << "/////////";
+  OS << "// Command IDs\n\n";
+  OS << "#ifdef OPTTABLE_COMMAND_IDS_TABLE_CODE\n";
+  OS << "static constexpr unsigned OptionCommandIDsTable[] = {\n";
+  {
+    // Ensure the first command set is always empty.
+    assert(!CommandIDs.empty() &&
+           "We should always emit an empty set of commands");
+    assert(CommandIDs.begin()->first.empty() &&
+           "First command set should always be empty");
+    llvm::ListSeparator Sep(",\n");
+    unsigned CurIndex = 0;
+    for (auto &[Command, CommandIndex] : CommandIDs) {
+      // First emit the number of command strings in this list of commands.
+      OS << Sep << "  " << Command.size() << " /* commands */";
+      CommandIndex = CurIndex;
+      assert((CurIndex == 0 || !Command.empty()) &&
+             "Only first command set should be empty!");
+      for (const auto &CommandKey : Command) {
+        auto It = llvm::find_if(Commands, [&](const Record *R) {
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PiJoules wrote:

We can use `std::find_if` directly. I think `llvm::find_if` just calls it.

https://github.com/llvm/llvm-project/pull/155026