[ELF] Fix multiple -mllvm after D70378

[MaskRay]

Summary

Fixes https://reviews.llvm.org/D70378#2299569 Multiple -mllvm is intended to be supported.

We don't have a proper test for -plugin-opt=-. This patch adds the test as well.

[MaskRay]

Improve a comment

[ayrivera]

Thanks for the quick patch. I tested it and it works. LGTM.

[aganea]

Looks good with one minor comment.

lld/ELF/Driver.cpp

1108

I would put this line just above the comment, because it has to do more with options in general, rather than LTO options specifically, but that's my preference.

[MaskRay]

Move ResetAllOptionOccurrences

lld/ELF/Driver.cpp

return m == EM_AARCH64 || m == EM_AMDGPU || m == EM_HEXAGON || m == EM_PPC ||
          m == EM_PPC64 || m == EM_RISCV || m == EM_X86_64;
 }
 
 static void parseClangOption(StringRef opt, const Twine &msg) {
   std::string err;
   raw_string_ostream os(err);
 
   const char *argv[] = {config->progName.data(), opt.data()};
-  cl::ResetAllOptionOccurrences();
   if (cl::ParseCommandLineOptions(2, argv, "", &os))
     return;
   os.flush();
   error(msg + ": " + StringRef(err).trim());
 }
 
 // Initializes Config members by the command line options.
 static void readConfigs(opt::InputArgList &args) {
if (!to_integer(kv.second, v))
             kv.second + "'");
     else if (Expected<GlobPattern> pat = GlobPattern::create(kv.first))
       config->deadRelocInNonAlloc.emplace_back(std::move(*pat), v);
     else
       error(errPrefix + toString(pat.takeError()));
   }
 
   // Parse LTO options.
+  cl::ResetAllOptionOccurrences();
   if (auto *arg = args.getLastArg(OPT_plugin_opt_mcpu_eq))
     parseClangOption(saver.save("-mcpu=" + StringRef(arg->getValue())),
                      arg->getSpelling());
 
   for (opt::Arg *arg : args.filtered(OPT_plugin_opt_eq_minus))
     parseClangOption(std::string("-") + arg->getValue(), arg->getSpelling());
 
   // GCC collect2 passes -plugin-opt=path/to/lto-wrapper with an absolute or

lld/test/ELF/lto/mllvm.ll

+; REQUIRES: x86
+; RUN: llvm-as %s -o %t.o
+; RUN: ld.lld %t.o -o %t -mllvm -debug-pass=Structure -mllvm -print-after-all 2>&1 | FileCheck %s
+
+;; We support -plugin-opt=- for LLVMgold.so compatibility. With a few exceptions,
+;; most -plugin-opt=- prefixed options are passed through to cl::ParseCommandLineOptions.
+; RUN: ld.lld %t.o -o %t -plugin-opt=-debug-pass=Structure -plugin-opt=-print-after-all 2>&1 | FileCheck %s
+
+; CHECK: Pass Arguments:
+; CHECK: # *** IR Dump
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @_start() {
+  ret void
+}