[lld-macho] Support -mcpu for LTO

[int3]

Summary

Verify it works by checking that the nopw opcode can be emitted. This
copies a similar test in LLD-ELF/COFF.

[compnerd]

I think that it makes sense to merge this with D92911 and D92912

[int3]

merging into D92912

lld/MachO/Driver.cpp

static bool isPie(opt::InputArgList &args) {
 
   if (config->platform.kind == MachO::PlatformKind::macOS &&
       config->platform.minimum >= VersionTuple(10, 6))
     return true;
 
   return args.hasArg(OPT_pie);
 }
 
+static void parseClangOption(StringRef opt, const Twine &msg) {
+  std::string err;
+  raw_string_ostream os(err);
+
+  const char *argv[] = {"lld", opt.data()};
+  if (cl::ParseCommandLineOptions(2, argv, "", &os))
+    return;
+  os.flush();
+  error(msg + ": " + StringRef(err).trim());
+}
+
 bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
                  raw_ostream &stdoutOS, raw_ostream &stderrOS) {
   lld::stdoutOS = &stdoutOS;
   lld::stderrOS = &stderrOS;
 
   stderrOS.enable_colors(stderrOS.has_colors());
   // TODO: Set up error handler properly, e.g. the errorLimitExceededMsg
 
bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
   // re-exported.
   for (opt::Arg *arg : args.filtered(OPT_sub_library)) {
     config->hasReexports = true;
     StringRef searchName = arg->getValue();
     if (!markSubLibrary(searchName))
       error("-sub_library " + searchName + " does not match a supplied dylib");
   }
 
+  // Parse LTO options.
+  if (auto *arg = args.getLastArg(OPT_mcpu))
+    parseClangOption(saver.save("-mcpu=" + StringRef(arg->getValue())),
+                     arg->getSpelling());
+
   initLLVM();
   compileBitcodeFiles();
   replaceCommonSymbols();
 
   StringRef orderFile = args.getLastArgValue(OPT_order_file);
   if (!orderFile.empty())
     parseOrderFile(orderFile);
 

lld/MachO/LTO.cpp

 using namespace lld;
 using namespace lld::macho;
 using namespace llvm;
 using namespace llvm::sys;
 
 static lto::Config createConfig() {
   lto::Config c;
   c.Options = initTargetOptionsFromCodeGenFlags();
+  c.CPU = getCPUStr();
   return c;
 }
 
 BitcodeCompiler::BitcodeCompiler() {
   auto backend =
       lto::createInProcessThinBackend(llvm::heavyweight_hardware_concurrency());
   ltoObj = std::make_unique<lto::LTO>(createConfig(), backend);
 }

lld/MachO/Options.td

 def not_for_dyld_shared_cache : Flag<["-"], "not_for_dyld_shared_cache">,
      HelpText<"Prevent system dylibs from being placed into the dylib shared cache">,
      Flags<[HelpHidden]>,
      Group<grp_rare>;
 def mllvm : Separate<["-"], "mllvm">,
      HelpText<"Options to pass to LLVM">,
      Flags<[HelpHidden]>,
      Group<grp_rare>;
+def mcpu : Separate<["-"], "mcpu">,
+     HelpText<"Processor family target for LTO code generation">,
+     Group<grp_rare>;
 
 def grp_deprecated : OptionGroup<"deprecated">, HelpText<"DEPRECATED">;
 
 def lazy_framework : Separate<["-"], "lazy_framework">,
      MetaVarName<"<name>">,
      HelpText<"This option is deprecated and is now an alias for -framework.">,
      Flags<[HelpHidden]>,
      Group<grp_deprecated>;
def iosmac_version_min : Flag<["-"], "iosmac_version_min">,
      HelpText<"Alias for -maccatalyst_version_min">,
      Flags<[HelpHidden]>,
      Group<grp_undocumented>;
 def uikitformac_version_min : Flag<["-"], "uikitformac_version_min">,
      Alias<maccatalyst_version_min>,
      HelpText<"Alias for -maccatalyst_version_min">,
      Flags<[HelpHidden]>,
      Group<grp_undocumented>;
-def mcpu : Flag<["-"], "mcpu">,
-     HelpText<"This option is undocumented in ld64">,
-     Flags<[HelpHidden]>,
-     Group<grp_undocumented>;
 def no_compact_unwind : Flag<["-"], "no_compact_unwind">,
      HelpText<"This option is undocumented in ld64">,
      Flags<[HelpHidden]>,
      Group<grp_undocumented>;
 def no_dtrace_dof : Flag<["-"], "no_dtrace_dof">,
      HelpText<"This option is undocumented in ld64">,
      Flags<[HelpHidden]>,
      Group<grp_undocumented>;

lld/test/MachO/cpu-string.ll

+; REQUIRES: x86
+; RUN: llvm-as %s -o %t.o
+
+; RUN: %lld %t.o -o %t.dylib -dylib
+; RUN: llvm-objdump -d --section="__text" --no-leading-addr --no-show-raw-insn %t.dylib | FileCheck %s
+; CHECK: nop{{$}}
+
+; RUN: %lld -mcpu znver1 %t.o -o %t.znver1.dylib -dylib
+; RUN: llvm-objdump -d --section="__text" --no-leading-addr --no-show-raw-insn %t.znver1.dylib | FileCheck %s --check-prefix=ZNVER1
+
+; ZNVER1: nopw
+; ZNVER1-NOT: nop{{$}}
+
+target triple = "x86_64-apple-darwin"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @foo() #0 {
+entry:
+  call void asm sideeffect ".p2align        4, 0x90", "~{dirflag},~{fpsr},~{flags}"()
+  ret void
+}
+
+attributes #0 = { "frame-pointer"="all" }