[lld-macho] Implement -arch_errors_fatal

[keith]

Summary

By default with ld64, architecture mismatches are just warnings, then
this flag can be passed to make these fail. This matches that behavior.

[keith]

lld/MachO/InputFiles.cpp

804

I'm not sure if the unconditional return here is the right behavior, or if in the warning case something else should be done here. I think this is right though

[keith]

Fix format

[int3]

Thanks!

lld/MachO/InputFiles.cpp

793

could we factor out the arguments somehow? E.g. something like auto f = config->errorForArchMismatch ? error : warning? (not sure if that compiles though)

804

yeah we do the same thing for checkCompatibility below so the early return of an incompletely initialized InputFile should be fine

lld/test/MachO/invalid/incompatible-arch.s

7

this should be no_fatal_warnings_lld too, otherwise we'll get an error regardless of whether -arch_errors_fatal is passed

[keith]

Improve test, deduplicate string

[keith]

lld/MachO/InputFiles.cpp

793

I couldn't get a version of assigning the functions to a variable to work due to reference to overloaded function could not be resolved, I might have been doing something wrong?

Either way for now I added a simple lambda to de-duplicate the string, lmk what you think.

Note the whole reason I didn't assign the string to a variable instead was it seems like Twine is prime to use-after-free issues so the string was garbled in the output, clang-tidy also warned about that.

[int3]

lld/MachO/InputFiles.cpp

793

ah yeah I guess we need to use static_cast to indicate which overload we want. this should work:

auto msg = config->errorForArchMismatch
               ? static_cast<void (*)(const Twine &)>(error)
               : warn;
msg(toString(this) + " has architecture " + getArchitectureName(arch) +
    " which is incompatible with target architecture " +
    getArchitectureName(config->arch()));

[keith]

Improve logic

lld/MachO/InputFiles.cpp

793

Ah thanks, I tried wrapping the whole ternary in the static_cast, but this works

[keith]

Remove whitespace

lld/MachO/Config.h

struct Configuration {
   llvm::StringRef thinLTOJobs;
   llvm::StringRef umbrella;
   uint32_t ltoo = 2;
   llvm::CachePruningPolicy thinLTOCachePolicy;
   llvm::StringRef thinLTOCacheDir;
   bool deadStripDylibs = false;
   bool demangle = false;
   bool deadStrip = false;
+  bool errorForArchMismatch = false;
   PlatformInfo platformInfo;
   NamespaceKind namespaceKind = NamespaceKind::twolevel;
   UndefinedSymbolTreatment undefinedSymbolTreatment =
       UndefinedSymbolTreatment::error;
   ICFLevel icfLevel = ICFLevel::none;
   llvm::MachO::HeaderFileType outputType;
   std::vector<llvm::StringRef> systemLibraryRoots;
   std::vector<llvm::StringRef> librarySearchPaths;

lld/MachO/Driver.cpp

bool macho::link(ArrayRef<const char *> argsArr, bool canExitEarly,
   config->headerPadMaxInstallNames =
       args.hasArg(OPT_headerpad_max_install_names);
   config->printDylibSearch =
       args.hasArg(OPT_print_dylib_search) || getenv("RC_TRACE_DYLIB_SEARCHING");
   config->printEachFile = args.hasArg(OPT_t);
   config->printWhyLoad = args.hasArg(OPT_why_load);
   config->omitDebugInfo = args.hasArg(OPT_S);
   config->outputType = getOutputType(args);
+  config->errorForArchMismatch = args.hasArg(OPT_arch_errors_fatal);
   if (const Arg *arg = args.getLastArg(OPT_bundle_loader)) {
     if (config->outputType != MH_BUNDLE)
       error("-bundle_loader can only be used with MachO bundle output");
     addFile(arg->getValue(), ForceLoad::Default, /*isExplicit=*/false,
             /*isBundleLoader=*/true);
   }
   if (const Arg *arg = args.getLastArg(OPT_umbrella)) {
     if (config->outputType != MH_DYLIB)

lld/MachO/InputFiles.cpp

template <class LP> void ObjFile::parse() {
   using Section = typename LP::section;
   using NList = typename LP::nlist;
 
   auto *buf = reinterpret_cast<const uint8_t *>(mb.getBufferStart());
   auto *hdr = reinterpret_cast<const Header *>(mb.getBufferStart());
 
   Architecture arch = getArchitectureFromCpuType(hdr->cputype, hdr->cpusubtype);
   if (arch != config->arch()) {
-    error(toString(this) + " has architecture " + getArchitectureName(arch) +
+    auto post = [&](bool fail, const Twine &message) -> void {
+      if (fail)
+        error(message);
+      else
+        warn(message);
+    };
+
+    post(config->errorForArchMismatch,
+         toString(this) + " has architecture " + getArchitectureName(arch) +
              " which is incompatible with target architecture " +
              getArchitectureName(config->arch()));
+
     return;
   }
 
   if (!checkCompatibility(this))
     return;
 
   for (auto *cmd : findCommands<linker_option_command>(hdr, LC_LINKER_OPTION)) {
     StringRef data{reinterpret_cast<const char *>(cmd + 1),
                    cmd->cmdsize - sizeof(linker_option_command)};

lld/MachO/Options.td

def force_cpusubtype_ALL : Flag<["-"], "force_cpusubtype_ALL">,
     Flags<[HelpHidden]>,
     Group<grp_rare>;
 def no_arch_warnings : Flag<["-"], "no_arch_warnings">,
     HelpText<"Suppresses warnings about inputs whose architecture does not match the -arch option">,
     Flags<[HelpHidden]>,
     Group<grp_rare>;
 def arch_errors_fatal : Flag<["-"], "arch_errors_fatal">,
     HelpText<"Escalate to errors any warnings about inputs whose architecture does not match the -arch option">,
-    Flags<[HelpHidden]>,
     Group<grp_rare>;
 def e : Separate<["-"], "e">,
     MetaVarName<"<symbol>">,
     HelpText<"Make <symbol> the entry point of an executable (default is \"start\" from crt1.o)">,
     Group<grp_rare>;
 def w : Flag<["-"], "w">,
     HelpText<"Suppress all warnings">,
     Flags<[HelpHidden]>,

lld/test/MachO/invalid/incompatible-arch.s

 # REQUIRES: aarch64, x86
 
 # RUN: rm -rf %t && mkdir -p %t
 
 # RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %s -o %t/test.o
-# RUN: not %lld -arch x86_64 -lSystem %t/test.o -o /dev/null 2>&1 | FileCheck %s -DFILE=%t/test.o
-# CHECK: error: {{.*}}[[FILE]] has architecture arm64 which is incompatible with target architecture x86_64
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t/native.o
+# RUN: not %no_fatal_warnings_lld -arch x86_64 -lSystem %t/test.o -o /dev/null -arch_errors_fatal 2>&1 | FileCheck %s -DFILE=%t/test.o --check-prefix=CHECK-ERROR
+# RUN: %no_fatal_warnings_lld -arch x86_64 -lSystem %t/test.o %t/native.o -o /dev/null 2>&1 | FileCheck %s -DFILE=%t/test.o --check-prefix=CHECK-WARNING
+# RUN: %lld -arch arm64 -lSystem %t/test.o -arch_errors_fatal -o /dev/null
+# CHECK-ERROR: error: {{.*}}[[FILE]] has architecture arm64 which is incompatible with target architecture x86_64
+# CHECK-WARNING: warning: {{.*}}[[FILE]] has architecture arm64 which is incompatible with target architecture x86_64
 
 # RUN: %lld -dylib -arch arm64 -platform_version macOS 10.14 10.15 -o %t/out.dylib %t/test.o
 
 # RUN: not %lld -dylib -arch arm64 -platform_version iOS 9.0 11.0 %t/out.dylib \
 # RUN:  -o /dev/null 2>&1 | FileCheck %s --check-prefix=DYLIB-PLAT
 # DYLIB-PLAT: {{.*}}out.dylib has platform macOS, which is different from target platform iOS
 
 # RUN: %lld -lSystem -dylib -arch arm64 -platform_version macOS 10.14.0 10.15.0 %t/out.dylib -o /dev/null

 # OBJ-PLAT: {{.*}}test_x86.o has platform macOS, which is different from target platform iOS
 
 # RUN: %lld %t/test_x86.o -lSystem -arch x86_64 -platform_version macOS 10.15.0 10.15.0 -o /dev/null
 
 # RUN: %no_fatal_warnings_lld %t/test_x86.o -lSystem -arch x86_64 -platform_version macOS 10.14.0 10.15.0 \
 # RUN:  -o /dev/null 2>&1 | FileCheck %s --check-prefix=OBJ-VERSION
 # OBJ-VERSION: warning: {{.*}}test_x86.o has version 10.15.0, which is newer than target minimum of 10.14.0
 
-## Test that simulators platforms are compat with their simulatees.   
+## Test that simulators platforms are compat with their simulatees.
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-ios14.0 %s -o %t/test_x86_ios.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-ios14.0-simulator %s -o %t/test_x86_ios_sim.o
 
 # RUN: %lld -dylib -platform_version ios-simulator 14.0.0 14.0.0 %t/test_x86_ios.o -o /dev/null
 # RUN: %lld -dylib -platform_version ios 14.0.0 14.0.0 %t/test_x86_ios_sim.o -o /dev/null
 
 # RUN: not %lld -dylib  -platform_version watchos-simulator 14.0.0 14.0.0 %t/test_x86_ios.o \
 # RUN:  -o /dev/null 2>&1 | FileCheck %s --check-prefix=CROSS-SIM
 # CROSS-SIM: {{.*}}test_x86_ios.o has platform iOS, which is different from target platform watchOS Simulator
 # RUN: not %lld -dylib  -platform_version watchos-simulator 14.0.0 14.0.0 %t/test_x86_ios_sim.o \
 # RUN:  -o /dev/null 2>&1 | FileCheck %s --check-prefix=CROSS-SIM2
 # CROSS-SIM2: {{.*}}test_x86_ios_sim.o has platform iOS Simulator, which is different from target platform watchOS Simulator
-  
-
 .globl _main
 _main:
   ret