[llvm-objcopy][NFC] Refactor output target parsing

Summary:
Use an enum instead of string to hold the output file format in Config.InputFormat and Config.OutputFormat. It's essential to support other output file formats other than ELF.

Reviewers: espindola, alexshap, rupprecht, jhenderson

Reviewed By: rupprecht, jhenderson

Subscribers: jyknight, compnerd, emaste, arichardson, fedor.sergeev, jakehehrlich, MaskRay, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63239

llvm-svn: 364254

llvm/tools/llvm-objcopy/CopyConfig.cpp

@@ -277,8 +277,13 @@ static Expected<const MachineInfo &> getMachineInfo(StringRef Arch) {
   return Iter->getValue();
 }
 
+struct TargetInfo {
+  FileFormat Format;
+  MachineInfo Machine;
+};
+
 // FIXME: consolidate with the bfd parsing used by lld.
-static const StringMap<MachineInfo> OutputFormatMap{
+static const StringMap<MachineInfo> TargetMap{
     // Name, {EMachine, 64bit, LittleEndian}
     // x86
     {"elf32-i386", {ELF::EM_386, false, true}},
@@ -312,18 +317,28 @@ static const StringMap<MachineInfo> OutputFormatMap{
     {"elf32-sparcel", {ELF::EM_SPARC, false, true}},
 };
 
-static Expected<MachineInfo> getOutputFormatMachineInfo(StringRef Format) {
-  StringRef OriginalFormat = Format;
-  bool IsFreeBSD = Format.consume_back("-freebsd");
-  auto Iter = OutputFormatMap.find(Format);
-  if (Iter == std::end(OutputFormatMap))
+static Expected<TargetInfo>
+getOutputTargetInfoByTargetName(StringRef TargetName) {
+  StringRef OriginalTargetName = TargetName;
+  bool IsFreeBSD = TargetName.consume_back("-freebsd");
+  auto Iter = TargetMap.find(TargetName);
+  if (Iter == std::end(TargetMap))
     return createStringError(errc::invalid_argument,
                              "invalid output format: '%s'",
-                             OriginalFormat.str().c_str());
+                             OriginalTargetName.str().c_str());
   MachineInfo MI = Iter->getValue();
   if (IsFreeBSD)
     MI.OSABI = ELF::ELFOSABI_FREEBSD;
-  return {MI};
+
+  FileFormat Format;
+  if (TargetName.startswith("elf"))
+    Format = FileFormat::ELF;
+  else
+    // This should never happen because `TargetName` is valid (it certainly
+    // exists in the TargetMap).
+    llvm_unreachable("unknown target prefix");
+
+  return {TargetInfo{Format, MI}};
 }
 
 static Error addSymbolsFromFile(std::vector<NameOrRegex> &Symbols,
@@ -445,14 +460,23 @@ Expected<DriverConfig> parseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
         "--target cannot be used with --input-target or --output-target");
 
   bool UseRegex = InputArgs.hasArg(OBJCOPY_regex);
+  StringRef InputFormat, OutputFormat;
   if (InputArgs.hasArg(OBJCOPY_target)) {
-    Config.InputFormat = InputArgs.getLastArgValue(OBJCOPY_target);
-    Config.OutputFormat = InputArgs.getLastArgValue(OBJCOPY_target);
+    InputFormat = InputArgs.getLastArgValue(OBJCOPY_target);
+    OutputFormat = InputArgs.getLastArgValue(OBJCOPY_target);
   } else {
-    Config.InputFormat = InputArgs.getLastArgValue(OBJCOPY_input_target);
-    Config.OutputFormat = InputArgs.getLastArgValue(OBJCOPY_output_target);
+    InputFormat = InputArgs.getLastArgValue(OBJCOPY_input_target);
+    OutputFormat = InputArgs.getLastArgValue(OBJCOPY_output_target);
   }
-  if (Config.InputFormat == "binary") {
+
+  // FIXME:  Currently, we ignore the target for non-binary/ihex formats
+  // explicitly specified by -I option (e.g. -Ielf32-x86-64) and guess the
+  // format by llvm::object::createBinary regardless of the option value.
+  Config.InputFormat = StringSwitch<FileFormat>(InputFormat)
+                           .Case("binary", FileFormat::Binary)
+                           .Case("ihex", FileFormat::IHex)
+                           .Default(FileFormat::Unspecified);
+  if (Config.InputFormat == FileFormat::Binary) {
     auto BinaryArch = InputArgs.getLastArgValue(OBJCOPY_binary_architecture);
     if (BinaryArch.empty())
       return createStringError(
@@ -463,12 +487,17 @@ Expected<DriverConfig> parseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
       return MI.takeError();
     Config.BinaryArch = *MI;
   }
-  if (!Config.OutputFormat.empty() && Config.OutputFormat != "binary" &&
-      Config.OutputFormat != "ihex") {
-    Expected<MachineInfo> MI = getOutputFormatMachineInfo(Config.OutputFormat);
-    if (!MI)
-      return MI.takeError();
-    Config.OutputArch = *MI;
+
+  Config.OutputFormat = StringSwitch<FileFormat>(OutputFormat)
+                            .Case("binary", FileFormat::Binary)
+                            .Case("ihex", FileFormat::IHex)
+                            .Default(FileFormat::Unspecified);
+  if (Config.OutputFormat == FileFormat::Unspecified && !OutputFormat.empty()) {
+    Expected<TargetInfo> Target = getOutputTargetInfoByTargetName(OutputFormat);
+    if (!Target)
+      return Target.takeError();
+    Config.OutputFormat = Target->Format;
+    Config.OutputArch = Target->Machine;
   }
 
   if (auto Arg = InputArgs.getLastArg(OBJCOPY_compress_debug_sections,

llvm/tools/llvm-objcopy/CopyConfig.h

@@ -26,6 +26,13 @@
 namespace llvm {
 namespace objcopy {
 
+enum class FileFormat {
+  Unspecified,
+  ELF,
+  Binary,
+  IHex,
+};
+
 // This type keeps track of the machine info for various architectures. This
 // lets us map architecture names to ELF types and the e_machine value of the
 // ELF file.
@@ -104,9 +111,9 @@ struct NewSymbolInfo {
 struct CopyConfig {
   // Main input/output options
   StringRef InputFilename;
-  StringRef InputFormat;
+  FileFormat InputFormat;
   StringRef OutputFilename;
-  StringRef OutputFormat;
+  FileFormat OutputFormat;
 
   // Only applicable for --input-format=binary
   MachineInfo BinaryArch;

llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp

@@ -154,12 +154,14 @@ static std::unique_ptr<Writer> createELFWriter(const CopyConfig &Config,
 static std::unique_ptr<Writer> createWriter(const CopyConfig &Config,
                                             Object &Obj, Buffer &Buf,
                                             ElfType OutputElfType) {
-  using Functor = std::function<std::unique_ptr<Writer>()>;
-  return StringSwitch<Functor>(Config.OutputFormat)
-      .Case("binary", [&] { return llvm::make_unique<BinaryWriter>(Obj, Buf); })
-      .Case("ihex", [&] { return llvm::make_unique<IHexWriter>(Obj, Buf); })
-      .Default(
-          [&] { return createELFWriter(Config, Obj, Buf, OutputElfType); })();
+  switch (Config.OutputFormat) {
+  case FileFormat::Binary:
+    return llvm::make_unique<BinaryWriter>(Obj, Buf);
+  case FileFormat::IHex:
+    return llvm::make_unique<IHexWriter>(Obj, Buf);
+  default:
+    return createELFWriter(Config, Obj, Buf, OutputElfType);
+  }
 }
 
 template <class ELFT>

llvm/tools/llvm-objcopy/llvm-objcopy.cpp

@@ -140,11 +140,16 @@ static Error executeObjcopyOnIHex(const CopyConfig &Config, MemoryBuffer &In,
 /// of the output specified by the command line options.
 static Error executeObjcopyOnRawBinary(const CopyConfig &Config,
                                        MemoryBuffer &In, Buffer &Out) {
-  // TODO: llvm-objcopy should parse CopyConfig.OutputFormat to recognize
-  // formats other than ELF / "binary" and invoke
-  // elf::executeObjcopyOnRawBinary, macho::executeObjcopyOnRawBinary or
-  // coff::executeObjcopyOnRawBinary accordingly.
-  return elf::executeObjcopyOnRawBinary(Config, In, Out);
+  switch (Config.OutputFormat) {
+  case FileFormat::ELF:
+  // FIXME: Currently, we call elf::executeObjcopyOnRawBinary even if the
+  // output format is binary/ihex or it's not given. This behavior differs from
+  // GNU objcopy. See https://bugs.llvm.org/show_bug.cgi?id=42171 for details.
+  case FileFormat::Binary:
+  case FileFormat::IHex:
+  case FileFormat::Unspecified:
+    return elf::executeObjcopyOnRawBinary(Config, In, Out);
+  }
 }
 
 /// The function executeObjcopyOnBinary does the dispatch based on the format
@@ -224,10 +229,17 @@ static Error executeObjcopy(const CopyConfig &Config) {
       return createFileError(Config.InputFilename, EC);
 
   typedef Error (*ProcessRawFn)(const CopyConfig &, MemoryBuffer &, Buffer &);
-  auto ProcessRaw = StringSwitch<ProcessRawFn>(Config.InputFormat)
-                        .Case("binary", executeObjcopyOnRawBinary)
-                        .Case("ihex", executeObjcopyOnIHex)
-                        .Default(nullptr);
+  ProcessRawFn ProcessRaw;
+  switch (Config.InputFormat) {
+  case FileFormat::Binary:
+    ProcessRaw = executeObjcopyOnRawBinary;
+    break;
+  case FileFormat::IHex:
+    ProcessRaw = executeObjcopyOnIHex;
+    break;
+  default:
+    ProcessRaw = nullptr;
+  }
 
   if (ProcessRaw) {
     auto BufOrErr = MemoryBuffer::getFileOrSTDIN(Config.InputFilename);