[MC/Mach-O] Add support for linker options in Mach-O files.

llvm-svn: 172779

llvm/include/llvm/MC/MCAssembler.h

@@ -849,6 +849,10 @@ private:
   std::vector<IndirectSymbolData> IndirectSymbols;
 
   std::vector<DataRegionData> DataRegions;
+
+  /// The list of linker options to propagate into the object file.
+  std::vector<std::vector<std::string> > LinkerOptions;
+
   /// The set of function symbols for which a .thumb_func directive has
   /// been seen.
   //
@@ -1059,6 +1063,14 @@ public:
 
   size_t indirect_symbol_size() const { return IndirectSymbols.size(); }
 
+  /// @}
+  /// @name Linker Option List Access
+  /// @{
+
+  std::vector<std::vector<std::string> > &getLinkerOptions() {
+    return LinkerOptions;
+  }
+
   /// @}
   /// @name Data Region List Access
   /// @{

llvm/include/llvm/MC/MCMachObjectWriter.h

@@ -196,6 +196,8 @@ public:
   void WriteLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset,
                                 uint32_t DataSize);
 
+  void WriteLinkerOptionsLoadCommand(const std::vector<std::string> &Options);
+
   // FIXME: We really need to improve the relocation validation. Basically, we
   // want to implement a separate computation which evaluates the relocation
   // entry as the linker would, and verifies that the resultant fixup value is

llvm/include/llvm/Object/MachOFormat.h

@@ -148,7 +148,8 @@ namespace macho {
     LCT_CodeSignature = 0x1d,
     LCT_SegmentSplitInfo = 0x1e,
     LCT_FunctionStarts = 0x26,
-    LCT_DataInCode = 0x29
+    LCT_DataInCode = 0x29,
+    LCT_LinkerOptions = 0x2D
   };
 
   /// \brief Load command structure.
@@ -236,6 +237,14 @@ namespace macho {
     uint32_t DataSize;
   };
 
+  struct LinkerOptionsLoadCommand {
+    uint32_t Type;
+    uint32_t Size;
+    uint32_t Count;
+    // Load command is followed by Count number of zero-terminated UTF8 strings,
+    // and then zero-filled to be 4-byte aligned.
+  };
+
   /// @}
   /// @name Section Data
   /// @{

llvm/include/llvm/Object/MachOObject.h

@@ -153,6 +153,9 @@ public:
   void ReadLinkeditDataLoadCommand(
     const LoadCommandInfo &LCI,
     InMemoryStruct<macho::LinkeditDataLoadCommand> &Res) const;
+  void ReadLinkerOptionsLoadCommand(
+    const LoadCommandInfo &LCI,
+    InMemoryStruct<macho::LinkerOptionsLoadCommand> &Res) const;
   void ReadIndirectSymbolTableEntry(
     const macho::DysymtabLoadCommand &DLC,
     unsigned Index,

llvm/lib/MC/MCMachOStreamer.cpp

@@ -48,6 +48,7 @@ public:
   virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
                                    MCSymbol *EHSymbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
+  virtual void EmitLinkerOptions(ArrayRef<std::string> Options);
   virtual void EmitDataRegion(MCDataRegionType Kind);
   virtual void EmitThumbFunc(MCSymbol *Func);
   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
@@ -178,6 +179,10 @@ void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
   }
 }
 
+void MCMachOStreamer::EmitLinkerOptions(ArrayRef<std::string> Options) {
+  getAssembler().getLinkerOptions().push_back(Options);
+}
+
 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
   switch (Kind) {
   case MCDR_DataRegion:

llvm/lib/MC/MachObjectWriter.cpp

@@ -376,6 +376,39 @@ void MachObjectWriter::WriteLinkeditLoadCommand(uint32_t Type,
   assert(OS.tell() - Start == macho::LinkeditLoadCommandSize);
 }
 
+static unsigned ComputeLinkerOptionsLoadCommandSize(
+  const std::vector<std::string> &Options)
+{
+  unsigned Size = sizeof(macho::LinkerOptionsLoadCommand);
+  for (unsigned i = 0, e = Options.size(); i != e; ++i)
+    Size += Options[i].size() + 1;
+  return RoundUpToAlignment(Size, 4);
+}
+
+void MachObjectWriter::WriteLinkerOptionsLoadCommand(
+  const std::vector<std::string> &Options)
+{
+  unsigned Size = ComputeLinkerOptionsLoadCommandSize(Options);
+  uint64_t Start = OS.tell();
+  (void) Start;
+
+  Write32(macho::LCT_LinkerOptions);
+  Write32(Size);
+  Write32(Options.size());
+  uint64_t BytesWritten = 0;
+  for (unsigned i = 0, e = Options.size(); i != e; ++i) {
+    // Write each string, including the null byte.
+    const std::string &Option = Options[i];
+    WriteBytes(Option.c_str(), Option.size() + 1);
+    BytesWritten += Option.size() + 1;
+  }
+
+  // Pad to a multiple of 4.
+  WriteBytes("", OffsetToAlignment(BytesWritten, 4));
+
+  assert(OS.tell() - Start == Size);
+}
+
 
 void MachObjectWriter::RecordRelocation(const MCAssembler &Asm,
                                         const MCAsmLayout &Layout,
@@ -693,6 +726,13 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
     macho::SegmentLoadCommand64Size + NumSections * macho::Section64Size :
     macho::SegmentLoadCommand32Size + NumSections * macho::Section32Size;
 
+  // Add the data-in-code load command size, if used.
+  unsigned NumDataRegions = Asm.getDataRegions().size();
+  if (NumDataRegions) {
+    ++NumLoadCommands;
+    LoadCommandsSize += macho::LinkeditLoadCommandSize;
+  }
+
   // Add the symbol table load command sizes, if used.
   unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
     UndefinedSymbolData.size();
@@ -702,13 +742,14 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
                          macho::DysymtabLoadCommandSize);
   }
 
-  // Add the data-in-code load command size, if used.
-  unsigned NumDataRegions = Asm.getDataRegions().size();
-  if (NumDataRegions) {
+  // Add the linker option load commands sizes.
+  const std::vector<std::vector<std::string> > &LinkerOptions =
+    Asm.getLinkerOptions();
+  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
     ++NumLoadCommands;
-    LoadCommandsSize += macho::LinkeditLoadCommandSize;
+    LoadCommandsSize += ComputeLinkerOptionsLoadCommandSize(LinkerOptions[i]);
   }
-
+  
   // Compute the total size of the section data, as well as its file size and vm
   // size.
   uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
@@ -799,6 +840,11 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
                              IndirectSymbolOffset, NumIndirectSymbols);
   }
 
+  // Write the linker options load commands.
+  for (unsigned i = 0, e = LinkerOptions.size(); i != e; ++i) {
+    WriteLinkerOptionsLoadCommand(LinkerOptions[i]);
+  }
+
   // Write the actual section data.
   for (MCAssembler::const_iterator it = Asm.begin(),
          ie = Asm.end(); it != ie; ++it) {

llvm/lib/Object/MachOObject.cpp

@@ -258,6 +258,17 @@ void MachOObject::ReadLinkeditDataLoadCommand(const LoadCommandInfo &LCI,
   ReadInMemoryStruct(*this, Buffer->getBuffer(), LCI.Offset, Res);
 }
 
+template<>
+void SwapStruct(macho::LinkerOptionsLoadCommand &Value) {
+  SwapValue(Value.Type);
+  SwapValue(Value.Size);
+  SwapValue(Value.Count);
+}
+void MachOObject::ReadLinkerOptionsLoadCommand(const LoadCommandInfo &LCI,
+                   InMemoryStruct<macho::LinkerOptionsLoadCommand> &Res) const {
+  ReadInMemoryStruct(*this, Buffer->getBuffer(), LCI.Offset, Res);
+}
+
 template<>
 void SwapStruct(macho::IndirectSymbolTableEntry &Value) {
   SwapValue(Value.Index);

llvm/test/MC/MachO/linker-option-2.s

@@ -0,0 +1,25 @@
+// RUN: llvm-mc -n -triple x86_64-apple-darwin10 %s -filetype=obj | macho-dump | FileCheck %s
+
+// CHECK: ('load_commands_size', 104)
+// CHECK: ('load_commands', [
+// CHECK:   # Load Command 1
+// CHECK:  (('command', 45)
+// CHECK:   ('size', 16)
+// CHECK:   ('count', 1)
+// CHECK:   ('_strings', [
+// CHECK: 	"a",
+// CHECK:   ])
+// CHECK:  ),
+// CHECK:   # Load Command 2
+// CHECK:  (('command', 45)
+// CHECK:   ('size', 16)
+// CHECK:   ('count', 2)
+// CHECK:   ('_strings', [
+// CHECK: 	"a",
+// CHECK: 	"b",
+// CHECK:   ])
+// CHECK:  ),
+// CHECK: ])
+
+.linker_option "a"
+.linker_option "a", "b"

llvm/tools/macho-dump/macho-dump.cpp

@@ -337,7 +337,7 @@ static int DumpDataInCodeDataCommand(MachOObject &Obj,
   InMemoryStruct<macho::LinkeditDataLoadCommand> LLC;
   Obj.ReadLinkeditDataLoadCommand(LCI, LLC);
   if (!LLC)
-    return Error("unable to read segment load command");
+    return Error("unable to read data-in-code load command");
 
   outs() << "  ('dataoff', " << LLC->DataOffset << ")\n"
          << "  ('datasize', " << LLC->DataSize << ")\n"
@@ -361,6 +361,31 @@ static int DumpDataInCodeDataCommand(MachOObject &Obj,
   return 0;
 }
 
+static int DumpLinkerOptionsCommand(MachOObject &Obj,
+                                    const MachOObject::LoadCommandInfo &LCI) {
+  InMemoryStruct<macho::LinkerOptionsLoadCommand> LOLC;
+  Obj.ReadLinkerOptionsLoadCommand(LCI, LOLC);
+  if (!LOLC)
+    return Error("unable to read linker options load command");
+
+  outs() << "  ('count', " << LOLC->Count << ")\n"
+         << "  ('_strings', [\n";
+
+  uint64_t DataSize = LOLC->Size - sizeof(macho::LinkerOptionsLoadCommand);
+  StringRef Data = Obj.getData(
+    LCI.Offset + sizeof(macho::LinkerOptionsLoadCommand), DataSize);
+  for (unsigned i = 0; i != LOLC->Count; ++i) {
+    std::pair<StringRef,StringRef> Split = Data.split('\0');
+    outs() << "\t\"";
+    outs().write_escaped(Split.first);
+    outs() << "\",\n";
+    Data = Split.second;
+  }
+  outs() <<"  ])\n";
+
+  return 0;
+}
+
 
 static int DumpLoadCommand(MachOObject &Obj, unsigned Index) {
   const MachOObject::LoadCommandInfo &LCI = Obj.getLoadCommandInfo(Index);
@@ -390,6 +415,9 @@ static int DumpLoadCommand(MachOObject &Obj, unsigned Index) {
   case macho::LCT_DataInCode:
     Res = DumpDataInCodeDataCommand(Obj, LCI);
     break;
+  case macho::LCT_LinkerOptions:
+    Res = DumpLinkerOptionsCommand(Obj, LCI);
+    break;
   default:
     Warning("unknown load command: " + Twine(LCI.Command.Type));
     break;