3 files changed, 436 insertions, 3 deletions

diff --git a/llvm/tools/dsymutil/DwarfLinker.cpp b/llvm/tools/dsymutil/DwarfLinker.cpp
index 0be12375b26..eece3a6d8be 100644
--- a/llvm/tools/dsymutil/DwarfLinker.cpp
+++ b/llvm/tools/dsymutil/DwarfLinker.cpp
@@ -10,6 +10,7 @@
 #include "BinaryHolder.h"
 #include "DebugMap.h"
 #include "dsymutil.h"
+#include "MachOUtils.h"
 #include "NonRelocatableStringpool.h"
 #include "llvm/ADT/IntervalMap.h"
 #include "llvm/ADT/StringMap.h"
@@ -475,7 +476,7 @@ public:
   bool init(Triple TheTriple, StringRef OutputFilename);
 
   /// \brief Dump the file to the disk.
-  bool finish();
+  bool finish(const DebugMap &);
 
   AsmPrinter &getAsmPrinter() const { return *Asm; }
 
@@ -617,7 +618,10 @@ bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) {
   return true;
 }
 
-bool DwarfStreamer::finish() {
+bool DwarfStreamer::finish(const DebugMap &DM) {
+  if (DM.getTriple().isOSDarwin() && !DM.getBinaryPath().empty())
+    return MachOUtils::generateDsymCompanion(DM, *MS, *OutFile);
+
   MS->Finish();
   return true;
 }
@@ -3041,7 +3045,7 @@ bool DwarfLinker::link(const DebugMap &Map) {
     Streamer->emitStrings(StringPool);
   }
 
-  return Options.NoOutput ? true : Streamer->finish();
+  return Options.NoOutput ? true : Streamer->finish(Map);
 }
 }
 
diff --git a/llvm/tools/dsymutil/MachOUtils.cpp b/llvm/tools/dsymutil/MachOUtils.cpp
index 8f4d2610b8f..e46eb7951bc 100644
--- a/llvm/tools/dsymutil/MachOUtils.cpp
+++ b/llvm/tools/dsymutil/MachOUtils.cpp
@@ -8,7 +8,16 @@
 //===----------------------------------------------------------------------===//
 
 #include "MachOUtils.h"
+#include "BinaryHolder.h"
+#include "DebugMap.h"
 #include "dsymutil.h"
+#include "NonRelocatableStringpool.h"
+#include "llvm/MC/MCSectionMachO.h"
+#include "llvm/MC/MCAsmLayout.h"
+#include "llvm/MC/MCSectionMachO.h"
+#include "llvm/MC/MCObjectStreamer.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Object/MachO.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/raw_ostream.h"
@@ -88,6 +97,420 @@ bool generateUniversalBinary(SmallVectorImpl<ArchAndFilename> &ArchFiles,
 
   return Options.NoOutput ? true : runLipo(Args);
 }
+
+// Return a MachO::segment_command_64 that holds the same values as
+// the passed MachO::segment_command. We do that to avoid having to
+// duplicat the logic for 32bits and 64bits segments.
+struct MachO::segment_command_64 adaptFrom32bits(MachO::segment_command Seg) {
+  MachO::segment_command_64 Seg64;
+  Seg64.cmd = Seg.cmd;
+  Seg64.cmdsize = Seg.cmdsize;
+  memcpy(Seg64.segname, Seg.segname, sizeof(Seg.segname));
+  Seg64.vmaddr = Seg.vmaddr;
+  Seg64.vmsize = Seg.vmsize;
+  Seg64.fileoff = Seg.fileoff;
+  Seg64.filesize = Seg.filesize;
+  Seg64.maxprot = Seg.maxprot;
+  Seg64.initprot = Seg.initprot;
+  Seg64.nsects = Seg.nsects;
+  Seg64.flags = Seg.flags;
+  return Seg64;
+}
+
+// Iterate on all \a Obj segments, and apply \a Handler to them.
+template <typename FunctionTy>
+static void iterateOnSegments(const object::MachOObjectFile &Obj,
+                              FunctionTy Handler) {
+  for (const auto &LCI : Obj.load_commands()) {
+    MachO::segment_command_64 Segment;
+    if (LCI.C.cmd == MachO::LC_SEGMENT)
+      Segment = adaptFrom32bits(Obj.getSegmentLoadCommand(LCI));
+    else if (LCI.C.cmd == MachO::LC_SEGMENT_64)
+      Segment = Obj.getSegment64LoadCommand(LCI);
+    else
+      continue;
+
+    Handler(Segment);
+  }
+}
+
+// Transfer the symbols described by \a NList to \a NewSymtab which is
+// just the raw contents of the symbol table for the dSYM companion file.
+// \returns whether the symbol was tranfered or not.
+template <typename NListTy>
+static bool transferSymbol(NListTy NList, bool IsLittleEndian,
+                           StringRef Strings, SmallVectorImpl<char> &NewSymtab,
+                           NonRelocatableStringpool &NewStrings,
+                           bool &InDebugNote) {
+  // Do not transfer undefined symbols, we want real addresses.
+  if ((NList.n_type & MachO::N_TYPE) == MachO::N_UNDF)
+    return false;
+
+  StringRef Name = StringRef(Strings.begin() + NList.n_strx);
+  if (InDebugNote) {
+    InDebugNote =
+        (NList.n_type != MachO::N_SO) || (!Name.empty() && Name[0] != '\0');
+    return false;
+  } else if (NList.n_type == MachO::N_SO) {
+    InDebugNote = true;
+    return false;
+  }
+
+  // FIXME: The + 1 is here to mimic dsymutil-classic that has 2 empty
+  // strings at the start of the generated string table (There is
+  // corresponding code in the string table emission).
+  NList.n_strx = NewStrings.getStringOffset(Name) + 1;
+  if (IsLittleEndian != sys::IsLittleEndianHost)
+    MachO::swapStruct(NList);
+
+  NewSymtab.append((char *)&NList, (char *)(&NList + 1));
+  return true;
+}
+
+// Wrapper around transferSymbol to transfer all of \a Obj symbols
+// to \a NewSymtab. This function does not write in the output file.
+// \returns the number of symbols in \a NewSymtab.
+static unsigned transferSymbols(const object::MachOObjectFile &Obj,
+                                SmallVectorImpl<char> &NewSymtab,
+                                NonRelocatableStringpool &NewStrings) {
+  unsigned Syms = 0;
+  StringRef Strings = Obj.getStringTableData();
+  bool IsLittleEndian = Obj.isLittleEndian();
+  bool InDebugNote = false;
+
+  if (Obj.is64Bit()) {
+    for (const object::SymbolRef &Symbol : Obj.symbols()) {
+      object::DataRefImpl DRI = Symbol.getRawDataRefImpl();
+      if (transferSymbol(Obj.getSymbol64TableEntry(DRI), IsLittleEndian,
+                         Strings, NewSymtab, NewStrings, InDebugNote))
+        ++Syms;
+    }
+  } else {
+    for (const object::SymbolRef &Symbol : Obj.symbols()) {
+      object::DataRefImpl DRI = Symbol.getRawDataRefImpl();
+      if (transferSymbol(Obj.getSymbolTableEntry(DRI), IsLittleEndian, Strings,
+                         NewSymtab, NewStrings, InDebugNote))
+        ++Syms;
+    }
+  }
+  return Syms;
+}
+
+static MachO::section
+getSection(const object::MachOObjectFile &Obj,
+           const MachO::segment_command &Seg,
+           const object::MachOObjectFile::LoadCommandInfo &LCI, unsigned Idx) {
+  return Obj.getSection(LCI, Idx);
+}
+
+static MachO::section_64
+getSection(const object::MachOObjectFile &Obj,
+           const MachO::segment_command_64 &Seg,
+           const object::MachOObjectFile::LoadCommandInfo &LCI, unsigned Idx) {
+  return Obj.getSection64(LCI, Idx);
+}
+
+// Transfer \a Segment from \a Obj to the output file. This calls into \a Writer
+// to write these load commands directly in the output file at the current
+// position.
+// The function also tries to find a hole in the address map to fit the __DWARF
+// segment of \a DwarfSegmentSize size. \a EndAddress is updated to point at the
+// highest segment address.
+// When the __LINKEDIT segment is transfered, its offset and size are set resp.
+// to \a LinkeditOffset and \a LinkeditSize.
+template <typename SegmentTy>
+static void transferSegmentAndSections(
+    const object::MachOObjectFile::LoadCommandInfo &LCI, SegmentTy Segment,
+    const object::MachOObjectFile &Obj, MCObjectWriter &Writer,
+    uint64_t LinkeditOffset, uint64_t LinkeditSize, uint64_t DwarfSegmentSize,
+    uint64_t &GapForDwarf, uint64_t &EndAddress) {
+  if (StringRef("__DWARF") == Segment.segname)
+    return;
+
+  Segment.fileoff = Segment.filesize = 0;
+
+  if (StringRef("__LINKEDIT") == Segment.segname) {
+    Segment.fileoff = LinkeditOffset;
+    Segment.filesize = LinkeditSize;
+  }
+
+  // Check if the end address of the last segment and our current
+  // start address leave a sufficient gap to store the __DWARF
+  // segment.
+  uint64_t PrevEndAddress = EndAddress;
+  EndAddress = RoundUpToAlignment(EndAddress, 0x1000);
+  if (GapForDwarf == UINT64_MAX && Segment.vmaddr > EndAddress &&
+      Segment.vmaddr - EndAddress >= DwarfSegmentSize)
+    GapForDwarf = EndAddress;
+
+  // The segments are not necessarily sorted by their vmaddr.
+  EndAddress =
+      std::max<uint64_t>(PrevEndAddress, Segment.vmaddr + Segment.vmsize);
+  if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
+    MachO::swapStruct(Segment);
+  Writer.writeBytes(
+      StringRef(reinterpret_cast<char *>(&Segment), sizeof(Segment)));
+  for (unsigned i = 0; i < Segment.nsects; ++i) {
+    auto Sect = getSection(Obj, Segment, LCI, i);
+    Sect.offset = Sect.reloff = Sect.nreloc = 0;
+    if (Obj.isLittleEndian() != sys::IsLittleEndianHost)
+      MachO::swapStruct(Sect);
+    Writer.writeBytes(StringRef(reinterpret_cast<char *>(&Sect), sizeof(Sect)));
+  }
+}
+
+// Write the __DWARF segment load command to the output file.
+static void createDwarfSegment(uint64_t VMAddr, uint64_t FileOffset,
+                               uint64_t FileSize, unsigned NumSections,
+                               MCAsmLayout &Layout, MachObjectWriter &Writer) {
+  Writer.writeSegmentLoadCommand("__DWARF", NumSections, VMAddr,
+                                 RoundUpToAlignment(FileSize, 0x1000),
+                                 FileOffset, FileSize, /* MaxProt */ 7,
+                                 /* InitProt =*/3);
+
+  for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
+    MCSection *Sec = Layout.getSectionOrder()[i];
+    if (Sec->begin() == Sec->end() || !Layout.getSectionFileSize(Sec))
+      continue;
+
+    unsigned Align = Sec->getAlignment();
+    if (Align > 1) {
+      VMAddr = RoundUpToAlignment(VMAddr, Align);
+      FileOffset = RoundUpToAlignment(FileOffset, Align);
+    }
+    Writer.writeSection(Layout, *Sec, VMAddr, FileOffset, 0, 0, 0);
+
+    FileOffset += Layout.getSectionAddressSize(Sec);
+    VMAddr += Layout.getSectionAddressSize(Sec);
+  }
+}
+
+static bool isExecutable(const object::MachOObjectFile &Obj) {
+  if (Obj.is64Bit())
+    return Obj.getHeader64().filetype != MachO::MH_OBJECT;
+  else
+    return Obj.getHeader().filetype != MachO::MH_OBJECT;
+}
+
+static bool hasLinkEditSegment(const object::MachOObjectFile &Obj) {
+  bool HasLinkEditSegment = false;
+  iterateOnSegments(Obj, [&](const MachO::segment_command_64 &Segment) {
+    if (StringRef("__LINKEDIT") == Segment.segname)
+      HasLinkEditSegment = true;
+  });
+  return HasLinkEditSegment;
+}
+
+static unsigned segmentLoadCommandSize(bool Is64Bit, unsigned NumSections) {
+  if (Is64Bit)
+    return sizeof(MachO::segment_command_64) +
+           NumSections * sizeof(MachO::section_64);
+
+  return sizeof(MachO::segment_command) + NumSections * sizeof(MachO::section);
+}
+
+// Stream a dSYM companion binary file corresponding to the binary referenced
+// by \a DM to \a OutFile. The passed \a MS MCStreamer is setup to write to
+// \a OutFile and it must be using a MachObjectWriter object to do so.
+bool generateDsymCompanion(const DebugMap &DM, MCStreamer &MS,
+                           raw_fd_ostream &OutFile) {
+  auto &ObjectStreamer = static_cast<MCObjectStreamer &>(MS);
+  MCAssembler &MCAsm = ObjectStreamer.getAssembler();
+  auto &Writer = static_cast<MachObjectWriter &>(MCAsm.getWriter());
+  MCAsmLayout Layout(MCAsm);
+
+  MCAsm.layout(Layout);
+
+  BinaryHolder InputBinaryHolder(false);
+  auto ErrOrObjs = InputBinaryHolder.GetObjectFiles(DM.getBinaryPath());
+  if (auto Error = ErrOrObjs.getError())
+    return error(Twine("opening ") + DM.getBinaryPath() + ": " +
+                     Error.message(),
+                 "output file streaming");
+
+  auto ErrOrInputBinary =
+      InputBinaryHolder.GetAs<object::MachOObjectFile>(DM.getTriple());
+  if (auto Error = ErrOrInputBinary.getError())
+    return error(Twine("opening ") + DM.getBinaryPath() + ": " +
+                     Error.message(),
+                 "output file streaming");
+  auto &InputBinary = *ErrOrInputBinary;
+
+  bool Is64Bit = Writer.is64Bit();
+  MachO::symtab_command SymtabCmd = InputBinary.getSymtabLoadCommand();
+
+  // Get UUID.
+  MachO::uuid_command UUIDCmd;
+  memset(&UUIDCmd, 0, sizeof(UUIDCmd));
+  UUIDCmd.cmd = MachO::LC_UUID;
+  UUIDCmd.cmdsize = sizeof(MachO::uuid_command);
+  for (auto &LCI : InputBinary.load_commands()) {
+    if (LCI.C.cmd == MachO::LC_UUID) {
+      UUIDCmd = InputBinary.getUuidCommand(LCI);
+      break;
+    }
+  }
+
+  // Compute the number of load commands we will need.
+  unsigned LoadCommandSize = 0;
+  unsigned NumLoadCommands = 0;
+  // We will copy the UUID if there is one.
+  if (UUIDCmd.cmd != 0) {
+    ++NumLoadCommands;
+    LoadCommandSize += sizeof(MachO::uuid_command);
+  }
+
+  // If we have a valid symtab to copy, do it.
+  bool ShouldEmitSymtab =
+      isExecutable(InputBinary) && hasLinkEditSegment(InputBinary);
+  if (ShouldEmitSymtab) {
+    LoadCommandSize += sizeof(MachO::symtab_command);
+    ++NumLoadCommands;
+  }
+
+  unsigned HeaderSize =
+      Is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
+  // We will copy every segment that isn't __DWARF.
+  iterateOnSegments(InputBinary, [&](const MachO::segment_command_64 &Segment) {
+    if (StringRef("__DWARF") == Segment.segname)
+      return;
+
+    ++NumLoadCommands;
+    LoadCommandSize += segmentLoadCommandSize(Is64Bit, Segment.nsects);
+  });
+
+  // We will add our own brand new __DWARF segment if we have debug
+  // info.
+  unsigned NumDwarfSections = 0;
+  uint64_t DwarfSegmentSize = 0;
+
+  for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
+    MCSection *Sec = Layout.getSectionOrder()[i];
+    if (Sec->begin() == Sec->end())
+      continue;
+
+    if (uint64_t Size = Layout.getSectionFileSize(Sec)) {
+      DwarfSegmentSize =
+          RoundUpToAlignment(DwarfSegmentSize, Sec->getAlignment());
+      DwarfSegmentSize += Size;
+      ++NumDwarfSections;
+    }
+  }
+
+  if (NumDwarfSections) {
+    ++NumLoadCommands;
+    LoadCommandSize += segmentLoadCommandSize(Is64Bit, NumDwarfSections);
+  }
+
+  SmallString<0> NewSymtab;
+  NonRelocatableStringpool NewStrings;
+  unsigned NListSize = Is64Bit ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist);
+  unsigned NumSyms = 0;
+  uint64_t NewStringsSize = 0;
+  if (ShouldEmitSymtab) {
+    NewSymtab.reserve(SymtabCmd.nsyms * NListSize / 2);
+    NumSyms = transferSymbols(InputBinary, NewSymtab, NewStrings);
+    NewStringsSize = NewStrings.getSize() + 1;
+  }
+
+  uint64_t SymtabStart = LoadCommandSize;
+  SymtabStart += HeaderSize;
+  SymtabStart = RoundUpToAlignment(SymtabStart, 0x1000);
+
+  // We gathered all the information we need, start emitting the output file.
+  Writer.writeHeader(MachO::MH_DSYM, NumLoadCommands, LoadCommandSize, false);
+
+  // Write the load commands.
+  assert(OutFile.tell() == HeaderSize);
+  if (UUIDCmd.cmd != 0) {
+    Writer.write32(UUIDCmd.cmd);
+    Writer.write32(UUIDCmd.cmdsize);
+    Writer.writeBytes(StringRef((const char *)UUIDCmd.uuid, 16));
+    assert(OutFile.tell() == HeaderSize + sizeof(UUIDCmd));
+  }
+
+  assert(SymtabCmd.cmd && "No symbol table.");
+  uint64_t StringStart = SymtabStart + NumSyms * NListSize;
+  if (ShouldEmitSymtab)
+    Writer.writeSymtabLoadCommand(SymtabStart, NumSyms, StringStart,
+                                  NewStringsSize);
+
+  uint64_t DwarfSegmentStart = StringStart + NewStringsSize;
+  DwarfSegmentStart = RoundUpToAlignment(DwarfSegmentStart, 0x1000);
+
+  // Write the load commands for the segments and sections we 'import' from
+  // the original binary.
+  uint64_t EndAddress = 0;
+  uint64_t GapForDwarf = UINT64_MAX;
+  for (auto &LCI : InputBinary.load_commands()) {
+    if (LCI.C.cmd == MachO::LC_SEGMENT)
+      transferSegmentAndSections(LCI, InputBinary.getSegmentLoadCommand(LCI),
+                                 InputBinary, Writer, SymtabStart,
+                                 StringStart + NewStringsSize - SymtabStart,
+                                 DwarfSegmentSize, GapForDwarf, EndAddress);
+    else if (LCI.C.cmd == MachO::LC_SEGMENT_64)
+      transferSegmentAndSections(LCI, InputBinary.getSegment64LoadCommand(LCI),
+                                 InputBinary, Writer, SymtabStart,
+                                 StringStart + NewStringsSize - SymtabStart,
+                                 DwarfSegmentSize, GapForDwarf, EndAddress);
+  }
+
+  uint64_t DwarfVMAddr = RoundUpToAlignment(EndAddress, 0x1000);
+  uint64_t DwarfVMMax = Is64Bit ? UINT64_MAX : UINT32_MAX;
+  if (DwarfVMAddr + DwarfSegmentSize > DwarfVMMax ||
+      DwarfVMAddr + DwarfSegmentSize < DwarfVMAddr /* Overflow */) {
+    // There is no room for the __DWARF segment at the end of the
+    // address space. Look trhough segments to find a gap.
+    DwarfVMAddr = GapForDwarf;
+    if (DwarfVMAddr == UINT64_MAX)
+      warn("not enough VM space for the __DWARF segment.",
+           "output file streaming");
+  }
+
+  // Write the load command for the __DWARF segment.
+  createDwarfSegment(DwarfVMAddr, DwarfSegmentStart, DwarfSegmentSize,
+                     NumDwarfSections, Layout, Writer);
+
+  assert(OutFile.tell() == LoadCommandSize + HeaderSize);
+  Writer.WriteZeros(SymtabStart - (LoadCommandSize + HeaderSize));
+  assert(OutFile.tell() == SymtabStart);
+
+  // Transfer symbols.
+  if (ShouldEmitSymtab) {
+    Writer.writeBytes(NewSymtab.str());
+    assert(OutFile.tell() == StringStart);
+
+    // Transfer string table.
+    // FIXME: The NonRelocatableStringpool starts with an empty string, but
+    // dsymutil-classic starts the reconstructed string table with 2 of these.
+    // Reproduce that behavior for now (there is corresponding code in
+    // transferSymbol).
+    Writer.WriteZeros(1);
+    typedef NonRelocatableStringpool::MapTy MapTy;
+    for (auto *Entry = NewStrings.getFirstEntry(); Entry;
+         Entry = static_cast<MapTy::MapEntryTy *>(Entry->getValue().second))
+      Writer.writeBytes(
+          StringRef(Entry->getKey().data(), Entry->getKey().size() + 1));
+  }
+
+  assert(OutFile.tell() == StringStart + NewStringsSize);
+
+  // Pad till the Dwarf segment start.
+  Writer.WriteZeros(DwarfSegmentStart - (StringStart + NewStringsSize));
+  assert(OutFile.tell() == DwarfSegmentStart);
+
+  // Emit the Dwarf sections contents.
+  for (const MCSection &Sec : MCAsm) {
+    if (Sec.begin() == Sec.end())
+      continue;
+
+    uint64_t Pos = OutFile.tell();
+    Writer.WriteZeros(RoundUpToAlignment(Pos, Sec.getAlignment()) - Pos);
+    MCAsm.writeSectionData(&Sec, Layout);
+  }
+
+  return true;
+}
 }
 }
 }
diff --git a/llvm/tools/dsymutil/MachOUtils.h b/llvm/tools/dsymutil/MachOUtils.h
index d6b6f3d61c3..9a63645ab4a 100644
--- a/llvm/tools/dsymutil/MachOUtils.h
+++ b/llvm/tools/dsymutil/MachOUtils.h
@@ -13,7 +13,10 @@
 #include "llvm/ADT/StringRef.h"
 
 namespace llvm {
+class MCStreamer;
+class raw_fd_ostream;
 namespace dsymutil {
+class DebugMap;
 struct LinkOptions;
 namespace MachOUtils {
 
@@ -25,6 +28,9 @@ struct ArchAndFilename {
 bool generateUniversalBinary(SmallVectorImpl<ArchAndFilename> &ArchFiles,
                              StringRef OutputFileName, const LinkOptions &);
 
+bool generateDsymCompanion(const DebugMap &DM, MCStreamer &MS,
+                           raw_fd_ostream &OutFile);
+
 std::string getArchName(StringRef Arch);
 }
 }