Revert r153694. It was causing failures in the buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153701 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 516 insertions, 111 deletions

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
index 1318b44542..7130e0e174 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
@@ -21,55 +21,41 @@ using namespace llvm::object;
 
 namespace llvm {
 
-void RuntimeDyldMachO::resolveRelocation(uint8_t *LocalAddress,
-                                         uint64_t FinalAddress,
-                                         uint64_t Value,
-                                         uint32_t Type,
-                                         int64_t Addend) {
-  bool isPCRel = (Type >> 24) & 1;
-  unsigned MachoType = (Type >> 28) & 0xf;
-  unsigned Size = 1 << ((Type >> 25) & 3);
-
-  DEBUG(dbgs() << "resolveRelocation LocalAddress: " << format("%p", LocalAddress)
-        << " FinalAddress: " << format("%p", FinalAddress)
-        << " Value: " << format("%p", Value)
-        << " Addend: " << Addend
-        << " isPCRel: " << isPCRel
-        << " MachoType: " << MachoType
-        << " Size: " << Size
-        << "\n");
-
+bool RuntimeDyldMachO::
+resolveRelocation(uint8_t *LocalAddress,
+                  uint64_t FinalAddress,
+                  uint64_t Value,
+                  bool isPCRel,
+                  unsigned Type,
+                  unsigned Size,
+                  int64_t Addend) {
   // This just dispatches to the proper target specific routine.
-  switch (Arch) {
+  switch (CPUType) {
   default: llvm_unreachable("Unsupported CPU type!");
-  case Triple::x86_64:
-    resolveX86_64Relocation(LocalAddress,
-                            FinalAddress,
-                            (uintptr_t)Value,
-                            isPCRel,
-                            MachoType,
-                            Size,
-                            Addend);
-    break;
-  case Triple::x86:
-    resolveI386Relocation(LocalAddress,
+  case mach::CTM_i386:
+    return resolveI386Relocation(LocalAddress,
                                  FinalAddress,
                                  (uintptr_t)Value,
                                  isPCRel,
                                  Type,
                                  Size,
                                  Addend);
-    break;
-  case Triple::arm:    // Fall through.
-  case Triple::thumb:
-    resolveARMRelocation(LocalAddress,
-                         FinalAddress,
-                         (uintptr_t)Value,
-                         isPCRel,
-                         MachoType,
-                         Size,
-                         Addend);
-    break;
+  case mach::CTM_x86_64:
+    return resolveX86_64Relocation(LocalAddress,
+                                   FinalAddress,
+                                   (uintptr_t)Value,
+                                   isPCRel,
+                                   Type,
+                                   Size,
+                                   Addend);
+  case mach::CTM_ARM:
+    return resolveARMRelocation(LocalAddress,
+                                FinalAddress,
+                                (uintptr_t)Value,
+                                isPCRel,
+                                Type,
+                                Size,
+                                Addend);
   }
 }
 
@@ -204,84 +190,503 @@ resolveARMRelocation(uint8_t *LocalAddress,
   return false;
 }
 
-void RuntimeDyldMachO::processRelocationRef(const ObjRelocationInfo &Rel,
-                                            const ObjectFile &Obj,
-                                            ObjSectionToIDMap &ObjSectionToID,
-                                            LocalSymbolMap &Symbols,
-                                            StubMap &Stubs) {
-
-  uint32_t RelType = (uint32_t) (Rel.Type & 0xffffffffL);
-  RelocationValueRef Value;
-  SectionEntry &Section = Sections[Rel.SectionID];
-  uint8_t *Target = Section.Address + Rel.Offset;
-
-  bool isExtern = (RelType >> 27) & 1;
-  if (isExtern) {
-    StringRef TargetName;
-    const SymbolRef &Symbol = Rel.Symbol;
-    Symbol.getName(TargetName);
-    // First look the symbol in object file symbols.
-    LocalSymbolMap::iterator lsi = Symbols.find(TargetName.data());
-    if (lsi != Symbols.end()) {
-      Value.SectionID = lsi->second.first;
-      Value.Addend = lsi->second.second;
-    } else {
-      // Second look the symbol in global symbol table.
-      StringMap<SymbolLoc>::iterator gsi = SymbolTable.find(TargetName.data());
-      if (gsi != SymbolTable.end()) {
-        Value.SectionID = gsi->second.first;
-        Value.Addend = gsi->second.second;
-      } else
-        Value.SymbolName = TargetName.data();
-    }
-  } else {
-    error_code err;
-    uint8_t sectionIndex = static_cast<uint8_t>(RelType & 0xFF);
-    section_iterator si = Obj.begin_sections(),
-                     se = Obj.end_sections();
-    for (uint8_t i = 1; i < sectionIndex; i++) {
-      error_code err;
-      si.increment(err);
-      if (si == se)
-        break;
+bool RuntimeDyldMachO::
+loadSegment32(const MachOObject *Obj,
+              const MachOObject::LoadCommandInfo *SegmentLCI,
+              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
+  // FIXME: This should really be combined w/ loadSegment64. Templatized
+  // function on the 32/64 datatypes maybe?
+  InMemoryStruct<macho::SegmentLoadCommand> SegmentLC;
+  Obj->ReadSegmentLoadCommand(*SegmentLCI, SegmentLC);
+  if (!SegmentLC)
+    return Error("unable to load segment load command");
+
+
+  SmallVector<unsigned, 16> SectionMap;
+  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
+    InMemoryStruct<macho::Section> Sect;
+    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
+    if (!Sect)
+      return Error("unable to load section: '" + Twine(SectNum) + "'");
+
+    // Allocate memory via the MM for the section.
+    uint8_t *Buffer;
+    uint32_t SectionID = Sections.size();
+    if (Sect->Flags == 0x80000400)
+      Buffer = MemMgr->allocateCodeSection(Sect->Size, Sect->Align, SectionID);
+    else
+      Buffer = MemMgr->allocateDataSection(Sect->Size, Sect->Align, SectionID);
+
+    DEBUG(dbgs() << "Loading "
+                 << ((Sect->Flags == 0x80000400) ? "text" : "data")
+                 << " (ID #" << SectionID << ")"
+                 << " '" << Sect->SegmentName << ","
+                 << Sect->Name << "' of size " << Sect->Size
+                 << " to address " << Buffer << ".\n");
+
+    // Copy the payload from the object file into the allocated buffer.
+    uint8_t *Base = (uint8_t*)Obj->getData(SegmentLC->FileOffset,
+                                           SegmentLC->FileSize).data();
+    memcpy(Buffer, Base + Sect->Address, Sect->Size);
+
+    // Remember what got allocated for this SectionID.
+    Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
+    SectionLocalMemToID[Buffer] = SectionID;
+
+    // By default, the load address of a section is its memory buffer.
+    SectionLoadAddress.push_back((uint64_t)Buffer);
+
+    // Keep a map of object file section numbers to corresponding SectionIDs
+    // while processing the file.
+    SectionMap.push_back(SectionID);
+  }
+
+  // Process the symbol table.
+  SmallVector<StringRef, 64> SymbolNames;
+  processSymbols32(Obj, SectionMap, SymbolNames, SymtabLC);
+
+  // Process the relocations for each section we're loading.
+  Relocations.grow(Relocations.size() + SegmentLC->NumSections);
+  Referrers.grow(Referrers.size() + SegmentLC->NumSections);
+  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
+    InMemoryStruct<macho::Section> Sect;
+    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
+    if (!Sect)
+      return Error("unable to load section: '" + Twine(SectNum) + "'");
+    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
+      InMemoryStruct<macho::RelocationEntry> RE;
+      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
+      if (RE->Word0 & macho::RF_Scattered)
+        return Error("NOT YET IMPLEMENTED: scattered relocations.");
+      // Word0 of the relocation is the offset into the section where the
+      // relocation should be applied. We need to translate that into an
+      // offset into a function since that's our atom.
+      uint32_t Offset = RE->Word0;
+      bool isExtern = (RE->Word1 >> 27) & 1;
+
+      // FIXME: Get the relocation addend from the target address.
+      // FIXME: VERY imporant for internal relocations.
+
+      // Figure out the source symbol of the relocation. If isExtern is true,
+      // this relocation references the symbol table, otherwise it references
+      // a section in the same object, numbered from 1 through NumSections
+      // (SectionBases is [0, NumSections-1]).
+      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
+      if (!isExtern) {
+        assert(SourceNum > 0 && "Invalid relocation section number!");
+        unsigned SectionID = SectionMap[SourceNum - 1];
+        unsigned TargetID = SectionMap[SectNum];
+        DEBUG(dbgs() << "Internal relocation at Section #"
+                     << TargetID << " + " << Offset
+                     << " from Section #"
+                     << SectionID << " (Word1: "
+                     << format("0x%x", RE->Word1) << ")\n");
+
+        // Store the relocation information. It will get resolved when
+        // the section addresses are assigned.
+        uint32_t RelocationIndex = Relocations[SectionID].size();
+        Relocations[SectionID].push_back(RelocationEntry(TargetID,
+                                                         Offset,
+                                                         RE->Word1,
+                                                         0 /*Addend*/));
+        Referrers[TargetID].push_back(Referrer(SectionID, RelocationIndex));
+      } else {
+        StringRef SourceName = SymbolNames[SourceNum];
+
+        // Now store the relocation information. Associate it with the source
+        // symbol. Just add it to the unresolved list and let the general
+        // path post-load resolve it if we know where the symbol is.
+        UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
+                                                                    Offset,
+                                                                    RE->Word1,
+                                                                 0 /*Addend*/));
+        DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
+              << " from '" << SourceName << "(Word1: "
+              << format("0x%x", RE->Word1) << ")\n");
+      }
     }
-    assert(si != se && "No section containing relocation!");
-    Value.SectionID = findOrEmitSection(*si, true, ObjSectionToID);
-    Value.Addend = *(const intptr_t *)Target;
-    if (Value.Addend) {
-      // The MachO addend is offset from the current section, we need set it
-      // as offset from destination section
-      Value.Addend += Section.ObjAddress - Sections[Value.SectionID].ObjAddress;
+  }
+
+  // Resolve the addresses of any symbols that were defined in this segment.
+  for (int i = 0, e = SymbolNames.size(); i != e; ++i)
+    resolveSymbol(SymbolNames[i]);
+
+  return false;
+}
+
+
+bool RuntimeDyldMachO::
+loadSegment64(const MachOObject *Obj,
+              const MachOObject::LoadCommandInfo *SegmentLCI,
+              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
+  InMemoryStruct<macho::Segment64LoadCommand> Segment64LC;
+  Obj->ReadSegment64LoadCommand(*SegmentLCI, Segment64LC);
+  if (!Segment64LC)
+    return Error("unable to load segment load command");
+
+
+  SmallVector<unsigned, 16> SectionMap;
+  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
+    InMemoryStruct<macho::Section64> Sect;
+    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
+    if (!Sect)
+      return Error("unable to load section: '" + Twine(SectNum) + "'");
+
+    // Allocate memory via the MM for the section.
+    uint8_t *Buffer;
+    uint32_t SectionID = Sections.size();
+    unsigned Align = 1 << Sect->Align; // .o file has log2 alignment.
+    if (Sect->Flags == 0x80000400)
+      Buffer = MemMgr->allocateCodeSection(Sect->Size, Align, SectionID);
+    else
+      Buffer = MemMgr->allocateDataSection(Sect->Size, Align, SectionID);
+
+    DEBUG(dbgs() << "Loading "
+                 << ((Sect->Flags == 0x80000400) ? "text" : "data")
+                 << " (ID #" << SectionID << ")"
+                 << " '" << Sect->SegmentName << ","
+                 << Sect->Name << "' of size " << Sect->Size
+                 << " (align " << Align << ")"
+                 << " to address " << Buffer << ".\n");
+
+    // Copy the payload from the object file into the allocated buffer.
+    uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
+                                           Segment64LC->FileSize).data();
+    memcpy(Buffer, Base + Sect->Address, Sect->Size);
+
+    // Remember what got allocated for this SectionID.
+    Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
+    SectionLocalMemToID[Buffer] = SectionID;
+
+    // By default, the load address of a section is its memory buffer.
+    SectionLoadAddress.push_back((uint64_t)Buffer);
+
+    // Keep a map of object file section numbers to corresponding SectionIDs
+    // while processing the file.
+    SectionMap.push_back(SectionID);
+  }
+
+  // Process the symbol table.
+  SmallVector<StringRef, 64> SymbolNames;
+  processSymbols64(Obj, SectionMap, SymbolNames, SymtabLC);
+
+  // Process the relocations for each section we're loading.
+  Relocations.grow(Relocations.size() + Segment64LC->NumSections);
+  Referrers.grow(Referrers.size() + Segment64LC->NumSections);
+  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
+    InMemoryStruct<macho::Section64> Sect;
+    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
+    if (!Sect)
+      return Error("unable to load section: '" + Twine(SectNum) + "'");
+    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
+      InMemoryStruct<macho::RelocationEntry> RE;
+      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
+      if (RE->Word0 & macho::RF_Scattered)
+        return Error("NOT YET IMPLEMENTED: scattered relocations.");
+      // Word0 of the relocation is the offset into the section where the
+      // relocation should be applied. We need to translate that into an
+      // offset into a function since that's our atom.
+      uint32_t Offset = RE->Word0;
+      bool isExtern = (RE->Word1 >> 27) & 1;
+
+      // FIXME: Get the relocation addend from the target address.
+      // FIXME: VERY imporant for internal relocations.
+
+      // Figure out the source symbol of the relocation. If isExtern is true,
+      // this relocation references the symbol table, otherwise it references
+      // a section in the same object, numbered from 1 through NumSections
+      // (SectionBases is [0, NumSections-1]).
+      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
+      if (!isExtern) {
+        assert(SourceNum > 0 && "Invalid relocation section number!");
+        unsigned SectionID = SectionMap[SourceNum - 1];
+        unsigned TargetID = SectionMap[SectNum];
+        DEBUG(dbgs() << "Internal relocation at Section #"
+                     << TargetID << " + " << Offset
+                     << " from Section #"
+                     << SectionID << " (Word1: "
+                     << format("0x%x", RE->Word1) << ")\n");
+
+        // Store the relocation information. It will get resolved when
+        // the section addresses are assigned.
+        uint32_t RelocationIndex = Relocations[SectionID].size();
+        Relocations[SectionID].push_back(RelocationEntry(TargetID,
+                                                         Offset,
+                                                         RE->Word1,
+                                                         0 /*Addend*/));
+        Referrers[TargetID].push_back(Referrer(SectionID, RelocationIndex));
+      } else {
+        StringRef SourceName = SymbolNames[SourceNum];
+
+        // Now store the relocation information. Associate it with the source
+        // symbol. Just add it to the unresolved list and let the general
+        // path post-load resolve it if we know where the symbol is.
+        UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
+                                                                    Offset,
+                                                                    RE->Word1,
+                                                                 0 /*Addend*/));
+        DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
+              << " from '" << SourceName << "(Word1: "
+              << format("0x%x", RE->Word1) << ")\n");
+      }
     }
   }
 
-  if (Arch == Triple::arm && RelType == macho::RIT_ARM_Branch24Bit) {
-    // This is an ARM branch relocation, need to use a stub function.
-
-    //  Look up for existing stub.
-    StubMap::const_iterator i = Stubs.find(Value);
-    if (i != Stubs.end())
-      resolveRelocation(Target, (uint64_t)Target,
-                        (uint64_t)Section.Address + i->second,
-                        RelType, 0);
-    else {
-      // Create a new stub function.
-      Stubs[Value] = Section.StubOffset;
-      uint8_t *StubTargetAddr = createStubFunction(Section.Address +
-                                                   Section.StubOffset);
-      AddRelocation(Value, Rel.SectionID, StubTargetAddr - Section.Address,
-                    macho::RIT_Vanilla);
-      resolveRelocation(Target, (uint64_t)Target,
-                        (uint64_t)Section.Address + Section.StubOffset,
-                        RelType, 0);
-      Section.StubOffset += getMaxStubSize();
+  // Resolve the addresses of any symbols that were defined in this segment.
+  for (int i = 0, e = SymbolNames.size(); i != e; ++i)
+    resolveSymbol(SymbolNames[i]);
+
+  return false;
+}
+
+bool RuntimeDyldMachO::
+processSymbols32(const MachOObject *Obj,
+                 SmallVectorImpl<unsigned> &SectionMap,
+                 SmallVectorImpl<StringRef> &SymbolNames,
+                 const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
+  // FIXME: Combine w/ processSymbols64. Factor 64/32 datatype and such.
+  for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
+    InMemoryStruct<macho::SymbolTableEntry> STE;
+    Obj->ReadSymbolTableEntry(SymtabLC->SymbolTableOffset, i, STE);
+    if (!STE)
+      return Error("unable to read symbol: '" + Twine(i) + "'");
+    // Get the symbol name.
+    StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
+    SymbolNames.push_back(Name);
+
+    // FIXME: Check the symbol type and flags.
+    if (STE->Type != 0xF)  // external, defined in this segment.
+      continue;
+    // Flags in the upper nibble we don't care about.
+    if ((STE->Flags & 0xf) != 0x0)
+      continue;
+
+    // Remember the symbol.
+    uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
+    SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
+
+    DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
+                 << (getSectionAddress(SectionID) + STE->Value)
+                 << "\n");
+  }
+  return false;
+}
+
+bool RuntimeDyldMachO::
+processSymbols64(const MachOObject *Obj,
+                 SmallVectorImpl<unsigned> &SectionMap,
+                 SmallVectorImpl<StringRef> &SymbolNames,
+                 const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
+  for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
+    InMemoryStruct<macho::Symbol64TableEntry> STE;
+    Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE);
+    if (!STE)
+      return Error("unable to read symbol: '" + Twine(i) + "'");
+    // Get the symbol name.
+    StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
+    SymbolNames.push_back(Name);
+
+    // FIXME: Check the symbol type and flags.
+    if (STE->Type != 0xF)  // external, defined in this segment.
+      continue;
+    // Flags in the upper nibble we don't care about.
+    if ((STE->Flags & 0xf) != 0x0)
+      continue;
+
+    // Remember the symbol.
+    uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
+    SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
+
+    DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
+                 << (getSectionAddress(SectionID) + STE->Value)
+                 << "\n");
+  }
+  return false;
+}
+
+// resolveSymbol - Resolve any relocations to the specified symbol if
+// we know where it lives.
+void RuntimeDyldMachO::resolveSymbol(StringRef Name) {
+  StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
+  if (Loc == SymbolTable.end())
+    return;
+
+  RelocationList &Relocs = UnresolvedRelocations[Name];
+  DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
+  for (int i = 0, e = Relocs.size(); i != e; ++i) {
+    // Change the relocation to be section relative rather than symbol
+    // relative and move it to the resolved relocation list.
+    RelocationEntry Entry = Relocs[i];
+    Entry.Addend += Loc->second.second;
+    uint32_t RelocationIndex = Relocations[Loc->second.first].size();
+    Relocations[Loc->second.first].push_back(Entry);
+    Referrers[Entry.SectionID].push_back(Referrer(Loc->second.first, RelocationIndex));
+  }
+  // FIXME: Keep a worklist of the relocations we've added so that we can
+  // resolve more selectively later.
+  Relocs.clear();
+}
+
+bool RuntimeDyldMachO::loadObject(MemoryBuffer *InputBuffer) {
+  // If the linker is in an error state, don't do anything.
+  if (hasError())
+    return true;
+  // Load the Mach-O wrapper object.
+  std::string ErrorStr;
+  OwningPtr<MachOObject> Obj(
+    MachOObject::LoadFromBuffer(InputBuffer, &ErrorStr));
+  if (!Obj)
+    return Error("unable to load object: '" + ErrorStr + "'");
+
+  // Get the CPU type information from the header.
+  const macho::Header &Header = Obj->getHeader();
+
+  // FIXME: Error checking that the loaded object is compatible with
+  //        the system we're running on.
+  CPUType = Header.CPUType;
+  CPUSubtype = Header.CPUSubtype;
+
+  // Validate that the load commands match what we expect.
+  const MachOObject::LoadCommandInfo *SegmentLCI = 0, *SymtabLCI = 0,
+    *DysymtabLCI = 0;
+  for (unsigned i = 0; i != Header.NumLoadCommands; ++i) {
+    const MachOObject::LoadCommandInfo &LCI = Obj->getLoadCommandInfo(i);
+    switch (LCI.Command.Type) {
+    case macho::LCT_Segment:
+    case macho::LCT_Segment64:
+      if (SegmentLCI)
+        return Error("unexpected input object (multiple segments)");
+      SegmentLCI = &LCI;
+      break;
+    case macho::LCT_Symtab:
+      if (SymtabLCI)
+        return Error("unexpected input object (multiple symbol tables)");
+      SymtabLCI = &LCI;
+      break;
+    case macho::LCT_Dysymtab:
+      if (DysymtabLCI)
+        return Error("unexpected input object (multiple symbol tables)");
+      DysymtabLCI = &LCI;
+      break;
+    default:
+      return Error("unexpected input object (unexpected load command");
     }
-  } else
-    AddRelocation(Value, Rel.SectionID, Rel.Offset, RelType);
+  }
+
+  if (!SymtabLCI)
+    return Error("no symbol table found in object");
+  if (!SegmentLCI)
+    return Error("no segments found in object");
+
+  // Read and register the symbol table data.
+  InMemoryStruct<macho::SymtabLoadCommand> SymtabLC;
+  Obj->ReadSymtabLoadCommand(*SymtabLCI, SymtabLC);
+  if (!SymtabLC)
+    return Error("unable to load symbol table load command");
+  Obj->RegisterStringTable(*SymtabLC);
+
+  // Read the dynamic link-edit information, if present (not present in static
+  // objects).
+  if (DysymtabLCI) {
+    InMemoryStruct<macho::DysymtabLoadCommand> DysymtabLC;
+    Obj->ReadDysymtabLoadCommand(*DysymtabLCI, DysymtabLC);
+    if (!DysymtabLC)
+      return Error("unable to load dynamic link-exit load command");
+
+    // FIXME: We don't support anything interesting yet.
+//    if (DysymtabLC->LocalSymbolsIndex != 0)
+//      return Error("NOT YET IMPLEMENTED: local symbol entries");
+//    if (DysymtabLC->ExternalSymbolsIndex != 0)
+//      return Error("NOT YET IMPLEMENTED: non-external symbol entries");
+//    if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
+//      return Error("NOT YET IMPLEMENTED: undefined symbol entries");
+  }
+
+  // Load the segment load command.
+  if (SegmentLCI->Command.Type == macho::LCT_Segment) {
+    if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC))
+      return true;
+  } else {
+    if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC))
+      return true;
+  }
+
+  // Assign the addresses of the sections from the object so that any
+  // relocations to them get set properly.
+  // FIXME: This is done directly from the client at the moment. We should
+  // default the values to the local storage, at least when the target arch
+  // is the same as the host arch.
+
+  return false;
 }
 
+// Assign an address to a symbol name and resolve all the relocations
+// associated with it.
+void RuntimeDyldMachO::reassignSectionAddress(unsigned SectionID,
+                                              uint64_t Addr) {
+  // The address to use for relocation resolution is not
+  // the address of the local section buffer. We must be doing
+  // a remote execution environment of some sort. Re-apply any
+  // relocations referencing this section with the given address.
+  //
+  // Addr is a uint64_t because we can't assume the pointer width
+  // of the target is the same as that of the host. Just use a generic
+  // "big enough" type.
+
+  SectionLoadAddress[SectionID] = Addr;
+
+  RelocationList &Relocs = Relocations[SectionID];
+  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
+    RelocationEntry &RE = Relocs[i];
+    uint8_t *Target = (uint8_t*)Sections[RE.SectionID].base() + RE.Offset;
+    uint64_t FinalTarget = (uint64_t)SectionLoadAddress[RE.SectionID] + RE.Offset;
+    bool isPCRel = (RE.Data >> 24) & 1;
+    unsigned Type = (RE.Data >> 28) & 0xf;
+    unsigned Size = 1 << ((RE.Data >> 25) & 3);
+
+    DEBUG(dbgs() << "Resolving relocation at Section #" << RE.SectionID
+          << " + " << RE.Offset << " (" << format("%p", Target) << ")"
+          << " from Section #" << SectionID << " (" << format("%p", Addr) << ")"
+          << "(" << (isPCRel ? "pcrel" : "absolute")
+          << ", type: " << Type << ", Size: " << Size << ", Addend: "
+          << RE.Addend << ").\n");
+
+    resolveRelocation(Target,
+                      FinalTarget,
+                      Addr,
+                      isPCRel,
+                      Type,
+                      Size,
+                      RE.Addend);
+  }
+  ReferrerList &Refers = Referrers[SectionID];
+  for (unsigned i = 0, e = Refers.size(); i != e; ++i) {
+    Referrer &R = Refers[i];
+    RelocationEntry &RE = Relocations[R.SectionID][R.Index];
+    uint8_t *Target = (uint8_t*)Sections[RE.SectionID].base() + RE.Offset;
+    uint64_t FinalTarget = (uint64_t)SectionLoadAddress[RE.SectionID] + RE.Offset;
+    bool isPCRel = (RE.Data >> 24) & 1;
+    unsigned Type = (RE.Data >> 28) & 0xf;
+    unsigned Size = 1 << ((RE.Data >> 25) & 3);
+
+    DEBUG(dbgs() << "Resolving relocation at Section #" << RE.SectionID
+          << " + " << RE.Offset << " (" << format("%p", Target) << ")"
+          << " from Section #" << SectionID << " (" << format("%p", Addr) << ")"
+          << "(" << (isPCRel ? "pcrel" : "absolute")
+          << ", type: " << Type << ", Size: " << Size << ", Addend: "
+          << RE.Addend << ").\n");
+
+    resolveRelocation(Target,
+                      FinalTarget,
+                      Addr,
+                      isPCRel,
+                      Type,
+                      Size,
+                      RE.Addend);
+  }
+}
 
-bool RuntimeDyldMachO::isCompatibleFormat(const MemoryBuffer *InputBuffer) const {
+bool RuntimeDyldMachO::isKnownFormat(const MemoryBuffer *InputBuffer) {
   StringRef Magic = InputBuffer->getBuffer().slice(0, 4);
   if (Magic == "\xFE\xED\xFA\xCE") return true;
   if (Magic == "\xCE\xFA\xED\xFE") return true;