Revert a series of commits to MCJIT to get the build working in CMake

(and hopefully on Windows). The bots have been down most of the day
because of this, and it's not clear to me what all will be required to
fix it.

The commits started with r153205, then r153207, r153208, and r153221.
The first commit seems to be the real culprit, but I couldn't revert
a smaller number of patches.

When resubmitting, r153207 and r153208 should be folded into r153205,
they were simple build fixes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153241 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 514 insertions, 108 deletions

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
index 24437e0f96..0b72b567c3 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
@@ -21,47 +21,33 @@ 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: // Fall through.
-  case Triple::x86:
-    resolveX86_64Relocation(LocalAddress,
-                            FinalAddress,
-                            (uintptr_t)Value,
-                            isPCRel,
-                            MachoType,
-                            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);
   }
 }
 
@@ -167,83 +153,503 @@ 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 it = Symbols.find(TargetName.data());
-    if (it != Symbols.end()) {
-      Value.SectionID = it->second.first;
-      Value.Addend = it->second.second;
-    } else {
-      // Second look the symbol in global symbol table.
-      StringMap<SymbolLoc>::iterator itS = SymbolTable.find(TargetName.data());
-      if (itS != SymbolTable.end()) {
-        Value.SectionID = itS->second.first;
-        Value.Addend = itS->second.second;
-      } else
-        Value.SymbolName = TargetName.data();
-    }
-  } else {
-    error_code err;
-    uint8_t sIdx = static_cast<uint8_t>(RelType & 0xFF);
-    section_iterator sIt = Obj.begin_sections(),
-                     sItEnd = Obj.end_sections();
-    for (uint8_t i = 1; i < sIdx; i++) {
-      error_code err;
-      sIt.increment(err);
-      if (sIt == sItEnd)
-        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(sIt != sItEnd && "No section containing relocation!");
-    Value.SectionID = findOrEmitSection(*sIt, 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 stubIt = Stubs.find(Value);
-    if (stubIt != Stubs.end())
-      resolveRelocation(Target, (uint64_t)Target,
-                        (uint64_t)Section.Address + stubIt->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;