Convert getFileOffset to getOffset and move it to its only user.
[oota-llvm.git] / lib / ExecutionEngine / RuntimeDyld / RuntimeDyld.cpp
index 9cbaaa19f846294b69a76b924a58774943d9bda2..f9a81db4df0aa73a2e751068619d7524a7d81bed 100644 (file)
@@ -1,4 +1,4 @@
-//===-- RuntimeDyld.h - Run-time dynamic linker for MC-JIT ------*- C++ -*-===//
+//===-- RuntimeDyld.cpp - Run-time dynamic linker for MC-JIT ----*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "dyld"
-#include "llvm/ADT/OwningPtr.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringMap.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/Twine.h"
 #include "llvm/ExecutionEngine/RuntimeDyld.h"
-#include "llvm/Object/MachOObject.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/Format.h"
-#include "llvm/Support/Memory.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/system_error.h"
-#include "llvm/Support/raw_ostream.h"
+#include "JITRegistrar.h"
+#include "ObjectImageCommon.h"
+#include "RuntimeDyldELF.h"
+#include "RuntimeDyldImpl.h"
+#include "RuntimeDyldMachO.h"
+#include "llvm/Object/ELF.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/MutexGuard.h"
+
 using namespace llvm;
 using namespace llvm::object;
 
 // Empty out-of-line virtual destructor as the key function.
-RTDyldMemoryManager::~RTDyldMemoryManager() {}
+RuntimeDyldImpl::~RuntimeDyldImpl() {}
 
-namespace llvm {
-class RuntimeDyldImpl {
-  unsigned CPUType;
-  unsigned CPUSubtype;
+// Pin the JITRegistrar's and ObjectImage*'s vtables to this file.
+void JITRegistrar::anchor() {}
+void ObjectImage::anchor() {}
+void ObjectImageCommon::anchor() {}
 
-  // The MemoryManager to load objects into.
-  RTDyldMemoryManager *MemMgr;
+namespace llvm {
 
+void RuntimeDyldImpl::registerEHFrames() {}
 
-  // For each function, we have a MemoryBlock of it's instruction data.
-  StringMap<sys::MemoryBlock> Functions;
+void RuntimeDyldImpl::deregisterEHFrames() {}
 
-  // Master symbol table. As modules are loaded and external symbols are
-  // resolved, their addresses are stored here.
-  StringMap<uint64_t> SymbolTable;
+// Resolve the relocations for all symbols we currently know about.
+void RuntimeDyldImpl::resolveRelocations() {
+  MutexGuard locked(lock);
 
-  // FIXME: Should have multiple data blocks, one for each loaded chunk of
-  //        compiled code.
-  sys::MemoryBlock Data;
+  // First, resolve relocations associated with external symbols.
+  resolveExternalSymbols();
 
-  bool HasError;
-  std::string ErrorStr;
+  // Just iterate over the sections we have and resolve all the relocations
+  // in them. Gross overkill, but it gets the job done.
+  for (int i = 0, e = Sections.size(); i != e; ++i) {
+    // The Section here (Sections[i]) refers to the section in which the
+    // symbol for the relocation is located.  The SectionID in the relocation
+    // entry provides the section to which the relocation will be applied.
+    uint64_t Addr = Sections[i].LoadAddress;
+    DEBUG(dbgs() << "Resolving relocations Section #" << i << "\t"
+                 << format("%p", (uint8_t *)Addr) << "\n");
+    resolveRelocationList(Relocations[i], Addr);
+    Relocations.erase(i);
+  }
+}
 
-  // Set the error state and record an error string.
-  bool Error(const Twine &Msg) {
-    ErrorStr = Msg.str();
-    HasError = true;
-    return true;
+void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
+                                        uint64_t TargetAddress) {
+  MutexGuard locked(lock);
+  for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
+    if (Sections[i].Address == LocalAddress) {
+      reassignSectionAddress(i, TargetAddress);
+      return;
+    }
   }
+  llvm_unreachable("Attempting to remap address of unknown section!");
+}
 
-  void extractFunction(StringRef Name, uint8_t *StartAddress,
-                       uint8_t *EndAddress);
-  bool resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE,
-                         SmallVectorImpl<void *> &SectionBases,
-                         SmallVectorImpl<StringRef> &SymbolNames);
-  bool resolveX86_64Relocation(intptr_t Address, intptr_t Value, bool isPCRel,
-                               unsigned Type, unsigned Size);
-  bool resolveARMRelocation(intptr_t Address, intptr_t Value, bool isPCRel,
-                            unsigned Type, unsigned Size);
-
-  bool loadSegment32(const MachOObject *Obj,
-                     const MachOObject::LoadCommandInfo *SegmentLCI,
-                     const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC);
-  bool loadSegment64(const MachOObject *Obj,
-                     const MachOObject::LoadCommandInfo *SegmentLCI,
-                     const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC);
-
-public:
-  RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
-
-  bool loadObject(MemoryBuffer *InputBuffer);
-
-  void *getSymbolAddress(StringRef Name) {
-    // FIXME: Just look up as a function for now. Overly simple of course.
-    // Work in progress.
-    return Functions.lookup(Name).base();
+static error_code getOffset(const SymbolRef &Sym, uint64_t &Result) {
+  uint64_t Address;
+  if (error_code EC = Sym.getAddress(Address))
+    return EC;
+
+  if (Address == UnknownAddressOrSize) {
+    Result = UnknownAddressOrSize;
+    return object_error::success;
   }
 
-  sys::MemoryBlock getMemoryBlock() { return Data; }
-
-  // Is the linker in an error state?
-  bool hasError() { return HasError; }
-
-  // Mark the error condition as handled and continue.
-  void clearError() { HasError = false; }
-
-  // Get the error message.
-  StringRef getErrorString() { return ErrorStr; }
-};
-
-void RuntimeDyldImpl::extractFunction(StringRef Name, uint8_t *StartAddress,
-                                      uint8_t *EndAddress) {
-  // Allocate memory for the function via the memory manager.
-  uintptr_t Size = EndAddress - StartAddress + 1;
-  uint8_t *Mem = MemMgr->startFunctionBody(Name.data(), Size);
-  assert(Size >= (uint64_t)(EndAddress - StartAddress + 1) &&
-         "Memory manager failed to allocate enough memory!");
-  // Copy the function payload into the memory block.
-  memcpy(Mem, StartAddress, EndAddress - StartAddress + 1);
-  MemMgr->endFunctionBody(Name.data(), Mem, Mem + Size);
-  // Remember where we put it.
-  Functions[Name] = sys::MemoryBlock(Mem, Size);
-  DEBUG(dbgs() << "    allocated to " << Mem << "\n");
+  const ObjectFile *Obj = Sym.getObject();
+  section_iterator SecI(Obj->section_begin());
+  if (error_code EC = Sym.getSection(SecI))
+    return EC;
+
+ if (SecI == Obj->section_end()) {
+   Result = UnknownAddressOrSize;
+   return object_error::success;
+ }
+
+  uint64_t SectionAddress;
+  if (error_code EC = SecI->getAddress(SectionAddress))
+    return EC;
+
+  Result = Address - SectionAddress;
+  return object_error::success;
 }
 
-bool RuntimeDyldImpl::
-resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE,
-                  SmallVectorImpl<void *> &SectionBases,
-                  SmallVectorImpl<StringRef> &SymbolNames) {
-  // struct relocation_info {
-  //   int32_t r_address;
-  //   uint32_t r_symbolnum:24,
-  //            r_pcrel:1,
-  //            r_length:2,
-  //            r_extern:1,
-  //            r_type:4;
-  // };
-  uint32_t SymbolNum = RE.Word1 & 0xffffff; // 24-bit value
-  bool isPCRel = (RE.Word1 >> 24) & 1;
-  unsigned Log2Size = (RE.Word1 >> 25) & 3;
-  bool isExtern = (RE.Word1 >> 27) & 1;
-  unsigned Type = (RE.Word1 >> 28) & 0xf;
-  if (RE.Word0 & macho::RF_Scattered)
-    return Error("NOT YET IMPLEMENTED: scattered relocations.");
-
-  // The address requiring a relocation.
-  intptr_t Address = (intptr_t)SectionBases[BaseSection] + RE.Word0;
-
-  // Figure out the target address 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]).
-  intptr_t Value;
-  if (isExtern) {
-    StringRef Name = SymbolNames[SymbolNum];
-    if (SymbolTable.lookup(Name)) {
-      // The symbol is in our symbol table, so we can resolve it directly.
-      Value = (intptr_t)SymbolTable[Name];
+ObjectImage *RuntimeDyldImpl::loadObject(ObjectImage *InputObject) {
+  MutexGuard locked(lock);
+
+  std::unique_ptr<ObjectImage> Obj(InputObject);
+  if (!Obj)
+    return NULL;
+
+  // Save information about our target
+  Arch = (Triple::ArchType)Obj->getArch();
+  IsTargetLittleEndian = Obj->getObjectFile()->isLittleEndian();
+
+  // Compute the memory size required to load all sections to be loaded
+  // and pass this information to the memory manager
+  if (MemMgr->needsToReserveAllocationSpace()) {
+    uint64_t CodeSize = 0, DataSizeRO = 0, DataSizeRW = 0;
+    computeTotalAllocSize(*Obj, CodeSize, DataSizeRO, DataSizeRW);
+    MemMgr->reserveAllocationSpace(CodeSize, DataSizeRO, DataSizeRW);
+  }
+
+  // Symbols found in this object
+  StringMap<SymbolLoc> LocalSymbols;
+  // Used sections from the object file
+  ObjSectionToIDMap LocalSections;
+
+  // Common symbols requiring allocation, with their sizes and alignments
+  CommonSymbolMap CommonSymbols;
+  // Maximum required total memory to allocate all common symbols
+  uint64_t CommonSize = 0;
+
+  // Parse symbols
+  DEBUG(dbgs() << "Parse symbols:\n");
+  for (symbol_iterator I = Obj->begin_symbols(), E = Obj->end_symbols(); I != E;
+       ++I) {
+    object::SymbolRef::Type SymType;
+    StringRef Name;
+    Check(I->getType(SymType));
+    Check(I->getName(Name));
+
+    uint32_t Flags = I->getFlags();
+
+    bool IsCommon = Flags & SymbolRef::SF_Common;
+    if (IsCommon) {
+      // Add the common symbols to a list.  We'll allocate them all below.
+      uint32_t Align;
+      Check(I->getAlignment(Align));
+      uint64_t Size = 0;
+      Check(I->getSize(Size));
+      CommonSize += Size + Align;
+      CommonSymbols[*I] = CommonSymbolInfo(Size, Align);
     } else {
-      return Error("NOT YET IMPLEMENTED: relocations to pre-compiled code.");
+      if (SymType == object::SymbolRef::ST_Function ||
+          SymType == object::SymbolRef::ST_Data ||
+          SymType == object::SymbolRef::ST_Unknown) {
+        uint64_t SectOffset;
+        StringRef SectionData;
+        bool IsCode;
+        section_iterator SI = Obj->end_sections();
+        Check(getOffset(*I, SectOffset));
+        Check(I->getSection(SI));
+        if (SI == Obj->end_sections())
+          continue;
+        Check(SI->getContents(SectionData));
+        Check(SI->isText(IsCode));
+        unsigned SectionID =
+            findOrEmitSection(*Obj, *SI, IsCode, LocalSections);
+        LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
+        DEBUG(dbgs() << "\tOffset: " << format("%p", (uintptr_t)SectOffset)
+                     << " flags: " << Flags << " SID: " << SectionID);
+        GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
+      }
     }
-    DEBUG(dbgs() << "Resolve relocation(" << Type << ") from '" << Name
-                 << "' to " << format("0x%x", Address) << ".\n");
-  } else {
-    // For non-external relocations, the SymbolNum is actual a section number
-    // as described above.
-    Value = (intptr_t)SectionBases[SymbolNum - 1];
+    DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
   }
 
-  unsigned Size = 1 << Log2Size;
-  switch (CPUType) {
-  default: assert(0 && "Unsupported CPU type!");
-  case mach::CTM_x86_64:
-    return resolveX86_64Relocation(Address, Value, isPCRel, Type, Size);
-  case mach::CTM_ARM:
-    return resolveARMRelocation(Address, Value, isPCRel, Type, Size);
+  // Allocate common symbols
+  if (CommonSize != 0)
+    emitCommonSymbols(*Obj, CommonSymbols, CommonSize, LocalSymbols);
+
+  // Parse and process relocations
+  DEBUG(dbgs() << "Parse relocations:\n");
+  for (section_iterator SI = Obj->begin_sections(), SE = Obj->end_sections();
+       SI != SE; ++SI) {
+    unsigned SectionID = 0;
+    StubMap Stubs;
+    section_iterator RelocatedSection = SI->getRelocatedSection();
+
+    relocation_iterator I = SI->relocation_begin();
+    relocation_iterator E = SI->relocation_end();
+
+    if (I == E && !ProcessAllSections)
+      continue;
+
+    bool IsCode = false;
+    Check(RelocatedSection->isText(IsCode));
+    SectionID =
+        findOrEmitSection(*Obj, *RelocatedSection, IsCode, LocalSections);
+    DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
+
+    for (; I != E;)
+      I = processRelocationRef(SectionID, I, *Obj, LocalSections, LocalSymbols,
+                               Stubs);
   }
-  llvm_unreachable("");
+
+  // Give the subclasses a chance to tie-up any loose ends.
+  finalizeLoad(LocalSections);
+
+  return Obj.release();
 }
 
-bool RuntimeDyldImpl::resolveX86_64Relocation(intptr_t Address, intptr_t Value,
-                                              bool isPCRel, unsigned Type,
-                                              unsigned Size) {
-  // If the relocation is PC-relative, the value to be encoded is the
-  // pointer difference.
-  if (isPCRel)
-    // FIXME: It seems this value needs to be adjusted by 4 for an effective PC
-    // address. Is that expected? Only for branches, perhaps?
-    Value -= Address + 4;
-
-  switch(Type) {
-  default:
-    llvm_unreachable("Invalid relocation type!");
-  case macho::RIT_X86_64_Unsigned:
-  case macho::RIT_X86_64_Branch: {
-    // Mask in the target value a byte at a time (we don't have an alignment
-    // guarantee for the target address, so this is safest).
-    uint8_t *p = (uint8_t*)Address;
-    for (unsigned i = 0; i < Size; ++i) {
-      *p++ = (uint8_t)Value;
-      Value >>= 8;
-    }
-    return false;
-  }
-  case macho::RIT_X86_64_Signed:
-  case macho::RIT_X86_64_GOTLoad:
-  case macho::RIT_X86_64_GOT:
-  case macho::RIT_X86_64_Subtractor:
-  case macho::RIT_X86_64_Signed1:
-  case macho::RIT_X86_64_Signed2:
-  case macho::RIT_X86_64_Signed4:
-  case macho::RIT_X86_64_TLV:
-    return Error("Relocation type not implemented yet!");
+// A helper method for computeTotalAllocSize.
+// Computes the memory size required to allocate sections with the given sizes,
+// assuming that all sections are allocated with the given alignment
+static uint64_t
+computeAllocationSizeForSections(std::vector<uint64_t> &SectionSizes,
+                                 uint64_t Alignment) {
+  uint64_t TotalSize = 0;
+  for (size_t Idx = 0, Cnt = SectionSizes.size(); Idx < Cnt; Idx++) {
+    uint64_t AlignedSize =
+        (SectionSizes[Idx] + Alignment - 1) / Alignment * Alignment;
+    TotalSize += AlignedSize;
   }
-  return false;
+  return TotalSize;
 }
 
-bool RuntimeDyldImpl::resolveARMRelocation(intptr_t Address, intptr_t Value,
-                                           bool isPCRel, unsigned Type,
-                                           unsigned Size) {
-  // If the relocation is PC-relative, the value to be encoded is the
-  // pointer difference.
-  if (isPCRel) {
-    Value -= Address;
-    // ARM PCRel relocations have an effective-PC offset of two instructions
-    // (four bytes in Thumb mode, 8 bytes in ARM mode).
-    // FIXME: For now, assume ARM mode.
-    Value -= 8;
+// Compute an upper bound of the memory size that is required to load all
+// sections
+void RuntimeDyldImpl::computeTotalAllocSize(ObjectImage &Obj,
+                                            uint64_t &CodeSize,
+                                            uint64_t &DataSizeRO,
+                                            uint64_t &DataSizeRW) {
+  // Compute the size of all sections required for execution
+  std::vector<uint64_t> CodeSectionSizes;
+  std::vector<uint64_t> ROSectionSizes;
+  std::vector<uint64_t> RWSectionSizes;
+  uint64_t MaxAlignment = sizeof(void *);
+
+  // Collect sizes of all sections to be loaded;
+  // also determine the max alignment of all sections
+  for (section_iterator SI = Obj.begin_sections(), SE = Obj.end_sections();
+       SI != SE; ++SI) {
+    const SectionRef &Section = *SI;
+
+    bool IsRequired;
+    Check(Section.isRequiredForExecution(IsRequired));
+
+    // Consider only the sections that are required to be loaded for execution
+    if (IsRequired) {
+      uint64_t DataSize = 0;
+      uint64_t Alignment64 = 0;
+      bool IsCode = false;
+      bool IsReadOnly = false;
+      StringRef Name;
+      Check(Section.getSize(DataSize));
+      Check(Section.getAlignment(Alignment64));
+      Check(Section.isText(IsCode));
+      Check(Section.isReadOnlyData(IsReadOnly));
+      Check(Section.getName(Name));
+      unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
+
+      uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
+      uint64_t SectionSize = DataSize + StubBufSize;
+
+      // The .eh_frame section (at least on Linux) needs an extra four bytes
+      // padded
+      // with zeroes added at the end.  For MachO objects, this section has a
+      // slightly different name, so this won't have any effect for MachO
+      // objects.
+      if (Name == ".eh_frame")
+        SectionSize += 4;
+
+      if (SectionSize > 0) {
+        // save the total size of the section
+        if (IsCode) {
+          CodeSectionSizes.push_back(SectionSize);
+        } else if (IsReadOnly) {
+          ROSectionSizes.push_back(SectionSize);
+        } else {
+          RWSectionSizes.push_back(SectionSize);
+        }
+        // update the max alignment
+        if (Alignment > MaxAlignment) {
+          MaxAlignment = Alignment;
+        }
+      }
+    }
   }
 
-  switch(Type) {
-  default:
-  case macho::RIT_Vanilla: {
-    llvm_unreachable("Invalid relocation type!");
-    // Mask in the target value a byte at a time (we don't have an alignment
-    // guarantee for the target address, so this is safest).
-    uint8_t *p = (uint8_t*)Address;
-    for (unsigned i = 0; i < Size; ++i) {
-      *p++ = (uint8_t)Value;
-      Value >>= 8;
+  // Compute the size of all common symbols
+  uint64_t CommonSize = 0;
+  for (symbol_iterator I = Obj.begin_symbols(), E = Obj.end_symbols(); I != E;
+       ++I) {
+    uint32_t Flags = I->getFlags();
+    if (Flags & SymbolRef::SF_Common) {
+      // Add the common symbols to a list.  We'll allocate them all below.
+      uint64_t Size = 0;
+      Check(I->getSize(Size));
+      CommonSize += Size;
     }
-    break;
   }
-  case macho::RIT_Pair:
-  case macho::RIT_Difference:
-  case macho::RIT_ARM_LocalDifference:
-  case macho::RIT_ARM_PreboundLazyPointer:
-  case macho::RIT_ARM_Branch24Bit: {
-    // Mask the value into the target address. We know instructions are
-    // 32-bit aligned, so we can do it all at once.
-    uint32_t *p = (uint32_t*)Address;
-    // The low two bits of the value are not encoded.
-    Value >>= 2;
-    // Mask the value to 24 bits.
-    Value &= 0xffffff;
-    // FIXME: If the destination is a Thumb function (and the instruction
-    // is a non-predicated BL instruction), we need to change it to a BLX
-    // instruction instead.
-
-    // Insert the value into the instruction.
-    *p = (*p & ~0xffffff) | Value;
-    break;
+  if (CommonSize != 0) {
+    RWSectionSizes.push_back(CommonSize);
   }
-  case macho::RIT_ARM_ThumbBranch22Bit:
-  case macho::RIT_ARM_ThumbBranch32Bit:
-  case macho::RIT_ARM_Half:
-  case macho::RIT_ARM_HalfDifference:
-    return Error("Relocation type not implemented yet!");
-  }
-  return false;
+
+  // Compute the required allocation space for each different type of sections
+  // (code, read-only data, read-write data) assuming that all sections are
+  // allocated with the max alignment. Note that we cannot compute with the
+  // individual alignments of the sections, because then the required size
+  // depends on the order, in which the sections are allocated.
+  CodeSize = computeAllocationSizeForSections(CodeSectionSizes, MaxAlignment);
+  DataSizeRO = computeAllocationSizeForSections(ROSectionSizes, MaxAlignment);
+  DataSizeRW = computeAllocationSizeForSections(RWSectionSizes, MaxAlignment);
 }
 
-bool RuntimeDyldImpl::
-loadSegment32(const MachOObject *Obj,
-              const MachOObject::LoadCommandInfo *SegmentLCI,
-              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
-  InMemoryStruct<macho::SegmentLoadCommand> Segment32LC;
-  Obj->ReadSegmentLoadCommand(*SegmentLCI, Segment32LC);
-  if (!Segment32LC)
-    return Error("unable to load segment load command");
-
-  for (unsigned SectNum = 0; SectNum != Segment32LC->NumSections; ++SectNum) {
-    InMemoryStruct<macho::Section> Sect;
-    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
-    if (!Sect)
-      return Error("unable to load section: '" + Twine(SectNum) + "'");
-
-    // FIXME: Improve check.
-    if (Sect->Flags != 0x80000400)
-      return Error("unsupported section type!");
-
-    // Address and names of symbols in the section.
-    typedef std::pair<uint64_t, StringRef> SymbolEntry;
-    SmallVector<SymbolEntry, 32> Symbols;
-    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) + "'");
-      if (STE->SectionIndex > Segment32LC->NumSections)
-        return Error("invalid section index for symbol: '" + Twine() + "'");
-
-      // Just skip symbols not defined in this section.
-      if (STE->SectionIndex - 1 != SectNum)
-        continue;
-
-      // Get the symbol name.
-      StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
-
-      // FIXME: Check the symbol type and flags.
-      if (STE->Type != 0xF)  // external, defined in this section.
-        return Error("unexpected symbol type!");
-      if (STE->Flags != 0x0)
-        return Error("unexpected symbol type!");
-
-      uint64_t BaseAddress = Sect->Address;
-      uint64_t Address = BaseAddress + STE->Value;
-
-      // Remember the symbol.
-      Symbols.push_back(SymbolEntry(Address, Name));
-
-      DEBUG(dbgs() << "Function sym: '" << Name << "' @ " << Address << "\n");
-    }
-    // Sort the symbols by address, just in case they didn't come in that
-    // way.
-    array_pod_sort(Symbols.begin(), Symbols.end());
-
-    // Extract the function data.
-    uint8_t *Base = (uint8_t*)Obj->getData(Segment32LC->FileOffset,
-                                           Segment32LC->FileSize).data();
-    for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) {
-      uint64_t StartOffset = Symbols[i].first;
-      uint64_t EndOffset = Symbols[i + 1].first - 1;
-      DEBUG(dbgs() << "Extracting function: " << Symbols[i].second
-                   << " from [" << StartOffset << ", " << EndOffset << "]\n");
-      extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset);
+// compute stub buffer size for the given section
+unsigned RuntimeDyldImpl::computeSectionStubBufSize(ObjectImage &Obj,
+                                                    const SectionRef &Section) {
+  unsigned StubSize = getMaxStubSize();
+  if (StubSize == 0) {
+    return 0;
+  }
+  // FIXME: this is an inefficient way to handle this. We should computed the
+  // necessary section allocation size in loadObject by walking all the sections
+  // once.
+  unsigned StubBufSize = 0;
+  for (section_iterator SI = Obj.begin_sections(), SE = Obj.end_sections();
+       SI != SE; ++SI) {
+    section_iterator RelSecI = SI->getRelocatedSection();
+    if (!(RelSecI == Section))
+      continue;
+
+    for (const RelocationRef &Reloc : SI->relocations()) {
+      (void)Reloc;
+      StubBufSize += StubSize;
     }
-    // The last symbol we do after since the end address is calculated
-    // differently because there is no next symbol to reference.
-    uint64_t StartOffset = Symbols[Symbols.size() - 1].first;
-    uint64_t EndOffset = Sect->Size - 1;
-    DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second
-                 << " from [" << StartOffset << ", " << EndOffset << "]\n");
-    extractFunction(Symbols[Symbols.size()-1].second,
-                    Base + StartOffset, Base + EndOffset);
   }
 
-  return false;
+  // Get section data size and alignment
+  uint64_t Alignment64;
+  uint64_t DataSize;
+  Check(Section.getSize(DataSize));
+  Check(Section.getAlignment(Alignment64));
+
+  // Add stubbuf size alignment
+  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
+  unsigned StubAlignment = getStubAlignment();
+  unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
+  if (StubAlignment > EndAlignment)
+    StubBufSize += StubAlignment - EndAlignment;
+  return StubBufSize;
 }
 
-
-bool RuntimeDyldImpl::
-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");
-
-  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) + "'");
-
-    // FIXME: Improve check.
-    if (Sect->Flags != 0x80000400)
-      return Error("unsupported section type!");
-
-    // Address and names of symbols in the section.
-    typedef std::pair<uint64_t, StringRef> SymbolEntry;
-    SmallVector<SymbolEntry, 64> Symbols;
-    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) + "'");
-      if (STE->SectionIndex > Segment64LC->NumSections)
-        return Error("invalid section index for symbol: '" + Twine() + "'");
-
-      // Just skip symbols not defined in this section.
-      if (STE->SectionIndex - 1 != SectNum)
-        continue;
-
-      // Get the symbol name.
-      StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
-
-      // FIXME: Check the symbol type and flags.
-      if (STE->Type != 0xF)  // external, defined in this section.
-        return Error("unexpected symbol type!");
-      if (STE->Flags != 0x0)
-        return Error("unexpected symbol type!");
-
-      uint64_t BaseAddress = Sect->Address;
-      uint64_t Address = BaseAddress + STE->Value;
-
-      // Remember the symbol.
-      Symbols.push_back(SymbolEntry(Address, Name));
-
-      DEBUG(dbgs() << "Function sym: '" << Name << "' @ " << Address << "\n");
-    }
-    // Sort the symbols by address, just in case they didn't come in that
-    // way.
-    array_pod_sort(Symbols.begin(), Symbols.end());
-
-    // Extract the function data.
-    uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
-                                           Segment64LC->FileSize).data();
-    for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) {
-      uint64_t StartOffset = Symbols[i].first;
-      uint64_t EndOffset = Symbols[i + 1].first - 1;
-      DEBUG(dbgs() << "Extracting function: " << Symbols[i].second
-                   << " from [" << StartOffset << ", " << EndOffset << "]\n");
-      extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset);
+void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
+                                        const CommonSymbolMap &CommonSymbols,
+                                        uint64_t TotalSize,
+                                        SymbolTableMap &SymbolTable) {
+  // Allocate memory for the section
+  unsigned SectionID = Sections.size();
+  uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void *),
+                                              SectionID, StringRef(), false);
+  if (!Addr)
+    report_fatal_error("Unable to allocate memory for common symbols!");
+  uint64_t Offset = 0;
+  Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, 0));
+  memset(Addr, 0, TotalSize);
+
+  DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID << " new addr: "
+               << format("%p", Addr) << " DataSize: " << TotalSize << "\n");
+
+  // Assign the address of each symbol
+  for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
+       itEnd = CommonSymbols.end(); it != itEnd; ++it) {
+    uint64_t Size = it->second.first;
+    uint64_t Align = it->second.second;
+    StringRef Name;
+    it->first.getName(Name);
+    if (Align) {
+      // This symbol has an alignment requirement.
+      uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
+      Addr += AlignOffset;
+      Offset += AlignOffset;
+      DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
+                   << format("%p\n", Addr));
     }
-    // The last symbol we do after since the end address is calculated
-    // differently because there is no next symbol to reference.
-    uint64_t StartOffset = Symbols[Symbols.size() - 1].first;
-    uint64_t EndOffset = Sect->Size - 1;
-    DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second
-                 << " from [" << StartOffset << ", " << EndOffset << "]\n");
-    extractFunction(Symbols[Symbols.size()-1].second,
-                    Base + StartOffset, Base + EndOffset);
+    Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
+    SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
+    Offset += Size;
+    Addr += Size;
   }
-
-  return false;
 }
 
-bool RuntimeDyldImpl::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");
+unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
+                                      const SectionRef &Section, bool IsCode) {
+
+  StringRef data;
+  uint64_t Alignment64;
+  Check(Section.getContents(data));
+  Check(Section.getAlignment(Alignment64));
+
+  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
+  bool IsRequired;
+  bool IsVirtual;
+  bool IsZeroInit;
+  bool IsReadOnly;
+  uint64_t DataSize;
+  unsigned PaddingSize = 0;
+  unsigned StubBufSize = 0;
+  StringRef Name;
+  Check(Section.isRequiredForExecution(IsRequired));
+  Check(Section.isVirtual(IsVirtual));
+  Check(Section.isZeroInit(IsZeroInit));
+  Check(Section.isReadOnlyData(IsReadOnly));
+  Check(Section.getSize(DataSize));
+  Check(Section.getName(Name));
+
+  StubBufSize = computeSectionStubBufSize(Obj, Section);
+
+  // The .eh_frame section (at least on Linux) needs an extra four bytes padded
+  // with zeroes added at the end.  For MachO objects, this section has a
+  // slightly different name, so this won't have any effect for MachO objects.
+  if (Name == ".eh_frame")
+    PaddingSize = 4;
+
+  uintptr_t Allocate;
+  unsigned SectionID = Sections.size();
+  uint8_t *Addr;
+  const char *pData = 0;
+
+  // Some sections, such as debug info, don't need to be loaded for execution.
+  // Leave those where they are.
+  if (IsRequired) {
+    Allocate = DataSize + PaddingSize + StubBufSize;
+    Addr = IsCode ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID,
+                                                Name)
+                  : MemMgr->allocateDataSection(Allocate, Alignment, SectionID,
+                                                Name, IsReadOnly);
+    if (!Addr)
+      report_fatal_error("Unable to allocate section memory!");
+
+    // Virtual sections have no data in the object image, so leave pData = 0
+    if (!IsVirtual)
+      pData = data.data();
+
+    // Zero-initialize or copy the data from the image
+    if (IsZeroInit || IsVirtual)
+      memset(Addr, 0, DataSize);
+    else
+      memcpy(Addr, pData, DataSize);
+
+    // Fill in any extra bytes we allocated for padding
+    if (PaddingSize != 0) {
+      memset(Addr + DataSize, 0, PaddingSize);
+      // Update the DataSize variable so that the stub offset is set correctly.
+      DataSize += PaddingSize;
     }
+
+    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
+                 << " obj addr: " << format("%p", pData)
+                 << " new addr: " << format("%p", Addr)
+                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
+                 << " Allocate: " << Allocate << "\n");
+    Obj.updateSectionAddress(Section, (uint64_t)Addr);
+  } else {
+    // Even if we didn't load the section, we need to record an entry for it
+    // to handle later processing (and by 'handle' I mean don't do anything
+    // with these sections).
+    Allocate = 0;
+    Addr = 0;
+    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
+                 << " obj addr: " << format("%p", data.data()) << " new addr: 0"
+                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
+                 << " Allocate: " << Allocate << "\n");
   }
 
-  if (!SymtabLCI)
-    return Error("no symbol table found in object");
-  if (!SegmentLCI)
-    return Error("no symbol table 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");
+  Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
+  return SectionID;
+}
+
+unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
+                                            const SectionRef &Section,
+                                            bool IsCode,
+                                            ObjSectionToIDMap &LocalSections) {
+
+  unsigned SectionID = 0;
+  ObjSectionToIDMap::iterator i = LocalSections.find(Section);
+  if (i != LocalSections.end())
+    SectionID = i->second;
+  else {
+    SectionID = emitSection(Obj, Section, IsCode);
+    LocalSections[Section] = SectionID;
   }
+  return SectionID;
+}
+
+void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
+                                              unsigned SectionID) {
+  Relocations[SectionID].push_back(RE);
+}
 
-  // Load the segment load command.
-  if (SegmentLCI->Command.Type == macho::LCT_Segment) {
-    if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC))
-      return true;
+void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
+                                             StringRef SymbolName) {
+  // Relocation by symbol.  If the symbol is found in the global symbol table,
+  // create an appropriate section relocation.  Otherwise, add it to
+  // ExternalSymbolRelocations.
+  SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
+  if (Loc == GlobalSymbolTable.end()) {
+    ExternalSymbolRelocations[SymbolName].push_back(RE);
   } else {
-    if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC))
-      return true;
+    // Copy the RE since we want to modify its addend.
+    RelocationEntry RECopy = RE;
+    RECopy.Addend += Loc->second.second;
+    Relocations[Loc->second.first].push_back(RECopy);
   }
+}
 
-  return false;
+uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
+  if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be) {
+    // This stub has to be able to access the full address space,
+    // since symbol lookup won't necessarily find a handy, in-range,
+    // PLT stub for functions which could be anywhere.
+    uint32_t *StubAddr = (uint32_t *)Addr;
+
+    // Stub can use ip0 (== x16) to calculate address
+    *StubAddr = 0xd2e00010; // movz ip0, #:abs_g3:<addr>
+    StubAddr++;
+    *StubAddr = 0xf2c00010; // movk ip0, #:abs_g2_nc:<addr>
+    StubAddr++;
+    *StubAddr = 0xf2a00010; // movk ip0, #:abs_g1_nc:<addr>
+    StubAddr++;
+    *StubAddr = 0xf2800010; // movk ip0, #:abs_g0_nc:<addr>
+    StubAddr++;
+    *StubAddr = 0xd61f0200; // br ip0
+
+    return Addr;
+  } else if (Arch == Triple::arm || Arch == Triple::armeb) {
+    // TODO: There is only ARM far stub now. We should add the Thumb stub,
+    // and stubs for branches Thumb - ARM and ARM - Thumb.
+    uint32_t *StubAddr = (uint32_t *)Addr;
+    *StubAddr = 0xe51ff004; // ldr pc,<label>
+    return (uint8_t *)++StubAddr;
+  } else if (Arch == Triple::mipsel || Arch == Triple::mips) {
+    uint32_t *StubAddr = (uint32_t *)Addr;
+    // 0:   3c190000        lui     t9,%hi(addr).
+    // 4:   27390000        addiu   t9,t9,%lo(addr).
+    // 8:   03200008        jr      t9.
+    // c:   00000000        nop.
+    const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
+    const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
+
+    *StubAddr = LuiT9Instr;
+    StubAddr++;
+    *StubAddr = AdduiT9Instr;
+    StubAddr++;
+    *StubAddr = JrT9Instr;
+    StubAddr++;
+    *StubAddr = NopInstr;
+    return Addr;
+  } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
+    // PowerPC64 stub: the address points to a function descriptor
+    // instead of the function itself. Load the function address
+    // on r11 and sets it to control register. Also loads the function
+    // TOC in r2 and environment pointer to r11.
+    writeInt32BE(Addr,    0x3D800000); // lis   r12, highest(addr)
+    writeInt32BE(Addr+4,  0x618C0000); // ori   r12, higher(addr)
+    writeInt32BE(Addr+8,  0x798C07C6); // sldi  r12, r12, 32
+    writeInt32BE(Addr+12, 0x658C0000); // oris  r12, r12, h(addr)
+    writeInt32BE(Addr+16, 0x618C0000); // ori   r12, r12, l(addr)
+    writeInt32BE(Addr+20, 0xF8410028); // std   r2,  40(r1)
+    writeInt32BE(Addr+24, 0xE96C0000); // ld    r11, 0(r12)
+    writeInt32BE(Addr+28, 0xE84C0008); // ld    r2,  0(r12)
+    writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
+    writeInt32BE(Addr+36, 0xE96C0010); // ld    r11, 16(r2)
+    writeInt32BE(Addr+40, 0x4E800420); // bctr
+
+    return Addr;
+  } else if (Arch == Triple::systemz) {
+    writeInt16BE(Addr,    0xC418);     // lgrl %r1,.+8
+    writeInt16BE(Addr+2,  0x0000);
+    writeInt16BE(Addr+4,  0x0004);
+    writeInt16BE(Addr+6,  0x07F1);     // brc 15,%r1
+    // 8-byte address stored at Addr + 8
+    return Addr;
+  } else if (Arch == Triple::x86_64) {
+    *Addr      = 0xFF; // jmp
+    *(Addr+1)  = 0x25; // rip
+    // 32-bit PC-relative address of the GOT entry will be stored at Addr+2
+  }
+  return Addr;
 }
 
+// Assign an address to a symbol name and resolve all the relocations
+// associated with it.
+void RuntimeDyldImpl::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. Relocations can't
+  // be applied until all the sections have been moved.  The client must
+  // trigger this with a call to MCJIT::finalize() or
+  // RuntimeDyld::resolveRelocations().
+  //
+  // 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.
+  Sections[SectionID].LoadAddress = Addr;
+}
+
+void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
+                                            uint64_t Value) {
+  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
+    const RelocationEntry &RE = Relocs[i];
+    // Ignore relocations for sections that were not loaded
+    if (Sections[RE.SectionID].Address == 0)
+      continue;
+    resolveRelocation(RE, Value);
+  }
+}
+
+void RuntimeDyldImpl::resolveExternalSymbols() {
+  while (!ExternalSymbolRelocations.empty()) {
+    StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
+
+    StringRef Name = i->first();
+    if (Name.size() == 0) {
+      // This is an absolute symbol, use an address of zero.
+      DEBUG(dbgs() << "Resolving absolute relocations."
+                   << "\n");
+      RelocationList &Relocs = i->second;
+      resolveRelocationList(Relocs, 0);
+    } else {
+      uint64_t Addr = 0;
+      SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
+      if (Loc == GlobalSymbolTable.end()) {
+        // This is an external symbol, try to get its address from
+        // MemoryManager.
+        Addr = MemMgr->getSymbolAddress(Name.data());
+        // The call to getSymbolAddress may have caused additional modules to
+        // be loaded, which may have added new entries to the
+        // ExternalSymbolRelocations map.  Consquently, we need to update our
+        // iterator.  This is also why retrieval of the relocation list
+        // associated with this symbol is deferred until below this point.
+        // New entries may have been added to the relocation list.
+        i = ExternalSymbolRelocations.find(Name);
+      } else {
+        // We found the symbol in our global table.  It was probably in a
+        // Module that we loaded previously.
+        SymbolLoc SymLoc = Loc->second;
+        Addr = getSectionLoadAddress(SymLoc.first) + SymLoc.second;
+      }
+
+      // FIXME: Implement error handling that doesn't kill the host program!
+      if (!Addr)
+        report_fatal_error("Program used external function '" + Name +
+                           "' which could not be resolved!");
+
+      updateGOTEntries(Name, Addr);
+      DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
+                   << format("0x%lx", Addr) << "\n");
+      // This list may have been updated when we called getSymbolAddress, so
+      // don't change this code to get the list earlier.
+      RelocationList &Relocs = i->second;
+      resolveRelocationList(Relocs, Addr);
+    }
+
+    ExternalSymbolRelocations.erase(i);
+  }
+}
 
 //===----------------------------------------------------------------------===//
 // RuntimeDyld class implementation
-RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *MM) {
-  Dyld = new RuntimeDyldImpl(MM);
+RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
+  // FIXME: There's a potential issue lurking here if a single instance of
+  // RuntimeDyld is used to load multiple objects.  The current implementation
+  // associates a single memory manager with a RuntimeDyld instance.  Even
+  // though the public class spawns a new 'impl' instance for each load,
+  // they share a single memory manager.  This can become a problem when page
+  // permissions are applied.
+  Dyld = 0;
+  MM = mm;
+  ProcessAllSections = false;
+}
+
+RuntimeDyld::~RuntimeDyld() { delete Dyld; }
+
+static std::unique_ptr<RuntimeDyldELF>
+createRuntimeDyldELF(RTDyldMemoryManager *MM, bool ProcessAllSections) {
+  std::unique_ptr<RuntimeDyldELF> Dyld(new RuntimeDyldELF(MM));
+  Dyld->setProcessAllSections(ProcessAllSections);
+  return Dyld;
 }
 
-RuntimeDyld::~RuntimeDyld() {
-  delete Dyld;
+static std::unique_ptr<RuntimeDyldMachO>
+createRuntimeDyldMachO(RTDyldMemoryManager *MM, bool ProcessAllSections) {
+  std::unique_ptr<RuntimeDyldMachO> Dyld(new RuntimeDyldMachO(MM));
+  Dyld->setProcessAllSections(ProcessAllSections);
+  return Dyld;
 }
 
-bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
-  return Dyld->loadObject(InputBuffer);
+ObjectImage *RuntimeDyld::loadObject(ObjectFile *InputObject) {
+  std::unique_ptr<ObjectImage> InputImage;
+
+  if (InputObject->isELF()) {
+    InputImage.reset(RuntimeDyldELF::createObjectImageFromFile(InputObject));
+    if (!Dyld)
+      Dyld = createRuntimeDyldELF(MM, ProcessAllSections).release();
+  } else if (InputObject->isMachO()) {
+    InputImage.reset(RuntimeDyldMachO::createObjectImageFromFile(InputObject));
+    if (!Dyld)
+      Dyld = createRuntimeDyldMachO(MM, ProcessAllSections).release();
+  } else
+    report_fatal_error("Incompatible object format!");
+
+  if (!Dyld->isCompatibleFile(InputObject))
+    report_fatal_error("Incompatible object format!");
+
+  Dyld->loadObject(InputImage.get());
+  return InputImage.release();
+}
+
+ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
+  std::unique_ptr<ObjectImage> InputImage;
+  sys::fs::file_magic Type = sys::fs::identify_magic(InputBuffer->getBuffer());
+
+  switch (Type) {
+  case sys::fs::file_magic::elf_relocatable:
+  case sys::fs::file_magic::elf_executable:
+  case sys::fs::file_magic::elf_shared_object:
+  case sys::fs::file_magic::elf_core:
+    InputImage.reset(RuntimeDyldELF::createObjectImage(InputBuffer));
+    if (!Dyld)
+      Dyld = createRuntimeDyldELF(MM, ProcessAllSections).release();
+    break;
+  case sys::fs::file_magic::macho_object:
+  case sys::fs::file_magic::macho_executable:
+  case sys::fs::file_magic::macho_fixed_virtual_memory_shared_lib:
+  case sys::fs::file_magic::macho_core:
+  case sys::fs::file_magic::macho_preload_executable:
+  case sys::fs::file_magic::macho_dynamically_linked_shared_lib:
+  case sys::fs::file_magic::macho_dynamic_linker:
+  case sys::fs::file_magic::macho_bundle:
+  case sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
+  case sys::fs::file_magic::macho_dsym_companion:
+    InputImage.reset(RuntimeDyldMachO::createObjectImage(InputBuffer));
+    if (!Dyld)
+      Dyld = createRuntimeDyldMachO(MM, ProcessAllSections).release();
+    break;
+  case sys::fs::file_magic::unknown:
+  case sys::fs::file_magic::bitcode:
+  case sys::fs::file_magic::archive:
+  case sys::fs::file_magic::coff_object:
+  case sys::fs::file_magic::coff_import_library:
+  case sys::fs::file_magic::pecoff_executable:
+  case sys::fs::file_magic::macho_universal_binary:
+  case sys::fs::file_magic::windows_resource:
+    report_fatal_error("Incompatible object format!");
+  }
+
+  if (!Dyld->isCompatibleFormat(InputBuffer))
+    report_fatal_error("Incompatible object format!");
+
+  Dyld->loadObject(InputImage.get());
+  return InputImage.release();
 }
 
 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
+  if (!Dyld)
+    return NULL;
   return Dyld->getSymbolAddress(Name);
 }
 
-sys::MemoryBlock RuntimeDyld::getMemoryBlock() {
-  return Dyld->getMemoryBlock();
+uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
+  if (!Dyld)
+    return 0;
+  return Dyld->getSymbolLoadAddress(Name);
+}
+
+void RuntimeDyld::resolveRelocations() { Dyld->resolveRelocations(); }
+
+void RuntimeDyld::reassignSectionAddress(unsigned SectionID, uint64_t Addr) {
+  Dyld->reassignSectionAddress(SectionID, Addr);
+}
+
+void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
+                                    uint64_t TargetAddress) {
+  Dyld->mapSectionAddress(LocalAddress, TargetAddress);
+}
+
+bool RuntimeDyld::hasError() { return Dyld->hasError(); }
+
+StringRef RuntimeDyld::getErrorString() { return Dyld->getErrorString(); }
+
+void RuntimeDyld::registerEHFrames() {
+  if (Dyld)
+    Dyld->registerEHFrames();
 }
 
-StringRef RuntimeDyld::getErrorString() {
-  return Dyld->getErrorString();
+void RuntimeDyld::deregisterEHFrames() {
+  if (Dyld)
+    Dyld->deregisterEHFrames();
 }
 
 } // end namespace llvm