RuntimeDyldMachO.cpp revision 652ca2fe0c8bd406222d064937adc28b281d7b89 
1//===-- RuntimeDyldMachO.cpp - Run-time dynamic linker for MC-JIT ------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Implementation of the MC-JIT runtime dynamic linker.
11//
12//===----------------------------------------------------------------------===//
13
14#define DEBUG_TYPE "dyld"
15#include "llvm/ADT/OwningPtr.h"
16#include "llvm/ADT/StringRef.h"
17#include "llvm/ADT/STLExtras.h"
18#include "RuntimeDyldImpl.h"
19using namespace llvm;
20using namespace llvm::object;
21
22namespace llvm {
23
24bool RuntimeDyldMachO::
25resolveRelocation(uint8_t *Address, uint64_t Value, bool isPCRel,
26                  unsigned Type, unsigned Size, int64_t Addend) {
27  // This just dispatches to the proper target specific routine.
28  switch (CPUType) {
29  default: assert(0 && "Unsupported CPU type!");
30  case mach::CTM_x86_64:
31    return resolveX86_64Relocation((uintptr_t)Address, (uintptr_t)Value,
32                                   isPCRel, Type, Size, Addend);
33  case mach::CTM_ARM:
34    return resolveARMRelocation((uintptr_t)Address, (uintptr_t)Value,
35                                isPCRel, Type, Size, Addend);
36  }
37  llvm_unreachable("");
38}
39
40bool RuntimeDyldMachO::
41resolveX86_64Relocation(uintptr_t Address, uintptr_t Value, bool isPCRel,
42                        unsigned Type, unsigned Size, int64_t Addend) {
43  // If the relocation is PC-relative, the value to be encoded is the
44  // pointer difference.
45  if (isPCRel)
46    // FIXME: It seems this value needs to be adjusted by 4 for an effective PC
47    // address. Is that expected? Only for branches, perhaps?
48    Value -= Address + 4;
49
50  switch(Type) {
51  default:
52    llvm_unreachable("Invalid relocation type!");
53  case macho::RIT_X86_64_Signed1:
54  case macho::RIT_X86_64_Signed2:
55  case macho::RIT_X86_64_Signed4:
56  case macho::RIT_X86_64_Signed:
57  case macho::RIT_X86_64_Unsigned:
58  case macho::RIT_X86_64_Branch: {
59    Value += Addend;
60    // Mask in the target value a byte at a time (we don't have an alignment
61    // guarantee for the target address, so this is safest).
62    uint8_t *p = (uint8_t*)Address;
63    for (unsigned i = 0; i < Size; ++i) {
64      *p++ = (uint8_t)Value;
65      Value >>= 8;
66    }
67    return false;
68  }
69  case macho::RIT_X86_64_GOTLoad:
70  case macho::RIT_X86_64_GOT:
71  case macho::RIT_X86_64_Subtractor:
72  case macho::RIT_X86_64_TLV:
73    return Error("Relocation type not implemented yet!");
74  }
75  return false;
76}
77
78bool RuntimeDyldMachO::
79resolveARMRelocation(uintptr_t Address, uintptr_t Value, bool isPCRel,
80                     unsigned Type, unsigned Size, int64_t Addend) {
81  // If the relocation is PC-relative, the value to be encoded is the
82  // pointer difference.
83  if (isPCRel) {
84    Value -= Address;
85    // ARM PCRel relocations have an effective-PC offset of two instructions
86    // (four bytes in Thumb mode, 8 bytes in ARM mode).
87    // FIXME: For now, assume ARM mode.
88    Value -= 8;
89  }
90
91  switch(Type) {
92  default:
93    llvm_unreachable("Invalid relocation type!");
94  case macho::RIT_Vanilla: {
95    llvm_unreachable("Invalid relocation type!");
96    // Mask in the target value a byte at a time (we don't have an alignment
97    // guarantee for the target address, so this is safest).
98    uint8_t *p = (uint8_t*)Address;
99    for (unsigned i = 0; i < Size; ++i) {
100      *p++ = (uint8_t)Value;
101      Value >>= 8;
102    }
103    break;
104  }
105  case macho::RIT_ARM_Branch24Bit: {
106    // Mask the value into the target address. We know instructions are
107    // 32-bit aligned, so we can do it all at once.
108    uint32_t *p = (uint32_t*)Address;
109    // The low two bits of the value are not encoded.
110    Value >>= 2;
111    // Mask the value to 24 bits.
112    Value &= 0xffffff;
113    // FIXME: If the destination is a Thumb function (and the instruction
114    // is a non-predicated BL instruction), we need to change it to a BLX
115    // instruction instead.
116
117    // Insert the value into the instruction.
118    *p = (*p & ~0xffffff) | Value;
119    break;
120  }
121  case macho::RIT_ARM_ThumbBranch22Bit:
122  case macho::RIT_ARM_ThumbBranch32Bit:
123  case macho::RIT_ARM_Half:
124  case macho::RIT_ARM_HalfDifference:
125  case macho::RIT_Pair:
126  case macho::RIT_Difference:
127  case macho::RIT_ARM_LocalDifference:
128  case macho::RIT_ARM_PreboundLazyPointer:
129    return Error("Relocation type not implemented yet!");
130  }
131  return false;
132}
133
134bool RuntimeDyldMachO::
135loadSegment32(const MachOObject *Obj,
136              const MachOObject::LoadCommandInfo *SegmentLCI,
137              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
138  // FIXME: This should really be combined w/ loadSegment64. Templatized
139  // function on the 32/64 datatypes maybe?
140  InMemoryStruct<macho::SegmentLoadCommand> SegmentLC;
141  Obj->ReadSegmentLoadCommand(*SegmentLCI, SegmentLC);
142  if (!SegmentLC)
143    return Error("unable to load segment load command");
144
145
146  SmallVector<unsigned, 16> SectionMap;
147  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
148    InMemoryStruct<macho::Section> Sect;
149    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
150    if (!Sect)
151      return Error("unable to load section: '" + Twine(SectNum) + "'");
152
153    // Allocate memory via the MM for the section.
154    uint8_t *Buffer;
155    uint32_t SectionID = Sections.size();
156    if (Sect->Flags != 0x80000400)
157      Buffer = MemMgr->allocateCodeSection(Sect->Size, Sect->Align, SectionID);
158    else
159      Buffer = MemMgr->allocateDataSection(Sect->Size, Sect->Align, SectionID);
160
161    DEBUG(dbgs() << "Loading "
162                 << ((Sect->Flags == 0x80000400) ? "text" : "data")
163                 << " (ID #" << SectionID << ")"
164                 << " '" << Sect->SegmentName << ","
165                 << Sect->Name << "' of size " << Sect->Size
166                 << " to address " << Buffer << ".\n");
167
168    // Copy the payload from the object file into the allocated buffer.
169    uint8_t *Base = (uint8_t*)Obj->getData(SegmentLC->FileOffset,
170                                           SegmentLC->FileSize).data();
171    memcpy(Buffer, Base + Sect->Address, Sect->Size);
172
173    // Remember what got allocated for this SectionID.
174    Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
175
176    // By default, the load address of a section is its memory buffer.
177    SectionLoadAddress.push_back((uint64_t)Buffer);
178
179    // Keep a map of object file section numbers to corresponding SectionIDs
180    // while processing the file.
181    SectionMap.push_back(SectionID);
182  }
183
184  // Process the symbol table.
185  SmallVector<StringRef, 64> SymbolNames;
186  processSymbols32(Obj, SectionMap, SymbolNames, SymtabLC);
187
188  // Process the relocations for each section we're loading.
189  Relocations.grow(Relocations.size() + SegmentLC->NumSections);
190  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
191    InMemoryStruct<macho::Section> Sect;
192    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
193    if (!Sect)
194      return Error("unable to load section: '" + Twine(SectNum) + "'");
195    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
196      InMemoryStruct<macho::RelocationEntry> RE;
197      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
198      if (RE->Word0 & macho::RF_Scattered)
199        return Error("NOT YET IMPLEMENTED: scattered relocations.");
200      // Word0 of the relocation is the offset into the section where the
201      // relocation should be applied. We need to translate that into an
202      // offset into a function since that's our atom.
203      uint32_t Offset = RE->Word0;
204      bool isExtern = (RE->Word1 >> 27) & 1;
205
206      // FIXME: Get the relocation addend from the target address.
207      // FIXME: VERY imporant for internal relocations.
208
209      // Figure out the source symbol of the relocation. If isExtern is true,
210      // this relocation references the symbol table, otherwise it references
211      // a section in the same object, numbered from 1 through NumSections
212      // (SectionBases is [0, NumSections-1]).
213      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
214      if (!isExtern) {
215        assert(SourceNum > 0 && "Invalid relocation section number!");
216        unsigned SectionID = SectionMap[SourceNum - 1];
217        unsigned TargetID = SectionMap[SectNum];
218        DEBUG(dbgs() << "Internal relocation at Section #"
219                     << TargetID << " + " << Offset
220                     << " from Section #"
221                     << SectionID << " (Word1: "
222                     << format("0x%x", RE->Word1) << ")\n");
223
224        // Store the relocation information. It will get resolved when
225        // the section addresses are assigned.
226        Relocations[SectionID].push_back(RelocationEntry(TargetID,
227                                                         Offset,
228                                                         RE->Word1,
229                                                         0 /*Addend*/));
230      } else {
231        StringRef SourceName = SymbolNames[SourceNum];
232
233        // Now store the relocation information. Associate it with the source
234        // symbol. Just add it to the unresolved list and let the general
235        // path post-load resolve it if we know where the symbol is.
236        UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
237                                                                    Offset,
238                                                                    RE->Word1,
239                                                                 0 /*Addend*/));
240        DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
241              << " from '" << SourceName << "(Word1: "
242              << format("0x%x", RE->Word1) << ")\n");
243      }
244    }
245  }
246
247  // Resolve the addresses of any symbols that were defined in this segment.
248  for (int i = 0, e = SymbolNames.size(); i != e; ++i)
249    resolveSymbol(SymbolNames[i]);
250
251  return false;
252}
253
254
255bool RuntimeDyldMachO::
256loadSegment64(const MachOObject *Obj,
257              const MachOObject::LoadCommandInfo *SegmentLCI,
258              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
259  InMemoryStruct<macho::Segment64LoadCommand> Segment64LC;
260  Obj->ReadSegment64LoadCommand(*SegmentLCI, Segment64LC);
261  if (!Segment64LC)
262    return Error("unable to load segment load command");
263
264
265  SmallVector<unsigned, 16> SectionMap;
266  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
267    InMemoryStruct<macho::Section64> Sect;
268    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
269    if (!Sect)
270      return Error("unable to load section: '" + Twine(SectNum) + "'");
271
272    // Allocate memory via the MM for the section.
273    uint8_t *Buffer;
274    uint32_t SectionID = Sections.size();
275    if (Sect->Flags != 0x80000400)
276      Buffer = MemMgr->allocateCodeSection(Sect->Size, Sect->Align, SectionID);
277    else
278      Buffer = MemMgr->allocateDataSection(Sect->Size, Sect->Align, SectionID);
279
280    DEBUG(dbgs() << "Loading "
281                 << ((Sect->Flags == 0x80000400) ? "text" : "data")
282                 << " (ID #" << SectionID << ")"
283                 << " '" << Sect->SegmentName << ","
284                 << Sect->Name << "' of size " << Sect->Size
285                 << " to address " << Buffer << ".\n");
286
287    // Copy the payload from the object file into the allocated buffer.
288    uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
289                                           Segment64LC->FileSize).data();
290    memcpy(Buffer, Base + Sect->Address, Sect->Size);
291
292    // Remember what got allocated for this SectionID.
293    Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
294
295    // By default, the load address of a section is its memory buffer.
296    SectionLoadAddress.push_back((uint64_t)Buffer);
297
298    // Keep a map of object file section numbers to corresponding SectionIDs
299    // while processing the file.
300    SectionMap.push_back(SectionID);
301  }
302
303  // Process the symbol table.
304  SmallVector<StringRef, 64> SymbolNames;
305  processSymbols64(Obj, SectionMap, SymbolNames, SymtabLC);
306
307  // Process the relocations for each section we're loading.
308  Relocations.grow(Relocations.size() + Segment64LC->NumSections);
309  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
310    InMemoryStruct<macho::Section64> Sect;
311    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
312    if (!Sect)
313      return Error("unable to load section: '" + Twine(SectNum) + "'");
314    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
315      InMemoryStruct<macho::RelocationEntry> RE;
316      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
317      if (RE->Word0 & macho::RF_Scattered)
318        return Error("NOT YET IMPLEMENTED: scattered relocations.");
319      // Word0 of the relocation is the offset into the section where the
320      // relocation should be applied. We need to translate that into an
321      // offset into a function since that's our atom.
322      uint32_t Offset = RE->Word0;
323      bool isExtern = (RE->Word1 >> 27) & 1;
324
325      // FIXME: Get the relocation addend from the target address.
326      // FIXME: VERY imporant for internal relocations.
327
328      // Figure out the source symbol of the relocation. If isExtern is true,
329      // this relocation references the symbol table, otherwise it references
330      // a section in the same object, numbered from 1 through NumSections
331      // (SectionBases is [0, NumSections-1]).
332      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
333      if (!isExtern) {
334        assert(SourceNum > 0 && "Invalid relocation section number!");
335        unsigned SectionID = SectionMap[SourceNum - 1];
336        unsigned TargetID = SectionMap[SectNum];
337        DEBUG(dbgs() << "Internal relocation at Section #"
338                     << TargetID << " + " << Offset
339                     << " from Section #"
340                     << SectionID << " (Word1: "
341                     << format("0x%x", RE->Word1) << ")\n");
342
343        // Store the relocation information. It will get resolved when
344        // the section addresses are assigned.
345        Relocations[SectionID].push_back(RelocationEntry(TargetID,
346                                                         Offset,
347                                                         RE->Word1,
348                                                         0 /*Addend*/));
349      } else {
350        StringRef SourceName = SymbolNames[SourceNum];
351
352        // Now store the relocation information. Associate it with the source
353        // symbol. Just add it to the unresolved list and let the general
354        // path post-load resolve it if we know where the symbol is.
355        UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
356                                                                    Offset,
357                                                                    RE->Word1,
358                                                                 0 /*Addend*/));
359        DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
360              << " from '" << SourceName << "(Word1: "
361              << format("0x%x", RE->Word1) << ")\n");
362      }
363    }
364  }
365
366  // Resolve the addresses of any symbols that were defined in this segment.
367  for (int i = 0, e = SymbolNames.size(); i != e; ++i)
368    resolveSymbol(SymbolNames[i]);
369
370  return false;
371}
372
373bool RuntimeDyldMachO::
374processSymbols32(const MachOObject *Obj,
375                 SmallVectorImpl<unsigned> &SectionMap,
376                 SmallVectorImpl<StringRef> &SymbolNames,
377                 const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
378  // FIXME: Combine w/ processSymbols64. Factor 64/32 datatype and such.
379  for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
380    InMemoryStruct<macho::SymbolTableEntry> STE;
381    Obj->ReadSymbolTableEntry(SymtabLC->SymbolTableOffset, i, STE);
382    if (!STE)
383      return Error("unable to read symbol: '" + Twine(i) + "'");
384    // Get the symbol name.
385    StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
386    SymbolNames.push_back(Name);
387
388    // FIXME: Check the symbol type and flags.
389    if (STE->Type != 0xF)  // external, defined in this segment.
390      continue;
391    // Flags in the upper nibble we don't care about.
392    if ((STE->Flags & 0xf) != 0x0)
393      continue;
394
395    // Remember the symbol.
396    uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
397    SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
398
399    DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
400                 << (getSectionAddress(SectionID) + STE->Value)
401                 << "\n");
402  }
403  return false;
404}
405
406bool RuntimeDyldMachO::
407processSymbols64(const MachOObject *Obj,
408                 SmallVectorImpl<unsigned> &SectionMap,
409                 SmallVectorImpl<StringRef> &SymbolNames,
410                 const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
411  for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
412    InMemoryStruct<macho::Symbol64TableEntry> STE;
413    Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE);
414    if (!STE)
415      return Error("unable to read symbol: '" + Twine(i) + "'");
416    // Get the symbol name.
417    StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
418    SymbolNames.push_back(Name);
419
420    // FIXME: Check the symbol type and flags.
421    if (STE->Type != 0xF)  // external, defined in this segment.
422      continue;
423    // Flags in the upper nibble we don't care about.
424    if ((STE->Flags & 0xf) != 0x0)
425      continue;
426
427    // Remember the symbol.
428    uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
429    SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
430
431    DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
432                 << (getSectionAddress(SectionID) + STE->Value)
433                 << "\n");
434  }
435  return false;
436}
437
438// resolveSymbol - Resolve any relocations to the specified symbol if
439// we know where it lives.
440void RuntimeDyldMachO::resolveSymbol(StringRef Name) {
441  StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
442  if (Loc == SymbolTable.end())
443    return;
444
445  RelocationList &Relocs = UnresolvedRelocations[Name];
446  DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
447  for (int i = 0, e = Relocs.size(); i != e; ++i) {
448    // Change the relocation to be section relative rather than symbol
449    // relative and move it to the resolved relocation list.
450    RelocationEntry Entry = Relocs[i];
451    Entry.Addend += Loc->second.second;
452    Relocations[Loc->second.first].push_back(Entry);
453  }
454  // FIXME: Keep a worklist of the relocations we've added so that we can
455  // resolve more selectively later.
456  Relocs.clear();
457}
458
459bool RuntimeDyldMachO::loadObject(MemoryBuffer *InputBuffer) {
460  // If the linker is in an error state, don't do anything.
461  if (hasError())
462    return true;
463  // Load the Mach-O wrapper object.
464  std::string ErrorStr;
465  OwningPtr<MachOObject> Obj(
466    MachOObject::LoadFromBuffer(InputBuffer, &ErrorStr));
467  if (!Obj)
468    return Error("unable to load object: '" + ErrorStr + "'");
469
470  // Get the CPU type information from the header.
471  const macho::Header &Header = Obj->getHeader();
472
473  // FIXME: Error checking that the loaded object is compatible with
474  //        the system we're running on.
475  CPUType = Header.CPUType;
476  CPUSubtype = Header.CPUSubtype;
477
478  // Validate that the load commands match what we expect.
479  const MachOObject::LoadCommandInfo *SegmentLCI = 0, *SymtabLCI = 0,
480    *DysymtabLCI = 0;
481  for (unsigned i = 0; i != Header.NumLoadCommands; ++i) {
482    const MachOObject::LoadCommandInfo &LCI = Obj->getLoadCommandInfo(i);
483    switch (LCI.Command.Type) {
484    case macho::LCT_Segment:
485    case macho::LCT_Segment64:
486      if (SegmentLCI)
487        return Error("unexpected input object (multiple segments)");
488      SegmentLCI = &LCI;
489      break;
490    case macho::LCT_Symtab:
491      if (SymtabLCI)
492        return Error("unexpected input object (multiple symbol tables)");
493      SymtabLCI = &LCI;
494      break;
495    case macho::LCT_Dysymtab:
496      if (DysymtabLCI)
497        return Error("unexpected input object (multiple symbol tables)");
498      DysymtabLCI = &LCI;
499      break;
500    default:
501      return Error("unexpected input object (unexpected load command");
502    }
503  }
504
505  if (!SymtabLCI)
506    return Error("no symbol table found in object");
507  if (!SegmentLCI)
508    return Error("no segments found in object");
509
510  // Read and register the symbol table data.
511  InMemoryStruct<macho::SymtabLoadCommand> SymtabLC;
512  Obj->ReadSymtabLoadCommand(*SymtabLCI, SymtabLC);
513  if (!SymtabLC)
514    return Error("unable to load symbol table load command");
515  Obj->RegisterStringTable(*SymtabLC);
516
517  // Read the dynamic link-edit information, if present (not present in static
518  // objects).
519  if (DysymtabLCI) {
520    InMemoryStruct<macho::DysymtabLoadCommand> DysymtabLC;
521    Obj->ReadDysymtabLoadCommand(*DysymtabLCI, DysymtabLC);
522    if (!DysymtabLC)
523      return Error("unable to load dynamic link-exit load command");
524
525    // FIXME: We don't support anything interesting yet.
526//    if (DysymtabLC->LocalSymbolsIndex != 0)
527//      return Error("NOT YET IMPLEMENTED: local symbol entries");
528//    if (DysymtabLC->ExternalSymbolsIndex != 0)
529//      return Error("NOT YET IMPLEMENTED: non-external symbol entries");
530//    if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
531//      return Error("NOT YET IMPLEMENTED: undefined symbol entries");
532  }
533
534  // Load the segment load command.
535  if (SegmentLCI->Command.Type == macho::LCT_Segment) {
536    if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC))
537      return true;
538  } else {
539    if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC))
540      return true;
541  }
542
543  // Assign the addresses of the sections from the object so that any
544  // relocations to them get set properly.
545  // FIXME: This is done directly from the client at the moment. We should
546  // default the values to the local storage, at least when the target arch
547  // is the same as the host arch.
548
549  return false;
550}
551
552// Assign an address to a symbol name and resolve all the relocations
553// associated with it.
554void RuntimeDyldMachO::reassignSectionAddress(unsigned SectionID,
555                                              uint64_t Addr) {
556  // The address to use for relocation resolution is not
557  // the address of the local section buffer. We must be doing
558  // a remote execution environment of some sort. Re-apply any
559  // relocations referencing this section with the given address.
560  //
561  // Addr is a uint64_t because we can't assume the pointer width
562  // of the target is the same as that of the host. Just use a generic
563  // "big enough" type.
564
565  SectionLoadAddress[SectionID] = Addr;
566
567  RelocationList &Relocs = Relocations[SectionID];
568  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
569    RelocationEntry &RE = Relocs[i];
570    uint8_t *Target = (uint8_t*)Sections[RE.SectionID].base() + RE.Offset;
571    bool isPCRel = (RE.Data >> 24) & 1;
572    unsigned Type = (RE.Data >> 28) & 0xf;
573    unsigned Size = 1 << ((RE.Data >> 25) & 3);
574
575    DEBUG(dbgs() << "Resolving relocation at Section #" << RE.SectionID
576          << " + " << RE.Offset << " (" << format("%p", Target) << ")"
577          << " from Section #" << SectionID << " (" << format("%p", Addr) << ")"
578          << "(" << (isPCRel ? "pcrel" : "absolute")
579          << ", type: " << Type << ", Size: " << Size << ", Addend: "
580          << RE.Addend << ").\n");
581
582    resolveRelocation(Target, Addr, isPCRel, Type, Size, RE.Addend);
583  }
584}
585
586bool RuntimeDyldMachO::isKnownFormat(const MemoryBuffer *InputBuffer) {
587  StringRef Magic = InputBuffer->getBuffer().slice(0, 4);
588  if (Magic == "\xFE\xED\xFA\xCE") return true;
589  if (Magic == "\xCE\xFA\xED\xFE") return true;
590  if (Magic == "\xFE\xED\xFA\xCF") return true;
591  if (Magic == "\xCF\xFA\xED\xFE") return true;
592  return false;
593}
594
595} // end namespace llvm
596