contrib/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

   1 //===-- RuntimeDyld.cpp - Run-time dynamic linker for MC-JIT ----*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Implementation of the MC-JIT runtime dynamic linker.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/ExecutionEngine/RuntimeDyld.h"
  14 #include "RuntimeDyldCOFF.h"
  15 #include "RuntimeDyldELF.h"
  16 #include "RuntimeDyldImpl.h"
  17 #include "RuntimeDyldMachO.h"
  18 #include "llvm/Object/COFF.h"
  19 #include "llvm/Object/ELFObjectFile.h"
  20 #include "llvm/Support/MSVCErrorWorkarounds.h"
  21 #include "llvm/Support/ManagedStatic.h"
  22 #include "llvm/Support/MathExtras.h"
  23 #include "llvm/Support/MutexGuard.h"
  24
  25 #include <future>
  26
  27 using namespace llvm;
  28 using namespace llvm::object;
  29
  30 #define DEBUG_TYPE "dyld"
  31
  32 namespace {
  33
  34 enum RuntimeDyldErrorCode {
  35   GenericRTDyldError = 1
  36 };
  37
  38 // FIXME: This class is only here to support the transition to llvm::Error. It
  39 // will be removed once this transition is complete. Clients should prefer to
  40 // deal with the Error value directly, rather than converting to error_code.
  41 class RuntimeDyldErrorCategory : public std::error_category {
  42 public:
  43   const char *name() const noexcept override { return "runtimedyld"; }
  44
  45   std::string message(int Condition) const override {
  46     switch (static_cast<RuntimeDyldErrorCode>(Condition)) {
  47       case GenericRTDyldError: return "Generic RuntimeDyld error";
  48     }
  49     llvm_unreachable("Unrecognized RuntimeDyldErrorCode");
  50   }
  51 };
  52
  53 static ManagedStatic<RuntimeDyldErrorCategory> RTDyldErrorCategory;
  54
  55 }
  56
  57 char RuntimeDyldError::ID = 0;
  58
  59 void RuntimeDyldError::log(raw_ostream &OS) const {
  60   OS << ErrMsg << "\n";
  61 }
  62
  63 std::error_code RuntimeDyldError::convertToErrorCode() const {
  64   return std::error_code(GenericRTDyldError, *RTDyldErrorCategory);
  65 }
  66
  67 // Empty out-of-line virtual destructor as the key function.
  68 RuntimeDyldImpl::~RuntimeDyldImpl() {}
  69
  70 // Pin LoadedObjectInfo's vtables to this file.
  71 void RuntimeDyld::LoadedObjectInfo::anchor() {}
  72
  73 namespace llvm {
  74
  75 void RuntimeDyldImpl::registerEHFrames() {}
  76
  77 void RuntimeDyldImpl::deregisterEHFrames() {
  78   MemMgr.deregisterEHFrames();
  79 }
  80
  81 #ifndef NDEBUG
  82 static void dumpSectionMemory(const SectionEntry &S, StringRef State) {
  83   dbgs() << "----- Contents of section " << S.getName() << " " << State
  84          << " -----";
  85
  86   if (S.getAddress() == nullptr) {
  87     dbgs() << "\n          <section not emitted>\n";
  88     return;
  89   }
  90
  91   const unsigned ColsPerRow = 16;
  92
  93   uint8_t *DataAddr = S.getAddress();
  94   uint64_t LoadAddr = S.getLoadAddress();
  95
  96   unsigned StartPadding = LoadAddr & (ColsPerRow - 1);
  97   unsigned BytesRemaining = S.getSize();
  98
  99   if (StartPadding) {
 100     dbgs() << "\n" << format("0x%016" PRIx64,
 101                              LoadAddr & ~(uint64_t)(ColsPerRow - 1)) << ":";
 102     while (StartPadding--)
 103       dbgs() << "   ";
 104   }
 105
 106   while (BytesRemaining > 0) {
 107     if ((LoadAddr & (ColsPerRow - 1)) == 0)
 108       dbgs() << "\n" << format("0x%016" PRIx64, LoadAddr) << ":";
 109
 110     dbgs() << " " << format("%02x", *DataAddr);
 111
 112     ++DataAddr;
 113     ++LoadAddr;
 114     --BytesRemaining;
 115   }
 116
 117   dbgs() << "\n";
 118 }
 119 #endif
 120
 121 // Resolve the relocations for all symbols we currently know about.
 122 void RuntimeDyldImpl::resolveRelocations() {
 123   MutexGuard locked(lock);
 124
 125   // Print out the sections prior to relocation.
 126   LLVM_DEBUG(for (int i = 0, e = Sections.size(); i != e; ++i)
 127                  dumpSectionMemory(Sections[i], "before relocations"););
 128
 129   // First, resolve relocations associated with external symbols.
 130   if (auto Err = resolveExternalSymbols()) {
 131     HasError = true;
 132     ErrorStr = toString(std::move(Err));
 133   }
 134
 135   resolveLocalRelocations();
 136
 137   // Print out sections after relocation.
 138   LLVM_DEBUG(for (int i = 0, e = Sections.size(); i != e; ++i)
 139                  dumpSectionMemory(Sections[i], "after relocations"););
 140 }
 141
 142 void RuntimeDyldImpl::resolveLocalRelocations() {
 143   // Iterate over all outstanding relocations
 144   for (auto it = Relocations.begin(), e = Relocations.end(); it != e; ++it) {
 145     // The Section here (Sections[i]) refers to the section in which the
 146     // symbol for the relocation is located.  The SectionID in the relocation
 147     // entry provides the section to which the relocation will be applied.
 148     int Idx = it->first;
 149     uint64_t Addr = Sections[Idx].getLoadAddress();
 150     LLVM_DEBUG(dbgs() << "Resolving relocations Section #" << Idx << "\t"
 151                       << format("%p", (uintptr_t)Addr) << "\n");
 152     resolveRelocationList(it->second, Addr);
 153   }
 154   Relocations.clear();
 155 }
 156
 157 void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
 158                                         uint64_t TargetAddress) {
 159   MutexGuard locked(lock);
 160   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
 161     if (Sections[i].getAddress() == LocalAddress) {
 162       reassignSectionAddress(i, TargetAddress);
 163       return;
 164     }
 165   }
 166   llvm_unreachable("Attempting to remap address of unknown section!");
 167 }
 168
 169 static Error getOffset(const SymbolRef &Sym, SectionRef Sec,
 170                        uint64_t &Result) {
 171   Expected<uint64_t> AddressOrErr = Sym.getAddress();
 172   if (!AddressOrErr)
 173     return AddressOrErr.takeError();
 174   Result = *AddressOrErr - Sec.getAddress();
 175   return Error::success();
 176 }
 177
 178 Expected<RuntimeDyldImpl::ObjSectionToIDMap>
 179 RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
 180   MutexGuard locked(lock);
 181
 182   // Save information about our target
 183   Arch = (Triple::ArchType)Obj.getArch();
 184   IsTargetLittleEndian = Obj.isLittleEndian();
 185   setMipsABI(Obj);
 186
 187   // Compute the memory size required to load all sections to be loaded
 188   // and pass this information to the memory manager
 189   if (MemMgr.needsToReserveAllocationSpace()) {
 190     uint64_t CodeSize = 0, RODataSize = 0, RWDataSize = 0;
 191     uint32_t CodeAlign = 1, RODataAlign = 1, RWDataAlign = 1;
 192     if (auto Err = computeTotalAllocSize(Obj,
 193                                          CodeSize, CodeAlign,
 194                                          RODataSize, RODataAlign,
 195                                          RWDataSize, RWDataAlign))
 196       return std::move(Err);
 197     MemMgr.reserveAllocationSpace(CodeSize, CodeAlign, RODataSize, RODataAlign,
 198                                   RWDataSize, RWDataAlign);
 199   }
 200
 201   // Used sections from the object file
 202   ObjSectionToIDMap LocalSections;
 203
 204   // Common symbols requiring allocation, with their sizes and alignments
 205   CommonSymbolList CommonSymbolsToAllocate;
 206
 207   uint64_t CommonSize = 0;
 208   uint32_t CommonAlign = 0;
 209
 210   // First, collect all weak and common symbols. We need to know if stronger
 211   // definitions occur elsewhere.
 212   JITSymbolResolver::LookupSet ResponsibilitySet;
 213   {
 214     JITSymbolResolver::LookupSet Symbols;
 215     for (auto &Sym : Obj.symbols()) {
 216       uint32_t Flags = Sym.getFlags();
 217       if ((Flags & SymbolRef::SF_Common) || (Flags & SymbolRef::SF_Weak)) {
 218         // Get symbol name.
 219         if (auto NameOrErr = Sym.getName())
 220           Symbols.insert(*NameOrErr);
 221         else
 222           return NameOrErr.takeError();
 223       }
 224     }
 225
 226     if (auto ResultOrErr = Resolver.getResponsibilitySet(Symbols))
 227       ResponsibilitySet = std::move(*ResultOrErr);
 228     else
 229       return ResultOrErr.takeError();
 230   }
 231
 232   // Parse symbols
 233   LLVM_DEBUG(dbgs() << "Parse symbols:\n");
 234   for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
 235        ++I) {
 236     uint32_t Flags = I->getFlags();
 237
 238     // Skip undefined symbols.
 239     if (Flags & SymbolRef::SF_Undefined)
 240       continue;
 241
 242     // Get the symbol type.
 243     object::SymbolRef::Type SymType;
 244     if (auto SymTypeOrErr = I->getType())
 245       SymType = *SymTypeOrErr;
 246     else
 247       return SymTypeOrErr.takeError();
 248
 249     // Get symbol name.
 250     StringRef Name;
 251     if (auto NameOrErr = I->getName())
 252       Name = *NameOrErr;
 253     else
 254       return NameOrErr.takeError();
 255
 256     // Compute JIT symbol flags.
 257     auto JITSymFlags = getJITSymbolFlags(*I);
 258     if (!JITSymFlags)
 259       return JITSymFlags.takeError();
 260
 261     // If this is a weak definition, check to see if there's a strong one.
 262     // If there is, skip this symbol (we won't be providing it: the strong
 263     // definition will). If there's no strong definition, make this definition
 264     // strong.
 265     if (JITSymFlags->isWeak() || JITSymFlags->isCommon()) {
 266       // First check whether there's already a definition in this instance.
 267       if (GlobalSymbolTable.count(Name))
 268         continue;
 269
 270       // If we're not responsible for this symbol, skip it.
 271       if (!ResponsibilitySet.count(Name))
 272         continue;
 273
 274       // Otherwise update the flags on the symbol to make this definition
 275       // strong.
 276       if (JITSymFlags->isWeak())
 277         *JITSymFlags &= ~JITSymbolFlags::Weak;
 278       if (JITSymFlags->isCommon()) {
 279         *JITSymFlags &= ~JITSymbolFlags::Common;
 280         uint32_t Align = I->getAlignment();
 281         uint64_t Size = I->getCommonSize();
 282         if (!CommonAlign)
 283           CommonAlign = Align;
 284         CommonSize = alignTo(CommonSize, Align) + Size;
 285         CommonSymbolsToAllocate.push_back(*I);
 286       }
 287     }
 288
 289     if (Flags & SymbolRef::SF_Absolute &&
 290         SymType != object::SymbolRef::ST_File) {
 291       uint64_t Addr = 0;
 292       if (auto AddrOrErr = I->getAddress())
 293         Addr = *AddrOrErr;
 294       else
 295         return AddrOrErr.takeError();
 296
 297       unsigned SectionID = AbsoluteSymbolSection;
 298
 299       LLVM_DEBUG(dbgs() << "\tType: " << SymType << " (absolute) Name: " << Name
 300                         << " SID: " << SectionID
 301                         << " Offset: " << format("%p", (uintptr_t)Addr)
 302                         << " flags: " << Flags << "\n");
 303       GlobalSymbolTable[Name] = SymbolTableEntry(SectionID, Addr, *JITSymFlags);
 304     } else if (SymType == object::SymbolRef::ST_Function ||
 305                SymType == object::SymbolRef::ST_Data ||
 306                SymType == object::SymbolRef::ST_Unknown ||
 307                SymType == object::SymbolRef::ST_Other) {
 308
 309       section_iterator SI = Obj.section_end();
 310       if (auto SIOrErr = I->getSection())
 311         SI = *SIOrErr;
 312       else
 313         return SIOrErr.takeError();
 314
 315       if (SI == Obj.section_end())
 316         continue;
 317
 318       // Get symbol offset.
 319       uint64_t SectOffset;
 320       if (auto Err = getOffset(*I, *SI, SectOffset))
 321         return std::move(Err);
 322
 323       bool IsCode = SI->isText();
 324       unsigned SectionID;
 325       if (auto SectionIDOrErr =
 326               findOrEmitSection(Obj, *SI, IsCode, LocalSections))
 327         SectionID = *SectionIDOrErr;
 328       else
 329         return SectionIDOrErr.takeError();
 330
 331       LLVM_DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name
 332                         << " SID: " << SectionID
 333                         << " Offset: " << format("%p", (uintptr_t)SectOffset)
 334                         << " flags: " << Flags << "\n");
 335       GlobalSymbolTable[Name] =
 336           SymbolTableEntry(SectionID, SectOffset, *JITSymFlags);
 337     }
 338   }
 339
 340   // Allocate common symbols
 341   if (auto Err = emitCommonSymbols(Obj, CommonSymbolsToAllocate, CommonSize,
 342                                    CommonAlign))
 343     return std::move(Err);
 344
 345   // Parse and process relocations
 346   LLVM_DEBUG(dbgs() << "Parse relocations:\n");
 347   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 348        SI != SE; ++SI) {
 349     StubMap Stubs;
 350     section_iterator RelocatedSection = SI->getRelocatedSection();
 351
 352     if (RelocatedSection == SE)
 353       continue;
 354
 355     relocation_iterator I = SI->relocation_begin();
 356     relocation_iterator E = SI->relocation_end();
 357
 358     if (I == E && !ProcessAllSections)
 359       continue;
 360
 361     bool IsCode = RelocatedSection->isText();
 362     unsigned SectionID = 0;
 363     if (auto SectionIDOrErr = findOrEmitSection(Obj, *RelocatedSection, IsCode,
 364                                                 LocalSections))
 365       SectionID = *SectionIDOrErr;
 366     else
 367       return SectionIDOrErr.takeError();
 368
 369     LLVM_DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 370
 371     for (; I != E;)
 372       if (auto IOrErr = processRelocationRef(SectionID, I, Obj, LocalSections, Stubs))
 373         I = *IOrErr;
 374       else
 375         return IOrErr.takeError();
 376
 377     // If there is a NotifyStubEmitted callback set, call it to register any
 378     // stubs created for this section.
 379     if (NotifyStubEmitted) {
 380       StringRef FileName = Obj.getFileName();
 381       StringRef SectionName = Sections[SectionID].getName();
 382       for (auto &KV : Stubs) {
 383
 384         auto &VR = KV.first;
 385         uint64_t StubAddr = KV.second;
 386
 387         // If this is a named stub, just call NotifyStubEmitted.
 388         if (VR.SymbolName) {
 389           NotifyStubEmitted(FileName, SectionName, VR.SymbolName, SectionID,
 390                             StubAddr);
 391           continue;
 392         }
 393
 394         // Otherwise we will have to try a reverse lookup on the globla symbol table.
 395         for (auto &GSTMapEntry : GlobalSymbolTable) {
 396           StringRef SymbolName = GSTMapEntry.first();
 397           auto &GSTEntry = GSTMapEntry.second;
 398           if (GSTEntry.getSectionID() == VR.SectionID &&
 399               GSTEntry.getOffset() == VR.Offset) {
 400             NotifyStubEmitted(FileName, SectionName, SymbolName, SectionID,
 401                               StubAddr);
 402             break;
 403           }
 404         }
 405       }
 406     }
 407   }
 408
 409   // Process remaining sections
 410   if (ProcessAllSections) {
 411     LLVM_DEBUG(dbgs() << "Process remaining sections:\n");
 412     for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 413          SI != SE; ++SI) {
 414
 415       /* Ignore already loaded sections */
 416       if (LocalSections.find(*SI) != LocalSections.end())
 417         continue;
 418
 419       bool IsCode = SI->isText();
 420       if (auto SectionIDOrErr =
 421               findOrEmitSection(Obj, *SI, IsCode, LocalSections))
 422         LLVM_DEBUG(dbgs() << "\tSectionID: " << (*SectionIDOrErr) << "\n");
 423       else
 424         return SectionIDOrErr.takeError();
 425     }
 426   }
 427
 428   // Give the subclasses a chance to tie-up any loose ends.
 429   if (auto Err = finalizeLoad(Obj, LocalSections))
 430     return std::move(Err);
 431
 432 //   for (auto E : LocalSections)
 433 //     llvm::dbgs() << "Added: " << E.first.getRawDataRefImpl() << " -> " << E.second << "\n";
 434
 435   return LocalSections;
 436 }
 437
 438 // A helper method for computeTotalAllocSize.
 439 // Computes the memory size required to allocate sections with the given sizes,
 440 // assuming that all sections are allocated with the given alignment
 441 static uint64_t
 442 computeAllocationSizeForSections(std::vector<uint64_t> &SectionSizes,
 443                                  uint64_t Alignment) {
 444   uint64_t TotalSize = 0;
 445   for (size_t Idx = 0, Cnt = SectionSizes.size(); Idx < Cnt; Idx++) {
 446     uint64_t AlignedSize =
 447         (SectionSizes[Idx] + Alignment - 1) / Alignment * Alignment;
 448     TotalSize += AlignedSize;
 449   }
 450   return TotalSize;
 451 }
 452
 453 static bool isRequiredForExecution(const SectionRef Section) {
 454   const ObjectFile *Obj = Section.getObject();
 455   if (isa<object::ELFObjectFileBase>(Obj))
 456     return ELFSectionRef(Section).getFlags() & ELF::SHF_ALLOC;
 457   if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj)) {
 458     const coff_section *CoffSection = COFFObj->getCOFFSection(Section);
 459     // Avoid loading zero-sized COFF sections.
 460     // In PE files, VirtualSize gives the section size, and SizeOfRawData
 461     // may be zero for sections with content. In Obj files, SizeOfRawData
 462     // gives the section size, and VirtualSize is always zero. Hence
 463     // the need to check for both cases below.
 464     bool HasContent =
 465         (CoffSection->VirtualSize > 0) || (CoffSection->SizeOfRawData > 0);
 466     bool IsDiscardable =
 467         CoffSection->Characteristics &
 468         (COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_LNK_INFO);
 469     return HasContent && !IsDiscardable;
 470   }
 471
 472   assert(isa<MachOObjectFile>(Obj));
 473   return true;
 474 }
 475
 476 static bool isReadOnlyData(const SectionRef Section) {
 477   const ObjectFile *Obj = Section.getObject();
 478   if (isa<object::ELFObjectFileBase>(Obj))
 479     return !(ELFSectionRef(Section).getFlags() &
 480              (ELF::SHF_WRITE | ELF::SHF_EXECINSTR));
 481   if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
 482     return ((COFFObj->getCOFFSection(Section)->Characteristics &
 483              (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
 484              | COFF::IMAGE_SCN_MEM_READ
 485              | COFF::IMAGE_SCN_MEM_WRITE))
 486              ==
 487              (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
 488              | COFF::IMAGE_SCN_MEM_READ));
 489
 490   assert(isa<MachOObjectFile>(Obj));
 491   return false;
 492 }
 493
 494 static bool isZeroInit(const SectionRef Section) {
 495   const ObjectFile *Obj = Section.getObject();
 496   if (isa<object::ELFObjectFileBase>(Obj))
 497     return ELFSectionRef(Section).getType() == ELF::SHT_NOBITS;
 498   if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
 499     return COFFObj->getCOFFSection(Section)->Characteristics &
 500             COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
 501
 502   auto *MachO = cast<MachOObjectFile>(Obj);
 503   unsigned SectionType = MachO->getSectionType(Section);
 504   return SectionType == MachO::S_ZEROFILL ||
 505          SectionType == MachO::S_GB_ZEROFILL;
 506 }
 507
 508 // Compute an upper bound of the memory size that is required to load all
 509 // sections
 510 Error RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
 511                                              uint64_t &CodeSize,
 512                                              uint32_t &CodeAlign,
 513                                              uint64_t &RODataSize,
 514                                              uint32_t &RODataAlign,
 515                                              uint64_t &RWDataSize,
 516                                              uint32_t &RWDataAlign) {
 517   // Compute the size of all sections required for execution
 518   std::vector<uint64_t> CodeSectionSizes;
 519   std::vector<uint64_t> ROSectionSizes;
 520   std::vector<uint64_t> RWSectionSizes;
 521
 522   // Collect sizes of all sections to be loaded;
 523   // also determine the max alignment of all sections
 524   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 525        SI != SE; ++SI) {
 526     const SectionRef &Section = *SI;
 527
 528     bool IsRequired = isRequiredForExecution(Section) || ProcessAllSections;
 529
 530     // Consider only the sections that are required to be loaded for execution
 531     if (IsRequired) {
 532       uint64_t DataSize = Section.getSize();
 533       uint64_t Alignment64 = Section.getAlignment();
 534       unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 535       bool IsCode = Section.isText();
 536       bool IsReadOnly = isReadOnlyData(Section);
 537
 538       StringRef Name;
 539       if (auto EC = Section.getName(Name))
 540         return errorCodeToError(EC);
 541
 542       uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
 543
 544       uint64_t PaddingSize = 0;
 545       if (Name == ".eh_frame")
 546         PaddingSize += 4;
 547       if (StubBufSize != 0)
 548         PaddingSize += getStubAlignment() - 1;
 549
 550       uint64_t SectionSize = DataSize + PaddingSize + StubBufSize;
 551
 552       // The .eh_frame section (at least on Linux) needs an extra four bytes
 553       // padded
 554       // with zeroes added at the end.  For MachO objects, this section has a
 555       // slightly different name, so this won't have any effect for MachO
 556       // objects.
 557       if (Name == ".eh_frame")
 558         SectionSize += 4;
 559
 560       if (!SectionSize)
 561         SectionSize = 1;
 562
 563       if (IsCode) {
 564         CodeAlign = std::max(CodeAlign, Alignment);
 565         CodeSectionSizes.push_back(SectionSize);
 566       } else if (IsReadOnly) {
 567         RODataAlign = std::max(RODataAlign, Alignment);
 568         ROSectionSizes.push_back(SectionSize);
 569       } else {
 570         RWDataAlign = std::max(RWDataAlign, Alignment);
 571         RWSectionSizes.push_back(SectionSize);
 572       }
 573     }
 574   }
 575
 576   // Compute Global Offset Table size. If it is not zero we
 577   // also update alignment, which is equal to a size of a
 578   // single GOT entry.
 579   if (unsigned GotSize = computeGOTSize(Obj)) {
 580     RWSectionSizes.push_back(GotSize);
 581     RWDataAlign = std::max<uint32_t>(RWDataAlign, getGOTEntrySize());
 582   }
 583
 584   // Compute the size of all common symbols
 585   uint64_t CommonSize = 0;
 586   uint32_t CommonAlign = 1;
 587   for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
 588        ++I) {
 589     uint32_t Flags = I->getFlags();
 590     if (Flags & SymbolRef::SF_Common) {
 591       // Add the common symbols to a list.  We'll allocate them all below.
 592       uint64_t Size = I->getCommonSize();
 593       uint32_t Align = I->getAlignment();
 594       // If this is the first common symbol, use its alignment as the alignment
 595       // for the common symbols section.
 596       if (CommonSize == 0)
 597         CommonAlign = Align;
 598       CommonSize = alignTo(CommonSize, Align) + Size;
 599     }
 600   }
 601   if (CommonSize != 0) {
 602     RWSectionSizes.push_back(CommonSize);
 603     RWDataAlign = std::max(RWDataAlign, CommonAlign);
 604   }
 605
 606   // Compute the required allocation space for each different type of sections
 607   // (code, read-only data, read-write data) assuming that all sections are
 608   // allocated with the max alignment. Note that we cannot compute with the
 609   // individual alignments of the sections, because then the required size
 610   // depends on the order, in which the sections are allocated.
 611   CodeSize = computeAllocationSizeForSections(CodeSectionSizes, CodeAlign);
 612   RODataSize = computeAllocationSizeForSections(ROSectionSizes, RODataAlign);
 613   RWDataSize = computeAllocationSizeForSections(RWSectionSizes, RWDataAlign);
 614
 615   return Error::success();
 616 }
 617
 618 // compute GOT size
 619 unsigned RuntimeDyldImpl::computeGOTSize(const ObjectFile &Obj) {
 620   size_t GotEntrySize = getGOTEntrySize();
 621   if (!GotEntrySize)
 622     return 0;
 623
 624   size_t GotSize = 0;
 625   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 626        SI != SE; ++SI) {
 627
 628     for (const RelocationRef &Reloc : SI->relocations())
 629       if (relocationNeedsGot(Reloc))
 630         GotSize += GotEntrySize;
 631   }
 632
 633   return GotSize;
 634 }
 635
 636 // compute stub buffer size for the given section
 637 unsigned RuntimeDyldImpl::computeSectionStubBufSize(const ObjectFile &Obj,
 638                                                     const SectionRef &Section) {
 639   unsigned StubSize = getMaxStubSize();
 640   if (StubSize == 0) {
 641     return 0;
 642   }
 643   // FIXME: this is an inefficient way to handle this. We should computed the
 644   // necessary section allocation size in loadObject by walking all the sections
 645   // once.
 646   unsigned StubBufSize = 0;
 647   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 648        SI != SE; ++SI) {
 649     section_iterator RelSecI = SI->getRelocatedSection();
 650     if (!(RelSecI == Section))
 651       continue;
 652
 653     for (const RelocationRef &Reloc : SI->relocations())
 654       if (relocationNeedsStub(Reloc))
 655         StubBufSize += StubSize;
 656   }
 657
 658   // Get section data size and alignment
 659   uint64_t DataSize = Section.getSize();
 660   uint64_t Alignment64 = Section.getAlignment();
 661
 662   // Add stubbuf size alignment
 663   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 664   unsigned StubAlignment = getStubAlignment();
 665   unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
 666   if (StubAlignment > EndAlignment)
 667     StubBufSize += StubAlignment - EndAlignment;
 668   return StubBufSize;
 669 }
 670
 671 uint64_t RuntimeDyldImpl::readBytesUnaligned(uint8_t *Src,
 672                                              unsigned Size) const {
 673   uint64_t Result = 0;
 674   if (IsTargetLittleEndian) {
 675     Src += Size - 1;
 676     while (Size--)
 677       Result = (Result << 8) | *Src--;
 678   } else
 679     while (Size--)
 680       Result = (Result << 8) | *Src++;
 681
 682   return Result;
 683 }
 684
 685 void RuntimeDyldImpl::writeBytesUnaligned(uint64_t Value, uint8_t *Dst,
 686                                           unsigned Size) const {
 687   if (IsTargetLittleEndian) {
 688     while (Size--) {
 689       *Dst++ = Value & 0xFF;
 690       Value >>= 8;
 691     }
 692   } else {
 693     Dst += Size - 1;
 694     while (Size--) {
 695       *Dst-- = Value & 0xFF;
 696       Value >>= 8;
 697     }
 698   }
 699 }
 700
 701 Expected<JITSymbolFlags>
 702 RuntimeDyldImpl::getJITSymbolFlags(const SymbolRef &SR) {
 703   return JITSymbolFlags::fromObjectSymbol(SR);
 704 }
 705
 706 Error RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
 707                                          CommonSymbolList &SymbolsToAllocate,
 708                                          uint64_t CommonSize,
 709                                          uint32_t CommonAlign) {
 710   if (SymbolsToAllocate.empty())
 711     return Error::success();
 712
 713   // Allocate memory for the section
 714   unsigned SectionID = Sections.size();
 715   uint8_t *Addr = MemMgr.allocateDataSection(CommonSize, CommonAlign, SectionID,
 716                                              "<common symbols>", false);
 717   if (!Addr)
 718     report_fatal_error("Unable to allocate memory for common symbols!");
 719   uint64_t Offset = 0;
 720   Sections.push_back(
 721       SectionEntry("<common symbols>", Addr, CommonSize, CommonSize, 0));
 722   memset(Addr, 0, CommonSize);
 723
 724   LLVM_DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 725                     << " new addr: " << format("%p", Addr)
 726                     << " DataSize: " << CommonSize << "\n");
 727
 728   // Assign the address of each symbol
 729   for (auto &Sym : SymbolsToAllocate) {
 730     uint32_t Align = Sym.getAlignment();
 731     uint64_t Size = Sym.getCommonSize();
 732     StringRef Name;
 733     if (auto NameOrErr = Sym.getName())
 734       Name = *NameOrErr;
 735     else
 736       return NameOrErr.takeError();
 737     if (Align) {
 738       // This symbol has an alignment requirement.
 739       uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
 740       Addr += AlignOffset;
 741       Offset += AlignOffset;
 742     }
 743     auto JITSymFlags = getJITSymbolFlags(Sym);
 744
 745     if (!JITSymFlags)
 746       return JITSymFlags.takeError();
 747
 748     LLVM_DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
 749                       << format("%p", Addr) << "\n");
 750     GlobalSymbolTable[Name] =
 751         SymbolTableEntry(SectionID, Offset, std::move(*JITSymFlags));
 752     Offset += Size;
 753     Addr += Size;
 754   }
 755
 756   return Error::success();
 757 }
 758
 759 Expected<unsigned>
 760 RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
 761                              const SectionRef &Section,
 762                              bool IsCode) {
 763   StringRef data;
 764   uint64_t Alignment64 = Section.getAlignment();
 765
 766   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 767   unsigned PaddingSize = 0;
 768   unsigned StubBufSize = 0;
 769   bool IsRequired = isRequiredForExecution(Section);
 770   bool IsVirtual = Section.isVirtual();
 771   bool IsZeroInit = isZeroInit(Section);
 772   bool IsReadOnly = isReadOnlyData(Section);
 773   uint64_t DataSize = Section.getSize();
 774
 775   // An alignment of 0 (at least with ELF) is identical to an alignment of 1,
 776   // while being more "polite".  Other formats do not support 0-aligned sections
 777   // anyway, so we should guarantee that the alignment is always at least 1.
 778   Alignment = std::max(1u, Alignment);
 779
 780   StringRef Name;
 781   if (auto EC = Section.getName(Name))
 782     return errorCodeToError(EC);
 783
 784   StubBufSize = computeSectionStubBufSize(Obj, Section);
 785
 786   // The .eh_frame section (at least on Linux) needs an extra four bytes padded
 787   // with zeroes added at the end.  For MachO objects, this section has a
 788   // slightly different name, so this won't have any effect for MachO objects.
 789   if (Name == ".eh_frame")
 790     PaddingSize = 4;
 791
 792   uintptr_t Allocate;
 793   unsigned SectionID = Sections.size();
 794   uint8_t *Addr;
 795   const char *pData = nullptr;
 796
 797   // If this section contains any bits (i.e. isn't a virtual or bss section),
 798   // grab a reference to them.
 799   if (!IsVirtual && !IsZeroInit) {
 800     // In either case, set the location of the unrelocated section in memory,
 801     // since we still process relocations for it even if we're not applying them.
 802     if (Expected<StringRef> E = Section.getContents())
 803       data = *E;
 804     else
 805       return E.takeError();
 806     pData = data.data();
 807   }
 808
 809   // If there are any stubs then the section alignment needs to be at least as
 810   // high as stub alignment or padding calculations may by incorrect when the
 811   // section is remapped.
 812   if (StubBufSize != 0) {
 813     Alignment = std::max(Alignment, getStubAlignment());
 814     PaddingSize += getStubAlignment() - 1;
 815   }
 816
 817   // Some sections, such as debug info, don't need to be loaded for execution.
 818   // Process those only if explicitly requested.
 819   if (IsRequired || ProcessAllSections) {
 820     Allocate = DataSize + PaddingSize + StubBufSize;
 821     if (!Allocate)
 822       Allocate = 1;
 823     Addr = IsCode ? MemMgr.allocateCodeSection(Allocate, Alignment, SectionID,
 824                                                Name)
 825                   : MemMgr.allocateDataSection(Allocate, Alignment, SectionID,
 826                                                Name, IsReadOnly);
 827     if (!Addr)
 828       report_fatal_error("Unable to allocate section memory!");
 829
 830     // Zero-initialize or copy the data from the image
 831     if (IsZeroInit || IsVirtual)
 832       memset(Addr, 0, DataSize);
 833     else
 834       memcpy(Addr, pData, DataSize);
 835
 836     // Fill in any extra bytes we allocated for padding
 837     if (PaddingSize != 0) {
 838       memset(Addr + DataSize, 0, PaddingSize);
 839       // Update the DataSize variable to include padding.
 840       DataSize += PaddingSize;
 841
 842       // Align DataSize to stub alignment if we have any stubs (PaddingSize will
 843       // have been increased above to account for this).
 844       if (StubBufSize > 0)
 845         DataSize &= -(uint64_t)getStubAlignment();
 846     }
 847
 848     LLVM_DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: "
 849                       << Name << " obj addr: " << format("%p", pData)
 850                       << " new addr: " << format("%p", Addr) << " DataSize: "
 851                       << DataSize << " StubBufSize: " << StubBufSize
 852                       << " Allocate: " << Allocate << "\n");
 853   } else {
 854     // Even if we didn't load the section, we need to record an entry for it
 855     // to handle later processing (and by 'handle' I mean don't do anything
 856     // with these sections).
 857     Allocate = 0;
 858     Addr = nullptr;
 859     LLVM_DEBUG(
 860         dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
 861                << " obj addr: " << format("%p", data.data()) << " new addr: 0"
 862                << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
 863                << " Allocate: " << Allocate << "\n");
 864   }
 865
 866   Sections.push_back(
 867       SectionEntry(Name, Addr, DataSize, Allocate, (uintptr_t)pData));
 868
 869   // Debug info sections are linked as if their load address was zero
 870   if (!IsRequired)
 871     Sections.back().setLoadAddress(0);
 872
 873   return SectionID;
 874 }
 875
 876 Expected<unsigned>
 877 RuntimeDyldImpl::findOrEmitSection(const ObjectFile &Obj,
 878                                    const SectionRef &Section,
 879                                    bool IsCode,
 880                                    ObjSectionToIDMap &LocalSections) {
 881
 882   unsigned SectionID = 0;
 883   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 884   if (i != LocalSections.end())
 885     SectionID = i->second;
 886   else {
 887     if (auto SectionIDOrErr = emitSection(Obj, Section, IsCode))
 888       SectionID = *SectionIDOrErr;
 889     else
 890       return SectionIDOrErr.takeError();
 891     LocalSections[Section] = SectionID;
 892   }
 893   return SectionID;
 894 }
 895
 896 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 897                                               unsigned SectionID) {
 898   Relocations[SectionID].push_back(RE);
 899 }
 900
 901 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 902                                              StringRef SymbolName) {
 903   // Relocation by symbol.  If the symbol is found in the global symbol table,
 904   // create an appropriate section relocation.  Otherwise, add it to
 905   // ExternalSymbolRelocations.
 906   RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
 907   if (Loc == GlobalSymbolTable.end()) {
 908     ExternalSymbolRelocations[SymbolName].push_back(RE);
 909   } else {
 910     // Copy the RE since we want to modify its addend.
 911     RelocationEntry RECopy = RE;
 912     const auto &SymInfo = Loc->second;
 913     RECopy.Addend += SymInfo.getOffset();
 914     Relocations[SymInfo.getSectionID()].push_back(RECopy);
 915   }
 916 }
 917
 918 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr,
 919                                              unsigned AbiVariant) {
 920   if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be) {
 921     // This stub has to be able to access the full address space,
 922     // since symbol lookup won't necessarily find a handy, in-range,
 923     // PLT stub for functions which could be anywhere.
 924     // Stub can use ip0 (== x16) to calculate address
 925     writeBytesUnaligned(0xd2e00010, Addr,    4); // movz ip0, #:abs_g3:<addr>
 926     writeBytesUnaligned(0xf2c00010, Addr+4,  4); // movk ip0, #:abs_g2_nc:<addr>
 927     writeBytesUnaligned(0xf2a00010, Addr+8,  4); // movk ip0, #:abs_g1_nc:<addr>
 928     writeBytesUnaligned(0xf2800010, Addr+12, 4); // movk ip0, #:abs_g0_nc:<addr>
 929     writeBytesUnaligned(0xd61f0200, Addr+16, 4); // br ip0
 930
 931     return Addr;
 932   } else if (Arch == Triple::arm || Arch == Triple::armeb) {
 933     // TODO: There is only ARM far stub now. We should add the Thumb stub,
 934     // and stubs for branches Thumb - ARM and ARM - Thumb.
 935     writeBytesUnaligned(0xe51ff004, Addr, 4); // ldr pc, [pc, #-4]
 936     return Addr + 4;
 937   } else if (IsMipsO32ABI || IsMipsN32ABI) {
 938     // 0:   3c190000        lui     t9,%hi(addr).
 939     // 4:   27390000        addiu   t9,t9,%lo(addr).
 940     // 8:   03200008        jr      t9.
 941     // c:   00000000        nop.
 942     const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
 943     const unsigned NopInstr = 0x0;
 944     unsigned JrT9Instr = 0x03200008;
 945     if ((AbiVariant & ELF::EF_MIPS_ARCH) == ELF::EF_MIPS_ARCH_32R6 ||
 946         (AbiVariant & ELF::EF_MIPS_ARCH) == ELF::EF_MIPS_ARCH_64R6)
 947       JrT9Instr = 0x03200009;
 948
 949     writeBytesUnaligned(LuiT9Instr, Addr, 4);
 950     writeBytesUnaligned(AdduiT9Instr, Addr + 4, 4);
 951     writeBytesUnaligned(JrT9Instr, Addr + 8, 4);
 952     writeBytesUnaligned(NopInstr, Addr + 12, 4);
 953     return Addr;
 954   } else if (IsMipsN64ABI) {
 955     // 0:   3c190000        lui     t9,%highest(addr).
 956     // 4:   67390000        daddiu  t9,t9,%higher(addr).
 957     // 8:   0019CC38        dsll    t9,t9,16.
 958     // c:   67390000        daddiu  t9,t9,%hi(addr).
 959     // 10:  0019CC38        dsll    t9,t9,16.
 960     // 14:  67390000        daddiu  t9,t9,%lo(addr).
 961     // 18:  03200008        jr      t9.
 962     // 1c:  00000000        nop.
 963     const unsigned LuiT9Instr = 0x3c190000, DaddiuT9Instr = 0x67390000,
 964                    DsllT9Instr = 0x19CC38;
 965     const unsigned NopInstr = 0x0;
 966     unsigned JrT9Instr = 0x03200008;
 967     if ((AbiVariant & ELF::EF_MIPS_ARCH) == ELF::EF_MIPS_ARCH_64R6)
 968       JrT9Instr = 0x03200009;
 969
 970     writeBytesUnaligned(LuiT9Instr, Addr, 4);
 971     writeBytesUnaligned(DaddiuT9Instr, Addr + 4, 4);
 972     writeBytesUnaligned(DsllT9Instr, Addr + 8, 4);
 973     writeBytesUnaligned(DaddiuT9Instr, Addr + 12, 4);
 974     writeBytesUnaligned(DsllT9Instr, Addr + 16, 4);
 975     writeBytesUnaligned(DaddiuT9Instr, Addr + 20, 4);
 976     writeBytesUnaligned(JrT9Instr, Addr + 24, 4);
 977     writeBytesUnaligned(NopInstr, Addr + 28, 4);
 978     return Addr;
 979   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
 980     // Depending on which version of the ELF ABI is in use, we need to
 981     // generate one of two variants of the stub.  They both start with
 982     // the same sequence to load the target address into r12.
 983     writeInt32BE(Addr,    0x3D800000); // lis   r12, highest(addr)
 984     writeInt32BE(Addr+4,  0x618C0000); // ori   r12, higher(addr)
 985     writeInt32BE(Addr+8,  0x798C07C6); // sldi  r12, r12, 32
 986     writeInt32BE(Addr+12, 0x658C0000); // oris  r12, r12, h(addr)
 987     writeInt32BE(Addr+16, 0x618C0000); // ori   r12, r12, l(addr)
 988     if (AbiVariant == 2) {
 989       // PowerPC64 stub ELFv2 ABI: The address points to the function itself.
 990       // The address is already in r12 as required by the ABI.  Branch to it.
 991       writeInt32BE(Addr+20, 0xF8410018); // std   r2,  24(r1)
 992       writeInt32BE(Addr+24, 0x7D8903A6); // mtctr r12
 993       writeInt32BE(Addr+28, 0x4E800420); // bctr
 994     } else {
 995       // PowerPC64 stub ELFv1 ABI: The address points to a function descriptor.
 996       // Load the function address on r11 and sets it to control register. Also
 997       // loads the function TOC in r2 and environment pointer to r11.
 998       writeInt32BE(Addr+20, 0xF8410028); // std   r2,  40(r1)
 999       writeInt32BE(Addr+24, 0xE96C0000); // ld    r11, 0(r12)
1000       writeInt32BE(Addr+28, 0xE84C0008); // ld    r2,  0(r12)
1001       writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
1002       writeInt32BE(Addr+36, 0xE96C0010); // ld    r11, 16(r2)
1003       writeInt32BE(Addr+40, 0x4E800420); // bctr
1004     }
1005     return Addr;
1006   } else if (Arch == Triple::systemz) {
1007     writeInt16BE(Addr,    0xC418);     // lgrl %r1,.+8
1008     writeInt16BE(Addr+2,  0x0000);
1009     writeInt16BE(Addr+4,  0x0004);
1010     writeInt16BE(Addr+6,  0x07F1);     // brc 15,%r1
1011     // 8-byte address stored at Addr + 8
1012     return Addr;
1013   } else if (Arch == Triple::x86_64) {
1014     *Addr      = 0xFF; // jmp
1015     *(Addr+1)  = 0x25; // rip
1016     // 32-bit PC-relative address of the GOT entry will be stored at Addr+2
1017   } else if (Arch == Triple::x86) {
1018     *Addr      = 0xE9; // 32-bit pc-relative jump.
1019   }
1020   return Addr;
1021 }
1022
1023 // Assign an address to a symbol name and resolve all the relocations
1024 // associated with it.
1025 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
1026                                              uint64_t Addr) {
1027   // The address to use for relocation resolution is not
1028   // the address of the local section buffer. We must be doing
1029   // a remote execution environment of some sort. Relocations can't
1030   // be applied until all the sections have been moved.  The client must
1031   // trigger this with a call to MCJIT::finalize() or
1032   // RuntimeDyld::resolveRelocations().
1033   //
1034   // Addr is a uint64_t because we can't assume the pointer width
1035   // of the target is the same as that of the host. Just use a generic
1036   // "big enough" type.
1037   LLVM_DEBUG(
1038       dbgs() << "Reassigning address for section " << SectionID << " ("
1039              << Sections[SectionID].getName() << "): "
1040              << format("0x%016" PRIx64, Sections[SectionID].getLoadAddress())
1041              << " -> " << format("0x%016" PRIx64, Addr) << "\n");
1042   Sections[SectionID].setLoadAddress(Addr);
1043 }
1044
1045 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
1046                                             uint64_t Value) {
1047   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1048     const RelocationEntry &RE = Relocs[i];
1049     // Ignore relocations for sections that were not loaded
1050     if (Sections[RE.SectionID].getAddress() == nullptr)
1051       continue;
1052     resolveRelocation(RE, Value);
1053   }
1054 }
1055
1056 void RuntimeDyldImpl::applyExternalSymbolRelocations(
1057     const StringMap<JITEvaluatedSymbol> ExternalSymbolMap) {
1058   while (!ExternalSymbolRelocations.empty()) {
1059
1060     StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
1061
1062     StringRef Name = i->first();
1063     if (Name.size() == 0) {
1064       // This is an absolute symbol, use an address of zero.
1065       LLVM_DEBUG(dbgs() << "Resolving absolute relocations."
1066                         << "\n");
1067       RelocationList &Relocs = i->second;
1068       resolveRelocationList(Relocs, 0);
1069     } else {
1070       uint64_t Addr = 0;
1071       JITSymbolFlags Flags;
1072       RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(Name);
1073       if (Loc == GlobalSymbolTable.end()) {
1074         auto RRI = ExternalSymbolMap.find(Name);
1075         assert(RRI != ExternalSymbolMap.end() && "No result for symbol");
1076         Addr = RRI->second.getAddress();
1077         Flags = RRI->second.getFlags();
1078         // The call to getSymbolAddress may have caused additional modules to
1079         // be loaded, which may have added new entries to the
1080         // ExternalSymbolRelocations map.  Consquently, we need to update our
1081         // iterator.  This is also why retrieval of the relocation list
1082         // associated with this symbol is deferred until below this point.
1083         // New entries may have been added to the relocation list.
1084         i = ExternalSymbolRelocations.find(Name);
1085       } else {
1086         // We found the symbol in our global table.  It was probably in a
1087         // Module that we loaded previously.
1088         const auto &SymInfo = Loc->second;
1089         Addr = getSectionLoadAddress(SymInfo.getSectionID()) +
1090                SymInfo.getOffset();
1091         Flags = SymInfo.getFlags();
1092       }
1093
1094       // FIXME: Implement error handling that doesn't kill the host program!
1095       if (!Addr)
1096         report_fatal_error("Program used external function '" + Name +
1097                            "' which could not be resolved!");
1098
1099       // If Resolver returned UINT64_MAX, the client wants to handle this symbol
1100       // manually and we shouldn't resolve its relocations.
1101       if (Addr != UINT64_MAX) {
1102
1103         // Tweak the address based on the symbol flags if necessary.
1104         // For example, this is used by RuntimeDyldMachOARM to toggle the low bit
1105         // if the target symbol is Thumb.
1106         Addr = modifyAddressBasedOnFlags(Addr, Flags);
1107
1108         LLVM_DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
1109                           << format("0x%lx", Addr) << "\n");
1110         // This list may have been updated when we called getSymbolAddress, so
1111         // don't change this code to get the list earlier.
1112         RelocationList &Relocs = i->second;
1113         resolveRelocationList(Relocs, Addr);
1114       }
1115     }
1116
1117     ExternalSymbolRelocations.erase(i);
1118   }
1119 }
1120
1121 Error RuntimeDyldImpl::resolveExternalSymbols() {
1122   StringMap<JITEvaluatedSymbol> ExternalSymbolMap;
1123
1124   // Resolution can trigger emission of more symbols, so iterate until
1125   // we've resolved *everything*.
1126   {
1127     JITSymbolResolver::LookupSet ResolvedSymbols;
1128
1129     while (true) {
1130       JITSymbolResolver::LookupSet NewSymbols;
1131
1132       for (auto &RelocKV : ExternalSymbolRelocations) {
1133         StringRef Name = RelocKV.first();
1134         if (!Name.empty() && !GlobalSymbolTable.count(Name) &&
1135             !ResolvedSymbols.count(Name))
1136           NewSymbols.insert(Name);
1137       }
1138
1139       if (NewSymbols.empty())
1140         break;
1141
1142 #ifdef _MSC_VER
1143       using ExpectedLookupResult =
1144           MSVCPExpected<JITSymbolResolver::LookupResult>;
1145 #else
1146       using ExpectedLookupResult = Expected<JITSymbolResolver::LookupResult>;
1147 #endif
1148
1149       auto NewSymbolsP = std::make_shared<std::promise<ExpectedLookupResult>>();
1150       auto NewSymbolsF = NewSymbolsP->get_future();
1151       Resolver.lookup(NewSymbols,
1152                       [=](Expected<JITSymbolResolver::LookupResult> Result) {
1153                         NewSymbolsP->set_value(std::move(Result));
1154                       });
1155
1156       auto NewResolverResults = NewSymbolsF.get();
1157
1158       if (!NewResolverResults)
1159         return NewResolverResults.takeError();
1160
1161       assert(NewResolverResults->size() == NewSymbols.size() &&
1162              "Should have errored on unresolved symbols");
1163
1164       for (auto &RRKV : *NewResolverResults) {
1165         assert(!ResolvedSymbols.count(RRKV.first) && "Redundant resolution?");
1166         ExternalSymbolMap.insert(RRKV);
1167         ResolvedSymbols.insert(RRKV.first);
1168       }
1169     }
1170   }
1171
1172   applyExternalSymbolRelocations(ExternalSymbolMap);
1173
1174   return Error::success();
1175 }
1176
1177 void RuntimeDyldImpl::finalizeAsync(
1178     std::unique_ptr<RuntimeDyldImpl> This, std::function<void(Error)> OnEmitted,
1179     std::unique_ptr<MemoryBuffer> UnderlyingBuffer) {
1180
1181   // FIXME: Move-capture OnRelocsApplied and UnderlyingBuffer once we have
1182   // c++14.
1183   auto SharedUnderlyingBuffer =
1184       std::shared_ptr<MemoryBuffer>(std::move(UnderlyingBuffer));
1185   auto SharedThis = std::shared_ptr<RuntimeDyldImpl>(std::move(This));
1186   auto PostResolveContinuation =
1187       [SharedThis, OnEmitted, SharedUnderlyingBuffer](
1188           Expected<JITSymbolResolver::LookupResult> Result) {
1189         if (!Result) {
1190           OnEmitted(Result.takeError());
1191           return;
1192         }
1193
1194         /// Copy the result into a StringMap, where the keys are held by value.
1195         StringMap<JITEvaluatedSymbol> Resolved;
1196         for (auto &KV : *Result)
1197           Resolved[KV.first] = KV.second;
1198
1199         SharedThis->applyExternalSymbolRelocations(Resolved);
1200         SharedThis->resolveLocalRelocations();
1201         SharedThis->registerEHFrames();
1202         std::string ErrMsg;
1203         if (SharedThis->MemMgr.finalizeMemory(&ErrMsg))
1204           OnEmitted(make_error<StringError>(std::move(ErrMsg),
1205                                             inconvertibleErrorCode()));
1206         else
1207           OnEmitted(Error::success());
1208       };
1209
1210   JITSymbolResolver::LookupSet Symbols;
1211
1212   for (auto &RelocKV : SharedThis->ExternalSymbolRelocations) {
1213     StringRef Name = RelocKV.first();
1214     assert(!Name.empty() && "Symbol has no name?");
1215     assert(!SharedThis->GlobalSymbolTable.count(Name) &&
1216            "Name already processed. RuntimeDyld instances can not be re-used "
1217            "when finalizing with finalizeAsync.");
1218     Symbols.insert(Name);
1219   }
1220
1221   if (!Symbols.empty()) {
1222     SharedThis->Resolver.lookup(Symbols, PostResolveContinuation);
1223   } else
1224     PostResolveContinuation(std::map<StringRef, JITEvaluatedSymbol>());
1225 }
1226
1227 //===----------------------------------------------------------------------===//
1228 // RuntimeDyld class implementation
1229
1230 uint64_t RuntimeDyld::LoadedObjectInfo::getSectionLoadAddress(
1231                                           const object::SectionRef &Sec) const {
1232
1233   auto I = ObjSecToIDMap.find(Sec);
1234   if (I != ObjSecToIDMap.end())
1235     return RTDyld.Sections[I->second].getLoadAddress();
1236
1237   return 0;
1238 }
1239
1240 void RuntimeDyld::MemoryManager::anchor() {}
1241 void JITSymbolResolver::anchor() {}
1242 void LegacyJITSymbolResolver::anchor() {}
1243
1244 RuntimeDyld::RuntimeDyld(RuntimeDyld::MemoryManager &MemMgr,
1245                          JITSymbolResolver &Resolver)
1246     : MemMgr(MemMgr), Resolver(Resolver) {
1247   // FIXME: There's a potential issue lurking here if a single instance of
1248   // RuntimeDyld is used to load multiple objects.  The current implementation
1249   // associates a single memory manager with a RuntimeDyld instance.  Even
1250   // though the public class spawns a new 'impl' instance for each load,
1251   // they share a single memory manager.  This can become a problem when page
1252   // permissions are applied.
1253   Dyld = nullptr;
1254   ProcessAllSections = false;
1255 }
1256
1257 RuntimeDyld::~RuntimeDyld() {}
1258
1259 static std::unique_ptr<RuntimeDyldCOFF>
1260 createRuntimeDyldCOFF(
1261                      Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
1262                      JITSymbolResolver &Resolver, bool ProcessAllSections,
1263                      RuntimeDyld::NotifyStubEmittedFunction NotifyStubEmitted) {
1264   std::unique_ptr<RuntimeDyldCOFF> Dyld =
1265     RuntimeDyldCOFF::create(Arch, MM, Resolver);
1266   Dyld->setProcessAllSections(ProcessAllSections);
1267   Dyld->setNotifyStubEmitted(std::move(NotifyStubEmitted));
1268   return Dyld;
1269 }
1270
1271 static std::unique_ptr<RuntimeDyldELF>
1272 createRuntimeDyldELF(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
1273                      JITSymbolResolver &Resolver, bool ProcessAllSections,
1274                      RuntimeDyld::NotifyStubEmittedFunction NotifyStubEmitted) {
1275   std::unique_ptr<RuntimeDyldELF> Dyld =
1276       RuntimeDyldELF::create(Arch, MM, Resolver);
1277   Dyld->setProcessAllSections(ProcessAllSections);
1278   Dyld->setNotifyStubEmitted(std::move(NotifyStubEmitted));
1279   return Dyld;
1280 }
1281
1282 static std::unique_ptr<RuntimeDyldMachO>
1283 createRuntimeDyldMachO(
1284                      Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
1285                      JITSymbolResolver &Resolver,
1286                      bool ProcessAllSections,
1287                      RuntimeDyld::NotifyStubEmittedFunction NotifyStubEmitted) {
1288   std::unique_ptr<RuntimeDyldMachO> Dyld =
1289     RuntimeDyldMachO::create(Arch, MM, Resolver);
1290   Dyld->setProcessAllSections(ProcessAllSections);
1291   Dyld->setNotifyStubEmitted(std::move(NotifyStubEmitted));
1292   return Dyld;
1293 }
1294
1295 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
1296 RuntimeDyld::loadObject(const ObjectFile &Obj) {
1297   if (!Dyld) {
1298     if (Obj.isELF())
1299       Dyld =
1300           createRuntimeDyldELF(static_cast<Triple::ArchType>(Obj.getArch()),
1301                                MemMgr, Resolver, ProcessAllSections,
1302                                std::move(NotifyStubEmitted));
1303     else if (Obj.isMachO())
1304       Dyld = createRuntimeDyldMachO(
1305                static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
1306                ProcessAllSections, std::move(NotifyStubEmitted));
1307     else if (Obj.isCOFF())
1308       Dyld = createRuntimeDyldCOFF(
1309                static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
1310                ProcessAllSections, std::move(NotifyStubEmitted));
1311     else
1312       report_fatal_error("Incompatible object format!");
1313   }
1314
1315   if (!Dyld->isCompatibleFile(Obj))
1316     report_fatal_error("Incompatible object format!");
1317
1318   auto LoadedObjInfo = Dyld->loadObject(Obj);
1319   MemMgr.notifyObjectLoaded(*this, Obj);
1320   return LoadedObjInfo;
1321 }
1322
1323 void *RuntimeDyld::getSymbolLocalAddress(StringRef Name) const {
1324   if (!Dyld)
1325     return nullptr;
1326   return Dyld->getSymbolLocalAddress(Name);
1327 }
1328
1329 unsigned RuntimeDyld::getSymbolSectionID(StringRef Name) const {
1330   assert(Dyld && "No RuntimeDyld instance attached");
1331   return Dyld->getSymbolSectionID(Name);
1332 }
1333
1334 JITEvaluatedSymbol RuntimeDyld::getSymbol(StringRef Name) const {
1335   if (!Dyld)
1336     return nullptr;
1337   return Dyld->getSymbol(Name);
1338 }
1339
1340 std::map<StringRef, JITEvaluatedSymbol> RuntimeDyld::getSymbolTable() const {
1341   if (!Dyld)
1342     return std::map<StringRef, JITEvaluatedSymbol>();
1343   return Dyld->getSymbolTable();
1344 }
1345
1346 void RuntimeDyld::resolveRelocations() { Dyld->resolveRelocations(); }
1347
1348 void RuntimeDyld::reassignSectionAddress(unsigned SectionID, uint64_t Addr) {
1349   Dyld->reassignSectionAddress(SectionID, Addr);
1350 }
1351
1352 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
1353                                     uint64_t TargetAddress) {
1354   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
1355 }
1356
1357 bool RuntimeDyld::hasError() { return Dyld->hasError(); }
1358
1359 StringRef RuntimeDyld::getErrorString() { return Dyld->getErrorString(); }
1360
1361 void RuntimeDyld::finalizeWithMemoryManagerLocking() {
1362   bool MemoryFinalizationLocked = MemMgr.FinalizationLocked;
1363   MemMgr.FinalizationLocked = true;
1364   resolveRelocations();
1365   registerEHFrames();
1366   if (!MemoryFinalizationLocked) {
1367     MemMgr.finalizeMemory();
1368     MemMgr.FinalizationLocked = false;
1369   }
1370 }
1371
1372 StringRef RuntimeDyld::getSectionContent(unsigned SectionID) const {
1373   assert(Dyld && "No Dyld instance attached");
1374   return Dyld->getSectionContent(SectionID);
1375 }
1376
1377 uint64_t RuntimeDyld::getSectionLoadAddress(unsigned SectionID) const {
1378   assert(Dyld && "No Dyld instance attached");
1379   return Dyld->getSectionLoadAddress(SectionID);
1380 }
1381
1382 void RuntimeDyld::registerEHFrames() {
1383   if (Dyld)
1384     Dyld->registerEHFrames();
1385 }
1386
1387 void RuntimeDyld::deregisterEHFrames() {
1388   if (Dyld)
1389     Dyld->deregisterEHFrames();
1390 }
1391 // FIXME: Kill this with fire once we have a new JIT linker: this is only here
1392 // so that we can re-use RuntimeDyld's implementation without twisting the
1393 // interface any further for ORC's purposes.
1394 void jitLinkForORC(object::ObjectFile &Obj,
1395                    std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
1396                    RuntimeDyld::MemoryManager &MemMgr,
1397                    JITSymbolResolver &Resolver, bool ProcessAllSections,
1398                    std::function<Error(
1399                        std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObj,
1400                        std::map<StringRef, JITEvaluatedSymbol>)>
1401                        OnLoaded,
1402                    std::function<void(Error)> OnEmitted) {
1403
1404   RuntimeDyld RTDyld(MemMgr, Resolver);
1405   RTDyld.setProcessAllSections(ProcessAllSections);
1406
1407   auto Info = RTDyld.loadObject(Obj);
1408
1409   if (RTDyld.hasError()) {
1410     OnEmitted(make_error<StringError>(RTDyld.getErrorString(),
1411                                       inconvertibleErrorCode()));
1412     return;
1413   }
1414
1415   if (auto Err = OnLoaded(std::move(Info), RTDyld.getSymbolTable()))
1416     OnEmitted(std::move(Err));
1417
1418   RuntimeDyldImpl::finalizeAsync(std::move(RTDyld.Dyld), std::move(OnEmitted),
1419                                  std::move(UnderlyingBuffer));
1420 }
1421
1422 } // end namespace llvm