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      1 //===-- llvm-rtdyld.cpp - MCJIT Testing Tool ------------------------------===//
      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 // This is a testing tool for use with the MC-JIT LLVM components.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/ADT/StringMap.h"
     15 #include "llvm/DebugInfo/DIContext.h"
     16 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
     17 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
     18 #include "llvm/ExecutionEngine/RuntimeDyld.h"
     19 #include "llvm/ExecutionEngine/RuntimeDyldChecker.h"
     20 #include "llvm/MC/MCAsmInfo.h"
     21 #include "llvm/MC/MCContext.h"
     22 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
     23 #include "llvm/MC/MCInstPrinter.h"
     24 #include "llvm/MC/MCInstrInfo.h"
     25 #include "llvm/MC/MCRegisterInfo.h"
     26 #include "llvm/MC/MCSubtargetInfo.h"
     27 #include "llvm/Object/MachO.h"
     28 #include "llvm/Object/SymbolSize.h"
     29 #include "llvm/Support/CommandLine.h"
     30 #include "llvm/Support/DynamicLibrary.h"
     31 #include "llvm/Support/ManagedStatic.h"
     32 #include "llvm/Support/Memory.h"
     33 #include "llvm/Support/MemoryBuffer.h"
     34 #include "llvm/Support/PrettyStackTrace.h"
     35 #include "llvm/Support/Signals.h"
     36 #include "llvm/Support/TargetRegistry.h"
     37 #include "llvm/Support/TargetSelect.h"
     38 #include "llvm/Support/raw_ostream.h"
     39 #include <list>
     40 #include <system_error>
     41 
     42 using namespace llvm;
     43 using namespace llvm::object;
     44 
     45 static cl::list<std::string>
     46 InputFileList(cl::Positional, cl::ZeroOrMore,
     47               cl::desc("<input file>"));
     48 
     49 enum ActionType {
     50   AC_Execute,
     51   AC_PrintObjectLineInfo,
     52   AC_PrintLineInfo,
     53   AC_PrintDebugLineInfo,
     54   AC_Verify
     55 };
     56 
     57 static cl::opt<ActionType>
     58 Action(cl::desc("Action to perform:"),
     59        cl::init(AC_Execute),
     60        cl::values(clEnumValN(AC_Execute, "execute",
     61                              "Load, link, and execute the inputs."),
     62                   clEnumValN(AC_PrintLineInfo, "printline",
     63                              "Load, link, and print line information for each function."),
     64                   clEnumValN(AC_PrintDebugLineInfo, "printdebugline",
     65                              "Load, link, and print line information for each function using the debug object"),
     66                   clEnumValN(AC_PrintObjectLineInfo, "printobjline",
     67                              "Like -printlineinfo but does not load the object first"),
     68                   clEnumValN(AC_Verify, "verify",
     69                              "Load, link and verify the resulting memory image."),
     70                   clEnumValEnd));
     71 
     72 static cl::opt<std::string>
     73 EntryPoint("entry",
     74            cl::desc("Function to call as entry point."),
     75            cl::init("_main"));
     76 
     77 static cl::list<std::string>
     78 Dylibs("dylib",
     79        cl::desc("Add library."),
     80        cl::ZeroOrMore);
     81 
     82 static cl::opt<std::string>
     83 TripleName("triple", cl::desc("Target triple for disassembler"));
     84 
     85 static cl::opt<std::string>
     86 MCPU("mcpu",
     87      cl::desc("Target a specific cpu type (-mcpu=help for details)"),
     88      cl::value_desc("cpu-name"),
     89      cl::init(""));
     90 
     91 static cl::list<std::string>
     92 CheckFiles("check",
     93            cl::desc("File containing RuntimeDyld verifier checks."),
     94            cl::ZeroOrMore);
     95 
     96 static cl::opt<uint64_t>
     97 PreallocMemory("preallocate",
     98               cl::desc("Allocate memory upfront rather than on-demand"),
     99               cl::init(0));
    100 
    101 static cl::opt<uint64_t>
    102 TargetAddrStart("target-addr-start",
    103                 cl::desc("For -verify only: start of phony target address "
    104                          "range."),
    105                 cl::init(4096), // Start at "page 1" - no allocating at "null".
    106                 cl::Hidden);
    107 
    108 static cl::opt<uint64_t>
    109 TargetAddrEnd("target-addr-end",
    110               cl::desc("For -verify only: end of phony target address range."),
    111               cl::init(~0ULL),
    112               cl::Hidden);
    113 
    114 static cl::opt<uint64_t>
    115 TargetSectionSep("target-section-sep",
    116                  cl::desc("For -verify only: Separation between sections in "
    117                           "phony target address space."),
    118                  cl::init(0),
    119                  cl::Hidden);
    120 
    121 static cl::list<std::string>
    122 SpecificSectionMappings("map-section",
    123                         cl::desc("For -verify only: Map a section to a "
    124                                  "specific address."),
    125                         cl::ZeroOrMore,
    126                         cl::Hidden);
    127 
    128 static cl::list<std::string>
    129 DummySymbolMappings("dummy-extern",
    130                     cl::desc("For -verify only: Inject a symbol into the extern "
    131                              "symbol table."),
    132                     cl::ZeroOrMore,
    133                     cl::Hidden);
    134 
    135 static cl::opt<bool>
    136 PrintAllocationRequests("print-alloc-requests",
    137                         cl::desc("Print allocation requests made to the memory "
    138                                  "manager by RuntimeDyld"),
    139                         cl::Hidden);
    140 
    141 /* *** */
    142 
    143 // A trivial memory manager that doesn't do anything fancy, just uses the
    144 // support library allocation routines directly.
    145 class TrivialMemoryManager : public RTDyldMemoryManager {
    146 public:
    147   SmallVector<sys::MemoryBlock, 16> FunctionMemory;
    148   SmallVector<sys::MemoryBlock, 16> DataMemory;
    149 
    150   uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
    151                                unsigned SectionID,
    152                                StringRef SectionName) override;
    153   uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
    154                                unsigned SectionID, StringRef SectionName,
    155                                bool IsReadOnly) override;
    156 
    157   void *getPointerToNamedFunction(const std::string &Name,
    158                                   bool AbortOnFailure = true) override {
    159     return nullptr;
    160   }
    161 
    162   bool finalizeMemory(std::string *ErrMsg) override { return false; }
    163 
    164   void addDummySymbol(const std::string &Name, uint64_t Addr) {
    165     DummyExterns[Name] = Addr;
    166   }
    167 
    168   RuntimeDyld::SymbolInfo findSymbol(const std::string &Name) override {
    169     auto I = DummyExterns.find(Name);
    170 
    171     if (I != DummyExterns.end())
    172       return RuntimeDyld::SymbolInfo(I->second, JITSymbolFlags::Exported);
    173 
    174     return RTDyldMemoryManager::findSymbol(Name);
    175   }
    176 
    177   void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
    178                         size_t Size) override {}
    179   void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr,
    180                           size_t Size) override {}
    181 
    182   void preallocateSlab(uint64_t Size) {
    183     std::string Err;
    184     sys::MemoryBlock MB = sys::Memory::AllocateRWX(Size, nullptr, &Err);
    185     if (!MB.base())
    186       report_fatal_error("Can't allocate enough memory: " + Err);
    187 
    188     PreallocSlab = MB;
    189     UsePreallocation = true;
    190     SlabSize = Size;
    191   }
    192 
    193   uint8_t *allocateFromSlab(uintptr_t Size, unsigned Alignment, bool isCode) {
    194     Size = alignTo(Size, Alignment);
    195     if (CurrentSlabOffset + Size > SlabSize)
    196       report_fatal_error("Can't allocate enough memory. Tune --preallocate");
    197 
    198     uintptr_t OldSlabOffset = CurrentSlabOffset;
    199     sys::MemoryBlock MB((void *)OldSlabOffset, Size);
    200     if (isCode)
    201       FunctionMemory.push_back(MB);
    202     else
    203       DataMemory.push_back(MB);
    204     CurrentSlabOffset += Size;
    205     return (uint8_t*)OldSlabOffset;
    206   }
    207 
    208 private:
    209   std::map<std::string, uint64_t> DummyExterns;
    210   sys::MemoryBlock PreallocSlab;
    211   bool UsePreallocation = false;
    212   uintptr_t SlabSize = 0;
    213   uintptr_t CurrentSlabOffset = 0;
    214 };
    215 
    216 uint8_t *TrivialMemoryManager::allocateCodeSection(uintptr_t Size,
    217                                                    unsigned Alignment,
    218                                                    unsigned SectionID,
    219                                                    StringRef SectionName) {
    220   if (PrintAllocationRequests)
    221     outs() << "allocateCodeSection(Size = " << Size << ", Alignment = "
    222            << Alignment << ", SectionName = " << SectionName << ")\n";
    223 
    224   if (UsePreallocation)
    225     return allocateFromSlab(Size, Alignment, true /* isCode */);
    226 
    227   std::string Err;
    228   sys::MemoryBlock MB = sys::Memory::AllocateRWX(Size, nullptr, &Err);
    229   if (!MB.base())
    230     report_fatal_error("MemoryManager allocation failed: " + Err);
    231   FunctionMemory.push_back(MB);
    232   return (uint8_t*)MB.base();
    233 }
    234 
    235 uint8_t *TrivialMemoryManager::allocateDataSection(uintptr_t Size,
    236                                                    unsigned Alignment,
    237                                                    unsigned SectionID,
    238                                                    StringRef SectionName,
    239                                                    bool IsReadOnly) {
    240   if (PrintAllocationRequests)
    241     outs() << "allocateDataSection(Size = " << Size << ", Alignment = "
    242            << Alignment << ", SectionName = " << SectionName << ")\n";
    243 
    244   if (UsePreallocation)
    245     return allocateFromSlab(Size, Alignment, false /* isCode */);
    246 
    247   std::string Err;
    248   sys::MemoryBlock MB = sys::Memory::AllocateRWX(Size, nullptr, &Err);
    249   if (!MB.base())
    250     report_fatal_error("MemoryManager allocation failed: " + Err);
    251   DataMemory.push_back(MB);
    252   return (uint8_t*)MB.base();
    253 }
    254 
    255 static const char *ProgramName;
    256 
    257 static void ErrorAndExit(const Twine &Msg) {
    258   errs() << ProgramName << ": error: " << Msg << "\n";
    259   exit(1);
    260 }
    261 
    262 static void loadDylibs() {
    263   for (const std::string &Dylib : Dylibs) {
    264     if (!sys::fs::is_regular_file(Dylib))
    265       report_fatal_error("Dylib not found: '" + Dylib + "'.");
    266     std::string ErrMsg;
    267     if (sys::DynamicLibrary::LoadLibraryPermanently(Dylib.c_str(), &ErrMsg))
    268       report_fatal_error("Error loading '" + Dylib + "': " + ErrMsg);
    269   }
    270 }
    271 
    272 /* *** */
    273 
    274 static int printLineInfoForInput(bool LoadObjects, bool UseDebugObj) {
    275   assert(LoadObjects || !UseDebugObj);
    276 
    277   // Load any dylibs requested on the command line.
    278   loadDylibs();
    279 
    280   // If we don't have any input files, read from stdin.
    281   if (!InputFileList.size())
    282     InputFileList.push_back("-");
    283   for (auto &File : InputFileList) {
    284     // Instantiate a dynamic linker.
    285     TrivialMemoryManager MemMgr;
    286     RuntimeDyld Dyld(MemMgr, MemMgr);
    287 
    288     // Load the input memory buffer.
    289 
    290     ErrorOr<std::unique_ptr<MemoryBuffer>> InputBuffer =
    291         MemoryBuffer::getFileOrSTDIN(File);
    292     if (std::error_code EC = InputBuffer.getError())
    293       ErrorAndExit("unable to read input: '" + EC.message() + "'");
    294 
    295     Expected<std::unique_ptr<ObjectFile>> MaybeObj(
    296       ObjectFile::createObjectFile((*InputBuffer)->getMemBufferRef()));
    297 
    298     if (!MaybeObj) {
    299       std::string Buf;
    300       raw_string_ostream OS(Buf);
    301       logAllUnhandledErrors(MaybeObj.takeError(), OS, "");
    302       OS.flush();
    303       ErrorAndExit("unable to create object file: '" + Buf + "'");
    304     }
    305 
    306     ObjectFile &Obj = **MaybeObj;
    307 
    308     OwningBinary<ObjectFile> DebugObj;
    309     std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObjInfo = nullptr;
    310     ObjectFile *SymbolObj = &Obj;
    311     if (LoadObjects) {
    312       // Load the object file
    313       LoadedObjInfo =
    314         Dyld.loadObject(Obj);
    315 
    316       if (Dyld.hasError())
    317         ErrorAndExit(Dyld.getErrorString());
    318 
    319       // Resolve all the relocations we can.
    320       Dyld.resolveRelocations();
    321 
    322       if (UseDebugObj) {
    323         DebugObj = LoadedObjInfo->getObjectForDebug(Obj);
    324         SymbolObj = DebugObj.getBinary();
    325         LoadedObjInfo.reset();
    326       }
    327     }
    328 
    329     std::unique_ptr<DIContext> Context(
    330       new DWARFContextInMemory(*SymbolObj,LoadedObjInfo.get()));
    331 
    332     std::vector<std::pair<SymbolRef, uint64_t>> SymAddr =
    333         object::computeSymbolSizes(*SymbolObj);
    334 
    335     // Use symbol info to iterate functions in the object.
    336     for (const auto &P : SymAddr) {
    337       object::SymbolRef Sym = P.first;
    338       Expected<SymbolRef::Type> TypeOrErr = Sym.getType();
    339       if (!TypeOrErr) {
    340         // TODO: Actually report errors helpfully.
    341         consumeError(TypeOrErr.takeError());
    342         continue;
    343       }
    344       SymbolRef::Type Type = *TypeOrErr;
    345       if (Type == object::SymbolRef::ST_Function) {
    346         Expected<StringRef> Name = Sym.getName();
    347         if (!Name) {
    348           // TODO: Actually report errors helpfully.
    349           consumeError(Name.takeError());
    350           continue;
    351         }
    352         Expected<uint64_t> AddrOrErr = Sym.getAddress();
    353         if (!AddrOrErr) {
    354           // TODO: Actually report errors helpfully.
    355           consumeError(AddrOrErr.takeError());
    356           continue;
    357         }
    358         uint64_t Addr = *AddrOrErr;
    359 
    360         uint64_t Size = P.second;
    361         // If we're not using the debug object, compute the address of the
    362         // symbol in memory (rather than that in the unrelocated object file)
    363         // and use that to query the DWARFContext.
    364         if (!UseDebugObj && LoadObjects) {
    365           auto SecOrErr = Sym.getSection();
    366           if (!SecOrErr) {
    367             // TODO: Actually report errors helpfully.
    368             consumeError(SecOrErr.takeError());
    369             continue;
    370           }
    371           object::section_iterator Sec = *SecOrErr;
    372           StringRef SecName;
    373           Sec->getName(SecName);
    374           uint64_t SectionLoadAddress =
    375             LoadedObjInfo->getSectionLoadAddress(*Sec);
    376           if (SectionLoadAddress != 0)
    377             Addr += SectionLoadAddress - Sec->getAddress();
    378         }
    379 
    380         outs() << "Function: " << *Name << ", Size = " << Size
    381                << ", Addr = " << Addr << "\n";
    382 
    383         DILineInfoTable Lines = Context->getLineInfoForAddressRange(Addr, Size);
    384         for (auto &D : Lines) {
    385           outs() << "  Line info @ " << D.first - Addr << ": "
    386                  << D.second.FileName << ", line:" << D.second.Line << "\n";
    387         }
    388       }
    389     }
    390   }
    391 
    392   return 0;
    393 }
    394 
    395 static void doPreallocation(TrivialMemoryManager &MemMgr) {
    396   // Allocate a slab of memory upfront, if required. This is used if
    397   // we want to test small code models.
    398   if (static_cast<intptr_t>(PreallocMemory) < 0)
    399     report_fatal_error("Pre-allocated bytes of memory must be a positive integer.");
    400 
    401   // FIXME: Limit the amount of memory that can be preallocated?
    402   if (PreallocMemory != 0)
    403     MemMgr.preallocateSlab(PreallocMemory);
    404 }
    405 
    406 static int executeInput() {
    407   // Load any dylibs requested on the command line.
    408   loadDylibs();
    409 
    410   // Instantiate a dynamic linker.
    411   TrivialMemoryManager MemMgr;
    412   doPreallocation(MemMgr);
    413   RuntimeDyld Dyld(MemMgr, MemMgr);
    414 
    415   // If we don't have any input files, read from stdin.
    416   if (!InputFileList.size())
    417     InputFileList.push_back("-");
    418   for (auto &File : InputFileList) {
    419     // Load the input memory buffer.
    420     ErrorOr<std::unique_ptr<MemoryBuffer>> InputBuffer =
    421         MemoryBuffer::getFileOrSTDIN(File);
    422     if (std::error_code EC = InputBuffer.getError())
    423       ErrorAndExit("unable to read input: '" + EC.message() + "'");
    424     Expected<std::unique_ptr<ObjectFile>> MaybeObj(
    425       ObjectFile::createObjectFile((*InputBuffer)->getMemBufferRef()));
    426 
    427     if (!MaybeObj) {
    428       std::string Buf;
    429       raw_string_ostream OS(Buf);
    430       logAllUnhandledErrors(MaybeObj.takeError(), OS, "");
    431       OS.flush();
    432       ErrorAndExit("unable to create object file: '" + Buf + "'");
    433     }
    434 
    435     ObjectFile &Obj = **MaybeObj;
    436 
    437     // Load the object file
    438     Dyld.loadObject(Obj);
    439     if (Dyld.hasError()) {
    440       ErrorAndExit(Dyld.getErrorString());
    441     }
    442   }
    443 
    444   // Resove all the relocations we can.
    445   // FIXME: Error out if there are unresolved relocations.
    446   Dyld.resolveRelocations();
    447 
    448   // Get the address of the entry point (_main by default).
    449   void *MainAddress = Dyld.getSymbolLocalAddress(EntryPoint);
    450   if (!MainAddress)
    451     ErrorAndExit("no definition for '" + EntryPoint + "'");
    452 
    453   // Invalidate the instruction cache for each loaded function.
    454   for (auto &FM : MemMgr.FunctionMemory) {
    455 
    456     // Make sure the memory is executable.
    457     // setExecutable will call InvalidateInstructionCache.
    458     std::string ErrorStr;
    459     if (!sys::Memory::setExecutable(FM, &ErrorStr))
    460       ErrorAndExit("unable to mark function executable: '" + ErrorStr + "'");
    461   }
    462 
    463   // Dispatch to _main().
    464   errs() << "loaded '" << EntryPoint << "' at: " << (void*)MainAddress << "\n";
    465 
    466   int (*Main)(int, const char**) =
    467     (int(*)(int,const char**)) uintptr_t(MainAddress);
    468   const char **Argv = new const char*[2];
    469   // Use the name of the first input object module as argv[0] for the target.
    470   Argv[0] = InputFileList[0].c_str();
    471   Argv[1] = nullptr;
    472   return Main(1, Argv);
    473 }
    474 
    475 static int checkAllExpressions(RuntimeDyldChecker &Checker) {
    476   for (const auto& CheckerFileName : CheckFiles) {
    477     ErrorOr<std::unique_ptr<MemoryBuffer>> CheckerFileBuf =
    478         MemoryBuffer::getFileOrSTDIN(CheckerFileName);
    479     if (std::error_code EC = CheckerFileBuf.getError())
    480       ErrorAndExit("unable to read input '" + CheckerFileName + "': " +
    481                    EC.message());
    482 
    483     if (!Checker.checkAllRulesInBuffer("# rtdyld-check:",
    484                                        CheckerFileBuf.get().get()))
    485       ErrorAndExit("some checks in '" + CheckerFileName + "' failed");
    486   }
    487   return 0;
    488 }
    489 
    490 static std::map<void *, uint64_t>
    491 applySpecificSectionMappings(RuntimeDyldChecker &Checker) {
    492 
    493   std::map<void*, uint64_t> SpecificMappings;
    494 
    495   for (StringRef Mapping : SpecificSectionMappings) {
    496 
    497     size_t EqualsIdx = Mapping.find_first_of("=");
    498     std::string SectionIDStr = Mapping.substr(0, EqualsIdx);
    499     size_t ComaIdx = Mapping.find_first_of(",");
    500 
    501     if (ComaIdx == StringRef::npos)
    502       report_fatal_error("Invalid section specification '" + Mapping +
    503                          "'. Should be '<file name>,<section name>=<addr>'");
    504 
    505     std::string FileName = SectionIDStr.substr(0, ComaIdx);
    506     std::string SectionName = SectionIDStr.substr(ComaIdx + 1);
    507 
    508     uint64_t OldAddrInt;
    509     std::string ErrorMsg;
    510     std::tie(OldAddrInt, ErrorMsg) =
    511       Checker.getSectionAddr(FileName, SectionName, true);
    512 
    513     if (ErrorMsg != "")
    514       report_fatal_error(ErrorMsg);
    515 
    516     void* OldAddr = reinterpret_cast<void*>(static_cast<uintptr_t>(OldAddrInt));
    517 
    518     std::string NewAddrStr = Mapping.substr(EqualsIdx + 1);
    519     uint64_t NewAddr;
    520 
    521     if (StringRef(NewAddrStr).getAsInteger(0, NewAddr))
    522       report_fatal_error("Invalid section address in mapping '" + Mapping +
    523                          "'.");
    524 
    525     Checker.getRTDyld().mapSectionAddress(OldAddr, NewAddr);
    526     SpecificMappings[OldAddr] = NewAddr;
    527   }
    528 
    529   return SpecificMappings;
    530 }
    531 
    532 // Scatter sections in all directions!
    533 // Remaps section addresses for -verify mode. The following command line options
    534 // can be used to customize the layout of the memory within the phony target's
    535 // address space:
    536 // -target-addr-start <s> -- Specify where the phony target addres range starts.
    537 // -target-addr-end   <e> -- Specify where the phony target address range ends.
    538 // -target-section-sep <d> -- Specify how big a gap should be left between the
    539 //                            end of one section and the start of the next.
    540 //                            Defaults to zero. Set to something big
    541 //                            (e.g. 1 << 32) to stress-test stubs, GOTs, etc.
    542 //
    543 static void remapSectionsAndSymbols(const llvm::Triple &TargetTriple,
    544                                     TrivialMemoryManager &MemMgr,
    545                                     RuntimeDyldChecker &Checker) {
    546 
    547   // Set up a work list (section addr/size pairs).
    548   typedef std::list<std::pair<void*, uint64_t>> WorklistT;
    549   WorklistT Worklist;
    550 
    551   for (const auto& CodeSection : MemMgr.FunctionMemory)
    552     Worklist.push_back(std::make_pair(CodeSection.base(), CodeSection.size()));
    553   for (const auto& DataSection : MemMgr.DataMemory)
    554     Worklist.push_back(std::make_pair(DataSection.base(), DataSection.size()));
    555 
    556   // Apply any section-specific mappings that were requested on the command
    557   // line.
    558   typedef std::map<void*, uint64_t> AppliedMappingsT;
    559   AppliedMappingsT AppliedMappings = applySpecificSectionMappings(Checker);
    560 
    561   // Keep an "already allocated" mapping of section target addresses to sizes.
    562   // Sections whose address mappings aren't specified on the command line will
    563   // allocated around the explicitly mapped sections while maintaining the
    564   // minimum separation.
    565   std::map<uint64_t, uint64_t> AlreadyAllocated;
    566 
    567   // Move the previously applied mappings into the already-allocated map.
    568   for (WorklistT::iterator I = Worklist.begin(), E = Worklist.end();
    569        I != E;) {
    570     WorklistT::iterator Tmp = I;
    571     ++I;
    572     AppliedMappingsT::iterator AI = AppliedMappings.find(Tmp->first);
    573 
    574     if (AI != AppliedMappings.end()) {
    575       AlreadyAllocated[AI->second] = Tmp->second;
    576       Worklist.erase(Tmp);
    577     }
    578   }
    579 
    580   // If the -target-addr-end option wasn't explicitly passed, then set it to a
    581   // sensible default based on the target triple.
    582   if (TargetAddrEnd.getNumOccurrences() == 0) {
    583     if (TargetTriple.isArch16Bit())
    584       TargetAddrEnd = (1ULL << 16) - 1;
    585     else if (TargetTriple.isArch32Bit())
    586       TargetAddrEnd = (1ULL << 32) - 1;
    587     // TargetAddrEnd already has a sensible default for 64-bit systems, so
    588     // there's nothing to do in the 64-bit case.
    589   }
    590 
    591   // Process any elements remaining in the worklist.
    592   while (!Worklist.empty()) {
    593     std::pair<void*, uint64_t> CurEntry = Worklist.front();
    594     Worklist.pop_front();
    595 
    596     uint64_t NextSectionAddr = TargetAddrStart;
    597 
    598     for (const auto &Alloc : AlreadyAllocated)
    599       if (NextSectionAddr + CurEntry.second + TargetSectionSep <= Alloc.first)
    600         break;
    601       else
    602         NextSectionAddr = Alloc.first + Alloc.second + TargetSectionSep;
    603 
    604     AlreadyAllocated[NextSectionAddr] = CurEntry.second;
    605     Checker.getRTDyld().mapSectionAddress(CurEntry.first, NextSectionAddr);
    606   }
    607 
    608   // Add dummy symbols to the memory manager.
    609   for (const auto &Mapping : DummySymbolMappings) {
    610     size_t EqualsIdx = Mapping.find_first_of("=");
    611 
    612     if (EqualsIdx == StringRef::npos)
    613       report_fatal_error("Invalid dummy symbol specification '" + Mapping +
    614                          "'. Should be '<symbol name>=<addr>'");
    615 
    616     std::string Symbol = Mapping.substr(0, EqualsIdx);
    617     std::string AddrStr = Mapping.substr(EqualsIdx + 1);
    618 
    619     uint64_t Addr;
    620     if (StringRef(AddrStr).getAsInteger(0, Addr))
    621       report_fatal_error("Invalid symbol mapping '" + Mapping + "'.");
    622 
    623     MemMgr.addDummySymbol(Symbol, Addr);
    624   }
    625 }
    626 
    627 // Load and link the objects specified on the command line, but do not execute
    628 // anything. Instead, attach a RuntimeDyldChecker instance and call it to
    629 // verify the correctness of the linked memory.
    630 static int linkAndVerify() {
    631 
    632   // Check for missing triple.
    633   if (TripleName == "")
    634     ErrorAndExit("-triple required when running in -verify mode.");
    635 
    636   // Look up the target and build the disassembler.
    637   Triple TheTriple(Triple::normalize(TripleName));
    638   std::string ErrorStr;
    639   const Target *TheTarget =
    640     TargetRegistry::lookupTarget("", TheTriple, ErrorStr);
    641   if (!TheTarget)
    642     ErrorAndExit("Error accessing target '" + TripleName + "': " + ErrorStr);
    643 
    644   TripleName = TheTriple.getTriple();
    645 
    646   std::unique_ptr<MCSubtargetInfo> STI(
    647     TheTarget->createMCSubtargetInfo(TripleName, MCPU, ""));
    648   if (!STI)
    649     ErrorAndExit("Unable to create subtarget info!");
    650 
    651   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
    652   if (!MRI)
    653     ErrorAndExit("Unable to create target register info!");
    654 
    655   std::unique_ptr<MCAsmInfo> MAI(TheTarget->createMCAsmInfo(*MRI, TripleName));
    656   if (!MAI)
    657     ErrorAndExit("Unable to create target asm info!");
    658 
    659   MCContext Ctx(MAI.get(), MRI.get(), nullptr);
    660 
    661   std::unique_ptr<MCDisassembler> Disassembler(
    662     TheTarget->createMCDisassembler(*STI, Ctx));
    663   if (!Disassembler)
    664     ErrorAndExit("Unable to create disassembler!");
    665 
    666   std::unique_ptr<MCInstrInfo> MII(TheTarget->createMCInstrInfo());
    667 
    668   std::unique_ptr<MCInstPrinter> InstPrinter(
    669       TheTarget->createMCInstPrinter(Triple(TripleName), 0, *MAI, *MII, *MRI));
    670 
    671   // Load any dylibs requested on the command line.
    672   loadDylibs();
    673 
    674   // Instantiate a dynamic linker.
    675   TrivialMemoryManager MemMgr;
    676   doPreallocation(MemMgr);
    677   RuntimeDyld Dyld(MemMgr, MemMgr);
    678   Dyld.setProcessAllSections(true);
    679   RuntimeDyldChecker Checker(Dyld, Disassembler.get(), InstPrinter.get(),
    680                              llvm::dbgs());
    681 
    682   // If we don't have any input files, read from stdin.
    683   if (!InputFileList.size())
    684     InputFileList.push_back("-");
    685   for (auto &Filename : InputFileList) {
    686     // Load the input memory buffer.
    687     ErrorOr<std::unique_ptr<MemoryBuffer>> InputBuffer =
    688         MemoryBuffer::getFileOrSTDIN(Filename);
    689 
    690     if (std::error_code EC = InputBuffer.getError())
    691       ErrorAndExit("unable to read input: '" + EC.message() + "'");
    692 
    693     Expected<std::unique_ptr<ObjectFile>> MaybeObj(
    694       ObjectFile::createObjectFile((*InputBuffer)->getMemBufferRef()));
    695 
    696     if (!MaybeObj) {
    697       std::string Buf;
    698       raw_string_ostream OS(Buf);
    699       logAllUnhandledErrors(MaybeObj.takeError(), OS, "");
    700       OS.flush();
    701       ErrorAndExit("unable to create object file: '" + Buf + "'");
    702     }
    703 
    704     ObjectFile &Obj = **MaybeObj;
    705 
    706     // Load the object file
    707     Dyld.loadObject(Obj);
    708     if (Dyld.hasError()) {
    709       ErrorAndExit(Dyld.getErrorString());
    710     }
    711   }
    712 
    713   // Re-map the section addresses into the phony target address space and add
    714   // dummy symbols.
    715   remapSectionsAndSymbols(TheTriple, MemMgr, Checker);
    716 
    717   // Resolve all the relocations we can.
    718   Dyld.resolveRelocations();
    719 
    720   // Register EH frames.
    721   Dyld.registerEHFrames();
    722 
    723   int ErrorCode = checkAllExpressions(Checker);
    724   if (Dyld.hasError())
    725     ErrorAndExit("RTDyld reported an error applying relocations:\n  " +
    726                  Dyld.getErrorString());
    727 
    728   return ErrorCode;
    729 }
    730 
    731 int main(int argc, char **argv) {
    732   sys::PrintStackTraceOnErrorSignal(argv[0]);
    733   PrettyStackTraceProgram X(argc, argv);
    734 
    735   ProgramName = argv[0];
    736   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    737 
    738   llvm::InitializeAllTargetInfos();
    739   llvm::InitializeAllTargetMCs();
    740   llvm::InitializeAllDisassemblers();
    741 
    742   cl::ParseCommandLineOptions(argc, argv, "llvm MC-JIT tool\n");
    743 
    744   switch (Action) {
    745   case AC_Execute:
    746     return executeInput();
    747   case AC_PrintDebugLineInfo:
    748     return printLineInfoForInput(/* LoadObjects */ true,/* UseDebugObj */ true);
    749   case AC_PrintLineInfo:
    750     return printLineInfoForInput(/* LoadObjects */ true,/* UseDebugObj */false);
    751   case AC_PrintObjectLineInfo:
    752     return printLineInfoForInput(/* LoadObjects */false,/* UseDebugObj */false);
    753   case AC_Verify:
    754     return linkAndVerify();
    755   }
    756 }
    757