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      1 //===-- ExecutionEngine.cpp - Common Implementation shared by EEs ---------===//
      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 file defines the common interface used by the various execution engine
     11 // subclasses.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "llvm/ExecutionEngine/ExecutionEngine.h"
     16 #include "llvm/ADT/STLExtras.h"
     17 #include "llvm/ADT/SmallString.h"
     18 #include "llvm/ADT/Statistic.h"
     19 #include "llvm/ExecutionEngine/GenericValue.h"
     20 #include "llvm/ExecutionEngine/JITEventListener.h"
     21 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
     22 #include "llvm/IR/Constants.h"
     23 #include "llvm/IR/DataLayout.h"
     24 #include "llvm/IR/DerivedTypes.h"
     25 #include "llvm/IR/Mangler.h"
     26 #include "llvm/IR/Module.h"
     27 #include "llvm/IR/Operator.h"
     28 #include "llvm/IR/ValueHandle.h"
     29 #include "llvm/Object/Archive.h"
     30 #include "llvm/Object/ObjectFile.h"
     31 #include "llvm/Support/Debug.h"
     32 #include "llvm/Support/DynamicLibrary.h"
     33 #include "llvm/Support/ErrorHandling.h"
     34 #include "llvm/Support/Host.h"
     35 #include "llvm/Support/MutexGuard.h"
     36 #include "llvm/Support/TargetRegistry.h"
     37 #include "llvm/Support/raw_ostream.h"
     38 #include "llvm/Target/TargetMachine.h"
     39 #include <cmath>
     40 #include <cstring>
     41 using namespace llvm;
     42 
     43 #define DEBUG_TYPE "jit"
     44 
     45 STATISTIC(NumInitBytes, "Number of bytes of global vars initialized");
     46 STATISTIC(NumGlobals  , "Number of global vars initialized");
     47 
     48 ExecutionEngine *(*ExecutionEngine::MCJITCtor)(
     49     std::unique_ptr<Module> M, std::string *ErrorStr,
     50     std::shared_ptr<MCJITMemoryManager> MemMgr,
     51     std::shared_ptr<RuntimeDyld::SymbolResolver> Resolver,
     52     std::unique_ptr<TargetMachine> TM) = nullptr;
     53 
     54 ExecutionEngine *(*ExecutionEngine::OrcMCJITReplacementCtor)(
     55   std::string *ErrorStr, std::shared_ptr<MCJITMemoryManager> MemMgr,
     56   std::shared_ptr<RuntimeDyld::SymbolResolver> Resolver,
     57   std::unique_ptr<TargetMachine> TM) = nullptr;
     58 
     59 ExecutionEngine *(*ExecutionEngine::InterpCtor)(std::unique_ptr<Module> M,
     60                                                 std::string *ErrorStr) =nullptr;
     61 
     62 void JITEventListener::anchor() {}
     63 
     64 void ExecutionEngine::Init(std::unique_ptr<Module> M) {
     65   CompilingLazily         = false;
     66   GVCompilationDisabled   = false;
     67   SymbolSearchingDisabled = false;
     68 
     69   // IR module verification is enabled by default in debug builds, and disabled
     70   // by default in release builds.
     71 #ifndef NDEBUG
     72   VerifyModules = true;
     73 #else
     74   VerifyModules = false;
     75 #endif
     76 
     77   assert(M && "Module is null?");
     78   Modules.push_back(std::move(M));
     79 }
     80 
     81 ExecutionEngine::ExecutionEngine(std::unique_ptr<Module> M)
     82     : DL(M->getDataLayout()), LazyFunctionCreator(nullptr) {
     83   Init(std::move(M));
     84 }
     85 
     86 ExecutionEngine::ExecutionEngine(DataLayout DL, std::unique_ptr<Module> M)
     87     : DL(std::move(DL)), LazyFunctionCreator(nullptr) {
     88   Init(std::move(M));
     89 }
     90 
     91 ExecutionEngine::~ExecutionEngine() {
     92   clearAllGlobalMappings();
     93 }
     94 
     95 namespace {
     96 /// \brief Helper class which uses a value handler to automatically deletes the
     97 /// memory block when the GlobalVariable is destroyed.
     98 class GVMemoryBlock final : public CallbackVH {
     99   GVMemoryBlock(const GlobalVariable *GV)
    100     : CallbackVH(const_cast<GlobalVariable*>(GV)) {}
    101 
    102 public:
    103   /// \brief Returns the address the GlobalVariable should be written into.  The
    104   /// GVMemoryBlock object prefixes that.
    105   static char *Create(const GlobalVariable *GV, const DataLayout& TD) {
    106     Type *ElTy = GV->getValueType();
    107     size_t GVSize = (size_t)TD.getTypeAllocSize(ElTy);
    108     void *RawMemory = ::operator new(
    109         alignTo(sizeof(GVMemoryBlock), TD.getPreferredAlignment(GV)) + GVSize);
    110     new(RawMemory) GVMemoryBlock(GV);
    111     return static_cast<char*>(RawMemory) + sizeof(GVMemoryBlock);
    112   }
    113 
    114   void deleted() override {
    115     // We allocated with operator new and with some extra memory hanging off the
    116     // end, so don't just delete this.  I'm not sure if this is actually
    117     // required.
    118     this->~GVMemoryBlock();
    119     ::operator delete(this);
    120   }
    121 };
    122 }  // anonymous namespace
    123 
    124 char *ExecutionEngine::getMemoryForGV(const GlobalVariable *GV) {
    125   return GVMemoryBlock::Create(GV, getDataLayout());
    126 }
    127 
    128 void ExecutionEngine::addObjectFile(std::unique_ptr<object::ObjectFile> O) {
    129   llvm_unreachable("ExecutionEngine subclass doesn't implement addObjectFile.");
    130 }
    131 
    132 void
    133 ExecutionEngine::addObjectFile(object::OwningBinary<object::ObjectFile> O) {
    134   llvm_unreachable("ExecutionEngine subclass doesn't implement addObjectFile.");
    135 }
    136 
    137 void ExecutionEngine::addArchive(object::OwningBinary<object::Archive> A) {
    138   llvm_unreachable("ExecutionEngine subclass doesn't implement addArchive.");
    139 }
    140 
    141 bool ExecutionEngine::removeModule(Module *M) {
    142   for (auto I = Modules.begin(), E = Modules.end(); I != E; ++I) {
    143     Module *Found = I->get();
    144     if (Found == M) {
    145       I->release();
    146       Modules.erase(I);
    147       clearGlobalMappingsFromModule(M);
    148       return true;
    149     }
    150   }
    151   return false;
    152 }
    153 
    154 Function *ExecutionEngine::FindFunctionNamed(const char *FnName) {
    155   for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
    156     Function *F = Modules[i]->getFunction(FnName);
    157     if (F && !F->isDeclaration())
    158       return F;
    159   }
    160   return nullptr;
    161 }
    162 
    163 GlobalVariable *ExecutionEngine::FindGlobalVariableNamed(const char *Name, bool AllowInternal) {
    164   for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
    165     GlobalVariable *GV = Modules[i]->getGlobalVariable(Name,AllowInternal);
    166     if (GV && !GV->isDeclaration())
    167       return GV;
    168   }
    169   return nullptr;
    170 }
    171 
    172 uint64_t ExecutionEngineState::RemoveMapping(StringRef Name) {
    173   GlobalAddressMapTy::iterator I = GlobalAddressMap.find(Name);
    174   uint64_t OldVal;
    175 
    176   // FIXME: This is silly, we shouldn't end up with a mapping -> 0 in the
    177   // GlobalAddressMap.
    178   if (I == GlobalAddressMap.end())
    179     OldVal = 0;
    180   else {
    181     GlobalAddressReverseMap.erase(I->second);
    182     OldVal = I->second;
    183     GlobalAddressMap.erase(I);
    184   }
    185 
    186   return OldVal;
    187 }
    188 
    189 std::string ExecutionEngine::getMangledName(const GlobalValue *GV) {
    190   assert(GV->hasName() && "Global must have name.");
    191 
    192   MutexGuard locked(lock);
    193   SmallString<128> FullName;
    194 
    195   const DataLayout &DL =
    196     GV->getParent()->getDataLayout().isDefault()
    197       ? getDataLayout()
    198       : GV->getParent()->getDataLayout();
    199 
    200   Mangler::getNameWithPrefix(FullName, GV->getName(), DL);
    201   return FullName.str();
    202 }
    203 
    204 void ExecutionEngine::addGlobalMapping(const GlobalValue *GV, void *Addr) {
    205   MutexGuard locked(lock);
    206   addGlobalMapping(getMangledName(GV), (uint64_t) Addr);
    207 }
    208 
    209 void ExecutionEngine::addGlobalMapping(StringRef Name, uint64_t Addr) {
    210   MutexGuard locked(lock);
    211 
    212   assert(!Name.empty() && "Empty GlobalMapping symbol name!");
    213 
    214   DEBUG(dbgs() << "JIT: Map \'" << Name  << "\' to [" << Addr << "]\n";);
    215   uint64_t &CurVal = EEState.getGlobalAddressMap()[Name];
    216   assert((!CurVal || !Addr) && "GlobalMapping already established!");
    217   CurVal = Addr;
    218 
    219   // If we are using the reverse mapping, add it too.
    220   if (!EEState.getGlobalAddressReverseMap().empty()) {
    221     std::string &V = EEState.getGlobalAddressReverseMap()[CurVal];
    222     assert((!V.empty() || !Name.empty()) &&
    223            "GlobalMapping already established!");
    224     V = Name;
    225   }
    226 }
    227 
    228 void ExecutionEngine::clearAllGlobalMappings() {
    229   MutexGuard locked(lock);
    230 
    231   EEState.getGlobalAddressMap().clear();
    232   EEState.getGlobalAddressReverseMap().clear();
    233 }
    234 
    235 void ExecutionEngine::clearGlobalMappingsFromModule(Module *M) {
    236   MutexGuard locked(lock);
    237 
    238   for (GlobalObject &GO : M->global_objects())
    239     EEState.RemoveMapping(getMangledName(&GO));
    240 }
    241 
    242 uint64_t ExecutionEngine::updateGlobalMapping(const GlobalValue *GV,
    243                                               void *Addr) {
    244   MutexGuard locked(lock);
    245   return updateGlobalMapping(getMangledName(GV), (uint64_t) Addr);
    246 }
    247 
    248 uint64_t ExecutionEngine::updateGlobalMapping(StringRef Name, uint64_t Addr) {
    249   MutexGuard locked(lock);
    250 
    251   ExecutionEngineState::GlobalAddressMapTy &Map =
    252     EEState.getGlobalAddressMap();
    253 
    254   // Deleting from the mapping?
    255   if (!Addr)
    256     return EEState.RemoveMapping(Name);
    257 
    258   uint64_t &CurVal = Map[Name];
    259   uint64_t OldVal = CurVal;
    260 
    261   if (CurVal && !EEState.getGlobalAddressReverseMap().empty())
    262     EEState.getGlobalAddressReverseMap().erase(CurVal);
    263   CurVal = Addr;
    264 
    265   // If we are using the reverse mapping, add it too.
    266   if (!EEState.getGlobalAddressReverseMap().empty()) {
    267     std::string &V = EEState.getGlobalAddressReverseMap()[CurVal];
    268     assert((!V.empty() || !Name.empty()) &&
    269            "GlobalMapping already established!");
    270     V = Name;
    271   }
    272   return OldVal;
    273 }
    274 
    275 uint64_t ExecutionEngine::getAddressToGlobalIfAvailable(StringRef S) {
    276   MutexGuard locked(lock);
    277   uint64_t Address = 0;
    278   ExecutionEngineState::GlobalAddressMapTy::iterator I =
    279     EEState.getGlobalAddressMap().find(S);
    280   if (I != EEState.getGlobalAddressMap().end())
    281     Address = I->second;
    282   return Address;
    283 }
    284 
    285 
    286 void *ExecutionEngine::getPointerToGlobalIfAvailable(StringRef S) {
    287   MutexGuard locked(lock);
    288   if (void* Address = (void *) getAddressToGlobalIfAvailable(S))
    289     return Address;
    290   return nullptr;
    291 }
    292 
    293 void *ExecutionEngine::getPointerToGlobalIfAvailable(const GlobalValue *GV) {
    294   MutexGuard locked(lock);
    295   return getPointerToGlobalIfAvailable(getMangledName(GV));
    296 }
    297 
    298 const GlobalValue *ExecutionEngine::getGlobalValueAtAddress(void *Addr) {
    299   MutexGuard locked(lock);
    300 
    301   // If we haven't computed the reverse mapping yet, do so first.
    302   if (EEState.getGlobalAddressReverseMap().empty()) {
    303     for (ExecutionEngineState::GlobalAddressMapTy::iterator
    304            I = EEState.getGlobalAddressMap().begin(),
    305            E = EEState.getGlobalAddressMap().end(); I != E; ++I) {
    306       StringRef Name = I->first();
    307       uint64_t Addr = I->second;
    308       EEState.getGlobalAddressReverseMap().insert(std::make_pair(
    309                                                           Addr, Name));
    310     }
    311   }
    312 
    313   std::map<uint64_t, std::string>::iterator I =
    314     EEState.getGlobalAddressReverseMap().find((uint64_t) Addr);
    315 
    316   if (I != EEState.getGlobalAddressReverseMap().end()) {
    317     StringRef Name = I->second;
    318     for (unsigned i = 0, e = Modules.size(); i != e; ++i)
    319       if (GlobalValue *GV = Modules[i]->getNamedValue(Name))
    320         return GV;
    321   }
    322   return nullptr;
    323 }
    324 
    325 namespace {
    326 class ArgvArray {
    327   std::unique_ptr<char[]> Array;
    328   std::vector<std::unique_ptr<char[]>> Values;
    329 public:
    330   /// Turn a vector of strings into a nice argv style array of pointers to null
    331   /// terminated strings.
    332   void *reset(LLVMContext &C, ExecutionEngine *EE,
    333               const std::vector<std::string> &InputArgv);
    334 };
    335 }  // anonymous namespace
    336 void *ArgvArray::reset(LLVMContext &C, ExecutionEngine *EE,
    337                        const std::vector<std::string> &InputArgv) {
    338   Values.clear();  // Free the old contents.
    339   Values.reserve(InputArgv.size());
    340   unsigned PtrSize = EE->getDataLayout().getPointerSize();
    341   Array = make_unique<char[]>((InputArgv.size()+1)*PtrSize);
    342 
    343   DEBUG(dbgs() << "JIT: ARGV = " << (void*)Array.get() << "\n");
    344   Type *SBytePtr = Type::getInt8PtrTy(C);
    345 
    346   for (unsigned i = 0; i != InputArgv.size(); ++i) {
    347     unsigned Size = InputArgv[i].size()+1;
    348     auto Dest = make_unique<char[]>(Size);
    349     DEBUG(dbgs() << "JIT: ARGV[" << i << "] = " << (void*)Dest.get() << "\n");
    350 
    351     std::copy(InputArgv[i].begin(), InputArgv[i].end(), Dest.get());
    352     Dest[Size-1] = 0;
    353 
    354     // Endian safe: Array[i] = (PointerTy)Dest;
    355     EE->StoreValueToMemory(PTOGV(Dest.get()),
    356                            (GenericValue*)(&Array[i*PtrSize]), SBytePtr);
    357     Values.push_back(std::move(Dest));
    358   }
    359 
    360   // Null terminate it
    361   EE->StoreValueToMemory(PTOGV(nullptr),
    362                          (GenericValue*)(&Array[InputArgv.size()*PtrSize]),
    363                          SBytePtr);
    364   return Array.get();
    365 }
    366 
    367 void ExecutionEngine::runStaticConstructorsDestructors(Module &module,
    368                                                        bool isDtors) {
    369   const char *Name = isDtors ? "llvm.global_dtors" : "llvm.global_ctors";
    370   GlobalVariable *GV = module.getNamedGlobal(Name);
    371 
    372   // If this global has internal linkage, or if it has a use, then it must be
    373   // an old-style (llvmgcc3) static ctor with __main linked in and in use.  If
    374   // this is the case, don't execute any of the global ctors, __main will do
    375   // it.
    376   if (!GV || GV->isDeclaration() || GV->hasLocalLinkage()) return;
    377 
    378   // Should be an array of '{ i32, void ()* }' structs.  The first value is
    379   // the init priority, which we ignore.
    380   ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
    381   if (!InitList)
    382     return;
    383   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
    384     ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i));
    385     if (!CS) continue;
    386 
    387     Constant *FP = CS->getOperand(1);
    388     if (FP->isNullValue())
    389       continue;  // Found a sentinal value, ignore.
    390 
    391     // Strip off constant expression casts.
    392     if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
    393       if (CE->isCast())
    394         FP = CE->getOperand(0);
    395 
    396     // Execute the ctor/dtor function!
    397     if (Function *F = dyn_cast<Function>(FP))
    398       runFunction(F, None);
    399 
    400     // FIXME: It is marginally lame that we just do nothing here if we see an
    401     // entry we don't recognize. It might not be unreasonable for the verifier
    402     // to not even allow this and just assert here.
    403   }
    404 }
    405 
    406 void ExecutionEngine::runStaticConstructorsDestructors(bool isDtors) {
    407   // Execute global ctors/dtors for each module in the program.
    408   for (std::unique_ptr<Module> &M : Modules)
    409     runStaticConstructorsDestructors(*M, isDtors);
    410 }
    411 
    412 #ifndef NDEBUG
    413 /// isTargetNullPtr - Return whether the target pointer stored at Loc is null.
    414 static bool isTargetNullPtr(ExecutionEngine *EE, void *Loc) {
    415   unsigned PtrSize = EE->getDataLayout().getPointerSize();
    416   for (unsigned i = 0; i < PtrSize; ++i)
    417     if (*(i + (uint8_t*)Loc))
    418       return false;
    419   return true;
    420 }
    421 #endif
    422 
    423 int ExecutionEngine::runFunctionAsMain(Function *Fn,
    424                                        const std::vector<std::string> &argv,
    425                                        const char * const * envp) {
    426   std::vector<GenericValue> GVArgs;
    427   GenericValue GVArgc;
    428   GVArgc.IntVal = APInt(32, argv.size());
    429 
    430   // Check main() type
    431   unsigned NumArgs = Fn->getFunctionType()->getNumParams();
    432   FunctionType *FTy = Fn->getFunctionType();
    433   Type* PPInt8Ty = Type::getInt8PtrTy(Fn->getContext())->getPointerTo();
    434 
    435   // Check the argument types.
    436   if (NumArgs > 3)
    437     report_fatal_error("Invalid number of arguments of main() supplied");
    438   if (NumArgs >= 3 && FTy->getParamType(2) != PPInt8Ty)
    439     report_fatal_error("Invalid type for third argument of main() supplied");
    440   if (NumArgs >= 2 && FTy->getParamType(1) != PPInt8Ty)
    441     report_fatal_error("Invalid type for second argument of main() supplied");
    442   if (NumArgs >= 1 && !FTy->getParamType(0)->isIntegerTy(32))
    443     report_fatal_error("Invalid type for first argument of main() supplied");
    444   if (!FTy->getReturnType()->isIntegerTy() &&
    445       !FTy->getReturnType()->isVoidTy())
    446     report_fatal_error("Invalid return type of main() supplied");
    447 
    448   ArgvArray CArgv;
    449   ArgvArray CEnv;
    450   if (NumArgs) {
    451     GVArgs.push_back(GVArgc); // Arg #0 = argc.
    452     if (NumArgs > 1) {
    453       // Arg #1 = argv.
    454       GVArgs.push_back(PTOGV(CArgv.reset(Fn->getContext(), this, argv)));
    455       assert(!isTargetNullPtr(this, GVTOP(GVArgs[1])) &&
    456              "argv[0] was null after CreateArgv");
    457       if (NumArgs > 2) {
    458         std::vector<std::string> EnvVars;
    459         for (unsigned i = 0; envp[i]; ++i)
    460           EnvVars.emplace_back(envp[i]);
    461         // Arg #2 = envp.
    462         GVArgs.push_back(PTOGV(CEnv.reset(Fn->getContext(), this, EnvVars)));
    463       }
    464     }
    465   }
    466 
    467   return runFunction(Fn, GVArgs).IntVal.getZExtValue();
    468 }
    469 
    470 EngineBuilder::EngineBuilder() : EngineBuilder(nullptr) {}
    471 
    472 EngineBuilder::EngineBuilder(std::unique_ptr<Module> M)
    473     : M(std::move(M)), WhichEngine(EngineKind::Either), ErrorStr(nullptr),
    474       OptLevel(CodeGenOpt::Default), MemMgr(nullptr), Resolver(nullptr),
    475       CMModel(CodeModel::JITDefault), UseOrcMCJITReplacement(false) {
    476 // IR module verification is enabled by default in debug builds, and disabled
    477 // by default in release builds.
    478 #ifndef NDEBUG
    479   VerifyModules = true;
    480 #else
    481   VerifyModules = false;
    482 #endif
    483 }
    484 
    485 EngineBuilder::~EngineBuilder() = default;
    486 
    487 EngineBuilder &EngineBuilder::setMCJITMemoryManager(
    488                                    std::unique_ptr<RTDyldMemoryManager> mcjmm) {
    489   auto SharedMM = std::shared_ptr<RTDyldMemoryManager>(std::move(mcjmm));
    490   MemMgr = SharedMM;
    491   Resolver = SharedMM;
    492   return *this;
    493 }
    494 
    495 EngineBuilder&
    496 EngineBuilder::setMemoryManager(std::unique_ptr<MCJITMemoryManager> MM) {
    497   MemMgr = std::shared_ptr<MCJITMemoryManager>(std::move(MM));
    498   return *this;
    499 }
    500 
    501 EngineBuilder&
    502 EngineBuilder::setSymbolResolver(std::unique_ptr<RuntimeDyld::SymbolResolver> SR) {
    503   Resolver = std::shared_ptr<RuntimeDyld::SymbolResolver>(std::move(SR));
    504   return *this;
    505 }
    506 
    507 ExecutionEngine *EngineBuilder::create(TargetMachine *TM) {
    508   std::unique_ptr<TargetMachine> TheTM(TM); // Take ownership.
    509 
    510   // Make sure we can resolve symbols in the program as well. The zero arg
    511   // to the function tells DynamicLibrary to load the program, not a library.
    512   if (sys::DynamicLibrary::LoadLibraryPermanently(nullptr, ErrorStr))
    513     return nullptr;
    514 
    515   // If the user specified a memory manager but didn't specify which engine to
    516   // create, we assume they only want the JIT, and we fail if they only want
    517   // the interpreter.
    518   if (MemMgr) {
    519     if (WhichEngine & EngineKind::JIT)
    520       WhichEngine = EngineKind::JIT;
    521     else {
    522       if (ErrorStr)
    523         *ErrorStr = "Cannot create an interpreter with a memory manager.";
    524       return nullptr;
    525     }
    526   }
    527 
    528   // Unless the interpreter was explicitly selected or the JIT is not linked,
    529   // try making a JIT.
    530   if ((WhichEngine & EngineKind::JIT) && TheTM) {
    531     Triple TT(M->getTargetTriple());
    532     if (!TM->getTarget().hasJIT()) {
    533       errs() << "WARNING: This target JIT is not designed for the host"
    534              << " you are running.  If bad things happen, please choose"
    535              << " a different -march switch.\n";
    536     }
    537 
    538     ExecutionEngine *EE = nullptr;
    539     if (ExecutionEngine::OrcMCJITReplacementCtor && UseOrcMCJITReplacement) {
    540       EE = ExecutionEngine::OrcMCJITReplacementCtor(ErrorStr, std::move(MemMgr),
    541                                                     std::move(Resolver),
    542                                                     std::move(TheTM));
    543       EE->addModule(std::move(M));
    544     } else if (ExecutionEngine::MCJITCtor)
    545       EE = ExecutionEngine::MCJITCtor(std::move(M), ErrorStr, std::move(MemMgr),
    546                                       std::move(Resolver), std::move(TheTM));
    547 
    548     if (EE) {
    549       EE->setVerifyModules(VerifyModules);
    550       return EE;
    551     }
    552   }
    553 
    554   // If we can't make a JIT and we didn't request one specifically, try making
    555   // an interpreter instead.
    556   if (WhichEngine & EngineKind::Interpreter) {
    557     if (ExecutionEngine::InterpCtor)
    558       return ExecutionEngine::InterpCtor(std::move(M), ErrorStr);
    559     if (ErrorStr)
    560       *ErrorStr = "Interpreter has not been linked in.";
    561     return nullptr;
    562   }
    563 
    564   if ((WhichEngine & EngineKind::JIT) && !ExecutionEngine::MCJITCtor) {
    565     if (ErrorStr)
    566       *ErrorStr = "JIT has not been linked in.";
    567   }
    568 
    569   return nullptr;
    570 }
    571 
    572 void *ExecutionEngine::getPointerToGlobal(const GlobalValue *GV) {
    573   if (Function *F = const_cast<Function*>(dyn_cast<Function>(GV)))
    574     return getPointerToFunction(F);
    575 
    576   MutexGuard locked(lock);
    577   if (void* P = getPointerToGlobalIfAvailable(GV))
    578     return P;
    579 
    580   // Global variable might have been added since interpreter started.
    581   if (GlobalVariable *GVar =
    582           const_cast<GlobalVariable *>(dyn_cast<GlobalVariable>(GV)))
    583     EmitGlobalVariable(GVar);
    584   else
    585     llvm_unreachable("Global hasn't had an address allocated yet!");
    586 
    587   return getPointerToGlobalIfAvailable(GV);
    588 }
    589 
    590 /// \brief Converts a Constant* into a GenericValue, including handling of
    591 /// ConstantExpr values.
    592 GenericValue ExecutionEngine::getConstantValue(const Constant *C) {
    593   // If its undefined, return the garbage.
    594   if (isa<UndefValue>(C)) {
    595     GenericValue Result;
    596     switch (C->getType()->getTypeID()) {
    597     default:
    598       break;
    599     case Type::IntegerTyID:
    600     case Type::X86_FP80TyID:
    601     case Type::FP128TyID:
    602     case Type::PPC_FP128TyID:
    603       // Although the value is undefined, we still have to construct an APInt
    604       // with the correct bit width.
    605       Result.IntVal = APInt(C->getType()->getPrimitiveSizeInBits(), 0);
    606       break;
    607     case Type::StructTyID: {
    608       // if the whole struct is 'undef' just reserve memory for the value.
    609       if(StructType *STy = dyn_cast<StructType>(C->getType())) {
    610         unsigned int elemNum = STy->getNumElements();
    611         Result.AggregateVal.resize(elemNum);
    612         for (unsigned int i = 0; i < elemNum; ++i) {
    613           Type *ElemTy = STy->getElementType(i);
    614           if (ElemTy->isIntegerTy())
    615             Result.AggregateVal[i].IntVal =
    616               APInt(ElemTy->getPrimitiveSizeInBits(), 0);
    617           else if (ElemTy->isAggregateType()) {
    618               const Constant *ElemUndef = UndefValue::get(ElemTy);
    619               Result.AggregateVal[i] = getConstantValue(ElemUndef);
    620             }
    621           }
    622         }
    623       }
    624       break;
    625     case Type::VectorTyID:
    626       // if the whole vector is 'undef' just reserve memory for the value.
    627       auto* VTy = dyn_cast<VectorType>(C->getType());
    628       Type *ElemTy = VTy->getElementType();
    629       unsigned int elemNum = VTy->getNumElements();
    630       Result.AggregateVal.resize(elemNum);
    631       if (ElemTy->isIntegerTy())
    632         for (unsigned int i = 0; i < elemNum; ++i)
    633           Result.AggregateVal[i].IntVal =
    634             APInt(ElemTy->getPrimitiveSizeInBits(), 0);
    635       break;
    636     }
    637     return Result;
    638   }
    639 
    640   // Otherwise, if the value is a ConstantExpr...
    641   if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
    642     Constant *Op0 = CE->getOperand(0);
    643     switch (CE->getOpcode()) {
    644     case Instruction::GetElementPtr: {
    645       // Compute the index
    646       GenericValue Result = getConstantValue(Op0);
    647       APInt Offset(DL.getPointerSizeInBits(), 0);
    648       cast<GEPOperator>(CE)->accumulateConstantOffset(DL, Offset);
    649 
    650       char* tmp = (char*) Result.PointerVal;
    651       Result = PTOGV(tmp + Offset.getSExtValue());
    652       return Result;
    653     }
    654     case Instruction::Trunc: {
    655       GenericValue GV = getConstantValue(Op0);
    656       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    657       GV.IntVal = GV.IntVal.trunc(BitWidth);
    658       return GV;
    659     }
    660     case Instruction::ZExt: {
    661       GenericValue GV = getConstantValue(Op0);
    662       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    663       GV.IntVal = GV.IntVal.zext(BitWidth);
    664       return GV;
    665     }
    666     case Instruction::SExt: {
    667       GenericValue GV = getConstantValue(Op0);
    668       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    669       GV.IntVal = GV.IntVal.sext(BitWidth);
    670       return GV;
    671     }
    672     case Instruction::FPTrunc: {
    673       // FIXME long double
    674       GenericValue GV = getConstantValue(Op0);
    675       GV.FloatVal = float(GV.DoubleVal);
    676       return GV;
    677     }
    678     case Instruction::FPExt:{
    679       // FIXME long double
    680       GenericValue GV = getConstantValue(Op0);
    681       GV.DoubleVal = double(GV.FloatVal);
    682       return GV;
    683     }
    684     case Instruction::UIToFP: {
    685       GenericValue GV = getConstantValue(Op0);
    686       if (CE->getType()->isFloatTy())
    687         GV.FloatVal = float(GV.IntVal.roundToDouble());
    688       else if (CE->getType()->isDoubleTy())
    689         GV.DoubleVal = GV.IntVal.roundToDouble();
    690       else if (CE->getType()->isX86_FP80Ty()) {
    691         APFloat apf = APFloat::getZero(APFloat::x87DoubleExtended);
    692         (void)apf.convertFromAPInt(GV.IntVal,
    693                                    false,
    694                                    APFloat::rmNearestTiesToEven);
    695         GV.IntVal = apf.bitcastToAPInt();
    696       }
    697       return GV;
    698     }
    699     case Instruction::SIToFP: {
    700       GenericValue GV = getConstantValue(Op0);
    701       if (CE->getType()->isFloatTy())
    702         GV.FloatVal = float(GV.IntVal.signedRoundToDouble());
    703       else if (CE->getType()->isDoubleTy())
    704         GV.DoubleVal = GV.IntVal.signedRoundToDouble();
    705       else if (CE->getType()->isX86_FP80Ty()) {
    706         APFloat apf = APFloat::getZero(APFloat::x87DoubleExtended);
    707         (void)apf.convertFromAPInt(GV.IntVal,
    708                                    true,
    709                                    APFloat::rmNearestTiesToEven);
    710         GV.IntVal = apf.bitcastToAPInt();
    711       }
    712       return GV;
    713     }
    714     case Instruction::FPToUI: // double->APInt conversion handles sign
    715     case Instruction::FPToSI: {
    716       GenericValue GV = getConstantValue(Op0);
    717       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    718       if (Op0->getType()->isFloatTy())
    719         GV.IntVal = APIntOps::RoundFloatToAPInt(GV.FloatVal, BitWidth);
    720       else if (Op0->getType()->isDoubleTy())
    721         GV.IntVal = APIntOps::RoundDoubleToAPInt(GV.DoubleVal, BitWidth);
    722       else if (Op0->getType()->isX86_FP80Ty()) {
    723         APFloat apf = APFloat(APFloat::x87DoubleExtended, GV.IntVal);
    724         uint64_t v;
    725         bool ignored;
    726         (void)apf.convertToInteger(&v, BitWidth,
    727                                    CE->getOpcode()==Instruction::FPToSI,
    728                                    APFloat::rmTowardZero, &ignored);
    729         GV.IntVal = v; // endian?
    730       }
    731       return GV;
    732     }
    733     case Instruction::PtrToInt: {
    734       GenericValue GV = getConstantValue(Op0);
    735       uint32_t PtrWidth = DL.getTypeSizeInBits(Op0->getType());
    736       assert(PtrWidth <= 64 && "Bad pointer width");
    737       GV.IntVal = APInt(PtrWidth, uintptr_t(GV.PointerVal));
    738       uint32_t IntWidth = DL.getTypeSizeInBits(CE->getType());
    739       GV.IntVal = GV.IntVal.zextOrTrunc(IntWidth);
    740       return GV;
    741     }
    742     case Instruction::IntToPtr: {
    743       GenericValue GV = getConstantValue(Op0);
    744       uint32_t PtrWidth = DL.getTypeSizeInBits(CE->getType());
    745       GV.IntVal = GV.IntVal.zextOrTrunc(PtrWidth);
    746       assert(GV.IntVal.getBitWidth() <= 64 && "Bad pointer width");
    747       GV.PointerVal = PointerTy(uintptr_t(GV.IntVal.getZExtValue()));
    748       return GV;
    749     }
    750     case Instruction::BitCast: {
    751       GenericValue GV = getConstantValue(Op0);
    752       Type* DestTy = CE->getType();
    753       switch (Op0->getType()->getTypeID()) {
    754         default: llvm_unreachable("Invalid bitcast operand");
    755         case Type::IntegerTyID:
    756           assert(DestTy->isFloatingPointTy() && "invalid bitcast");
    757           if (DestTy->isFloatTy())
    758             GV.FloatVal = GV.IntVal.bitsToFloat();
    759           else if (DestTy->isDoubleTy())
    760             GV.DoubleVal = GV.IntVal.bitsToDouble();
    761           break;
    762         case Type::FloatTyID:
    763           assert(DestTy->isIntegerTy(32) && "Invalid bitcast");
    764           GV.IntVal = APInt::floatToBits(GV.FloatVal);
    765           break;
    766         case Type::DoubleTyID:
    767           assert(DestTy->isIntegerTy(64) && "Invalid bitcast");
    768           GV.IntVal = APInt::doubleToBits(GV.DoubleVal);
    769           break;
    770         case Type::PointerTyID:
    771           assert(DestTy->isPointerTy() && "Invalid bitcast");
    772           break; // getConstantValue(Op0)  above already converted it
    773       }
    774       return GV;
    775     }
    776     case Instruction::Add:
    777     case Instruction::FAdd:
    778     case Instruction::Sub:
    779     case Instruction::FSub:
    780     case Instruction::Mul:
    781     case Instruction::FMul:
    782     case Instruction::UDiv:
    783     case Instruction::SDiv:
    784     case Instruction::URem:
    785     case Instruction::SRem:
    786     case Instruction::And:
    787     case Instruction::Or:
    788     case Instruction::Xor: {
    789       GenericValue LHS = getConstantValue(Op0);
    790       GenericValue RHS = getConstantValue(CE->getOperand(1));
    791       GenericValue GV;
    792       switch (CE->getOperand(0)->getType()->getTypeID()) {
    793       default: llvm_unreachable("Bad add type!");
    794       case Type::IntegerTyID:
    795         switch (CE->getOpcode()) {
    796           default: llvm_unreachable("Invalid integer opcode");
    797           case Instruction::Add: GV.IntVal = LHS.IntVal + RHS.IntVal; break;
    798           case Instruction::Sub: GV.IntVal = LHS.IntVal - RHS.IntVal; break;
    799           case Instruction::Mul: GV.IntVal = LHS.IntVal * RHS.IntVal; break;
    800           case Instruction::UDiv:GV.IntVal = LHS.IntVal.udiv(RHS.IntVal); break;
    801           case Instruction::SDiv:GV.IntVal = LHS.IntVal.sdiv(RHS.IntVal); break;
    802           case Instruction::URem:GV.IntVal = LHS.IntVal.urem(RHS.IntVal); break;
    803           case Instruction::SRem:GV.IntVal = LHS.IntVal.srem(RHS.IntVal); break;
    804           case Instruction::And: GV.IntVal = LHS.IntVal & RHS.IntVal; break;
    805           case Instruction::Or:  GV.IntVal = LHS.IntVal | RHS.IntVal; break;
    806           case Instruction::Xor: GV.IntVal = LHS.IntVal ^ RHS.IntVal; break;
    807         }
    808         break;
    809       case Type::FloatTyID:
    810         switch (CE->getOpcode()) {
    811           default: llvm_unreachable("Invalid float opcode");
    812           case Instruction::FAdd:
    813             GV.FloatVal = LHS.FloatVal + RHS.FloatVal; break;
    814           case Instruction::FSub:
    815             GV.FloatVal = LHS.FloatVal - RHS.FloatVal; break;
    816           case Instruction::FMul:
    817             GV.FloatVal = LHS.FloatVal * RHS.FloatVal; break;
    818           case Instruction::FDiv:
    819             GV.FloatVal = LHS.FloatVal / RHS.FloatVal; break;
    820           case Instruction::FRem:
    821             GV.FloatVal = std::fmod(LHS.FloatVal,RHS.FloatVal); break;
    822         }
    823         break;
    824       case Type::DoubleTyID:
    825         switch (CE->getOpcode()) {
    826           default: llvm_unreachable("Invalid double opcode");
    827           case Instruction::FAdd:
    828             GV.DoubleVal = LHS.DoubleVal + RHS.DoubleVal; break;
    829           case Instruction::FSub:
    830             GV.DoubleVal = LHS.DoubleVal - RHS.DoubleVal; break;
    831           case Instruction::FMul:
    832             GV.DoubleVal = LHS.DoubleVal * RHS.DoubleVal; break;
    833           case Instruction::FDiv:
    834             GV.DoubleVal = LHS.DoubleVal / RHS.DoubleVal; break;
    835           case Instruction::FRem:
    836             GV.DoubleVal = std::fmod(LHS.DoubleVal,RHS.DoubleVal); break;
    837         }
    838         break;
    839       case Type::X86_FP80TyID:
    840       case Type::PPC_FP128TyID:
    841       case Type::FP128TyID: {
    842         const fltSemantics &Sem = CE->getOperand(0)->getType()->getFltSemantics();
    843         APFloat apfLHS = APFloat(Sem, LHS.IntVal);
    844         switch (CE->getOpcode()) {
    845           default: llvm_unreachable("Invalid long double opcode");
    846           case Instruction::FAdd:
    847             apfLHS.add(APFloat(Sem, RHS.IntVal), APFloat::rmNearestTiesToEven);
    848             GV.IntVal = apfLHS.bitcastToAPInt();
    849             break;
    850           case Instruction::FSub:
    851             apfLHS.subtract(APFloat(Sem, RHS.IntVal),
    852                             APFloat::rmNearestTiesToEven);
    853             GV.IntVal = apfLHS.bitcastToAPInt();
    854             break;
    855           case Instruction::FMul:
    856             apfLHS.multiply(APFloat(Sem, RHS.IntVal),
    857                             APFloat::rmNearestTiesToEven);
    858             GV.IntVal = apfLHS.bitcastToAPInt();
    859             break;
    860           case Instruction::FDiv:
    861             apfLHS.divide(APFloat(Sem, RHS.IntVal),
    862                           APFloat::rmNearestTiesToEven);
    863             GV.IntVal = apfLHS.bitcastToAPInt();
    864             break;
    865           case Instruction::FRem:
    866             apfLHS.mod(APFloat(Sem, RHS.IntVal));
    867             GV.IntVal = apfLHS.bitcastToAPInt();
    868             break;
    869           }
    870         }
    871         break;
    872       }
    873       return GV;
    874     }
    875     default:
    876       break;
    877     }
    878 
    879     SmallString<256> Msg;
    880     raw_svector_ostream OS(Msg);
    881     OS << "ConstantExpr not handled: " << *CE;
    882     report_fatal_error(OS.str());
    883   }
    884 
    885   // Otherwise, we have a simple constant.
    886   GenericValue Result;
    887   switch (C->getType()->getTypeID()) {
    888   case Type::FloatTyID:
    889     Result.FloatVal = cast<ConstantFP>(C)->getValueAPF().convertToFloat();
    890     break;
    891   case Type::DoubleTyID:
    892     Result.DoubleVal = cast<ConstantFP>(C)->getValueAPF().convertToDouble();
    893     break;
    894   case Type::X86_FP80TyID:
    895   case Type::FP128TyID:
    896   case Type::PPC_FP128TyID:
    897     Result.IntVal = cast <ConstantFP>(C)->getValueAPF().bitcastToAPInt();
    898     break;
    899   case Type::IntegerTyID:
    900     Result.IntVal = cast<ConstantInt>(C)->getValue();
    901     break;
    902   case Type::PointerTyID:
    903     if (isa<ConstantPointerNull>(C))
    904       Result.PointerVal = nullptr;
    905     else if (const Function *F = dyn_cast<Function>(C))
    906       Result = PTOGV(getPointerToFunctionOrStub(const_cast<Function*>(F)));
    907     else if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
    908       Result = PTOGV(getOrEmitGlobalVariable(const_cast<GlobalVariable*>(GV)));
    909     else
    910       llvm_unreachable("Unknown constant pointer type!");
    911     break;
    912   case Type::VectorTyID: {
    913     unsigned elemNum;
    914     Type* ElemTy;
    915     const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(C);
    916     const ConstantVector *CV = dyn_cast<ConstantVector>(C);
    917     const ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(C);
    918 
    919     if (CDV) {
    920         elemNum = CDV->getNumElements();
    921         ElemTy = CDV->getElementType();
    922     } else if (CV || CAZ) {
    923         VectorType* VTy = dyn_cast<VectorType>(C->getType());
    924         elemNum = VTy->getNumElements();
    925         ElemTy = VTy->getElementType();
    926     } else {
    927         llvm_unreachable("Unknown constant vector type!");
    928     }
    929 
    930     Result.AggregateVal.resize(elemNum);
    931     // Check if vector holds floats.
    932     if(ElemTy->isFloatTy()) {
    933       if (CAZ) {
    934         GenericValue floatZero;
    935         floatZero.FloatVal = 0.f;
    936         std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
    937                   floatZero);
    938         break;
    939       }
    940       if(CV) {
    941         for (unsigned i = 0; i < elemNum; ++i)
    942           if (!isa<UndefValue>(CV->getOperand(i)))
    943             Result.AggregateVal[i].FloatVal = cast<ConstantFP>(
    944               CV->getOperand(i))->getValueAPF().convertToFloat();
    945         break;
    946       }
    947       if(CDV)
    948         for (unsigned i = 0; i < elemNum; ++i)
    949           Result.AggregateVal[i].FloatVal = CDV->getElementAsFloat(i);
    950 
    951       break;
    952     }
    953     // Check if vector holds doubles.
    954     if (ElemTy->isDoubleTy()) {
    955       if (CAZ) {
    956         GenericValue doubleZero;
    957         doubleZero.DoubleVal = 0.0;
    958         std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
    959                   doubleZero);
    960         break;
    961       }
    962       if(CV) {
    963         for (unsigned i = 0; i < elemNum; ++i)
    964           if (!isa<UndefValue>(CV->getOperand(i)))
    965             Result.AggregateVal[i].DoubleVal = cast<ConstantFP>(
    966               CV->getOperand(i))->getValueAPF().convertToDouble();
    967         break;
    968       }
    969       if(CDV)
    970         for (unsigned i = 0; i < elemNum; ++i)
    971           Result.AggregateVal[i].DoubleVal = CDV->getElementAsDouble(i);
    972 
    973       break;
    974     }
    975     // Check if vector holds integers.
    976     if (ElemTy->isIntegerTy()) {
    977       if (CAZ) {
    978         GenericValue intZero;
    979         intZero.IntVal = APInt(ElemTy->getScalarSizeInBits(), 0ull);
    980         std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
    981                   intZero);
    982         break;
    983       }
    984       if(CV) {
    985         for (unsigned i = 0; i < elemNum; ++i)
    986           if (!isa<UndefValue>(CV->getOperand(i)))
    987             Result.AggregateVal[i].IntVal = cast<ConstantInt>(
    988                                             CV->getOperand(i))->getValue();
    989           else {
    990             Result.AggregateVal[i].IntVal =
    991               APInt(CV->getOperand(i)->getType()->getPrimitiveSizeInBits(), 0);
    992           }
    993         break;
    994       }
    995       if(CDV)
    996         for (unsigned i = 0; i < elemNum; ++i)
    997           Result.AggregateVal[i].IntVal = APInt(
    998             CDV->getElementType()->getPrimitiveSizeInBits(),
    999             CDV->getElementAsInteger(i));
   1000 
   1001       break;
   1002     }
   1003     llvm_unreachable("Unknown constant pointer type!");
   1004   }
   1005   break;
   1006 
   1007   default:
   1008     SmallString<256> Msg;
   1009     raw_svector_ostream OS(Msg);
   1010     OS << "ERROR: Constant unimplemented for type: " << *C->getType();
   1011     report_fatal_error(OS.str());
   1012   }
   1013 
   1014   return Result;
   1015 }
   1016 
   1017 /// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst
   1018 /// with the integer held in IntVal.
   1019 static void StoreIntToMemory(const APInt &IntVal, uint8_t *Dst,
   1020                              unsigned StoreBytes) {
   1021   assert((IntVal.getBitWidth()+7)/8 >= StoreBytes && "Integer too small!");
   1022   const uint8_t *Src = (const uint8_t *)IntVal.getRawData();
   1023 
   1024   if (sys::IsLittleEndianHost) {
   1025     // Little-endian host - the source is ordered from LSB to MSB.  Order the
   1026     // destination from LSB to MSB: Do a straight copy.
   1027     memcpy(Dst, Src, StoreBytes);
   1028   } else {
   1029     // Big-endian host - the source is an array of 64 bit words ordered from
   1030     // LSW to MSW.  Each word is ordered from MSB to LSB.  Order the destination
   1031     // from MSB to LSB: Reverse the word order, but not the bytes in a word.
   1032     while (StoreBytes > sizeof(uint64_t)) {
   1033       StoreBytes -= sizeof(uint64_t);
   1034       // May not be aligned so use memcpy.
   1035       memcpy(Dst + StoreBytes, Src, sizeof(uint64_t));
   1036       Src += sizeof(uint64_t);
   1037     }
   1038 
   1039     memcpy(Dst, Src + sizeof(uint64_t) - StoreBytes, StoreBytes);
   1040   }
   1041 }
   1042 
   1043 void ExecutionEngine::StoreValueToMemory(const GenericValue &Val,
   1044                                          GenericValue *Ptr, Type *Ty) {
   1045   const unsigned StoreBytes = getDataLayout().getTypeStoreSize(Ty);
   1046 
   1047   switch (Ty->getTypeID()) {
   1048   default:
   1049     dbgs() << "Cannot store value of type " << *Ty << "!\n";
   1050     break;
   1051   case Type::IntegerTyID:
   1052     StoreIntToMemory(Val.IntVal, (uint8_t*)Ptr, StoreBytes);
   1053     break;
   1054   case Type::FloatTyID:
   1055     *((float*)Ptr) = Val.FloatVal;
   1056     break;
   1057   case Type::DoubleTyID:
   1058     *((double*)Ptr) = Val.DoubleVal;
   1059     break;
   1060   case Type::X86_FP80TyID:
   1061     memcpy(Ptr, Val.IntVal.getRawData(), 10);
   1062     break;
   1063   case Type::PointerTyID:
   1064     // Ensure 64 bit target pointers are fully initialized on 32 bit hosts.
   1065     if (StoreBytes != sizeof(PointerTy))
   1066       memset(&(Ptr->PointerVal), 0, StoreBytes);
   1067 
   1068     *((PointerTy*)Ptr) = Val.PointerVal;
   1069     break;
   1070   case Type::VectorTyID:
   1071     for (unsigned i = 0; i < Val.AggregateVal.size(); ++i) {
   1072       if (cast<VectorType>(Ty)->getElementType()->isDoubleTy())
   1073         *(((double*)Ptr)+i) = Val.AggregateVal[i].DoubleVal;
   1074       if (cast<VectorType>(Ty)->getElementType()->isFloatTy())
   1075         *(((float*)Ptr)+i) = Val.AggregateVal[i].FloatVal;
   1076       if (cast<VectorType>(Ty)->getElementType()->isIntegerTy()) {
   1077         unsigned numOfBytes =(Val.AggregateVal[i].IntVal.getBitWidth()+7)/8;
   1078         StoreIntToMemory(Val.AggregateVal[i].IntVal,
   1079           (uint8_t*)Ptr + numOfBytes*i, numOfBytes);
   1080       }
   1081     }
   1082     break;
   1083   }
   1084 
   1085   if (sys::IsLittleEndianHost != getDataLayout().isLittleEndian())
   1086     // Host and target are different endian - reverse the stored bytes.
   1087     std::reverse((uint8_t*)Ptr, StoreBytes + (uint8_t*)Ptr);
   1088 }
   1089 
   1090 /// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting
   1091 /// from Src into IntVal, which is assumed to be wide enough and to hold zero.
   1092 static void LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes) {
   1093   assert((IntVal.getBitWidth()+7)/8 >= LoadBytes && "Integer too small!");
   1094   uint8_t *Dst = reinterpret_cast<uint8_t *>(
   1095                    const_cast<uint64_t *>(IntVal.getRawData()));
   1096 
   1097   if (sys::IsLittleEndianHost)
   1098     // Little-endian host - the destination must be ordered from LSB to MSB.
   1099     // The source is ordered from LSB to MSB: Do a straight copy.
   1100     memcpy(Dst, Src, LoadBytes);
   1101   else {
   1102     // Big-endian - the destination is an array of 64 bit words ordered from
   1103     // LSW to MSW.  Each word must be ordered from MSB to LSB.  The source is
   1104     // ordered from MSB to LSB: Reverse the word order, but not the bytes in
   1105     // a word.
   1106     while (LoadBytes > sizeof(uint64_t)) {
   1107       LoadBytes -= sizeof(uint64_t);
   1108       // May not be aligned so use memcpy.
   1109       memcpy(Dst, Src + LoadBytes, sizeof(uint64_t));
   1110       Dst += sizeof(uint64_t);
   1111     }
   1112 
   1113     memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes);
   1114   }
   1115 }
   1116 
   1117 /// FIXME: document
   1118 ///
   1119 void ExecutionEngine::LoadValueFromMemory(GenericValue &Result,
   1120                                           GenericValue *Ptr,
   1121                                           Type *Ty) {
   1122   const unsigned LoadBytes = getDataLayout().getTypeStoreSize(Ty);
   1123 
   1124   switch (Ty->getTypeID()) {
   1125   case Type::IntegerTyID:
   1126     // An APInt with all words initially zero.
   1127     Result.IntVal = APInt(cast<IntegerType>(Ty)->getBitWidth(), 0);
   1128     LoadIntFromMemory(Result.IntVal, (uint8_t*)Ptr, LoadBytes);
   1129     break;
   1130   case Type::FloatTyID:
   1131     Result.FloatVal = *((float*)Ptr);
   1132     break;
   1133   case Type::DoubleTyID:
   1134     Result.DoubleVal = *((double*)Ptr);
   1135     break;
   1136   case Type::PointerTyID:
   1137     Result.PointerVal = *((PointerTy*)Ptr);
   1138     break;
   1139   case Type::X86_FP80TyID: {
   1140     // This is endian dependent, but it will only work on x86 anyway.
   1141     // FIXME: Will not trap if loading a signaling NaN.
   1142     uint64_t y[2];
   1143     memcpy(y, Ptr, 10);
   1144     Result.IntVal = APInt(80, y);
   1145     break;
   1146   }
   1147   case Type::VectorTyID: {
   1148     auto *VT = cast<VectorType>(Ty);
   1149     Type *ElemT = VT->getElementType();
   1150     const unsigned numElems = VT->getNumElements();
   1151     if (ElemT->isFloatTy()) {
   1152       Result.AggregateVal.resize(numElems);
   1153       for (unsigned i = 0; i < numElems; ++i)
   1154         Result.AggregateVal[i].FloatVal = *((float*)Ptr+i);
   1155     }
   1156     if (ElemT->isDoubleTy()) {
   1157       Result.AggregateVal.resize(numElems);
   1158       for (unsigned i = 0; i < numElems; ++i)
   1159         Result.AggregateVal[i].DoubleVal = *((double*)Ptr+i);
   1160     }
   1161     if (ElemT->isIntegerTy()) {
   1162       GenericValue intZero;
   1163       const unsigned elemBitWidth = cast<IntegerType>(ElemT)->getBitWidth();
   1164       intZero.IntVal = APInt(elemBitWidth, 0);
   1165       Result.AggregateVal.resize(numElems, intZero);
   1166       for (unsigned i = 0; i < numElems; ++i)
   1167         LoadIntFromMemory(Result.AggregateVal[i].IntVal,
   1168           (uint8_t*)Ptr+((elemBitWidth+7)/8)*i, (elemBitWidth+7)/8);
   1169     }
   1170   break;
   1171   }
   1172   default:
   1173     SmallString<256> Msg;
   1174     raw_svector_ostream OS(Msg);
   1175     OS << "Cannot load value of type " << *Ty << "!";
   1176     report_fatal_error(OS.str());
   1177   }
   1178 }
   1179 
   1180 void ExecutionEngine::InitializeMemory(const Constant *Init, void *Addr) {
   1181   DEBUG(dbgs() << "JIT: Initializing " << Addr << " ");
   1182   DEBUG(Init->dump());
   1183   if (isa<UndefValue>(Init))
   1184     return;
   1185 
   1186   if (const ConstantVector *CP = dyn_cast<ConstantVector>(Init)) {
   1187     unsigned ElementSize =
   1188         getDataLayout().getTypeAllocSize(CP->getType()->getElementType());
   1189     for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
   1190       InitializeMemory(CP->getOperand(i), (char*)Addr+i*ElementSize);
   1191     return;
   1192   }
   1193 
   1194   if (isa<ConstantAggregateZero>(Init)) {
   1195     memset(Addr, 0, (size_t)getDataLayout().getTypeAllocSize(Init->getType()));
   1196     return;
   1197   }
   1198 
   1199   if (const ConstantArray *CPA = dyn_cast<ConstantArray>(Init)) {
   1200     unsigned ElementSize =
   1201         getDataLayout().getTypeAllocSize(CPA->getType()->getElementType());
   1202     for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
   1203       InitializeMemory(CPA->getOperand(i), (char*)Addr+i*ElementSize);
   1204     return;
   1205   }
   1206 
   1207   if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(Init)) {
   1208     const StructLayout *SL =
   1209         getDataLayout().getStructLayout(cast<StructType>(CPS->getType()));
   1210     for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
   1211       InitializeMemory(CPS->getOperand(i), (char*)Addr+SL->getElementOffset(i));
   1212     return;
   1213   }
   1214 
   1215   if (const ConstantDataSequential *CDS =
   1216                dyn_cast<ConstantDataSequential>(Init)) {
   1217     // CDS is already laid out in host memory order.
   1218     StringRef Data = CDS->getRawDataValues();
   1219     memcpy(Addr, Data.data(), Data.size());
   1220     return;
   1221   }
   1222 
   1223   if (Init->getType()->isFirstClassType()) {
   1224     GenericValue Val = getConstantValue(Init);
   1225     StoreValueToMemory(Val, (GenericValue*)Addr, Init->getType());
   1226     return;
   1227   }
   1228 
   1229   DEBUG(dbgs() << "Bad Type: " << *Init->getType() << "\n");
   1230   llvm_unreachable("Unknown constant type to initialize memory with!");
   1231 }
   1232 
   1233 /// EmitGlobals - Emit all of the global variables to memory, storing their
   1234 /// addresses into GlobalAddress.  This must make sure to copy the contents of
   1235 /// their initializers into the memory.
   1236 void ExecutionEngine::emitGlobals() {
   1237   // Loop over all of the global variables in the program, allocating the memory
   1238   // to hold them.  If there is more than one module, do a prepass over globals
   1239   // to figure out how the different modules should link together.
   1240   std::map<std::pair<std::string, Type*>,
   1241            const GlobalValue*> LinkedGlobalsMap;
   1242 
   1243   if (Modules.size() != 1) {
   1244     for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
   1245       Module &M = *Modules[m];
   1246       for (const auto &GV : M.globals()) {
   1247         if (GV.hasLocalLinkage() || GV.isDeclaration() ||
   1248             GV.hasAppendingLinkage() || !GV.hasName())
   1249           continue;// Ignore external globals and globals with internal linkage.
   1250 
   1251         const GlobalValue *&GVEntry =
   1252           LinkedGlobalsMap[std::make_pair(GV.getName(), GV.getType())];
   1253 
   1254         // If this is the first time we've seen this global, it is the canonical
   1255         // version.
   1256         if (!GVEntry) {
   1257           GVEntry = &GV;
   1258           continue;
   1259         }
   1260 
   1261         // If the existing global is strong, never replace it.
   1262         if (GVEntry->hasExternalLinkage())
   1263           continue;
   1264 
   1265         // Otherwise, we know it's linkonce/weak, replace it if this is a strong
   1266         // symbol.  FIXME is this right for common?
   1267         if (GV.hasExternalLinkage() || GVEntry->hasExternalWeakLinkage())
   1268           GVEntry = &GV;
   1269       }
   1270     }
   1271   }
   1272 
   1273   std::vector<const GlobalValue*> NonCanonicalGlobals;
   1274   for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
   1275     Module &M = *Modules[m];
   1276     for (const auto &GV : M.globals()) {
   1277       // In the multi-module case, see what this global maps to.
   1278       if (!LinkedGlobalsMap.empty()) {
   1279         if (const GlobalValue *GVEntry =
   1280               LinkedGlobalsMap[std::make_pair(GV.getName(), GV.getType())]) {
   1281           // If something else is the canonical global, ignore this one.
   1282           if (GVEntry != &GV) {
   1283             NonCanonicalGlobals.push_back(&GV);
   1284             continue;
   1285           }
   1286         }
   1287       }
   1288 
   1289       if (!GV.isDeclaration()) {
   1290         addGlobalMapping(&GV, getMemoryForGV(&GV));
   1291       } else {
   1292         // External variable reference. Try to use the dynamic loader to
   1293         // get a pointer to it.
   1294         if (void *SymAddr =
   1295             sys::DynamicLibrary::SearchForAddressOfSymbol(GV.getName()))
   1296           addGlobalMapping(&GV, SymAddr);
   1297         else {
   1298           report_fatal_error("Could not resolve external global address: "
   1299                             +GV.getName());
   1300         }
   1301       }
   1302     }
   1303 
   1304     // If there are multiple modules, map the non-canonical globals to their
   1305     // canonical location.
   1306     if (!NonCanonicalGlobals.empty()) {
   1307       for (unsigned i = 0, e = NonCanonicalGlobals.size(); i != e; ++i) {
   1308         const GlobalValue *GV = NonCanonicalGlobals[i];
   1309         const GlobalValue *CGV =
   1310           LinkedGlobalsMap[std::make_pair(GV->getName(), GV->getType())];
   1311         void *Ptr = getPointerToGlobalIfAvailable(CGV);
   1312         assert(Ptr && "Canonical global wasn't codegen'd!");
   1313         addGlobalMapping(GV, Ptr);
   1314       }
   1315     }
   1316 
   1317     // Now that all of the globals are set up in memory, loop through them all
   1318     // and initialize their contents.
   1319     for (const auto &GV : M.globals()) {
   1320       if (!GV.isDeclaration()) {
   1321         if (!LinkedGlobalsMap.empty()) {
   1322           if (const GlobalValue *GVEntry =
   1323                 LinkedGlobalsMap[std::make_pair(GV.getName(), GV.getType())])
   1324             if (GVEntry != &GV)  // Not the canonical variable.
   1325               continue;
   1326         }
   1327         EmitGlobalVariable(&GV);
   1328       }
   1329     }
   1330   }
   1331 }
   1332 
   1333 // EmitGlobalVariable - This method emits the specified global variable to the
   1334 // address specified in GlobalAddresses, or allocates new memory if it's not
   1335 // already in the map.
   1336 void ExecutionEngine::EmitGlobalVariable(const GlobalVariable *GV) {
   1337   void *GA = getPointerToGlobalIfAvailable(GV);
   1338 
   1339   if (!GA) {
   1340     // If it's not already specified, allocate memory for the global.
   1341     GA = getMemoryForGV(GV);
   1342 
   1343     // If we failed to allocate memory for this global, return.
   1344     if (!GA) return;
   1345 
   1346     addGlobalMapping(GV, GA);
   1347   }
   1348 
   1349   // Don't initialize if it's thread local, let the client do it.
   1350   if (!GV->isThreadLocal())
   1351     InitializeMemory(GV->getInitializer(), GA);
   1352 
   1353   Type *ElTy = GV->getValueType();
   1354   size_t GVSize = (size_t)getDataLayout().getTypeAllocSize(ElTy);
   1355   NumInitBytes += (unsigned)GVSize;
   1356   ++NumGlobals;
   1357 }
   1358