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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->getType()->getElementType();
    107     size_t GVSize = (size_t)TD.getTypeAllocSize(ElTy);
    108     void *RawMemory = ::operator new(
    109       RoundUpToAlignment(sizeof(GVMemoryBlock),
    110                          TD.getPreferredAlignment(GV))
    111       + GVSize);
    112     new(RawMemory) GVMemoryBlock(GV);
    113     return static_cast<char*>(RawMemory) + sizeof(GVMemoryBlock);
    114   }
    115 
    116   void deleted() override {
    117     // We allocated with operator new and with some extra memory hanging off the
    118     // end, so don't just delete this.  I'm not sure if this is actually
    119     // required.
    120     this->~GVMemoryBlock();
    121     ::operator delete(this);
    122   }
    123 };
    124 }  // anonymous namespace
    125 
    126 char *ExecutionEngine::getMemoryForGV(const GlobalVariable *GV) {
    127   return GVMemoryBlock::Create(GV, getDataLayout());
    128 }
    129 
    130 void ExecutionEngine::addObjectFile(std::unique_ptr<object::ObjectFile> O) {
    131   llvm_unreachable("ExecutionEngine subclass doesn't implement addObjectFile.");
    132 }
    133 
    134 void
    135 ExecutionEngine::addObjectFile(object::OwningBinary<object::ObjectFile> O) {
    136   llvm_unreachable("ExecutionEngine subclass doesn't implement addObjectFile.");
    137 }
    138 
    139 void ExecutionEngine::addArchive(object::OwningBinary<object::Archive> A) {
    140   llvm_unreachable("ExecutionEngine subclass doesn't implement addArchive.");
    141 }
    142 
    143 bool ExecutionEngine::removeModule(Module *M) {
    144   for (auto I = Modules.begin(), E = Modules.end(); I != E; ++I) {
    145     Module *Found = I->get();
    146     if (Found == M) {
    147       I->release();
    148       Modules.erase(I);
    149       clearGlobalMappingsFromModule(M);
    150       return true;
    151     }
    152   }
    153   return false;
    154 }
    155 
    156 Function *ExecutionEngine::FindFunctionNamed(const char *FnName) {
    157   for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
    158     Function *F = Modules[i]->getFunction(FnName);
    159     if (F && !F->isDeclaration())
    160       return F;
    161   }
    162   return nullptr;
    163 }
    164 
    165 GlobalVariable *ExecutionEngine::FindGlobalVariableNamed(const char *Name, bool AllowInternal) {
    166   for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
    167     GlobalVariable *GV = Modules[i]->getGlobalVariable(Name,AllowInternal);
    168     if (GV && !GV->isDeclaration())
    169       return GV;
    170   }
    171   return nullptr;
    172 }
    173 
    174 uint64_t ExecutionEngineState::RemoveMapping(StringRef Name) {
    175   GlobalAddressMapTy::iterator I = GlobalAddressMap.find(Name);
    176   uint64_t OldVal;
    177 
    178   // FIXME: This is silly, we shouldn't end up with a mapping -> 0 in the
    179   // GlobalAddressMap.
    180   if (I == GlobalAddressMap.end())
    181     OldVal = 0;
    182   else {
    183     GlobalAddressReverseMap.erase(I->second);
    184     OldVal = I->second;
    185     GlobalAddressMap.erase(I);
    186   }
    187 
    188   return OldVal;
    189 }
    190 
    191 std::string ExecutionEngine::getMangledName(const GlobalValue *GV) {
    192   assert(GV->hasName() && "Global must have name.");
    193 
    194   MutexGuard locked(lock);
    195   SmallString<128> FullName;
    196 
    197   const DataLayout &DL =
    198     GV->getParent()->getDataLayout().isDefault()
    199       ? getDataLayout()
    200       : GV->getParent()->getDataLayout();
    201 
    202   Mangler::getNameWithPrefix(FullName, GV->getName(), DL);
    203   return FullName.str();
    204 }
    205 
    206 void ExecutionEngine::addGlobalMapping(const GlobalValue *GV, void *Addr) {
    207   MutexGuard locked(lock);
    208   addGlobalMapping(getMangledName(GV), (uint64_t) Addr);
    209 }
    210 
    211 void ExecutionEngine::addGlobalMapping(StringRef Name, uint64_t Addr) {
    212   MutexGuard locked(lock);
    213 
    214   assert(!Name.empty() && "Empty GlobalMapping symbol name!");
    215 
    216   DEBUG(dbgs() << "JIT: Map \'" << Name  << "\' to [" << Addr << "]\n";);
    217   uint64_t &CurVal = EEState.getGlobalAddressMap()[Name];
    218   assert((!CurVal || !Addr) && "GlobalMapping already established!");
    219   CurVal = Addr;
    220 
    221   // If we are using the reverse mapping, add it too.
    222   if (!EEState.getGlobalAddressReverseMap().empty()) {
    223     std::string &V = EEState.getGlobalAddressReverseMap()[CurVal];
    224     assert((!V.empty() || !Name.empty()) &&
    225            "GlobalMapping already established!");
    226     V = Name;
    227   }
    228 }
    229 
    230 void ExecutionEngine::clearAllGlobalMappings() {
    231   MutexGuard locked(lock);
    232 
    233   EEState.getGlobalAddressMap().clear();
    234   EEState.getGlobalAddressReverseMap().clear();
    235 }
    236 
    237 void ExecutionEngine::clearGlobalMappingsFromModule(Module *M) {
    238   MutexGuard locked(lock);
    239 
    240   for (Function &FI : *M)
    241     EEState.RemoveMapping(getMangledName(&FI));
    242   for (GlobalVariable &GI : M->globals())
    243     EEState.RemoveMapping(getMangledName(&GI));
    244 }
    245 
    246 uint64_t ExecutionEngine::updateGlobalMapping(const GlobalValue *GV,
    247                                               void *Addr) {
    248   MutexGuard locked(lock);
    249   return updateGlobalMapping(getMangledName(GV), (uint64_t) Addr);
    250 }
    251 
    252 uint64_t ExecutionEngine::updateGlobalMapping(StringRef Name, uint64_t Addr) {
    253   MutexGuard locked(lock);
    254 
    255   ExecutionEngineState::GlobalAddressMapTy &Map =
    256     EEState.getGlobalAddressMap();
    257 
    258   // Deleting from the mapping?
    259   if (!Addr)
    260     return EEState.RemoveMapping(Name);
    261 
    262   uint64_t &CurVal = Map[Name];
    263   uint64_t OldVal = CurVal;
    264 
    265   if (CurVal && !EEState.getGlobalAddressReverseMap().empty())
    266     EEState.getGlobalAddressReverseMap().erase(CurVal);
    267   CurVal = Addr;
    268 
    269   // If we are using the reverse mapping, add it too.
    270   if (!EEState.getGlobalAddressReverseMap().empty()) {
    271     std::string &V = EEState.getGlobalAddressReverseMap()[CurVal];
    272     assert((!V.empty() || !Name.empty()) &&
    273            "GlobalMapping already established!");
    274     V = Name;
    275   }
    276   return OldVal;
    277 }
    278 
    279 uint64_t ExecutionEngine::getAddressToGlobalIfAvailable(StringRef S) {
    280   MutexGuard locked(lock);
    281   uint64_t Address = 0;
    282   ExecutionEngineState::GlobalAddressMapTy::iterator I =
    283     EEState.getGlobalAddressMap().find(S);
    284   if (I != EEState.getGlobalAddressMap().end())
    285     Address = I->second;
    286   return Address;
    287 }
    288 
    289 
    290 void *ExecutionEngine::getPointerToGlobalIfAvailable(StringRef S) {
    291   MutexGuard locked(lock);
    292   if (void* Address = (void *) getAddressToGlobalIfAvailable(S))
    293     return Address;
    294   return nullptr;
    295 }
    296 
    297 void *ExecutionEngine::getPointerToGlobalIfAvailable(const GlobalValue *GV) {
    298   MutexGuard locked(lock);
    299   return getPointerToGlobalIfAvailable(getMangledName(GV));
    300 }
    301 
    302 const GlobalValue *ExecutionEngine::getGlobalValueAtAddress(void *Addr) {
    303   MutexGuard locked(lock);
    304 
    305   // If we haven't computed the reverse mapping yet, do so first.
    306   if (EEState.getGlobalAddressReverseMap().empty()) {
    307     for (ExecutionEngineState::GlobalAddressMapTy::iterator
    308            I = EEState.getGlobalAddressMap().begin(),
    309            E = EEState.getGlobalAddressMap().end(); I != E; ++I) {
    310       StringRef Name = I->first();
    311       uint64_t Addr = I->second;
    312       EEState.getGlobalAddressReverseMap().insert(std::make_pair(
    313                                                           Addr, Name));
    314     }
    315   }
    316 
    317   std::map<uint64_t, std::string>::iterator I =
    318     EEState.getGlobalAddressReverseMap().find((uint64_t) Addr);
    319 
    320   if (I != EEState.getGlobalAddressReverseMap().end()) {
    321     StringRef Name = I->second;
    322     for (unsigned i = 0, e = Modules.size(); i != e; ++i)
    323       if (GlobalValue *GV = Modules[i]->getNamedValue(Name))
    324         return GV;
    325   }
    326   return nullptr;
    327 }
    328 
    329 namespace {
    330 class ArgvArray {
    331   std::unique_ptr<char[]> Array;
    332   std::vector<std::unique_ptr<char[]>> Values;
    333 public:
    334   /// Turn a vector of strings into a nice argv style array of pointers to null
    335   /// terminated strings.
    336   void *reset(LLVMContext &C, ExecutionEngine *EE,
    337               const std::vector<std::string> &InputArgv);
    338 };
    339 }  // anonymous namespace
    340 void *ArgvArray::reset(LLVMContext &C, ExecutionEngine *EE,
    341                        const std::vector<std::string> &InputArgv) {
    342   Values.clear();  // Free the old contents.
    343   Values.reserve(InputArgv.size());
    344   unsigned PtrSize = EE->getDataLayout().getPointerSize();
    345   Array = make_unique<char[]>((InputArgv.size()+1)*PtrSize);
    346 
    347   DEBUG(dbgs() << "JIT: ARGV = " << (void*)Array.get() << "\n");
    348   Type *SBytePtr = Type::getInt8PtrTy(C);
    349 
    350   for (unsigned i = 0; i != InputArgv.size(); ++i) {
    351     unsigned Size = InputArgv[i].size()+1;
    352     auto Dest = make_unique<char[]>(Size);
    353     DEBUG(dbgs() << "JIT: ARGV[" << i << "] = " << (void*)Dest.get() << "\n");
    354 
    355     std::copy(InputArgv[i].begin(), InputArgv[i].end(), Dest.get());
    356     Dest[Size-1] = 0;
    357 
    358     // Endian safe: Array[i] = (PointerTy)Dest;
    359     EE->StoreValueToMemory(PTOGV(Dest.get()),
    360                            (GenericValue*)(&Array[i*PtrSize]), SBytePtr);
    361     Values.push_back(std::move(Dest));
    362   }
    363 
    364   // Null terminate it
    365   EE->StoreValueToMemory(PTOGV(nullptr),
    366                          (GenericValue*)(&Array[InputArgv.size()*PtrSize]),
    367                          SBytePtr);
    368   return Array.get();
    369 }
    370 
    371 void ExecutionEngine::runStaticConstructorsDestructors(Module &module,
    372                                                        bool isDtors) {
    373   const char *Name = isDtors ? "llvm.global_dtors" : "llvm.global_ctors";
    374   GlobalVariable *GV = module.getNamedGlobal(Name);
    375 
    376   // If this global has internal linkage, or if it has a use, then it must be
    377   // an old-style (llvmgcc3) static ctor with __main linked in and in use.  If
    378   // this is the case, don't execute any of the global ctors, __main will do
    379   // it.
    380   if (!GV || GV->isDeclaration() || GV->hasLocalLinkage()) return;
    381 
    382   // Should be an array of '{ i32, void ()* }' structs.  The first value is
    383   // the init priority, which we ignore.
    384   ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
    385   if (!InitList)
    386     return;
    387   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
    388     ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i));
    389     if (!CS) continue;
    390 
    391     Constant *FP = CS->getOperand(1);
    392     if (FP->isNullValue())
    393       continue;  // Found a sentinal value, ignore.
    394 
    395     // Strip off constant expression casts.
    396     if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
    397       if (CE->isCast())
    398         FP = CE->getOperand(0);
    399 
    400     // Execute the ctor/dtor function!
    401     if (Function *F = dyn_cast<Function>(FP))
    402       runFunction(F, None);
    403 
    404     // FIXME: It is marginally lame that we just do nothing here if we see an
    405     // entry we don't recognize. It might not be unreasonable for the verifier
    406     // to not even allow this and just assert here.
    407   }
    408 }
    409 
    410 void ExecutionEngine::runStaticConstructorsDestructors(bool isDtors) {
    411   // Execute global ctors/dtors for each module in the program.
    412   for (std::unique_ptr<Module> &M : Modules)
    413     runStaticConstructorsDestructors(*M, isDtors);
    414 }
    415 
    416 #ifndef NDEBUG
    417 /// isTargetNullPtr - Return whether the target pointer stored at Loc is null.
    418 static bool isTargetNullPtr(ExecutionEngine *EE, void *Loc) {
    419   unsigned PtrSize = EE->getDataLayout().getPointerSize();
    420   for (unsigned i = 0; i < PtrSize; ++i)
    421     if (*(i + (uint8_t*)Loc))
    422       return false;
    423   return true;
    424 }
    425 #endif
    426 
    427 int ExecutionEngine::runFunctionAsMain(Function *Fn,
    428                                        const std::vector<std::string> &argv,
    429                                        const char * const * envp) {
    430   std::vector<GenericValue> GVArgs;
    431   GenericValue GVArgc;
    432   GVArgc.IntVal = APInt(32, argv.size());
    433 
    434   // Check main() type
    435   unsigned NumArgs = Fn->getFunctionType()->getNumParams();
    436   FunctionType *FTy = Fn->getFunctionType();
    437   Type* PPInt8Ty = Type::getInt8PtrTy(Fn->getContext())->getPointerTo();
    438 
    439   // Check the argument types.
    440   if (NumArgs > 3)
    441     report_fatal_error("Invalid number of arguments of main() supplied");
    442   if (NumArgs >= 3 && FTy->getParamType(2) != PPInt8Ty)
    443     report_fatal_error("Invalid type for third argument of main() supplied");
    444   if (NumArgs >= 2 && FTy->getParamType(1) != PPInt8Ty)
    445     report_fatal_error("Invalid type for second argument of main() supplied");
    446   if (NumArgs >= 1 && !FTy->getParamType(0)->isIntegerTy(32))
    447     report_fatal_error("Invalid type for first argument of main() supplied");
    448   if (!FTy->getReturnType()->isIntegerTy() &&
    449       !FTy->getReturnType()->isVoidTy())
    450     report_fatal_error("Invalid return type of main() supplied");
    451 
    452   ArgvArray CArgv;
    453   ArgvArray CEnv;
    454   if (NumArgs) {
    455     GVArgs.push_back(GVArgc); // Arg #0 = argc.
    456     if (NumArgs > 1) {
    457       // Arg #1 = argv.
    458       GVArgs.push_back(PTOGV(CArgv.reset(Fn->getContext(), this, argv)));
    459       assert(!isTargetNullPtr(this, GVTOP(GVArgs[1])) &&
    460              "argv[0] was null after CreateArgv");
    461       if (NumArgs > 2) {
    462         std::vector<std::string> EnvVars;
    463         for (unsigned i = 0; envp[i]; ++i)
    464           EnvVars.emplace_back(envp[i]);
    465         // Arg #2 = envp.
    466         GVArgs.push_back(PTOGV(CEnv.reset(Fn->getContext(), this, EnvVars)));
    467       }
    468     }
    469   }
    470 
    471   return runFunction(Fn, GVArgs).IntVal.getZExtValue();
    472 }
    473 
    474 EngineBuilder::EngineBuilder() : EngineBuilder(nullptr) {}
    475 
    476 EngineBuilder::EngineBuilder(std::unique_ptr<Module> M)
    477     : M(std::move(M)), WhichEngine(EngineKind::Either), ErrorStr(nullptr),
    478       OptLevel(CodeGenOpt::Default), MemMgr(nullptr), Resolver(nullptr),
    479       RelocModel(Reloc::Default), CMModel(CodeModel::JITDefault),
    480       UseOrcMCJITReplacement(false) {
    481 // IR module verification is enabled by default in debug builds, and disabled
    482 // by default in release builds.
    483 #ifndef NDEBUG
    484   VerifyModules = true;
    485 #else
    486   VerifyModules = false;
    487 #endif
    488 }
    489 
    490 EngineBuilder::~EngineBuilder() = default;
    491 
    492 EngineBuilder &EngineBuilder::setMCJITMemoryManager(
    493                                    std::unique_ptr<RTDyldMemoryManager> mcjmm) {
    494   auto SharedMM = std::shared_ptr<RTDyldMemoryManager>(std::move(mcjmm));
    495   MemMgr = SharedMM;
    496   Resolver = SharedMM;
    497   return *this;
    498 }
    499 
    500 EngineBuilder&
    501 EngineBuilder::setMemoryManager(std::unique_ptr<MCJITMemoryManager> MM) {
    502   MemMgr = std::shared_ptr<MCJITMemoryManager>(std::move(MM));
    503   return *this;
    504 }
    505 
    506 EngineBuilder&
    507 EngineBuilder::setSymbolResolver(std::unique_ptr<RuntimeDyld::SymbolResolver> SR) {
    508   Resolver = std::shared_ptr<RuntimeDyld::SymbolResolver>(std::move(SR));
    509   return *this;
    510 }
    511 
    512 ExecutionEngine *EngineBuilder::create(TargetMachine *TM) {
    513   std::unique_ptr<TargetMachine> TheTM(TM); // Take ownership.
    514 
    515   // Make sure we can resolve symbols in the program as well. The zero arg
    516   // to the function tells DynamicLibrary to load the program, not a library.
    517   if (sys::DynamicLibrary::LoadLibraryPermanently(nullptr, ErrorStr))
    518     return nullptr;
    519 
    520   // If the user specified a memory manager but didn't specify which engine to
    521   // create, we assume they only want the JIT, and we fail if they only want
    522   // the interpreter.
    523   if (MemMgr) {
    524     if (WhichEngine & EngineKind::JIT)
    525       WhichEngine = EngineKind::JIT;
    526     else {
    527       if (ErrorStr)
    528         *ErrorStr = "Cannot create an interpreter with a memory manager.";
    529       return nullptr;
    530     }
    531   }
    532 
    533   // Unless the interpreter was explicitly selected or the JIT is not linked,
    534   // try making a JIT.
    535   if ((WhichEngine & EngineKind::JIT) && TheTM) {
    536     Triple TT(M->getTargetTriple());
    537     if (!TM->getTarget().hasJIT()) {
    538       errs() << "WARNING: This target JIT is not designed for the host"
    539              << " you are running.  If bad things happen, please choose"
    540              << " a different -march switch.\n";
    541     }
    542 
    543     ExecutionEngine *EE = nullptr;
    544     if (ExecutionEngine::OrcMCJITReplacementCtor && UseOrcMCJITReplacement) {
    545       EE = ExecutionEngine::OrcMCJITReplacementCtor(ErrorStr, std::move(MemMgr),
    546                                                     std::move(Resolver),
    547                                                     std::move(TheTM));
    548       EE->addModule(std::move(M));
    549     } else if (ExecutionEngine::MCJITCtor)
    550       EE = ExecutionEngine::MCJITCtor(std::move(M), ErrorStr, std::move(MemMgr),
    551                                       std::move(Resolver), std::move(TheTM));
    552 
    553     if (EE) {
    554       EE->setVerifyModules(VerifyModules);
    555       return EE;
    556     }
    557   }
    558 
    559   // If we can't make a JIT and we didn't request one specifically, try making
    560   // an interpreter instead.
    561   if (WhichEngine & EngineKind::Interpreter) {
    562     if (ExecutionEngine::InterpCtor)
    563       return ExecutionEngine::InterpCtor(std::move(M), ErrorStr);
    564     if (ErrorStr)
    565       *ErrorStr = "Interpreter has not been linked in.";
    566     return nullptr;
    567   }
    568 
    569   if ((WhichEngine & EngineKind::JIT) && !ExecutionEngine::MCJITCtor) {
    570     if (ErrorStr)
    571       *ErrorStr = "JIT has not been linked in.";
    572   }
    573 
    574   return nullptr;
    575 }
    576 
    577 void *ExecutionEngine::getPointerToGlobal(const GlobalValue *GV) {
    578   if (Function *F = const_cast<Function*>(dyn_cast<Function>(GV)))
    579     return getPointerToFunction(F);
    580 
    581   MutexGuard locked(lock);
    582   if (void* P = getPointerToGlobalIfAvailable(GV))
    583     return P;
    584 
    585   // Global variable might have been added since interpreter started.
    586   if (GlobalVariable *GVar =
    587           const_cast<GlobalVariable *>(dyn_cast<GlobalVariable>(GV)))
    588     EmitGlobalVariable(GVar);
    589   else
    590     llvm_unreachable("Global hasn't had an address allocated yet!");
    591 
    592   return getPointerToGlobalIfAvailable(GV);
    593 }
    594 
    595 /// \brief Converts a Constant* into a GenericValue, including handling of
    596 /// ConstantExpr values.
    597 GenericValue ExecutionEngine::getConstantValue(const Constant *C) {
    598   // If its undefined, return the garbage.
    599   if (isa<UndefValue>(C)) {
    600     GenericValue Result;
    601     switch (C->getType()->getTypeID()) {
    602     default:
    603       break;
    604     case Type::IntegerTyID:
    605     case Type::X86_FP80TyID:
    606     case Type::FP128TyID:
    607     case Type::PPC_FP128TyID:
    608       // Although the value is undefined, we still have to construct an APInt
    609       // with the correct bit width.
    610       Result.IntVal = APInt(C->getType()->getPrimitiveSizeInBits(), 0);
    611       break;
    612     case Type::StructTyID: {
    613       // if the whole struct is 'undef' just reserve memory for the value.
    614       if(StructType *STy = dyn_cast<StructType>(C->getType())) {
    615         unsigned int elemNum = STy->getNumElements();
    616         Result.AggregateVal.resize(elemNum);
    617         for (unsigned int i = 0; i < elemNum; ++i) {
    618           Type *ElemTy = STy->getElementType(i);
    619           if (ElemTy->isIntegerTy())
    620             Result.AggregateVal[i].IntVal =
    621               APInt(ElemTy->getPrimitiveSizeInBits(), 0);
    622           else if (ElemTy->isAggregateType()) {
    623               const Constant *ElemUndef = UndefValue::get(ElemTy);
    624               Result.AggregateVal[i] = getConstantValue(ElemUndef);
    625             }
    626           }
    627         }
    628       }
    629       break;
    630     case Type::VectorTyID:
    631       // if the whole vector is 'undef' just reserve memory for the value.
    632       auto* VTy = dyn_cast<VectorType>(C->getType());
    633       Type *ElemTy = VTy->getElementType();
    634       unsigned int elemNum = VTy->getNumElements();
    635       Result.AggregateVal.resize(elemNum);
    636       if (ElemTy->isIntegerTy())
    637         for (unsigned int i = 0; i < elemNum; ++i)
    638           Result.AggregateVal[i].IntVal =
    639             APInt(ElemTy->getPrimitiveSizeInBits(), 0);
    640       break;
    641     }
    642     return Result;
    643   }
    644 
    645   // Otherwise, if the value is a ConstantExpr...
    646   if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
    647     Constant *Op0 = CE->getOperand(0);
    648     switch (CE->getOpcode()) {
    649     case Instruction::GetElementPtr: {
    650       // Compute the index
    651       GenericValue Result = getConstantValue(Op0);
    652       APInt Offset(DL.getPointerSizeInBits(), 0);
    653       cast<GEPOperator>(CE)->accumulateConstantOffset(DL, Offset);
    654 
    655       char* tmp = (char*) Result.PointerVal;
    656       Result = PTOGV(tmp + Offset.getSExtValue());
    657       return Result;
    658     }
    659     case Instruction::Trunc: {
    660       GenericValue GV = getConstantValue(Op0);
    661       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    662       GV.IntVal = GV.IntVal.trunc(BitWidth);
    663       return GV;
    664     }
    665     case Instruction::ZExt: {
    666       GenericValue GV = getConstantValue(Op0);
    667       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    668       GV.IntVal = GV.IntVal.zext(BitWidth);
    669       return GV;
    670     }
    671     case Instruction::SExt: {
    672       GenericValue GV = getConstantValue(Op0);
    673       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    674       GV.IntVal = GV.IntVal.sext(BitWidth);
    675       return GV;
    676     }
    677     case Instruction::FPTrunc: {
    678       // FIXME long double
    679       GenericValue GV = getConstantValue(Op0);
    680       GV.FloatVal = float(GV.DoubleVal);
    681       return GV;
    682     }
    683     case Instruction::FPExt:{
    684       // FIXME long double
    685       GenericValue GV = getConstantValue(Op0);
    686       GV.DoubleVal = double(GV.FloatVal);
    687       return GV;
    688     }
    689     case Instruction::UIToFP: {
    690       GenericValue GV = getConstantValue(Op0);
    691       if (CE->getType()->isFloatTy())
    692         GV.FloatVal = float(GV.IntVal.roundToDouble());
    693       else if (CE->getType()->isDoubleTy())
    694         GV.DoubleVal = GV.IntVal.roundToDouble();
    695       else if (CE->getType()->isX86_FP80Ty()) {
    696         APFloat apf = APFloat::getZero(APFloat::x87DoubleExtended);
    697         (void)apf.convertFromAPInt(GV.IntVal,
    698                                    false,
    699                                    APFloat::rmNearestTiesToEven);
    700         GV.IntVal = apf.bitcastToAPInt();
    701       }
    702       return GV;
    703     }
    704     case Instruction::SIToFP: {
    705       GenericValue GV = getConstantValue(Op0);
    706       if (CE->getType()->isFloatTy())
    707         GV.FloatVal = float(GV.IntVal.signedRoundToDouble());
    708       else if (CE->getType()->isDoubleTy())
    709         GV.DoubleVal = GV.IntVal.signedRoundToDouble();
    710       else if (CE->getType()->isX86_FP80Ty()) {
    711         APFloat apf = APFloat::getZero(APFloat::x87DoubleExtended);
    712         (void)apf.convertFromAPInt(GV.IntVal,
    713                                    true,
    714                                    APFloat::rmNearestTiesToEven);
    715         GV.IntVal = apf.bitcastToAPInt();
    716       }
    717       return GV;
    718     }
    719     case Instruction::FPToUI: // double->APInt conversion handles sign
    720     case Instruction::FPToSI: {
    721       GenericValue GV = getConstantValue(Op0);
    722       uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
    723       if (Op0->getType()->isFloatTy())
    724         GV.IntVal = APIntOps::RoundFloatToAPInt(GV.FloatVal, BitWidth);
    725       else if (Op0->getType()->isDoubleTy())
    726         GV.IntVal = APIntOps::RoundDoubleToAPInt(GV.DoubleVal, BitWidth);
    727       else if (Op0->getType()->isX86_FP80Ty()) {
    728         APFloat apf = APFloat(APFloat::x87DoubleExtended, GV.IntVal);
    729         uint64_t v;
    730         bool ignored;
    731         (void)apf.convertToInteger(&v, BitWidth,
    732                                    CE->getOpcode()==Instruction::FPToSI,
    733                                    APFloat::rmTowardZero, &ignored);
    734         GV.IntVal = v; // endian?
    735       }
    736       return GV;
    737     }
    738     case Instruction::PtrToInt: {
    739       GenericValue GV = getConstantValue(Op0);
    740       uint32_t PtrWidth = DL.getTypeSizeInBits(Op0->getType());
    741       assert(PtrWidth <= 64 && "Bad pointer width");
    742       GV.IntVal = APInt(PtrWidth, uintptr_t(GV.PointerVal));
    743       uint32_t IntWidth = DL.getTypeSizeInBits(CE->getType());
    744       GV.IntVal = GV.IntVal.zextOrTrunc(IntWidth);
    745       return GV;
    746     }
    747     case Instruction::IntToPtr: {
    748       GenericValue GV = getConstantValue(Op0);
    749       uint32_t PtrWidth = DL.getTypeSizeInBits(CE->getType());
    750       GV.IntVal = GV.IntVal.zextOrTrunc(PtrWidth);
    751       assert(GV.IntVal.getBitWidth() <= 64 && "Bad pointer width");
    752       GV.PointerVal = PointerTy(uintptr_t(GV.IntVal.getZExtValue()));
    753       return GV;
    754     }
    755     case Instruction::BitCast: {
    756       GenericValue GV = getConstantValue(Op0);
    757       Type* DestTy = CE->getType();
    758       switch (Op0->getType()->getTypeID()) {
    759         default: llvm_unreachable("Invalid bitcast operand");
    760         case Type::IntegerTyID:
    761           assert(DestTy->isFloatingPointTy() && "invalid bitcast");
    762           if (DestTy->isFloatTy())
    763             GV.FloatVal = GV.IntVal.bitsToFloat();
    764           else if (DestTy->isDoubleTy())
    765             GV.DoubleVal = GV.IntVal.bitsToDouble();
    766           break;
    767         case Type::FloatTyID:
    768           assert(DestTy->isIntegerTy(32) && "Invalid bitcast");
    769           GV.IntVal = APInt::floatToBits(GV.FloatVal);
    770           break;
    771         case Type::DoubleTyID:
    772           assert(DestTy->isIntegerTy(64) && "Invalid bitcast");
    773           GV.IntVal = APInt::doubleToBits(GV.DoubleVal);
    774           break;
    775         case Type::PointerTyID:
    776           assert(DestTy->isPointerTy() && "Invalid bitcast");
    777           break; // getConstantValue(Op0)  above already converted it
    778       }
    779       return GV;
    780     }
    781     case Instruction::Add:
    782     case Instruction::FAdd:
    783     case Instruction::Sub:
    784     case Instruction::FSub:
    785     case Instruction::Mul:
    786     case Instruction::FMul:
    787     case Instruction::UDiv:
    788     case Instruction::SDiv:
    789     case Instruction::URem:
    790     case Instruction::SRem:
    791     case Instruction::And:
    792     case Instruction::Or:
    793     case Instruction::Xor: {
    794       GenericValue LHS = getConstantValue(Op0);
    795       GenericValue RHS = getConstantValue(CE->getOperand(1));
    796       GenericValue GV;
    797       switch (CE->getOperand(0)->getType()->getTypeID()) {
    798       default: llvm_unreachable("Bad add type!");
    799       case Type::IntegerTyID:
    800         switch (CE->getOpcode()) {
    801           default: llvm_unreachable("Invalid integer opcode");
    802           case Instruction::Add: GV.IntVal = LHS.IntVal + RHS.IntVal; break;
    803           case Instruction::Sub: GV.IntVal = LHS.IntVal - RHS.IntVal; break;
    804           case Instruction::Mul: GV.IntVal = LHS.IntVal * RHS.IntVal; break;
    805           case Instruction::UDiv:GV.IntVal = LHS.IntVal.udiv(RHS.IntVal); break;
    806           case Instruction::SDiv:GV.IntVal = LHS.IntVal.sdiv(RHS.IntVal); break;
    807           case Instruction::URem:GV.IntVal = LHS.IntVal.urem(RHS.IntVal); break;
    808           case Instruction::SRem:GV.IntVal = LHS.IntVal.srem(RHS.IntVal); break;
    809           case Instruction::And: GV.IntVal = LHS.IntVal & RHS.IntVal; break;
    810           case Instruction::Or:  GV.IntVal = LHS.IntVal | RHS.IntVal; break;
    811           case Instruction::Xor: GV.IntVal = LHS.IntVal ^ RHS.IntVal; break;
    812         }
    813         break;
    814       case Type::FloatTyID:
    815         switch (CE->getOpcode()) {
    816           default: llvm_unreachable("Invalid float opcode");
    817           case Instruction::FAdd:
    818             GV.FloatVal = LHS.FloatVal + RHS.FloatVal; break;
    819           case Instruction::FSub:
    820             GV.FloatVal = LHS.FloatVal - RHS.FloatVal; break;
    821           case Instruction::FMul:
    822             GV.FloatVal = LHS.FloatVal * RHS.FloatVal; break;
    823           case Instruction::FDiv:
    824             GV.FloatVal = LHS.FloatVal / RHS.FloatVal; break;
    825           case Instruction::FRem:
    826             GV.FloatVal = std::fmod(LHS.FloatVal,RHS.FloatVal); break;
    827         }
    828         break;
    829       case Type::DoubleTyID:
    830         switch (CE->getOpcode()) {
    831           default: llvm_unreachable("Invalid double opcode");
    832           case Instruction::FAdd:
    833             GV.DoubleVal = LHS.DoubleVal + RHS.DoubleVal; break;
    834           case Instruction::FSub:
    835             GV.DoubleVal = LHS.DoubleVal - RHS.DoubleVal; break;
    836           case Instruction::FMul:
    837             GV.DoubleVal = LHS.DoubleVal * RHS.DoubleVal; break;
    838           case Instruction::FDiv:
    839             GV.DoubleVal = LHS.DoubleVal / RHS.DoubleVal; break;
    840           case Instruction::FRem:
    841             GV.DoubleVal = std::fmod(LHS.DoubleVal,RHS.DoubleVal); break;
    842         }
    843         break;
    844       case Type::X86_FP80TyID:
    845       case Type::PPC_FP128TyID:
    846       case Type::FP128TyID: {
    847         const fltSemantics &Sem = CE->getOperand(0)->getType()->getFltSemantics();
    848         APFloat apfLHS = APFloat(Sem, LHS.IntVal);
    849         switch (CE->getOpcode()) {
    850           default: llvm_unreachable("Invalid long double opcode");
    851           case Instruction::FAdd:
    852             apfLHS.add(APFloat(Sem, RHS.IntVal), APFloat::rmNearestTiesToEven);
    853             GV.IntVal = apfLHS.bitcastToAPInt();
    854             break;
    855           case Instruction::FSub:
    856             apfLHS.subtract(APFloat(Sem, RHS.IntVal),
    857                             APFloat::rmNearestTiesToEven);
    858             GV.IntVal = apfLHS.bitcastToAPInt();
    859             break;
    860           case Instruction::FMul:
    861             apfLHS.multiply(APFloat(Sem, RHS.IntVal),
    862                             APFloat::rmNearestTiesToEven);
    863             GV.IntVal = apfLHS.bitcastToAPInt();
    864             break;
    865           case Instruction::FDiv:
    866             apfLHS.divide(APFloat(Sem, RHS.IntVal),
    867                           APFloat::rmNearestTiesToEven);
    868             GV.IntVal = apfLHS.bitcastToAPInt();
    869             break;
    870           case Instruction::FRem:
    871             apfLHS.mod(APFloat(Sem, RHS.IntVal));
    872             GV.IntVal = apfLHS.bitcastToAPInt();
    873             break;
    874           }
    875         }
    876         break;
    877       }
    878       return GV;
    879     }
    880     default:
    881       break;
    882     }
    883 
    884     SmallString<256> Msg;
    885     raw_svector_ostream OS(Msg);
    886     OS << "ConstantExpr not handled: " << *CE;
    887     report_fatal_error(OS.str());
    888   }
    889 
    890   // Otherwise, we have a simple constant.
    891   GenericValue Result;
    892   switch (C->getType()->getTypeID()) {
    893   case Type::FloatTyID:
    894     Result.FloatVal = cast<ConstantFP>(C)->getValueAPF().convertToFloat();
    895     break;
    896   case Type::DoubleTyID:
    897     Result.DoubleVal = cast<ConstantFP>(C)->getValueAPF().convertToDouble();
    898     break;
    899   case Type::X86_FP80TyID:
    900   case Type::FP128TyID:
    901   case Type::PPC_FP128TyID:
    902     Result.IntVal = cast <ConstantFP>(C)->getValueAPF().bitcastToAPInt();
    903     break;
    904   case Type::IntegerTyID:
    905     Result.IntVal = cast<ConstantInt>(C)->getValue();
    906     break;
    907   case Type::PointerTyID:
    908     if (isa<ConstantPointerNull>(C))
    909       Result.PointerVal = nullptr;
    910     else if (const Function *F = dyn_cast<Function>(C))
    911       Result = PTOGV(getPointerToFunctionOrStub(const_cast<Function*>(F)));
    912     else if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
    913       Result = PTOGV(getOrEmitGlobalVariable(const_cast<GlobalVariable*>(GV)));
    914     else
    915       llvm_unreachable("Unknown constant pointer type!");
    916     break;
    917   case Type::VectorTyID: {
    918     unsigned elemNum;
    919     Type* ElemTy;
    920     const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(C);
    921     const ConstantVector *CV = dyn_cast<ConstantVector>(C);
    922     const ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(C);
    923 
    924     if (CDV) {
    925         elemNum = CDV->getNumElements();
    926         ElemTy = CDV->getElementType();
    927     } else if (CV || CAZ) {
    928         VectorType* VTy = dyn_cast<VectorType>(C->getType());
    929         elemNum = VTy->getNumElements();
    930         ElemTy = VTy->getElementType();
    931     } else {
    932         llvm_unreachable("Unknown constant vector type!");
    933     }
    934 
    935     Result.AggregateVal.resize(elemNum);
    936     // Check if vector holds floats.
    937     if(ElemTy->isFloatTy()) {
    938       if (CAZ) {
    939         GenericValue floatZero;
    940         floatZero.FloatVal = 0.f;
    941         std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
    942                   floatZero);
    943         break;
    944       }
    945       if(CV) {
    946         for (unsigned i = 0; i < elemNum; ++i)
    947           if (!isa<UndefValue>(CV->getOperand(i)))
    948             Result.AggregateVal[i].FloatVal = cast<ConstantFP>(
    949               CV->getOperand(i))->getValueAPF().convertToFloat();
    950         break;
    951       }
    952       if(CDV)
    953         for (unsigned i = 0; i < elemNum; ++i)
    954           Result.AggregateVal[i].FloatVal = CDV->getElementAsFloat(i);
    955 
    956       break;
    957     }
    958     // Check if vector holds doubles.
    959     if (ElemTy->isDoubleTy()) {
    960       if (CAZ) {
    961         GenericValue doubleZero;
    962         doubleZero.DoubleVal = 0.0;
    963         std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
    964                   doubleZero);
    965         break;
    966       }
    967       if(CV) {
    968         for (unsigned i = 0; i < elemNum; ++i)
    969           if (!isa<UndefValue>(CV->getOperand(i)))
    970             Result.AggregateVal[i].DoubleVal = cast<ConstantFP>(
    971               CV->getOperand(i))->getValueAPF().convertToDouble();
    972         break;
    973       }
    974       if(CDV)
    975         for (unsigned i = 0; i < elemNum; ++i)
    976           Result.AggregateVal[i].DoubleVal = CDV->getElementAsDouble(i);
    977 
    978       break;
    979     }
    980     // Check if vector holds integers.
    981     if (ElemTy->isIntegerTy()) {
    982       if (CAZ) {
    983         GenericValue intZero;
    984         intZero.IntVal = APInt(ElemTy->getScalarSizeInBits(), 0ull);
    985         std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
    986                   intZero);
    987         break;
    988       }
    989       if(CV) {
    990         for (unsigned i = 0; i < elemNum; ++i)
    991           if (!isa<UndefValue>(CV->getOperand(i)))
    992             Result.AggregateVal[i].IntVal = cast<ConstantInt>(
    993                                             CV->getOperand(i))->getValue();
    994           else {
    995             Result.AggregateVal[i].IntVal =
    996               APInt(CV->getOperand(i)->getType()->getPrimitiveSizeInBits(), 0);
    997           }
    998         break;
    999       }
   1000       if(CDV)
   1001         for (unsigned i = 0; i < elemNum; ++i)
   1002           Result.AggregateVal[i].IntVal = APInt(
   1003             CDV->getElementType()->getPrimitiveSizeInBits(),
   1004             CDV->getElementAsInteger(i));
   1005 
   1006       break;
   1007     }
   1008     llvm_unreachable("Unknown constant pointer type!");
   1009   }
   1010   break;
   1011 
   1012   default:
   1013     SmallString<256> Msg;
   1014     raw_svector_ostream OS(Msg);
   1015     OS << "ERROR: Constant unimplemented for type: " << *C->getType();
   1016     report_fatal_error(OS.str());
   1017   }
   1018 
   1019   return Result;
   1020 }
   1021 
   1022 /// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst
   1023 /// with the integer held in IntVal.
   1024 static void StoreIntToMemory(const APInt &IntVal, uint8_t *Dst,
   1025                              unsigned StoreBytes) {
   1026   assert((IntVal.getBitWidth()+7)/8 >= StoreBytes && "Integer too small!");
   1027   const uint8_t *Src = (const uint8_t *)IntVal.getRawData();
   1028 
   1029   if (sys::IsLittleEndianHost) {
   1030     // Little-endian host - the source is ordered from LSB to MSB.  Order the
   1031     // destination from LSB to MSB: Do a straight copy.
   1032     memcpy(Dst, Src, StoreBytes);
   1033   } else {
   1034     // Big-endian host - the source is an array of 64 bit words ordered from
   1035     // LSW to MSW.  Each word is ordered from MSB to LSB.  Order the destination
   1036     // from MSB to LSB: Reverse the word order, but not the bytes in a word.
   1037     while (StoreBytes > sizeof(uint64_t)) {
   1038       StoreBytes -= sizeof(uint64_t);
   1039       // May not be aligned so use memcpy.
   1040       memcpy(Dst + StoreBytes, Src, sizeof(uint64_t));
   1041       Src += sizeof(uint64_t);
   1042     }
   1043 
   1044     memcpy(Dst, Src + sizeof(uint64_t) - StoreBytes, StoreBytes);
   1045   }
   1046 }
   1047 
   1048 void ExecutionEngine::StoreValueToMemory(const GenericValue &Val,
   1049                                          GenericValue *Ptr, Type *Ty) {
   1050   const unsigned StoreBytes = getDataLayout().getTypeStoreSize(Ty);
   1051 
   1052   switch (Ty->getTypeID()) {
   1053   default:
   1054     dbgs() << "Cannot store value of type " << *Ty << "!\n";
   1055     break;
   1056   case Type::IntegerTyID:
   1057     StoreIntToMemory(Val.IntVal, (uint8_t*)Ptr, StoreBytes);
   1058     break;
   1059   case Type::FloatTyID:
   1060     *((float*)Ptr) = Val.FloatVal;
   1061     break;
   1062   case Type::DoubleTyID:
   1063     *((double*)Ptr) = Val.DoubleVal;
   1064     break;
   1065   case Type::X86_FP80TyID:
   1066     memcpy(Ptr, Val.IntVal.getRawData(), 10);
   1067     break;
   1068   case Type::PointerTyID:
   1069     // Ensure 64 bit target pointers are fully initialized on 32 bit hosts.
   1070     if (StoreBytes != sizeof(PointerTy))
   1071       memset(&(Ptr->PointerVal), 0, StoreBytes);
   1072 
   1073     *((PointerTy*)Ptr) = Val.PointerVal;
   1074     break;
   1075   case Type::VectorTyID:
   1076     for (unsigned i = 0; i < Val.AggregateVal.size(); ++i) {
   1077       if (cast<VectorType>(Ty)->getElementType()->isDoubleTy())
   1078         *(((double*)Ptr)+i) = Val.AggregateVal[i].DoubleVal;
   1079       if (cast<VectorType>(Ty)->getElementType()->isFloatTy())
   1080         *(((float*)Ptr)+i) = Val.AggregateVal[i].FloatVal;
   1081       if (cast<VectorType>(Ty)->getElementType()->isIntegerTy()) {
   1082         unsigned numOfBytes =(Val.AggregateVal[i].IntVal.getBitWidth()+7)/8;
   1083         StoreIntToMemory(Val.AggregateVal[i].IntVal,
   1084           (uint8_t*)Ptr + numOfBytes*i, numOfBytes);
   1085       }
   1086     }
   1087     break;
   1088   }
   1089 
   1090   if (sys::IsLittleEndianHost != getDataLayout().isLittleEndian())
   1091     // Host and target are different endian - reverse the stored bytes.
   1092     std::reverse((uint8_t*)Ptr, StoreBytes + (uint8_t*)Ptr);
   1093 }
   1094 
   1095 /// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting
   1096 /// from Src into IntVal, which is assumed to be wide enough and to hold zero.
   1097 static void LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes) {
   1098   assert((IntVal.getBitWidth()+7)/8 >= LoadBytes && "Integer too small!");
   1099   uint8_t *Dst = reinterpret_cast<uint8_t *>(
   1100                    const_cast<uint64_t *>(IntVal.getRawData()));
   1101 
   1102   if (sys::IsLittleEndianHost)
   1103     // Little-endian host - the destination must be ordered from LSB to MSB.
   1104     // The source is ordered from LSB to MSB: Do a straight copy.
   1105     memcpy(Dst, Src, LoadBytes);
   1106   else {
   1107     // Big-endian - the destination is an array of 64 bit words ordered from
   1108     // LSW to MSW.  Each word must be ordered from MSB to LSB.  The source is
   1109     // ordered from MSB to LSB: Reverse the word order, but not the bytes in
   1110     // a word.
   1111     while (LoadBytes > sizeof(uint64_t)) {
   1112       LoadBytes -= sizeof(uint64_t);
   1113       // May not be aligned so use memcpy.
   1114       memcpy(Dst, Src + LoadBytes, sizeof(uint64_t));
   1115       Dst += sizeof(uint64_t);
   1116     }
   1117 
   1118     memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes);
   1119   }
   1120 }
   1121 
   1122 /// FIXME: document
   1123 ///
   1124 void ExecutionEngine::LoadValueFromMemory(GenericValue &Result,
   1125                                           GenericValue *Ptr,
   1126                                           Type *Ty) {
   1127   const unsigned LoadBytes = getDataLayout().getTypeStoreSize(Ty);
   1128 
   1129   switch (Ty->getTypeID()) {
   1130   case Type::IntegerTyID:
   1131     // An APInt with all words initially zero.
   1132     Result.IntVal = APInt(cast<IntegerType>(Ty)->getBitWidth(), 0);
   1133     LoadIntFromMemory(Result.IntVal, (uint8_t*)Ptr, LoadBytes);
   1134     break;
   1135   case Type::FloatTyID:
   1136     Result.FloatVal = *((float*)Ptr);
   1137     break;
   1138   case Type::DoubleTyID:
   1139     Result.DoubleVal = *((double*)Ptr);
   1140     break;
   1141   case Type::PointerTyID:
   1142     Result.PointerVal = *((PointerTy*)Ptr);
   1143     break;
   1144   case Type::X86_FP80TyID: {
   1145     // This is endian dependent, but it will only work on x86 anyway.
   1146     // FIXME: Will not trap if loading a signaling NaN.
   1147     uint64_t y[2];
   1148     memcpy(y, Ptr, 10);
   1149     Result.IntVal = APInt(80, y);
   1150     break;
   1151   }
   1152   case Type::VectorTyID: {
   1153     auto *VT = cast<VectorType>(Ty);
   1154     Type *ElemT = VT->getElementType();
   1155     const unsigned numElems = VT->getNumElements();
   1156     if (ElemT->isFloatTy()) {
   1157       Result.AggregateVal.resize(numElems);
   1158       for (unsigned i = 0; i < numElems; ++i)
   1159         Result.AggregateVal[i].FloatVal = *((float*)Ptr+i);
   1160     }
   1161     if (ElemT->isDoubleTy()) {
   1162       Result.AggregateVal.resize(numElems);
   1163       for (unsigned i = 0; i < numElems; ++i)
   1164         Result.AggregateVal[i].DoubleVal = *((double*)Ptr+i);
   1165     }
   1166     if (ElemT->isIntegerTy()) {
   1167       GenericValue intZero;
   1168       const unsigned elemBitWidth = cast<IntegerType>(ElemT)->getBitWidth();
   1169       intZero.IntVal = APInt(elemBitWidth, 0);
   1170       Result.AggregateVal.resize(numElems, intZero);
   1171       for (unsigned i = 0; i < numElems; ++i)
   1172         LoadIntFromMemory(Result.AggregateVal[i].IntVal,
   1173           (uint8_t*)Ptr+((elemBitWidth+7)/8)*i, (elemBitWidth+7)/8);
   1174     }
   1175   break;
   1176   }
   1177   default:
   1178     SmallString<256> Msg;
   1179     raw_svector_ostream OS(Msg);
   1180     OS << "Cannot load value of type " << *Ty << "!";
   1181     report_fatal_error(OS.str());
   1182   }
   1183 }
   1184 
   1185 void ExecutionEngine::InitializeMemory(const Constant *Init, void *Addr) {
   1186   DEBUG(dbgs() << "JIT: Initializing " << Addr << " ");
   1187   DEBUG(Init->dump());
   1188   if (isa<UndefValue>(Init))
   1189     return;
   1190 
   1191   if (const ConstantVector *CP = dyn_cast<ConstantVector>(Init)) {
   1192     unsigned ElementSize =
   1193         getDataLayout().getTypeAllocSize(CP->getType()->getElementType());
   1194     for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
   1195       InitializeMemory(CP->getOperand(i), (char*)Addr+i*ElementSize);
   1196     return;
   1197   }
   1198 
   1199   if (isa<ConstantAggregateZero>(Init)) {
   1200     memset(Addr, 0, (size_t)getDataLayout().getTypeAllocSize(Init->getType()));
   1201     return;
   1202   }
   1203 
   1204   if (const ConstantArray *CPA = dyn_cast<ConstantArray>(Init)) {
   1205     unsigned ElementSize =
   1206         getDataLayout().getTypeAllocSize(CPA->getType()->getElementType());
   1207     for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
   1208       InitializeMemory(CPA->getOperand(i), (char*)Addr+i*ElementSize);
   1209     return;
   1210   }
   1211 
   1212   if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(Init)) {
   1213     const StructLayout *SL =
   1214         getDataLayout().getStructLayout(cast<StructType>(CPS->getType()));
   1215     for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
   1216       InitializeMemory(CPS->getOperand(i), (char*)Addr+SL->getElementOffset(i));
   1217     return;
   1218   }
   1219 
   1220   if (const ConstantDataSequential *CDS =
   1221                dyn_cast<ConstantDataSequential>(Init)) {
   1222     // CDS is already laid out in host memory order.
   1223     StringRef Data = CDS->getRawDataValues();
   1224     memcpy(Addr, Data.data(), Data.size());
   1225     return;
   1226   }
   1227 
   1228   if (Init->getType()->isFirstClassType()) {
   1229     GenericValue Val = getConstantValue(Init);
   1230     StoreValueToMemory(Val, (GenericValue*)Addr, Init->getType());
   1231     return;
   1232   }
   1233 
   1234   DEBUG(dbgs() << "Bad Type: " << *Init->getType() << "\n");
   1235   llvm_unreachable("Unknown constant type to initialize memory with!");
   1236 }
   1237 
   1238 /// EmitGlobals - Emit all of the global variables to memory, storing their
   1239 /// addresses into GlobalAddress.  This must make sure to copy the contents of
   1240 /// their initializers into the memory.
   1241 void ExecutionEngine::emitGlobals() {
   1242   // Loop over all of the global variables in the program, allocating the memory
   1243   // to hold them.  If there is more than one module, do a prepass over globals
   1244   // to figure out how the different modules should link together.
   1245   std::map<std::pair<std::string, Type*>,
   1246            const GlobalValue*> LinkedGlobalsMap;
   1247 
   1248   if (Modules.size() != 1) {
   1249     for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
   1250       Module &M = *Modules[m];
   1251       for (const auto &GV : M.globals()) {
   1252         if (GV.hasLocalLinkage() || GV.isDeclaration() ||
   1253             GV.hasAppendingLinkage() || !GV.hasName())
   1254           continue;// Ignore external globals and globals with internal linkage.
   1255 
   1256         const GlobalValue *&GVEntry =
   1257           LinkedGlobalsMap[std::make_pair(GV.getName(), GV.getType())];
   1258 
   1259         // If this is the first time we've seen this global, it is the canonical
   1260         // version.
   1261         if (!GVEntry) {
   1262           GVEntry = &GV;
   1263           continue;
   1264         }
   1265 
   1266         // If the existing global is strong, never replace it.
   1267         if (GVEntry->hasExternalLinkage())
   1268           continue;
   1269 
   1270         // Otherwise, we know it's linkonce/weak, replace it if this is a strong
   1271         // symbol.  FIXME is this right for common?
   1272         if (GV.hasExternalLinkage() || GVEntry->hasExternalWeakLinkage())
   1273           GVEntry = &GV;
   1274       }
   1275     }
   1276   }
   1277 
   1278   std::vector<const GlobalValue*> NonCanonicalGlobals;
   1279   for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
   1280     Module &M = *Modules[m];
   1281     for (const auto &GV : M.globals()) {
   1282       // In the multi-module case, see what this global maps to.
   1283       if (!LinkedGlobalsMap.empty()) {
   1284         if (const GlobalValue *GVEntry =
   1285               LinkedGlobalsMap[std::make_pair(GV.getName(), GV.getType())]) {
   1286           // If something else is the canonical global, ignore this one.
   1287           if (GVEntry != &GV) {
   1288             NonCanonicalGlobals.push_back(&GV);
   1289             continue;
   1290           }
   1291         }
   1292       }
   1293 
   1294       if (!GV.isDeclaration()) {
   1295         addGlobalMapping(&GV, getMemoryForGV(&GV));
   1296       } else {
   1297         // External variable reference. Try to use the dynamic loader to
   1298         // get a pointer to it.
   1299         if (void *SymAddr =
   1300             sys::DynamicLibrary::SearchForAddressOfSymbol(GV.getName()))
   1301           addGlobalMapping(&GV, SymAddr);
   1302         else {
   1303           report_fatal_error("Could not resolve external global address: "
   1304                             +GV.getName());
   1305         }
   1306       }
   1307     }
   1308 
   1309     // If there are multiple modules, map the non-canonical globals to their
   1310     // canonical location.
   1311     if (!NonCanonicalGlobals.empty()) {
   1312       for (unsigned i = 0, e = NonCanonicalGlobals.size(); i != e; ++i) {
   1313         const GlobalValue *GV = NonCanonicalGlobals[i];
   1314         const GlobalValue *CGV =
   1315           LinkedGlobalsMap[std::make_pair(GV->getName(), GV->getType())];
   1316         void *Ptr = getPointerToGlobalIfAvailable(CGV);
   1317         assert(Ptr && "Canonical global wasn't codegen'd!");
   1318         addGlobalMapping(GV, Ptr);
   1319       }
   1320     }
   1321 
   1322     // Now that all of the globals are set up in memory, loop through them all
   1323     // and initialize their contents.
   1324     for (const auto &GV : M.globals()) {
   1325       if (!GV.isDeclaration()) {
   1326         if (!LinkedGlobalsMap.empty()) {
   1327           if (const GlobalValue *GVEntry =
   1328                 LinkedGlobalsMap[std::make_pair(GV.getName(), GV.getType())])
   1329             if (GVEntry != &GV)  // Not the canonical variable.
   1330               continue;
   1331         }
   1332         EmitGlobalVariable(&GV);
   1333       }
   1334     }
   1335   }
   1336 }
   1337 
   1338 // EmitGlobalVariable - This method emits the specified global variable to the
   1339 // address specified in GlobalAddresses, or allocates new memory if it's not
   1340 // already in the map.
   1341 void ExecutionEngine::EmitGlobalVariable(const GlobalVariable *GV) {
   1342   void *GA = getPointerToGlobalIfAvailable(GV);
   1343 
   1344   if (!GA) {
   1345     // If it's not already specified, allocate memory for the global.
   1346     GA = getMemoryForGV(GV);
   1347 
   1348     // If we failed to allocate memory for this global, return.
   1349     if (!GA) return;
   1350 
   1351     addGlobalMapping(GV, GA);
   1352   }
   1353 
   1354   // Don't initialize if it's thread local, let the client do it.
   1355   if (!GV->isThreadLocal())
   1356     InitializeMemory(GV->getInitializer(), GA);
   1357 
   1358   Type *ElTy = GV->getType()->getElementType();
   1359   size_t GVSize = (size_t)getDataLayout().getTypeAllocSize(ElTy);
   1360   NumInitBytes += (unsigned)GVSize;
   1361   ++NumGlobals;
   1362 }
   1363