1//===-- ExecutionEngine.cpp - Common Implementation shared by EEs ---------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the common interface used by the various execution engine
10// subclasses.
11//
12// FIXME: This file needs to be updated to support scalable vectors
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/ExecutionEngine/ExecutionEngine.h"
17#include "llvm/ADT/STLExtras.h"
18#include "llvm/ADT/SmallString.h"
19#include "llvm/ADT/Statistic.h"
20#include "llvm/ExecutionEngine/GenericValue.h"
21#include "llvm/ExecutionEngine/JITEventListener.h"
22#include "llvm/ExecutionEngine/ObjectCache.h"
23#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
24#include "llvm/IR/Constants.h"
25#include "llvm/IR/DataLayout.h"
26#include "llvm/IR/DerivedTypes.h"
27#include "llvm/IR/Mangler.h"
28#include "llvm/IR/Module.h"
29#include "llvm/IR/Operator.h"
30#include "llvm/IR/ValueHandle.h"
31#include "llvm/MC/TargetRegistry.h"
32#include "llvm/Object/Archive.h"
33#include "llvm/Object/ObjectFile.h"
34#include "llvm/Support/Debug.h"
35#include "llvm/Support/DynamicLibrary.h"
36#include "llvm/Support/ErrorHandling.h"
37#include "llvm/Support/raw_ostream.h"
38#include "llvm/Target/TargetMachine.h"
39#include "llvm/TargetParser/Host.h"
40#include <cmath>
41#include <cstring>
42#include <mutex>
43using namespace llvm;
44
45#define DEBUG_TYPE "jit"
46
47STATISTIC(NumInitBytes, "Number of bytes of global vars initialized");
48STATISTIC(NumGlobals  , "Number of global vars initialized");
49
50ExecutionEngine *(*ExecutionEngine::MCJITCtor)(
51    std::unique_ptr<Module> M, std::string *ErrorStr,
52    std::shared_ptr<MCJITMemoryManager> MemMgr,
53    std::shared_ptr<LegacyJITSymbolResolver> Resolver,
54    std::unique_ptr<TargetMachine> TM) = nullptr;
55
56ExecutionEngine *(*ExecutionEngine::InterpCtor)(std::unique_ptr<Module> M,
57                                                std::string *ErrorStr) =nullptr;
58
59void JITEventListener::anchor() {}
60
61void ObjectCache::anchor() {}
62
63void ExecutionEngine::Init(std::unique_ptr<Module> M) {
64  CompilingLazily         = false;
65  GVCompilationDisabled   = false;
66  SymbolSearchingDisabled = false;
67
68  // IR module verification is enabled by default in debug builds, and disabled
69  // by default in release builds.
70#ifndef NDEBUG
71  VerifyModules = true;
72#else
73  VerifyModules = false;
74#endif
75
76  assert(M && "Module is null?");
77  Modules.push_back(std::move(M));
78}
79
80ExecutionEngine::ExecutionEngine(std::unique_ptr<Module> M)
81    : DL(M->getDataLayout()), LazyFunctionCreator(nullptr) {
82  Init(std::move(M));
83}
84
85ExecutionEngine::ExecutionEngine(DataLayout DL, std::unique_ptr<Module> M)
86    : DL(std::move(DL)), LazyFunctionCreator(nullptr) {
87  Init(std::move(M));
88}
89
90ExecutionEngine::~ExecutionEngine() {
91  clearAllGlobalMappings();
92}
93
94namespace {
95/// Helper class which uses a value handler to automatically deletes the
96/// memory block when the GlobalVariable is destroyed.
97class GVMemoryBlock final : public CallbackVH {
98  GVMemoryBlock(const GlobalVariable *GV)
99    : CallbackVH(const_cast<GlobalVariable*>(GV)) {}
100
101public:
102  /// Returns the address the GlobalVariable should be written into.  The
103  /// GVMemoryBlock object prefixes that.
104  static char *Create(const GlobalVariable *GV, const DataLayout& TD) {
105    Type *ElTy = GV->getValueType();
106    size_t GVSize = (size_t)TD.getTypeAllocSize(ElTy);
107    void *RawMemory = ::operator new(
108        alignTo(sizeof(GVMemoryBlock), TD.getPreferredAlign(GV)) + GVSize);
109    new(RawMemory) GVMemoryBlock(GV);
110    return static_cast<char*>(RawMemory) + sizeof(GVMemoryBlock);
111  }
112
113  void deleted() override {
114    // We allocated with operator new and with some extra memory hanging off the
115    // end, so don't just delete this.  I'm not sure if this is actually
116    // required.
117    this->~GVMemoryBlock();
118    ::operator delete(this);
119  }
120};
121}  // anonymous namespace
122
123char *ExecutionEngine::getMemoryForGV(const GlobalVariable *GV) {
124  return GVMemoryBlock::Create(GV, getDataLayout());
125}
126
127void ExecutionEngine::addObjectFile(std::unique_ptr<object::ObjectFile> O) {
128  llvm_unreachable("ExecutionEngine subclass doesn't implement addObjectFile.");
129}
130
131void
132ExecutionEngine::addObjectFile(object::OwningBinary<object::ObjectFile> O) {
133  llvm_unreachable("ExecutionEngine subclass doesn't implement addObjectFile.");
134}
135
136void ExecutionEngine::addArchive(object::OwningBinary<object::Archive> A) {
137  llvm_unreachable("ExecutionEngine subclass doesn't implement addArchive.");
138}
139
140bool ExecutionEngine::removeModule(Module *M) {
141  for (auto I = Modules.begin(), E = Modules.end(); I != E; ++I) {
142    Module *Found = I->get();
143    if (Found == M) {
144      I->release();
145      Modules.erase(I);
146      clearGlobalMappingsFromModule(M);
147      return true;
148    }
149  }
150  return false;
151}
152
153Function *ExecutionEngine::FindFunctionNamed(StringRef FnName) {
154  for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
155    Function *F = Modules[i]->getFunction(FnName);
156    if (F && !F->isDeclaration())
157      return F;
158  }
159  return nullptr;
160}
161
162GlobalVariable *ExecutionEngine::FindGlobalVariableNamed(StringRef Name, bool AllowInternal) {
163  for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
164    GlobalVariable *GV = Modules[i]->getGlobalVariable(Name,AllowInternal);
165    if (GV && !GV->isDeclaration())
166      return GV;
167  }
168  return nullptr;
169}
170
171uint64_t ExecutionEngineState::RemoveMapping(StringRef Name) {
172  GlobalAddressMapTy::iterator I = GlobalAddressMap.find(Name);
173  uint64_t OldVal;
174
175  // FIXME: This is silly, we shouldn't end up with a mapping -> 0 in the
176  // GlobalAddressMap.
177  if (I == GlobalAddressMap.end())
178    OldVal = 0;
179  else {
180    GlobalAddressReverseMap.erase(I->second);
181    OldVal = I->second;
182    GlobalAddressMap.erase(I);
183  }
184
185  return OldVal;
186}
187
188std::string ExecutionEngine::getMangledName(const GlobalValue *GV) {
189  assert(GV->hasName() && "Global must have name.");
190
191  std::lock_guard<sys::Mutex> locked(lock);
192  SmallString<128> FullName;
193
194  const DataLayout &DL =
195    GV->getParent()->getDataLayout().isDefault()
196      ? getDataLayout()
197      : GV->getParent()->getDataLayout();
198
199  Mangler::getNameWithPrefix(FullName, GV->getName(), DL);
200  return std::string(FullName);
201}
202
203void ExecutionEngine::addGlobalMapping(const GlobalValue *GV, void *Addr) {
204  std::lock_guard<sys::Mutex> locked(lock);
205  addGlobalMapping(getMangledName(GV), (uint64_t) Addr);
206}
207
208void ExecutionEngine::addGlobalMapping(StringRef Name, uint64_t Addr) {
209  std::lock_guard<sys::Mutex> locked(lock);
210
211  assert(!Name.empty() && "Empty GlobalMapping symbol name!");
212
213  LLVM_DEBUG(dbgs() << "JIT: Map \'" << Name << "\' to [" << Addr << "]\n";);
214  uint64_t &CurVal = EEState.getGlobalAddressMap()[Name];
215  assert((!CurVal || !Addr) && "GlobalMapping already established!");
216  CurVal = Addr;
217
218  // If we are using the reverse mapping, add it too.
219  if (!EEState.getGlobalAddressReverseMap().empty()) {
220    std::string &V = EEState.getGlobalAddressReverseMap()[CurVal];
221    assert((!V.empty() || !Name.empty()) &&
222           "GlobalMapping already established!");
223    V = std::string(Name);
224  }
225}
226
227void ExecutionEngine::clearAllGlobalMappings() {
228  std::lock_guard<sys::Mutex> locked(lock);
229
230  EEState.getGlobalAddressMap().clear();
231  EEState.getGlobalAddressReverseMap().clear();
232}
233
234void ExecutionEngine::clearGlobalMappingsFromModule(Module *M) {
235  std::lock_guard<sys::Mutex> locked(lock);
236
237  for (GlobalObject &GO : M->global_objects())
238    EEState.RemoveMapping(getMangledName(&GO));
239}
240
241uint64_t ExecutionEngine::updateGlobalMapping(const GlobalValue *GV,
242                                              void *Addr) {
243  std::lock_guard<sys::Mutex> locked(lock);
244  return updateGlobalMapping(getMangledName(GV), (uint64_t) Addr);
245}
246
247uint64_t ExecutionEngine::updateGlobalMapping(StringRef Name, uint64_t Addr) {
248  std::lock_guard<sys::Mutex> locked(lock);
249
250  ExecutionEngineState::GlobalAddressMapTy &Map =
251    EEState.getGlobalAddressMap();
252
253  // Deleting from the mapping?
254  if (!Addr)
255    return EEState.RemoveMapping(Name);
256
257  uint64_t &CurVal = Map[Name];
258  uint64_t OldVal = CurVal;
259
260  if (CurVal && !EEState.getGlobalAddressReverseMap().empty())
261    EEState.getGlobalAddressReverseMap().erase(CurVal);
262  CurVal = Addr;
263
264  // If we are using the reverse mapping, add it too.
265  if (!EEState.getGlobalAddressReverseMap().empty()) {
266    std::string &V = EEState.getGlobalAddressReverseMap()[CurVal];
267    assert((!V.empty() || !Name.empty()) &&
268           "GlobalMapping already established!");
269    V = std::string(Name);
270  }
271  return OldVal;
272}
273
274uint64_t ExecutionEngine::getAddressToGlobalIfAvailable(StringRef S) {
275  std::lock_guard<sys::Mutex> locked(lock);
276  uint64_t Address = 0;
277  ExecutionEngineState::GlobalAddressMapTy::iterator I =
278    EEState.getGlobalAddressMap().find(S);
279  if (I != EEState.getGlobalAddressMap().end())
280    Address = I->second;
281  return Address;
282}
283
284
285void *ExecutionEngine::getPointerToGlobalIfAvailable(StringRef S) {
286  std::lock_guard<sys::Mutex> locked(lock);
287  if (void* Address = (void *) getAddressToGlobalIfAvailable(S))
288    return Address;
289  return nullptr;
290}
291
292void *ExecutionEngine::getPointerToGlobalIfAvailable(const GlobalValue *GV) {
293  std::lock_guard<sys::Mutex> locked(lock);
294  return getPointerToGlobalIfAvailable(getMangledName(GV));
295}
296
297const GlobalValue *ExecutionEngine::getGlobalValueAtAddress(void *Addr) {
298  std::lock_guard<sys::Mutex> locked(lock);
299
300  // If we haven't computed the reverse mapping yet, do so first.
301  if (EEState.getGlobalAddressReverseMap().empty()) {
302    for (ExecutionEngineState::GlobalAddressMapTy::iterator
303           I = EEState.getGlobalAddressMap().begin(),
304           E = EEState.getGlobalAddressMap().end(); I != E; ++I) {
305      StringRef Name = I->first();
306      uint64_t Addr = I->second;
307      EEState.getGlobalAddressReverseMap().insert(
308          std::make_pair(Addr, std::string(Name)));
309    }
310  }
311
312  std::map<uint64_t, std::string>::iterator I =
313    EEState.getGlobalAddressReverseMap().find((uint64_t) Addr);
314
315  if (I != EEState.getGlobalAddressReverseMap().end()) {
316    StringRef Name = I->second;
317    for (unsigned i = 0, e = Modules.size(); i != e; ++i)
318      if (GlobalValue *GV = Modules[i]->getNamedValue(Name))
319        return GV;
320  }
321  return nullptr;
322}
323
324namespace {
325class ArgvArray {
326  std::unique_ptr<char[]> Array;
327  std::vector<std::unique_ptr<char[]>> Values;
328public:
329  /// Turn a vector of strings into a nice argv style array of pointers to null
330  /// terminated strings.
331  void *reset(LLVMContext &C, ExecutionEngine *EE,
332              const std::vector<std::string> &InputArgv);
333};
334}  // anonymous namespace
335void *ArgvArray::reset(LLVMContext &C, ExecutionEngine *EE,
336                       const std::vector<std::string> &InputArgv) {
337  Values.clear();  // Free the old contents.
338  Values.reserve(InputArgv.size());
339  unsigned PtrSize = EE->getDataLayout().getPointerSize();
340  Array = std::make_unique<char[]>((InputArgv.size()+1)*PtrSize);
341
342  LLVM_DEBUG(dbgs() << "JIT: ARGV = " << (void *)Array.get() << "\n");
343  Type *SBytePtr = PointerType::getUnqual(C);
344
345  for (unsigned i = 0; i != InputArgv.size(); ++i) {
346    unsigned Size = InputArgv[i].size()+1;
347    auto Dest = std::make_unique<char[]>(Size);
348    LLVM_DEBUG(dbgs() << "JIT: ARGV[" << i << "] = " << (void *)Dest.get()
349                      << "\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
367void ExecutionEngine::runStaticConstructorsDestructors(Module &module,
368                                                       bool isDtors) {
369  StringRef 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 sentinel 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, std::nullopt);
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
406void 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.
414static 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
423int 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 = PointerType::get(Fn->getContext(), 0);
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
470EngineBuilder::EngineBuilder() : EngineBuilder(nullptr) {}
471
472EngineBuilder::EngineBuilder(std::unique_ptr<Module> M)
473    : M(std::move(M)), WhichEngine(EngineKind::Either), ErrorStr(nullptr),
474      OptLevel(CodeGenOptLevel::Default), MemMgr(nullptr), Resolver(nullptr) {
475// IR module verification is enabled by default in debug builds, and disabled
476// by default in release builds.
477#ifndef NDEBUG
478  VerifyModules = true;
479#else
480  VerifyModules = false;
481#endif
482}
483
484EngineBuilder::~EngineBuilder() = default;
485
486EngineBuilder &EngineBuilder::setMCJITMemoryManager(
487                                   std::unique_ptr<RTDyldMemoryManager> mcjmm) {
488  auto SharedMM = std::shared_ptr<RTDyldMemoryManager>(std::move(mcjmm));
489  MemMgr = SharedMM;
490  Resolver = SharedMM;
491  return *this;
492}
493
494EngineBuilder&
495EngineBuilder::setMemoryManager(std::unique_ptr<MCJITMemoryManager> MM) {
496  MemMgr = std::shared_ptr<MCJITMemoryManager>(std::move(MM));
497  return *this;
498}
499
500EngineBuilder &
501EngineBuilder::setSymbolResolver(std::unique_ptr<LegacyJITSymbolResolver> SR) {
502  Resolver = std::shared_ptr<LegacyJITSymbolResolver>(std::move(SR));
503  return *this;
504}
505
506ExecutionEngine *EngineBuilder::create(TargetMachine *TM) {
507  std::unique_ptr<TargetMachine> TheTM(TM); // Take ownership.
508
509  // Make sure we can resolve symbols in the program as well. The zero arg
510  // to the function tells DynamicLibrary to load the program, not a library.
511  if (sys::DynamicLibrary::LoadLibraryPermanently(nullptr, ErrorStr))
512    return nullptr;
513
514  // If the user specified a memory manager but didn't specify which engine to
515  // create, we assume they only want the JIT, and we fail if they only want
516  // the interpreter.
517  if (MemMgr) {
518    if (WhichEngine & EngineKind::JIT)
519      WhichEngine = EngineKind::JIT;
520    else {
521      if (ErrorStr)
522        *ErrorStr = "Cannot create an interpreter with a memory manager.";
523      return nullptr;
524    }
525  }
526
527  // Unless the interpreter was explicitly selected or the JIT is not linked,
528  // try making a JIT.
529  if ((WhichEngine & EngineKind::JIT) && TheTM) {
530    if (!TM->getTarget().hasJIT()) {
531      errs() << "WARNING: This target JIT is not designed for the host"
532             << " you are running.  If bad things happen, please choose"
533             << " a different -march switch.\n";
534    }
535
536    ExecutionEngine *EE = nullptr;
537    if (ExecutionEngine::MCJITCtor)
538      EE = ExecutionEngine::MCJITCtor(std::move(M), ErrorStr, std::move(MemMgr),
539                                      std::move(Resolver), std::move(TheTM));
540
541    if (EE) {
542      EE->setVerifyModules(VerifyModules);
543      return EE;
544    }
545  }
546
547  // If we can't make a JIT and we didn't request one specifically, try making
548  // an interpreter instead.
549  if (WhichEngine & EngineKind::Interpreter) {
550    if (ExecutionEngine::InterpCtor)
551      return ExecutionEngine::InterpCtor(std::move(M), ErrorStr);
552    if (ErrorStr)
553      *ErrorStr = "Interpreter has not been linked in.";
554    return nullptr;
555  }
556
557  if ((WhichEngine & EngineKind::JIT) && !ExecutionEngine::MCJITCtor) {
558    if (ErrorStr)
559      *ErrorStr = "JIT has not been linked in.";
560  }
561
562  return nullptr;
563}
564
565void *ExecutionEngine::getPointerToGlobal(const GlobalValue *GV) {
566  if (Function *F = const_cast<Function*>(dyn_cast<Function>(GV)))
567    return getPointerToFunction(F);
568
569  std::lock_guard<sys::Mutex> locked(lock);
570  if (void* P = getPointerToGlobalIfAvailable(GV))
571    return P;
572
573  // Global variable might have been added since interpreter started.
574  if (GlobalVariable *GVar =
575          const_cast<GlobalVariable *>(dyn_cast<GlobalVariable>(GV)))
576    emitGlobalVariable(GVar);
577  else
578    llvm_unreachable("Global hasn't had an address allocated yet!");
579
580  return getPointerToGlobalIfAvailable(GV);
581}
582
583/// Converts a Constant* into a GenericValue, including handling of
584/// ConstantExpr values.
585GenericValue ExecutionEngine::getConstantValue(const Constant *C) {
586  // If its undefined, return the garbage.
587  if (isa<UndefValue>(C)) {
588    GenericValue Result;
589    switch (C->getType()->getTypeID()) {
590    default:
591      break;
592    case Type::IntegerTyID:
593    case Type::X86_FP80TyID:
594    case Type::FP128TyID:
595    case Type::PPC_FP128TyID:
596      // Although the value is undefined, we still have to construct an APInt
597      // with the correct bit width.
598      Result.IntVal = APInt(C->getType()->getPrimitiveSizeInBits(), 0);
599      break;
600    case Type::StructTyID: {
601      // if the whole struct is 'undef' just reserve memory for the value.
602      if(StructType *STy = dyn_cast<StructType>(C->getType())) {
603        unsigned int elemNum = STy->getNumElements();
604        Result.AggregateVal.resize(elemNum);
605        for (unsigned int i = 0; i < elemNum; ++i) {
606          Type *ElemTy = STy->getElementType(i);
607          if (ElemTy->isIntegerTy())
608            Result.AggregateVal[i].IntVal =
609              APInt(ElemTy->getPrimitiveSizeInBits(), 0);
610          else if (ElemTy->isAggregateType()) {
611              const Constant *ElemUndef = UndefValue::get(ElemTy);
612              Result.AggregateVal[i] = getConstantValue(ElemUndef);
613            }
614          }
615        }
616      }
617      break;
618      case Type::ScalableVectorTyID:
619        report_fatal_error(
620            "Scalable vector support not yet implemented in ExecutionEngine");
621      case Type::ArrayTyID: {
622        auto *ArrTy = cast<ArrayType>(C->getType());
623        Type *ElemTy = ArrTy->getElementType();
624        unsigned int elemNum = ArrTy->getNumElements();
625        Result.AggregateVal.resize(elemNum);
626        if (ElemTy->isIntegerTy())
627          for (unsigned int i = 0; i < elemNum; ++i)
628            Result.AggregateVal[i].IntVal =
629                APInt(ElemTy->getPrimitiveSizeInBits(), 0);
630        break;
631      }
632      case Type::FixedVectorTyID: {
633        // if the whole vector is 'undef' just reserve memory for the value.
634        auto *VTy = cast<FixedVectorType>(C->getType());
635        Type *ElemTy = VTy->getElementType();
636        unsigned int elemNum = VTy->getNumElements();
637        Result.AggregateVal.resize(elemNum);
638        if (ElemTy->isIntegerTy())
639          for (unsigned int i = 0; i < elemNum; ++i)
640            Result.AggregateVal[i].IntVal =
641                APInt(ElemTy->getPrimitiveSizeInBits(), 0);
642        break;
643      }
644    }
645    return Result;
646  }
647
648  // Otherwise, if the value is a ConstantExpr...
649  if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
650    Constant *Op0 = CE->getOperand(0);
651    switch (CE->getOpcode()) {
652    case Instruction::GetElementPtr: {
653      // Compute the index
654      GenericValue Result = getConstantValue(Op0);
655      APInt Offset(DL.getPointerSizeInBits(), 0);
656      cast<GEPOperator>(CE)->accumulateConstantOffset(DL, Offset);
657
658      char* tmp = (char*) Result.PointerVal;
659      Result = PTOGV(tmp + Offset.getSExtValue());
660      return Result;
661    }
662    case Instruction::Trunc: {
663      GenericValue GV = getConstantValue(Op0);
664      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
665      GV.IntVal = GV.IntVal.trunc(BitWidth);
666      return GV;
667    }
668    case Instruction::ZExt: {
669      GenericValue GV = getConstantValue(Op0);
670      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
671      GV.IntVal = GV.IntVal.zext(BitWidth);
672      return GV;
673    }
674    case Instruction::SExt: {
675      GenericValue GV = getConstantValue(Op0);
676      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
677      GV.IntVal = GV.IntVal.sext(BitWidth);
678      return GV;
679    }
680    case Instruction::FPTrunc: {
681      // FIXME long double
682      GenericValue GV = getConstantValue(Op0);
683      GV.FloatVal = float(GV.DoubleVal);
684      return GV;
685    }
686    case Instruction::FPExt:{
687      // FIXME long double
688      GenericValue GV = getConstantValue(Op0);
689      GV.DoubleVal = double(GV.FloatVal);
690      return GV;
691    }
692    case Instruction::UIToFP: {
693      GenericValue GV = getConstantValue(Op0);
694      if (CE->getType()->isFloatTy())
695        GV.FloatVal = float(GV.IntVal.roundToDouble());
696      else if (CE->getType()->isDoubleTy())
697        GV.DoubleVal = GV.IntVal.roundToDouble();
698      else if (CE->getType()->isX86_FP80Ty()) {
699        APFloat apf = APFloat::getZero(APFloat::x87DoubleExtended());
700        (void)apf.convertFromAPInt(GV.IntVal,
701                                   false,
702                                   APFloat::rmNearestTiesToEven);
703        GV.IntVal = apf.bitcastToAPInt();
704      }
705      return GV;
706    }
707    case Instruction::SIToFP: {
708      GenericValue GV = getConstantValue(Op0);
709      if (CE->getType()->isFloatTy())
710        GV.FloatVal = float(GV.IntVal.signedRoundToDouble());
711      else if (CE->getType()->isDoubleTy())
712        GV.DoubleVal = GV.IntVal.signedRoundToDouble();
713      else if (CE->getType()->isX86_FP80Ty()) {
714        APFloat apf = APFloat::getZero(APFloat::x87DoubleExtended());
715        (void)apf.convertFromAPInt(GV.IntVal,
716                                   true,
717                                   APFloat::rmNearestTiesToEven);
718        GV.IntVal = apf.bitcastToAPInt();
719      }
720      return GV;
721    }
722    case Instruction::FPToUI: // double->APInt conversion handles sign
723    case Instruction::FPToSI: {
724      GenericValue GV = getConstantValue(Op0);
725      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
726      if (Op0->getType()->isFloatTy())
727        GV.IntVal = APIntOps::RoundFloatToAPInt(GV.FloatVal, BitWidth);
728      else if (Op0->getType()->isDoubleTy())
729        GV.IntVal = APIntOps::RoundDoubleToAPInt(GV.DoubleVal, BitWidth);
730      else if (Op0->getType()->isX86_FP80Ty()) {
731        APFloat apf = APFloat(APFloat::x87DoubleExtended(), GV.IntVal);
732        uint64_t v;
733        bool ignored;
734        (void)apf.convertToInteger(MutableArrayRef(v), BitWidth,
735                                   CE->getOpcode()==Instruction::FPToSI,
736                                   APFloat::rmTowardZero, &ignored);
737        GV.IntVal = v; // endian?
738      }
739      return GV;
740    }
741    case Instruction::PtrToInt: {
742      GenericValue GV = getConstantValue(Op0);
743      uint32_t PtrWidth = DL.getTypeSizeInBits(Op0->getType());
744      assert(PtrWidth <= 64 && "Bad pointer width");
745      GV.IntVal = APInt(PtrWidth, uintptr_t(GV.PointerVal));
746      uint32_t IntWidth = DL.getTypeSizeInBits(CE->getType());
747      GV.IntVal = GV.IntVal.zextOrTrunc(IntWidth);
748      return GV;
749    }
750    case Instruction::IntToPtr: {
751      GenericValue GV = getConstantValue(Op0);
752      uint32_t PtrWidth = DL.getTypeSizeInBits(CE->getType());
753      GV.IntVal = GV.IntVal.zextOrTrunc(PtrWidth);
754      assert(GV.IntVal.getBitWidth() <= 64 && "Bad pointer width");
755      GV.PointerVal = PointerTy(uintptr_t(GV.IntVal.getZExtValue()));
756      return GV;
757    }
758    case Instruction::BitCast: {
759      GenericValue GV = getConstantValue(Op0);
760      Type* DestTy = CE->getType();
761      switch (Op0->getType()->getTypeID()) {
762        default: llvm_unreachable("Invalid bitcast operand");
763        case Type::IntegerTyID:
764          assert(DestTy->isFloatingPointTy() && "invalid bitcast");
765          if (DestTy->isFloatTy())
766            GV.FloatVal = GV.IntVal.bitsToFloat();
767          else if (DestTy->isDoubleTy())
768            GV.DoubleVal = GV.IntVal.bitsToDouble();
769          break;
770        case Type::FloatTyID:
771          assert(DestTy->isIntegerTy(32) && "Invalid bitcast");
772          GV.IntVal = APInt::floatToBits(GV.FloatVal);
773          break;
774        case Type::DoubleTyID:
775          assert(DestTy->isIntegerTy(64) && "Invalid bitcast");
776          GV.IntVal = APInt::doubleToBits(GV.DoubleVal);
777          break;
778        case Type::PointerTyID:
779          assert(DestTy->isPointerTy() && "Invalid bitcast");
780          break; // getConstantValue(Op0)  above already converted it
781      }
782      return GV;
783    }
784    case Instruction::Add:
785    case Instruction::FAdd:
786    case Instruction::Sub:
787    case Instruction::FSub:
788    case Instruction::Mul:
789    case Instruction::FMul:
790    case Instruction::UDiv:
791    case Instruction::SDiv:
792    case Instruction::URem:
793    case Instruction::SRem:
794    case Instruction::And:
795    case Instruction::Or:
796    case Instruction::Xor: {
797      GenericValue LHS = getConstantValue(Op0);
798      GenericValue RHS = getConstantValue(CE->getOperand(1));
799      GenericValue GV;
800      switch (CE->getOperand(0)->getType()->getTypeID()) {
801      default: llvm_unreachable("Bad add type!");
802      case Type::IntegerTyID:
803        switch (CE->getOpcode()) {
804          default: llvm_unreachable("Invalid integer opcode");
805          case Instruction::Add: GV.IntVal = LHS.IntVal + RHS.IntVal; break;
806          case Instruction::Sub: GV.IntVal = LHS.IntVal - RHS.IntVal; break;
807          case Instruction::Mul: GV.IntVal = LHS.IntVal * RHS.IntVal; break;
808          case Instruction::UDiv:GV.IntVal = LHS.IntVal.udiv(RHS.IntVal); break;
809          case Instruction::SDiv:GV.IntVal = LHS.IntVal.sdiv(RHS.IntVal); break;
810          case Instruction::URem:GV.IntVal = LHS.IntVal.urem(RHS.IntVal); break;
811          case Instruction::SRem:GV.IntVal = LHS.IntVal.srem(RHS.IntVal); break;
812          case Instruction::And: GV.IntVal = LHS.IntVal & RHS.IntVal; break;
813          case Instruction::Or:  GV.IntVal = LHS.IntVal | RHS.IntVal; break;
814          case Instruction::Xor: GV.IntVal = LHS.IntVal ^ RHS.IntVal; break;
815        }
816        break;
817      case Type::FloatTyID:
818        switch (CE->getOpcode()) {
819          default: llvm_unreachable("Invalid float opcode");
820          case Instruction::FAdd:
821            GV.FloatVal = LHS.FloatVal + RHS.FloatVal; break;
822          case Instruction::FSub:
823            GV.FloatVal = LHS.FloatVal - RHS.FloatVal; break;
824          case Instruction::FMul:
825            GV.FloatVal = LHS.FloatVal * RHS.FloatVal; break;
826          case Instruction::FDiv:
827            GV.FloatVal = LHS.FloatVal / RHS.FloatVal; break;
828          case Instruction::FRem:
829            GV.FloatVal = std::fmod(LHS.FloatVal,RHS.FloatVal); break;
830        }
831        break;
832      case Type::DoubleTyID:
833        switch (CE->getOpcode()) {
834          default: llvm_unreachable("Invalid double opcode");
835          case Instruction::FAdd:
836            GV.DoubleVal = LHS.DoubleVal + RHS.DoubleVal; break;
837          case Instruction::FSub:
838            GV.DoubleVal = LHS.DoubleVal - RHS.DoubleVal; break;
839          case Instruction::FMul:
840            GV.DoubleVal = LHS.DoubleVal * RHS.DoubleVal; break;
841          case Instruction::FDiv:
842            GV.DoubleVal = LHS.DoubleVal / RHS.DoubleVal; break;
843          case Instruction::FRem:
844            GV.DoubleVal = std::fmod(LHS.DoubleVal,RHS.DoubleVal); break;
845        }
846        break;
847      case Type::X86_FP80TyID:
848      case Type::PPC_FP128TyID:
849      case Type::FP128TyID: {
850        const fltSemantics &Sem = CE->getOperand(0)->getType()->getFltSemantics();
851        APFloat apfLHS = APFloat(Sem, LHS.IntVal);
852        switch (CE->getOpcode()) {
853          default: llvm_unreachable("Invalid long double opcode");
854          case Instruction::FAdd:
855            apfLHS.add(APFloat(Sem, RHS.IntVal), APFloat::rmNearestTiesToEven);
856            GV.IntVal = apfLHS.bitcastToAPInt();
857            break;
858          case Instruction::FSub:
859            apfLHS.subtract(APFloat(Sem, RHS.IntVal),
860                            APFloat::rmNearestTiesToEven);
861            GV.IntVal = apfLHS.bitcastToAPInt();
862            break;
863          case Instruction::FMul:
864            apfLHS.multiply(APFloat(Sem, RHS.IntVal),
865                            APFloat::rmNearestTiesToEven);
866            GV.IntVal = apfLHS.bitcastToAPInt();
867            break;
868          case Instruction::FDiv:
869            apfLHS.divide(APFloat(Sem, RHS.IntVal),
870                          APFloat::rmNearestTiesToEven);
871            GV.IntVal = apfLHS.bitcastToAPInt();
872            break;
873          case Instruction::FRem:
874            apfLHS.mod(APFloat(Sem, RHS.IntVal));
875            GV.IntVal = apfLHS.bitcastToAPInt();
876            break;
877          }
878        }
879        break;
880      }
881      return GV;
882    }
883    default:
884      break;
885    }
886
887    SmallString<256> Msg;
888    raw_svector_ostream OS(Msg);
889    OS << "ConstantExpr not handled: " << *CE;
890    report_fatal_error(OS.str());
891  }
892
893  if (auto *TETy = dyn_cast<TargetExtType>(C->getType())) {
894    assert(TETy->hasProperty(TargetExtType::HasZeroInit) && C->isNullValue() &&
895           "TargetExtType only supports null constant value");
896    C = Constant::getNullValue(TETy->getLayoutType());
897  }
898
899  // Otherwise, we have a simple constant.
900  GenericValue Result;
901  switch (C->getType()->getTypeID()) {
902  case Type::FloatTyID:
903    Result.FloatVal = cast<ConstantFP>(C)->getValueAPF().convertToFloat();
904    break;
905  case Type::DoubleTyID:
906    Result.DoubleVal = cast<ConstantFP>(C)->getValueAPF().convertToDouble();
907    break;
908  case Type::X86_FP80TyID:
909  case Type::FP128TyID:
910  case Type::PPC_FP128TyID:
911    Result.IntVal = cast <ConstantFP>(C)->getValueAPF().bitcastToAPInt();
912    break;
913  case Type::IntegerTyID:
914    Result.IntVal = cast<ConstantInt>(C)->getValue();
915    break;
916  case Type::PointerTyID:
917    while (auto *A = dyn_cast<GlobalAlias>(C)) {
918      C = A->getAliasee();
919    }
920    if (isa<ConstantPointerNull>(C))
921      Result.PointerVal = nullptr;
922    else if (const Function *F = dyn_cast<Function>(C))
923      Result = PTOGV(getPointerToFunctionOrStub(const_cast<Function*>(F)));
924    else if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
925      Result = PTOGV(getOrEmitGlobalVariable(const_cast<GlobalVariable*>(GV)));
926    else
927      llvm_unreachable("Unknown constant pointer type!");
928    break;
929  case Type::ScalableVectorTyID:
930    report_fatal_error(
931        "Scalable vector support not yet implemented in ExecutionEngine");
932  case Type::FixedVectorTyID: {
933    unsigned elemNum;
934    Type* ElemTy;
935    const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(C);
936    const ConstantVector *CV = dyn_cast<ConstantVector>(C);
937    const ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(C);
938
939    if (CDV) {
940        elemNum = CDV->getNumElements();
941        ElemTy = CDV->getElementType();
942    } else if (CV || CAZ) {
943      auto *VTy = cast<FixedVectorType>(C->getType());
944      elemNum = VTy->getNumElements();
945      ElemTy = VTy->getElementType();
946    } else {
947        llvm_unreachable("Unknown constant vector type!");
948    }
949
950    Result.AggregateVal.resize(elemNum);
951    // Check if vector holds floats.
952    if(ElemTy->isFloatTy()) {
953      if (CAZ) {
954        GenericValue floatZero;
955        floatZero.FloatVal = 0.f;
956        std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
957                  floatZero);
958        break;
959      }
960      if(CV) {
961        for (unsigned i = 0; i < elemNum; ++i)
962          if (!isa<UndefValue>(CV->getOperand(i)))
963            Result.AggregateVal[i].FloatVal = cast<ConstantFP>(
964              CV->getOperand(i))->getValueAPF().convertToFloat();
965        break;
966      }
967      if(CDV)
968        for (unsigned i = 0; i < elemNum; ++i)
969          Result.AggregateVal[i].FloatVal = CDV->getElementAsFloat(i);
970
971      break;
972    }
973    // Check if vector holds doubles.
974    if (ElemTy->isDoubleTy()) {
975      if (CAZ) {
976        GenericValue doubleZero;
977        doubleZero.DoubleVal = 0.0;
978        std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
979                  doubleZero);
980        break;
981      }
982      if(CV) {
983        for (unsigned i = 0; i < elemNum; ++i)
984          if (!isa<UndefValue>(CV->getOperand(i)))
985            Result.AggregateVal[i].DoubleVal = cast<ConstantFP>(
986              CV->getOperand(i))->getValueAPF().convertToDouble();
987        break;
988      }
989      if(CDV)
990        for (unsigned i = 0; i < elemNum; ++i)
991          Result.AggregateVal[i].DoubleVal = CDV->getElementAsDouble(i);
992
993      break;
994    }
995    // Check if vector holds integers.
996    if (ElemTy->isIntegerTy()) {
997      if (CAZ) {
998        GenericValue intZero;
999        intZero.IntVal = APInt(ElemTy->getScalarSizeInBits(), 0ull);
1000        std::fill(Result.AggregateVal.begin(), Result.AggregateVal.end(),
1001                  intZero);
1002        break;
1003      }
1004      if(CV) {
1005        for (unsigned i = 0; i < elemNum; ++i)
1006          if (!isa<UndefValue>(CV->getOperand(i)))
1007            Result.AggregateVal[i].IntVal = cast<ConstantInt>(
1008                                            CV->getOperand(i))->getValue();
1009          else {
1010            Result.AggregateVal[i].IntVal =
1011              APInt(CV->getOperand(i)->getType()->getPrimitiveSizeInBits(), 0);
1012          }
1013        break;
1014      }
1015      if(CDV)
1016        for (unsigned i = 0; i < elemNum; ++i)
1017          Result.AggregateVal[i].IntVal = APInt(
1018            CDV->getElementType()->getPrimitiveSizeInBits(),
1019            CDV->getElementAsInteger(i));
1020
1021      break;
1022    }
1023    llvm_unreachable("Unknown constant pointer type!");
1024  } break;
1025
1026  default:
1027    SmallString<256> Msg;
1028    raw_svector_ostream OS(Msg);
1029    OS << "ERROR: Constant unimplemented for type: " << *C->getType();
1030    report_fatal_error(OS.str());
1031  }
1032
1033  return Result;
1034}
1035
1036void ExecutionEngine::StoreValueToMemory(const GenericValue &Val,
1037                                         GenericValue *Ptr, Type *Ty) {
1038  // It is safe to treat TargetExtType as its layout type since the underlying
1039  // bits are only copied and are not inspected.
1040  if (auto *TETy = dyn_cast<TargetExtType>(Ty))
1041    Ty = TETy->getLayoutType();
1042
1043  const unsigned StoreBytes = getDataLayout().getTypeStoreSize(Ty);
1044
1045  switch (Ty->getTypeID()) {
1046  default:
1047    dbgs() << "Cannot store value of type " << *Ty << "!\n";
1048    break;
1049  case Type::IntegerTyID:
1050    StoreIntToMemory(Val.IntVal, (uint8_t*)Ptr, StoreBytes);
1051    break;
1052  case Type::FloatTyID:
1053    *((float*)Ptr) = Val.FloatVal;
1054    break;
1055  case Type::DoubleTyID:
1056    *((double*)Ptr) = Val.DoubleVal;
1057    break;
1058  case Type::X86_FP80TyID:
1059    memcpy(Ptr, Val.IntVal.getRawData(), 10);
1060    break;
1061  case Type::PointerTyID:
1062    // Ensure 64 bit target pointers are fully initialized on 32 bit hosts.
1063    if (StoreBytes != sizeof(PointerTy))
1064      memset(&(Ptr->PointerVal), 0, StoreBytes);
1065
1066    *((PointerTy*)Ptr) = Val.PointerVal;
1067    break;
1068  case Type::FixedVectorTyID:
1069  case Type::ScalableVectorTyID:
1070    for (unsigned i = 0; i < Val.AggregateVal.size(); ++i) {
1071      if (cast<VectorType>(Ty)->getElementType()->isDoubleTy())
1072        *(((double*)Ptr)+i) = Val.AggregateVal[i].DoubleVal;
1073      if (cast<VectorType>(Ty)->getElementType()->isFloatTy())
1074        *(((float*)Ptr)+i) = Val.AggregateVal[i].FloatVal;
1075      if (cast<VectorType>(Ty)->getElementType()->isIntegerTy()) {
1076        unsigned numOfBytes =(Val.AggregateVal[i].IntVal.getBitWidth()+7)/8;
1077        StoreIntToMemory(Val.AggregateVal[i].IntVal,
1078          (uint8_t*)Ptr + numOfBytes*i, numOfBytes);
1079      }
1080    }
1081    break;
1082  }
1083
1084  if (sys::IsLittleEndianHost != getDataLayout().isLittleEndian())
1085    // Host and target are different endian - reverse the stored bytes.
1086    std::reverse((uint8_t*)Ptr, StoreBytes + (uint8_t*)Ptr);
1087}
1088
1089/// FIXME: document
1090///
1091void ExecutionEngine::LoadValueFromMemory(GenericValue &Result,
1092                                          GenericValue *Ptr,
1093                                          Type *Ty) {
1094  if (auto *TETy = dyn_cast<TargetExtType>(Ty))
1095    Ty = TETy->getLayoutType();
1096
1097  const unsigned LoadBytes = getDataLayout().getTypeStoreSize(Ty);
1098
1099  switch (Ty->getTypeID()) {
1100  case Type::IntegerTyID:
1101    // An APInt with all words initially zero.
1102    Result.IntVal = APInt(cast<IntegerType>(Ty)->getBitWidth(), 0);
1103    LoadIntFromMemory(Result.IntVal, (uint8_t*)Ptr, LoadBytes);
1104    break;
1105  case Type::FloatTyID:
1106    Result.FloatVal = *((float*)Ptr);
1107    break;
1108  case Type::DoubleTyID:
1109    Result.DoubleVal = *((double*)Ptr);
1110    break;
1111  case Type::PointerTyID:
1112    Result.PointerVal = *((PointerTy*)Ptr);
1113    break;
1114  case Type::X86_FP80TyID: {
1115    // This is endian dependent, but it will only work on x86 anyway.
1116    // FIXME: Will not trap if loading a signaling NaN.
1117    uint64_t y[2];
1118    memcpy(y, Ptr, 10);
1119    Result.IntVal = APInt(80, y);
1120    break;
1121  }
1122  case Type::ScalableVectorTyID:
1123    report_fatal_error(
1124        "Scalable vector support not yet implemented in ExecutionEngine");
1125  case Type::FixedVectorTyID: {
1126    auto *VT = cast<FixedVectorType>(Ty);
1127    Type *ElemT = VT->getElementType();
1128    const unsigned numElems = VT->getNumElements();
1129    if (ElemT->isFloatTy()) {
1130      Result.AggregateVal.resize(numElems);
1131      for (unsigned i = 0; i < numElems; ++i)
1132        Result.AggregateVal[i].FloatVal = *((float*)Ptr+i);
1133    }
1134    if (ElemT->isDoubleTy()) {
1135      Result.AggregateVal.resize(numElems);
1136      for (unsigned i = 0; i < numElems; ++i)
1137        Result.AggregateVal[i].DoubleVal = *((double*)Ptr+i);
1138    }
1139    if (ElemT->isIntegerTy()) {
1140      GenericValue intZero;
1141      const unsigned elemBitWidth = cast<IntegerType>(ElemT)->getBitWidth();
1142      intZero.IntVal = APInt(elemBitWidth, 0);
1143      Result.AggregateVal.resize(numElems, intZero);
1144      for (unsigned i = 0; i < numElems; ++i)
1145        LoadIntFromMemory(Result.AggregateVal[i].IntVal,
1146          (uint8_t*)Ptr+((elemBitWidth+7)/8)*i, (elemBitWidth+7)/8);
1147    }
1148  break;
1149  }
1150  default:
1151    SmallString<256> Msg;
1152    raw_svector_ostream OS(Msg);
1153    OS << "Cannot load value of type " << *Ty << "!";
1154    report_fatal_error(OS.str());
1155  }
1156}
1157
1158void ExecutionEngine::InitializeMemory(const Constant *Init, void *Addr) {
1159  LLVM_DEBUG(dbgs() << "JIT: Initializing " << Addr << " ");
1160  LLVM_DEBUG(Init->dump());
1161  if (isa<UndefValue>(Init))
1162    return;
1163
1164  if (const ConstantVector *CP = dyn_cast<ConstantVector>(Init)) {
1165    unsigned ElementSize =
1166        getDataLayout().getTypeAllocSize(CP->getType()->getElementType());
1167    for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
1168      InitializeMemory(CP->getOperand(i), (char*)Addr+i*ElementSize);
1169    return;
1170  }
1171
1172  if (isa<ConstantAggregateZero>(Init)) {
1173    memset(Addr, 0, (size_t)getDataLayout().getTypeAllocSize(Init->getType()));
1174    return;
1175  }
1176
1177  if (const ConstantArray *CPA = dyn_cast<ConstantArray>(Init)) {
1178    unsigned ElementSize =
1179        getDataLayout().getTypeAllocSize(CPA->getType()->getElementType());
1180    for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
1181      InitializeMemory(CPA->getOperand(i), (char*)Addr+i*ElementSize);
1182    return;
1183  }
1184
1185  if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(Init)) {
1186    const StructLayout *SL =
1187        getDataLayout().getStructLayout(cast<StructType>(CPS->getType()));
1188    for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
1189      InitializeMemory(CPS->getOperand(i), (char*)Addr+SL->getElementOffset(i));
1190    return;
1191  }
1192
1193  if (const ConstantDataSequential *CDS =
1194               dyn_cast<ConstantDataSequential>(Init)) {
1195    // CDS is already laid out in host memory order.
1196    StringRef Data = CDS->getRawDataValues();
1197    memcpy(Addr, Data.data(), Data.size());
1198    return;
1199  }
1200
1201  if (Init->getType()->isFirstClassType()) {
1202    GenericValue Val = getConstantValue(Init);
1203    StoreValueToMemory(Val, (GenericValue*)Addr, Init->getType());
1204    return;
1205  }
1206
1207  LLVM_DEBUG(dbgs() << "Bad Type: " << *Init->getType() << "\n");
1208  llvm_unreachable("Unknown constant type to initialize memory with!");
1209}
1210
1211/// EmitGlobals - Emit all of the global variables to memory, storing their
1212/// addresses into GlobalAddress.  This must make sure to copy the contents of
1213/// their initializers into the memory.
1214void ExecutionEngine::emitGlobals() {
1215  // Loop over all of the global variables in the program, allocating the memory
1216  // to hold them.  If there is more than one module, do a prepass over globals
1217  // to figure out how the different modules should link together.
1218  std::map<std::pair<std::string, Type*>,
1219           const GlobalValue*> LinkedGlobalsMap;
1220
1221  if (Modules.size() != 1) {
1222    for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
1223      Module &M = *Modules[m];
1224      for (const auto &GV : M.globals()) {
1225        if (GV.hasLocalLinkage() || GV.isDeclaration() ||
1226            GV.hasAppendingLinkage() || !GV.hasName())
1227          continue;// Ignore external globals and globals with internal linkage.
1228
1229        const GlobalValue *&GVEntry = LinkedGlobalsMap[std::make_pair(
1230            std::string(GV.getName()), GV.getType())];
1231
1232        // If this is the first time we've seen this global, it is the canonical
1233        // version.
1234        if (!GVEntry) {
1235          GVEntry = &GV;
1236          continue;
1237        }
1238
1239        // If the existing global is strong, never replace it.
1240        if (GVEntry->hasExternalLinkage())
1241          continue;
1242
1243        // Otherwise, we know it's linkonce/weak, replace it if this is a strong
1244        // symbol.  FIXME is this right for common?
1245        if (GV.hasExternalLinkage() || GVEntry->hasExternalWeakLinkage())
1246          GVEntry = &GV;
1247      }
1248    }
1249  }
1250
1251  std::vector<const GlobalValue*> NonCanonicalGlobals;
1252  for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
1253    Module &M = *Modules[m];
1254    for (const auto &GV : M.globals()) {
1255      // In the multi-module case, see what this global maps to.
1256      if (!LinkedGlobalsMap.empty()) {
1257        if (const GlobalValue *GVEntry = LinkedGlobalsMap[std::make_pair(
1258                std::string(GV.getName()), GV.getType())]) {
1259          // If something else is the canonical global, ignore this one.
1260          if (GVEntry != &GV) {
1261            NonCanonicalGlobals.push_back(&GV);
1262            continue;
1263          }
1264        }
1265      }
1266
1267      if (!GV.isDeclaration()) {
1268        addGlobalMapping(&GV, getMemoryForGV(&GV));
1269      } else {
1270        // External variable reference. Try to use the dynamic loader to
1271        // get a pointer to it.
1272        if (void *SymAddr = sys::DynamicLibrary::SearchForAddressOfSymbol(
1273                std::string(GV.getName())))
1274          addGlobalMapping(&GV, SymAddr);
1275        else {
1276          report_fatal_error("Could not resolve external global address: "
1277                            +GV.getName());
1278        }
1279      }
1280    }
1281
1282    // If there are multiple modules, map the non-canonical globals to their
1283    // canonical location.
1284    if (!NonCanonicalGlobals.empty()) {
1285      for (const GlobalValue *GV : NonCanonicalGlobals) {
1286        const GlobalValue *CGV = LinkedGlobalsMap[std::make_pair(
1287            std::string(GV->getName()), GV->getType())];
1288        void *Ptr = getPointerToGlobalIfAvailable(CGV);
1289        assert(Ptr && "Canonical global wasn't codegen'd!");
1290        addGlobalMapping(GV, Ptr);
1291      }
1292    }
1293
1294    // Now that all of the globals are set up in memory, loop through them all
1295    // and initialize their contents.
1296    for (const auto &GV : M.globals()) {
1297      if (!GV.isDeclaration()) {
1298        if (!LinkedGlobalsMap.empty()) {
1299          if (const GlobalValue *GVEntry = LinkedGlobalsMap[std::make_pair(
1300                  std::string(GV.getName()), GV.getType())])
1301            if (GVEntry != &GV)  // Not the canonical variable.
1302              continue;
1303        }
1304        emitGlobalVariable(&GV);
1305      }
1306    }
1307  }
1308}
1309
1310// EmitGlobalVariable - This method emits the specified global variable to the
1311// address specified in GlobalAddresses, or allocates new memory if it's not
1312// already in the map.
1313void ExecutionEngine::emitGlobalVariable(const GlobalVariable *GV) {
1314  void *GA = getPointerToGlobalIfAvailable(GV);
1315
1316  if (!GA) {
1317    // If it's not already specified, allocate memory for the global.
1318    GA = getMemoryForGV(GV);
1319
1320    // If we failed to allocate memory for this global, return.
1321    if (!GA) return;
1322
1323    addGlobalMapping(GV, GA);
1324  }
1325
1326  // Don't initialize if it's thread local, let the client do it.
1327  if (!GV->isThreadLocal())
1328    InitializeMemory(GV->getInitializer(), GA);
1329
1330  Type *ElTy = GV->getValueType();
1331  size_t GVSize = (size_t)getDataLayout().getTypeAllocSize(ElTy);
1332  NumInitBytes += (unsigned)GVSize;
1333  ++NumGlobals;
1334}
1335