llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp

   1 //===-- MCJIT.cpp - MC-based Just-in-Time Compiler ------------------------===//
   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 #include "MCJIT.h"
  10 #include "llvm/ADT/STLExtras.h"
  11 #include "llvm/ExecutionEngine/GenericValue.h"
  12 #include "llvm/ExecutionEngine/JITEventListener.h"
  13 #include "llvm/ExecutionEngine/MCJIT.h"
  14 #include "llvm/ExecutionEngine/ObjectCache.h"
  15 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
  16 #include "llvm/IR/DataLayout.h"
  17 #include "llvm/IR/DerivedTypes.h"
  18 #include "llvm/IR/Function.h"
  19 #include "llvm/IR/LegacyPassManager.h"
  20 #include "llvm/IR/Mangler.h"
  21 #include "llvm/IR/Module.h"
  22 #include "llvm/Object/Archive.h"
  23 #include "llvm/Object/ObjectFile.h"
  24 #include "llvm/Support/DynamicLibrary.h"
  25 #include "llvm/Support/ErrorHandling.h"
  26 #include "llvm/Support/MemoryBuffer.h"
  27 #include "llvm/Support/SmallVectorMemoryBuffer.h"
  28 #include <mutex>
  29
  30 using namespace llvm;
  31
  32 namespace {
  33
  34 static struct RegisterJIT {
  35   RegisterJIT() { MCJIT::Register(); }
  36 } JITRegistrator;
  37
  38 }
  39
  40 extern "C" void LLVMLinkInMCJIT() {
  41 }
  42
  43 ExecutionEngine *
  44 MCJIT::createJIT(std::unique_ptr<Module> M, std::string *ErrorStr,
  45                  std::shared_ptr<MCJITMemoryManager> MemMgr,
  46                  std::shared_ptr<LegacyJITSymbolResolver> Resolver,
  47                  std::unique_ptr<TargetMachine> TM) {
  48   // Try to register the program as a source of symbols to resolve against.
  49   //
  50   // FIXME: Don't do this here.
  51   sys::DynamicLibrary::LoadLibraryPermanently(nullptr, nullptr);
  52
  53   if (!MemMgr || !Resolver) {
  54     auto RTDyldMM = std::make_shared<SectionMemoryManager>();
  55     if (!MemMgr)
  56       MemMgr = RTDyldMM;
  57     if (!Resolver)
  58       Resolver = RTDyldMM;
  59   }
  60
  61   return new MCJIT(std::move(M), std::move(TM), std::move(MemMgr),
  62                    std::move(Resolver));
  63 }
  64
  65 MCJIT::MCJIT(std::unique_ptr<Module> M, std::unique_ptr<TargetMachine> TM,
  66              std::shared_ptr<MCJITMemoryManager> MemMgr,
  67              std::shared_ptr<LegacyJITSymbolResolver> Resolver)
  68     : ExecutionEngine(TM->createDataLayout(), std::move(M)), TM(std::move(TM)),
  69       Ctx(nullptr), MemMgr(std::move(MemMgr)),
  70       Resolver(*this, std::move(Resolver)), Dyld(*this->MemMgr, this->Resolver),
  71       ObjCache(nullptr) {
  72   // FIXME: We are managing our modules, so we do not want the base class
  73   // ExecutionEngine to manage them as well. To avoid double destruction
  74   // of the first (and only) module added in ExecutionEngine constructor
  75   // we remove it from EE and will destruct it ourselves.
  76   //
  77   // It may make sense to move our module manager (based on SmallStPtr) back
  78   // into EE if the JIT and Interpreter can live with it.
  79   // If so, additional functions: addModule, removeModule, FindFunctionNamed,
  80   // runStaticConstructorsDestructors could be moved back to EE as well.
  81   //
  82   std::unique_ptr<Module> First = std::move(Modules[0]);
  83   Modules.clear();
  84
  85   if (First->getDataLayout().isDefault())
  86     First->setDataLayout(getDataLayout());
  87
  88   OwnedModules.addModule(std::move(First));
  89   RegisterJITEventListener(JITEventListener::createGDBRegistrationListener());
  90 }
  91
  92 MCJIT::~MCJIT() {
  93   std::lock_guard<sys::Mutex> locked(lock);
  94
  95   Dyld.deregisterEHFrames();
  96
  97   for (auto &Obj : LoadedObjects)
  98     if (Obj)
  99       notifyFreeingObject(*Obj);
 100
 101   Archives.clear();
 102 }
 103
 104 void MCJIT::addModule(std::unique_ptr<Module> M) {
 105   std::lock_guard<sys::Mutex> locked(lock);
 106
 107   if (M->getDataLayout().isDefault())
 108     M->setDataLayout(getDataLayout());
 109
 110   OwnedModules.addModule(std::move(M));
 111 }
 112
 113 bool MCJIT::removeModule(Module *M) {
 114   std::lock_guard<sys::Mutex> locked(lock);
 115   return OwnedModules.removeModule(M);
 116 }
 117
 118 void MCJIT::addObjectFile(std::unique_ptr<object::ObjectFile> Obj) {
 119   std::unique_ptr<RuntimeDyld::LoadedObjectInfo> L = Dyld.loadObject(*Obj);
 120   if (Dyld.hasError())
 121     report_fatal_error(Dyld.getErrorString());
 122
 123   notifyObjectLoaded(*Obj, *L);
 124
 125   LoadedObjects.push_back(std::move(Obj));
 126 }
 127
 128 void MCJIT::addObjectFile(object::OwningBinary<object::ObjectFile> Obj) {
 129   std::unique_ptr<object::ObjectFile> ObjFile;
 130   std::unique_ptr<MemoryBuffer> MemBuf;
 131   std::tie(ObjFile, MemBuf) = Obj.takeBinary();
 132   addObjectFile(std::move(ObjFile));
 133   Buffers.push_back(std::move(MemBuf));
 134 }
 135
 136 void MCJIT::addArchive(object::OwningBinary<object::Archive> A) {
 137   Archives.push_back(std::move(A));
 138 }
 139
 140 void MCJIT::setObjectCache(ObjectCache* NewCache) {
 141   std::lock_guard<sys::Mutex> locked(lock);
 142   ObjCache = NewCache;
 143 }
 144
 145 std::unique_ptr<MemoryBuffer> MCJIT::emitObject(Module *M) {
 146   assert(M && "Can not emit a null module");
 147
 148   std::lock_guard<sys::Mutex> locked(lock);
 149
 150   // Materialize all globals in the module if they have not been
 151   // materialized already.
 152   cantFail(M->materializeAll());
 153
 154   // This must be a module which has already been added but not loaded to this
 155   // MCJIT instance, since these conditions are tested by our caller,
 156   // generateCodeForModule.
 157
 158   legacy::PassManager PM;
 159
 160   // The RuntimeDyld will take ownership of this shortly
 161   SmallVector<char, 4096> ObjBufferSV;
 162   raw_svector_ostream ObjStream(ObjBufferSV);
 163
 164   // Turn the machine code intermediate representation into bytes in memory
 165   // that may be executed.
 166   if (TM->addPassesToEmitMC(PM, Ctx, ObjStream, !getVerifyModules()))
 167     report_fatal_error("Target does not support MC emission!");
 168
 169   // Initialize passes.
 170   PM.run(*M);
 171   // Flush the output buffer to get the generated code into memory
 172
 173   auto CompiledObjBuffer = std::make_unique<SmallVectorMemoryBuffer>(
 174       std::move(ObjBufferSV), /*RequiresNullTerminator=*/false);
 175
 176   // If we have an object cache, tell it about the new object.
 177   // Note that we're using the compiled image, not the loaded image (as below).
 178   if (ObjCache) {
 179     // MemoryBuffer is a thin wrapper around the actual memory, so it's OK
 180     // to create a temporary object here and delete it after the call.
 181     MemoryBufferRef MB = CompiledObjBuffer->getMemBufferRef();
 182     ObjCache->notifyObjectCompiled(M, MB);
 183   }
 184
 185   return CompiledObjBuffer;
 186 }
 187
 188 void MCJIT::generateCodeForModule(Module *M) {
 189   // Get a thread lock to make sure we aren't trying to load multiple times
 190   std::lock_guard<sys::Mutex> locked(lock);
 191
 192   // This must be a module which has already been added to this MCJIT instance.
 193   assert(OwnedModules.ownsModule(M) &&
 194          "MCJIT::generateCodeForModule: Unknown module.");
 195
 196   // Re-compilation is not supported
 197   if (OwnedModules.hasModuleBeenLoaded(M))
 198     return;
 199
 200   std::unique_ptr<MemoryBuffer> ObjectToLoad;
 201   // Try to load the pre-compiled object from cache if possible
 202   if (ObjCache)
 203     ObjectToLoad = ObjCache->getObject(M);
 204
 205   assert(M->getDataLayout() == getDataLayout() && "DataLayout Mismatch");
 206
 207   // If the cache did not contain a suitable object, compile the object
 208   if (!ObjectToLoad) {
 209     ObjectToLoad = emitObject(M);
 210     assert(ObjectToLoad && "Compilation did not produce an object.");
 211   }
 212
 213   // Load the object into the dynamic linker.
 214   // MCJIT now owns the ObjectImage pointer (via its LoadedObjects list).
 215   Expected<std::unique_ptr<object::ObjectFile>> LoadedObject =
 216     object::ObjectFile::createObjectFile(ObjectToLoad->getMemBufferRef());
 217   if (!LoadedObject) {
 218     std::string Buf;
 219     raw_string_ostream OS(Buf);
 220     logAllUnhandledErrors(LoadedObject.takeError(), OS);
 221     report_fatal_error(Twine(Buf));
 222   }
 223   std::unique_ptr<RuntimeDyld::LoadedObjectInfo> L =
 224     Dyld.loadObject(*LoadedObject.get());
 225
 226   if (Dyld.hasError())
 227     report_fatal_error(Dyld.getErrorString());
 228
 229   notifyObjectLoaded(*LoadedObject.get(), *L);
 230
 231   Buffers.push_back(std::move(ObjectToLoad));
 232   LoadedObjects.push_back(std::move(*LoadedObject));
 233
 234   OwnedModules.markModuleAsLoaded(M);
 235 }
 236
 237 void MCJIT::finalizeLoadedModules() {
 238   std::lock_guard<sys::Mutex> locked(lock);
 239
 240   // Resolve any outstanding relocations.
 241   Dyld.resolveRelocations();
 242
 243   // Check for Dyld error.
 244   if (Dyld.hasError())
 245     ErrMsg = Dyld.getErrorString().str();
 246
 247   OwnedModules.markAllLoadedModulesAsFinalized();
 248
 249   // Register EH frame data for any module we own which has been loaded
 250   Dyld.registerEHFrames();
 251
 252   // Set page permissions.
 253   MemMgr->finalizeMemory();
 254 }
 255
 256 // FIXME: Rename this.
 257 void MCJIT::finalizeObject() {
 258   std::lock_guard<sys::Mutex> locked(lock);
 259
 260   // Generate code for module is going to move objects out of the 'added' list,
 261   // so we need to copy that out before using it:
 262   SmallVector<Module *, 16> ModsToAdd(OwnedModules.added());
 263
 264   for (auto *M : ModsToAdd)
 265     generateCodeForModule(M);
 266
 267   finalizeLoadedModules();
 268 }
 269
 270 void MCJIT::finalizeModule(Module *M) {
 271   std::lock_guard<sys::Mutex> locked(lock);
 272
 273   // This must be a module which has already been added to this MCJIT instance.
 274   assert(OwnedModules.ownsModule(M) && "MCJIT::finalizeModule: Unknown module.");
 275
 276   // If the module hasn't been compiled, just do that.
 277   if (!OwnedModules.hasModuleBeenLoaded(M))
 278     generateCodeForModule(M);
 279
 280   finalizeLoadedModules();
 281 }
 282
 283 JITSymbol MCJIT::findExistingSymbol(const std::string &Name) {
 284   if (void *Addr = getPointerToGlobalIfAvailable(Name))
 285     return JITSymbol(static_cast<uint64_t>(
 286                          reinterpret_cast<uintptr_t>(Addr)),
 287                      JITSymbolFlags::Exported);
 288
 289   return Dyld.getSymbol(Name);
 290 }
 291
 292 Module *MCJIT::findModuleForSymbol(const std::string &Name,
 293                                    bool CheckFunctionsOnly) {
 294   StringRef DemangledName = Name;
 295   if (DemangledName[0] == getDataLayout().getGlobalPrefix())
 296     DemangledName = DemangledName.substr(1);
 297
 298   std::lock_guard<sys::Mutex> locked(lock);
 299
 300   // If it hasn't already been generated, see if it's in one of our modules.
 301   for (ModulePtrSet::iterator I = OwnedModules.begin_added(),
 302                               E = OwnedModules.end_added();
 303        I != E; ++I) {
 304     Module *M = *I;
 305     Function *F = M->getFunction(DemangledName);
 306     if (F && !F->isDeclaration())
 307       return M;
 308     if (!CheckFunctionsOnly) {
 309       GlobalVariable *G = M->getGlobalVariable(DemangledName);
 310       if (G && !G->isDeclaration())
 311         return M;
 312       // FIXME: Do we need to worry about global aliases?
 313     }
 314   }
 315   // We didn't find the symbol in any of our modules.
 316   return nullptr;
 317 }
 318
 319 uint64_t MCJIT::getSymbolAddress(const std::string &Name,
 320                                  bool CheckFunctionsOnly) {
 321   std::string MangledName;
 322   {
 323     raw_string_ostream MangledNameStream(MangledName);
 324     Mangler::getNameWithPrefix(MangledNameStream, Name, getDataLayout());
 325   }
 326   if (auto Sym = findSymbol(MangledName, CheckFunctionsOnly)) {
 327     if (auto AddrOrErr = Sym.getAddress())
 328       return *AddrOrErr;
 329     else
 330       report_fatal_error(AddrOrErr.takeError());
 331   } else if (auto Err = Sym.takeError())
 332     report_fatal_error(Sym.takeError());
 333   return 0;
 334 }
 335
 336 JITSymbol MCJIT::findSymbol(const std::string &Name,
 337                             bool CheckFunctionsOnly) {
 338   std::lock_guard<sys::Mutex> locked(lock);
 339
 340   // First, check to see if we already have this symbol.
 341   if (auto Sym = findExistingSymbol(Name))
 342     return Sym;
 343
 344   for (object::OwningBinary<object::Archive> &OB : Archives) {
 345     object::Archive *A = OB.getBinary();
 346     // Look for our symbols in each Archive
 347     auto OptionalChildOrErr = A->findSym(Name);
 348     if (!OptionalChildOrErr)
 349       report_fatal_error(OptionalChildOrErr.takeError());
 350     auto &OptionalChild = *OptionalChildOrErr;
 351     if (OptionalChild) {
 352       // FIXME: Support nested archives?
 353       Expected<std::unique_ptr<object::Binary>> ChildBinOrErr =
 354           OptionalChild->getAsBinary();
 355       if (!ChildBinOrErr) {
 356         // TODO: Actually report errors helpfully.
 357         consumeError(ChildBinOrErr.takeError());
 358         continue;
 359       }
 360       std::unique_ptr<object::Binary> &ChildBin = ChildBinOrErr.get();
 361       if (ChildBin->isObject()) {
 362         std::unique_ptr<object::ObjectFile> OF(
 363             static_cast<object::ObjectFile *>(ChildBin.release()));
 364         // This causes the object file to be loaded.
 365         addObjectFile(std::move(OF));
 366         // The address should be here now.
 367         if (auto Sym = findExistingSymbol(Name))
 368           return Sym;
 369       }
 370     }
 371   }
 372
 373   // If it hasn't already been generated, see if it's in one of our modules.
 374   Module *M = findModuleForSymbol(Name, CheckFunctionsOnly);
 375   if (M) {
 376     generateCodeForModule(M);
 377
 378     // Check the RuntimeDyld table again, it should be there now.
 379     return findExistingSymbol(Name);
 380   }
 381
 382   // If a LazyFunctionCreator is installed, use it to get/create the function.
 383   // FIXME: Should we instead have a LazySymbolCreator callback?
 384   if (LazyFunctionCreator) {
 385     auto Addr = static_cast<uint64_t>(
 386                   reinterpret_cast<uintptr_t>(LazyFunctionCreator(Name)));
 387     return JITSymbol(Addr, JITSymbolFlags::Exported);
 388   }
 389
 390   return nullptr;
 391 }
 392
 393 uint64_t MCJIT::getGlobalValueAddress(const std::string &Name) {
 394   std::lock_guard<sys::Mutex> locked(lock);
 395   uint64_t Result = getSymbolAddress(Name, false);
 396   if (Result != 0)
 397     finalizeLoadedModules();
 398   return Result;
 399 }
 400
 401 uint64_t MCJIT::getFunctionAddress(const std::string &Name) {
 402   std::lock_guard<sys::Mutex> locked(lock);
 403   uint64_t Result = getSymbolAddress(Name, true);
 404   if (Result != 0)
 405     finalizeLoadedModules();
 406   return Result;
 407 }
 408
 409 // Deprecated.  Use getFunctionAddress instead.
 410 void *MCJIT::getPointerToFunction(Function *F) {
 411   std::lock_guard<sys::Mutex> locked(lock);
 412
 413   Mangler Mang;
 414   SmallString<128> Name;
 415   TM->getNameWithPrefix(Name, F, Mang);
 416
 417   if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
 418     bool AbortOnFailure = !F->hasExternalWeakLinkage();
 419     void *Addr = getPointerToNamedFunction(Name, AbortOnFailure);
 420     updateGlobalMapping(F, Addr);
 421     return Addr;
 422   }
 423
 424   Module *M = F->getParent();
 425   bool HasBeenAddedButNotLoaded = OwnedModules.hasModuleBeenAddedButNotLoaded(M);
 426
 427   // Make sure the relevant module has been compiled and loaded.
 428   if (HasBeenAddedButNotLoaded)
 429     generateCodeForModule(M);
 430   else if (!OwnedModules.hasModuleBeenLoaded(M)) {
 431     // If this function doesn't belong to one of our modules, we're done.
 432     // FIXME: Asking for the pointer to a function that hasn't been registered,
 433     //        and isn't a declaration (which is handled above) should probably
 434     //        be an assertion.
 435     return nullptr;
 436   }
 437
 438   // FIXME: Should the Dyld be retaining module information? Probably not.
 439   //
 440   // This is the accessor for the target address, so make sure to check the
 441   // load address of the symbol, not the local address.
 442   return (void*)Dyld.getSymbol(Name).getAddress();
 443 }
 444
 445 void MCJIT::runStaticConstructorsDestructorsInModulePtrSet(
 446     bool isDtors, ModulePtrSet::iterator I, ModulePtrSet::iterator E) {
 447   for (; I != E; ++I) {
 448     ExecutionEngine::runStaticConstructorsDestructors(**I, isDtors);
 449   }
 450 }
 451
 452 void MCJIT::runStaticConstructorsDestructors(bool isDtors) {
 453   // Execute global ctors/dtors for each module in the program.
 454   runStaticConstructorsDestructorsInModulePtrSet(
 455       isDtors, OwnedModules.begin_added(), OwnedModules.end_added());
 456   runStaticConstructorsDestructorsInModulePtrSet(
 457       isDtors, OwnedModules.begin_loaded(), OwnedModules.end_loaded());
 458   runStaticConstructorsDestructorsInModulePtrSet(
 459       isDtors, OwnedModules.begin_finalized(), OwnedModules.end_finalized());
 460 }
 461
 462 Function *MCJIT::FindFunctionNamedInModulePtrSet(StringRef FnName,
 463                                                  ModulePtrSet::iterator I,
 464                                                  ModulePtrSet::iterator E) {
 465   for (; I != E; ++I) {
 466     Function *F = (*I)->getFunction(FnName);
 467     if (F && !F->isDeclaration())
 468       return F;
 469   }
 470   return nullptr;
 471 }
 472
 473 GlobalVariable *MCJIT::FindGlobalVariableNamedInModulePtrSet(StringRef Name,
 474                                                              bool AllowInternal,
 475                                                              ModulePtrSet::iterator I,
 476                                                              ModulePtrSet::iterator E) {
 477   for (; I != E; ++I) {
 478     GlobalVariable *GV = (*I)->getGlobalVariable(Name, AllowInternal);
 479     if (GV && !GV->isDeclaration())
 480       return GV;
 481   }
 482   return nullptr;
 483 }
 484
 485
 486 Function *MCJIT::FindFunctionNamed(StringRef FnName) {
 487   Function *F = FindFunctionNamedInModulePtrSet(
 488       FnName, OwnedModules.begin_added(), OwnedModules.end_added());
 489   if (!F)
 490     F = FindFunctionNamedInModulePtrSet(FnName, OwnedModules.begin_loaded(),
 491                                         OwnedModules.end_loaded());
 492   if (!F)
 493     F = FindFunctionNamedInModulePtrSet(FnName, OwnedModules.begin_finalized(),
 494                                         OwnedModules.end_finalized());
 495   return F;
 496 }
 497
 498 GlobalVariable *MCJIT::FindGlobalVariableNamed(StringRef Name, bool AllowInternal) {
 499   GlobalVariable *GV = FindGlobalVariableNamedInModulePtrSet(
 500       Name, AllowInternal, OwnedModules.begin_added(), OwnedModules.end_added());
 501   if (!GV)
 502     GV = FindGlobalVariableNamedInModulePtrSet(Name, AllowInternal, OwnedModules.begin_loaded(),
 503                                         OwnedModules.end_loaded());
 504   if (!GV)
 505     GV = FindGlobalVariableNamedInModulePtrSet(Name, AllowInternal, OwnedModules.begin_finalized(),
 506                                         OwnedModules.end_finalized());
 507   return GV;
 508 }
 509
 510 GenericValue MCJIT::runFunction(Function *F, ArrayRef<GenericValue> ArgValues) {
 511   assert(F && "Function *F was null at entry to run()");
 512
 513   void *FPtr = getPointerToFunction(F);
 514   finalizeModule(F->getParent());
 515   assert(FPtr && "Pointer to fn's code was null after getPointerToFunction");
 516   FunctionType *FTy = F->getFunctionType();
 517   Type *RetTy = FTy->getReturnType();
 518
 519   assert((FTy->getNumParams() == ArgValues.size() ||
 520           (FTy->isVarArg() && FTy->getNumParams() <= ArgValues.size())) &&
 521          "Wrong number of arguments passed into function!");
 522   assert(FTy->getNumParams() == ArgValues.size() &&
 523          "This doesn't support passing arguments through varargs (yet)!");
 524
 525   // Handle some common cases first.  These cases correspond to common `main'
 526   // prototypes.
 527   if (RetTy->isIntegerTy(32) || RetTy->isVoidTy()) {
 528     switch (ArgValues.size()) {
 529     case 3:
 530       if (FTy->getParamType(0)->isIntegerTy(32) &&
 531           FTy->getParamType(1)->isPointerTy() &&
 532           FTy->getParamType(2)->isPointerTy()) {
 533         int (*PF)(int, char **, const char **) =
 534           (int(*)(int, char **, const char **))(intptr_t)FPtr;
 535
 536         // Call the function.
 537         GenericValue rv;
 538         rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),
 539                                  (char **)GVTOP(ArgValues[1]),
 540                                  (const char **)GVTOP(ArgValues[2])));
 541         return rv;
 542       }
 543       break;
 544     case 2:
 545       if (FTy->getParamType(0)->isIntegerTy(32) &&
 546           FTy->getParamType(1)->isPointerTy()) {
 547         int (*PF)(int, char **) = (int(*)(int, char **))(intptr_t)FPtr;
 548
 549         // Call the function.
 550         GenericValue rv;
 551         rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),
 552                                  (char **)GVTOP(ArgValues[1])));
 553         return rv;
 554       }
 555       break;
 556     case 1:
 557       if (FTy->getNumParams() == 1 &&
 558           FTy->getParamType(0)->isIntegerTy(32)) {
 559         GenericValue rv;
 560         int (*PF)(int) = (int(*)(int))(intptr_t)FPtr;
 561         rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue()));
 562         return rv;
 563       }
 564       break;
 565     }
 566   }
 567
 568   // Handle cases where no arguments are passed first.
 569   if (ArgValues.empty()) {
 570     GenericValue rv;
 571     switch (RetTy->getTypeID()) {
 572     default: llvm_unreachable("Unknown return type for function call!");
 573     case Type::IntegerTyID: {
 574       unsigned BitWidth = cast<IntegerType>(RetTy)->getBitWidth();
 575       if (BitWidth == 1)
 576         rv.IntVal = APInt(BitWidth, ((bool(*)())(intptr_t)FPtr)());
 577       else if (BitWidth <= 8)
 578         rv.IntVal = APInt(BitWidth, ((char(*)())(intptr_t)FPtr)());
 579       else if (BitWidth <= 16)
 580         rv.IntVal = APInt(BitWidth, ((short(*)())(intptr_t)FPtr)());
 581       else if (BitWidth <= 32)
 582         rv.IntVal = APInt(BitWidth, ((int(*)())(intptr_t)FPtr)());
 583       else if (BitWidth <= 64)
 584         rv.IntVal = APInt(BitWidth, ((int64_t(*)())(intptr_t)FPtr)());
 585       else
 586         llvm_unreachable("Integer types > 64 bits not supported");
 587       return rv;
 588     }
 589     case Type::VoidTyID:
 590       rv.IntVal = APInt(32, ((int (*)())(intptr_t)FPtr)(), true);
 591       return rv;
 592     case Type::FloatTyID:
 593       rv.FloatVal = ((float(*)())(intptr_t)FPtr)();
 594       return rv;
 595     case Type::DoubleTyID:
 596       rv.DoubleVal = ((double(*)())(intptr_t)FPtr)();
 597       return rv;
 598     case Type::X86_FP80TyID:
 599     case Type::FP128TyID:
 600     case Type::PPC_FP128TyID:
 601       llvm_unreachable("long double not supported yet");
 602     case Type::PointerTyID:
 603       return PTOGV(((void*(*)())(intptr_t)FPtr)());
 604     }
 605   }
 606
 607   report_fatal_error("MCJIT::runFunction does not support full-featured "
 608                      "argument passing. Please use "
 609                      "ExecutionEngine::getFunctionAddress and cast the result "
 610                      "to the desired function pointer type.");
 611 }
 612
 613 void *MCJIT::getPointerToNamedFunction(StringRef Name, bool AbortOnFailure) {
 614   if (!isSymbolSearchingDisabled()) {
 615     if (auto Sym = Resolver.findSymbol(std::string(Name))) {
 616       if (auto AddrOrErr = Sym.getAddress())
 617         return reinterpret_cast<void*>(
 618                  static_cast<uintptr_t>(*AddrOrErr));
 619     } else if (auto Err = Sym.takeError())
 620       report_fatal_error(std::move(Err));
 621   }
 622
 623   /// If a LazyFunctionCreator is installed, use it to get/create the function.
 624   if (LazyFunctionCreator)
 625     if (void *RP = LazyFunctionCreator(std::string(Name)))
 626       return RP;
 627
 628   if (AbortOnFailure) {
 629     report_fatal_error("Program used external function '"+Name+
 630                        "' which could not be resolved!");
 631   }
 632   return nullptr;
 633 }
 634
 635 void MCJIT::RegisterJITEventListener(JITEventListener *L) {
 636   if (!L)
 637     return;
 638   std::lock_guard<sys::Mutex> locked(lock);
 639   EventListeners.push_back(L);
 640 }
 641
 642 void MCJIT::UnregisterJITEventListener(JITEventListener *L) {
 643   if (!L)
 644     return;
 645   std::lock_guard<sys::Mutex> locked(lock);
 646   auto I = find(reverse(EventListeners), L);
 647   if (I != EventListeners.rend()) {
 648     std::swap(*I, EventListeners.back());
 649     EventListeners.pop_back();
 650   }
 651 }
 652
 653 void MCJIT::notifyObjectLoaded(const object::ObjectFile &Obj,
 654                                const RuntimeDyld::LoadedObjectInfo &L) {
 655   uint64_t Key =
 656       static_cast<uint64_t>(reinterpret_cast<uintptr_t>(Obj.getData().data()));
 657   std::lock_guard<sys::Mutex> locked(lock);
 658   MemMgr->notifyObjectLoaded(this, Obj);
 659   for (JITEventListener *EL : EventListeners)
 660     EL->notifyObjectLoaded(Key, Obj, L);
 661 }
 662
 663 void MCJIT::notifyFreeingObject(const object::ObjectFile &Obj) {
 664   uint64_t Key =
 665       static_cast<uint64_t>(reinterpret_cast<uintptr_t>(Obj.getData().data()));
 666   std::lock_guard<sys::Mutex> locked(lock);
 667   for (JITEventListener *L : EventListeners)
 668     L->notifyFreeingObject(Key);
 669 }
 670
 671 JITSymbol
 672 LinkingSymbolResolver::findSymbol(const std::string &Name) {
 673   auto Result = ParentEngine.findSymbol(Name, false);
 674   if (Result)
 675     return Result;
 676   if (ParentEngine.isSymbolSearchingDisabled())
 677     return nullptr;
 678   return ClientResolver->findSymbol(Name);
 679 }
 680
 681 void LinkingSymbolResolver::anchor() {}