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      1 //===- ExecutionEngine.h - Abstract Execution Engine Interface --*- C++ -*-===//
      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 abstract interface that implements execution support
     11 // for LLVM.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_EXECUTIONENGINE_EXECUTIONENGINE_H
     16 #define LLVM_EXECUTIONENGINE_EXECUTIONENGINE_H
     17 
     18 #include "RuntimeDyld.h"
     19 #include "llvm-c/ExecutionEngine.h"
     20 #include "llvm/ADT/SmallVector.h"
     21 #include "llvm/ADT/StringRef.h"
     22 #include "llvm/IR/Module.h"
     23 #include "llvm/IR/ValueHandle.h"
     24 #include "llvm/IR/ValueMap.h"
     25 #include "llvm/Object/Binary.h"
     26 #include "llvm/Support/ErrorHandling.h"
     27 #include "llvm/Support/Mutex.h"
     28 #include "llvm/Target/TargetMachine.h"
     29 #include "llvm/Target/TargetOptions.h"
     30 #include <functional>
     31 #include <map>
     32 #include <string>
     33 #include <vector>
     34 
     35 namespace llvm {
     36 
     37 struct GenericValue;
     38 class Constant;
     39 class DataLayout;
     40 class ExecutionEngine;
     41 class Function;
     42 class GlobalVariable;
     43 class GlobalValue;
     44 class JITEventListener;
     45 class MachineCodeInfo;
     46 class MCJITMemoryManager;
     47 class MutexGuard;
     48 class ObjectCache;
     49 class RTDyldMemoryManager;
     50 class Triple;
     51 class Type;
     52 
     53 namespace object {
     54   class Archive;
     55   class ObjectFile;
     56 }
     57 
     58 /// \brief Helper class for helping synchronize access to the global address map
     59 /// table.  Access to this class should be serialized under a mutex.
     60 class ExecutionEngineState {
     61 public:
     62   typedef StringMap<uint64_t> GlobalAddressMapTy;
     63 
     64 private:
     65 
     66   /// GlobalAddressMap - A mapping between LLVM global symbol names values and
     67   /// their actualized version...
     68   GlobalAddressMapTy GlobalAddressMap;
     69 
     70   /// GlobalAddressReverseMap - This is the reverse mapping of GlobalAddressMap,
     71   /// used to convert raw addresses into the LLVM global value that is emitted
     72   /// at the address.  This map is not computed unless getGlobalValueAtAddress
     73   /// is called at some point.
     74   std::map<uint64_t, std::string> GlobalAddressReverseMap;
     75 
     76 public:
     77 
     78   GlobalAddressMapTy &getGlobalAddressMap() {
     79     return GlobalAddressMap;
     80   }
     81 
     82   std::map<uint64_t, std::string> &getGlobalAddressReverseMap() {
     83     return GlobalAddressReverseMap;
     84   }
     85 
     86   /// \brief Erase an entry from the mapping table.
     87   ///
     88   /// \returns The address that \p ToUnmap was happed to.
     89   uint64_t RemoveMapping(StringRef Name);
     90 };
     91 
     92 using FunctionCreator = std::function<void *(const std::string &)>;
     93 
     94 /// \brief Abstract interface for implementation execution of LLVM modules,
     95 /// designed to support both interpreter and just-in-time (JIT) compiler
     96 /// implementations.
     97 class ExecutionEngine {
     98   /// The state object holding the global address mapping, which must be
     99   /// accessed synchronously.
    100   //
    101   // FIXME: There is no particular need the entire map needs to be
    102   // synchronized.  Wouldn't a reader-writer design be better here?
    103   ExecutionEngineState EEState;
    104 
    105   /// The target data for the platform for which execution is being performed.
    106   ///
    107   /// Note: the DataLayout is LLVMContext specific because it has an
    108   /// internal cache based on type pointers. It makes unsafe to reuse the
    109   /// ExecutionEngine across context, we don't enforce this rule but undefined
    110   /// behavior can occurs if the user tries to do it.
    111   const DataLayout DL;
    112 
    113   /// Whether lazy JIT compilation is enabled.
    114   bool CompilingLazily;
    115 
    116   /// Whether JIT compilation of external global variables is allowed.
    117   bool GVCompilationDisabled;
    118 
    119   /// Whether the JIT should perform lookups of external symbols (e.g.,
    120   /// using dlsym).
    121   bool SymbolSearchingDisabled;
    122 
    123   /// Whether the JIT should verify IR modules during compilation.
    124   bool VerifyModules;
    125 
    126   friend class EngineBuilder;  // To allow access to JITCtor and InterpCtor.
    127 
    128 protected:
    129   /// The list of Modules that we are JIT'ing from.  We use a SmallVector to
    130   /// optimize for the case where there is only one module.
    131   SmallVector<std::unique_ptr<Module>, 1> Modules;
    132 
    133   /// getMemoryforGV - Allocate memory for a global variable.
    134   virtual char *getMemoryForGV(const GlobalVariable *GV);
    135 
    136   static ExecutionEngine *(*MCJITCtor)(
    137                                 std::unique_ptr<Module> M,
    138                                 std::string *ErrorStr,
    139                                 std::shared_ptr<MCJITMemoryManager> MM,
    140                                 std::shared_ptr<JITSymbolResolver> SR,
    141                                 std::unique_ptr<TargetMachine> TM);
    142 
    143   static ExecutionEngine *(*OrcMCJITReplacementCtor)(
    144                                 std::string *ErrorStr,
    145                                 std::shared_ptr<MCJITMemoryManager> MM,
    146                                 std::shared_ptr<JITSymbolResolver> SR,
    147                                 std::unique_ptr<TargetMachine> TM);
    148 
    149   static ExecutionEngine *(*InterpCtor)(std::unique_ptr<Module> M,
    150                                         std::string *ErrorStr);
    151 
    152   /// LazyFunctionCreator - If an unknown function is needed, this function
    153   /// pointer is invoked to create it.  If this returns null, the JIT will
    154   /// abort.
    155   FunctionCreator LazyFunctionCreator;
    156 
    157   /// getMangledName - Get mangled name.
    158   std::string getMangledName(const GlobalValue *GV);
    159 
    160 public:
    161   /// lock - This lock protects the ExecutionEngine and MCJIT classes. It must
    162   /// be held while changing the internal state of any of those classes.
    163   sys::Mutex lock;
    164 
    165   //===--------------------------------------------------------------------===//
    166   //  ExecutionEngine Startup
    167   //===--------------------------------------------------------------------===//
    168 
    169   virtual ~ExecutionEngine();
    170 
    171   /// Add a Module to the list of modules that we can JIT from.
    172   virtual void addModule(std::unique_ptr<Module> M) {
    173     Modules.push_back(std::move(M));
    174   }
    175 
    176   /// addObjectFile - Add an ObjectFile to the execution engine.
    177   ///
    178   /// This method is only supported by MCJIT.  MCJIT will immediately load the
    179   /// object into memory and adds its symbols to the list used to resolve
    180   /// external symbols while preparing other objects for execution.
    181   ///
    182   /// Objects added using this function will not be made executable until
    183   /// needed by another object.
    184   ///
    185   /// MCJIT will take ownership of the ObjectFile.
    186   virtual void addObjectFile(std::unique_ptr<object::ObjectFile> O);
    187   virtual void addObjectFile(object::OwningBinary<object::ObjectFile> O);
    188 
    189   /// addArchive - Add an Archive to the execution engine.
    190   ///
    191   /// This method is only supported by MCJIT.  MCJIT will use the archive to
    192   /// resolve external symbols in objects it is loading.  If a symbol is found
    193   /// in the Archive the contained object file will be extracted (in memory)
    194   /// and loaded for possible execution.
    195   virtual void addArchive(object::OwningBinary<object::Archive> A);
    196 
    197   //===--------------------------------------------------------------------===//
    198 
    199   const DataLayout &getDataLayout() const { return DL; }
    200 
    201   /// removeModule - Removes a Module from the list of modules, but does not
    202   /// free the module's memory. Returns true if M is found, in which case the
    203   /// caller assumes responsibility for deleting the module.
    204   //
    205   // FIXME: This stealth ownership transfer is horrible. This will probably be
    206   //        fixed by deleting ExecutionEngine.
    207   virtual bool removeModule(Module *M);
    208 
    209   /// FindFunctionNamed - Search all of the active modules to find the function that
    210   /// defines FnName.  This is very slow operation and shouldn't be used for
    211   /// general code.
    212   virtual Function *FindFunctionNamed(StringRef FnName);
    213 
    214   /// FindGlobalVariableNamed - Search all of the active modules to find the global variable
    215   /// that defines Name.  This is very slow operation and shouldn't be used for
    216   /// general code.
    217   virtual GlobalVariable *FindGlobalVariableNamed(StringRef Name, bool AllowInternal = false);
    218 
    219   /// runFunction - Execute the specified function with the specified arguments,
    220   /// and return the result.
    221   ///
    222   /// For MCJIT execution engines, clients are encouraged to use the
    223   /// "GetFunctionAddress" method (rather than runFunction) and cast the
    224   /// returned uint64_t to the desired function pointer type. However, for
    225   /// backwards compatibility MCJIT's implementation can execute 'main-like'
    226   /// function (i.e. those returning void or int, and taking either no
    227   /// arguments or (int, char*[])).
    228   virtual GenericValue runFunction(Function *F,
    229                                    ArrayRef<GenericValue> ArgValues) = 0;
    230 
    231   /// getPointerToNamedFunction - This method returns the address of the
    232   /// specified function by using the dlsym function call.  As such it is only
    233   /// useful for resolving library symbols, not code generated symbols.
    234   ///
    235   /// If AbortOnFailure is false and no function with the given name is
    236   /// found, this function silently returns a null pointer. Otherwise,
    237   /// it prints a message to stderr and aborts.
    238   ///
    239   /// This function is deprecated for the MCJIT execution engine.
    240   virtual void *getPointerToNamedFunction(StringRef Name,
    241                                           bool AbortOnFailure = true) = 0;
    242 
    243   /// mapSectionAddress - map a section to its target address space value.
    244   /// Map the address of a JIT section as returned from the memory manager
    245   /// to the address in the target process as the running code will see it.
    246   /// This is the address which will be used for relocation resolution.
    247   virtual void mapSectionAddress(const void *LocalAddress,
    248                                  uint64_t TargetAddress) {
    249     llvm_unreachable("Re-mapping of section addresses not supported with this "
    250                      "EE!");
    251   }
    252 
    253   /// generateCodeForModule - Run code generation for the specified module and
    254   /// load it into memory.
    255   ///
    256   /// When this function has completed, all code and data for the specified
    257   /// module, and any module on which this module depends, will be generated
    258   /// and loaded into memory, but relocations will not yet have been applied
    259   /// and all memory will be readable and writable but not executable.
    260   ///
    261   /// This function is primarily useful when generating code for an external
    262   /// target, allowing the client an opportunity to remap section addresses
    263   /// before relocations are applied.  Clients that intend to execute code
    264   /// locally can use the getFunctionAddress call, which will generate code
    265   /// and apply final preparations all in one step.
    266   ///
    267   /// This method has no effect for the interpeter.
    268   virtual void generateCodeForModule(Module *M) {}
    269 
    270   /// finalizeObject - ensure the module is fully processed and is usable.
    271   ///
    272   /// It is the user-level function for completing the process of making the
    273   /// object usable for execution.  It should be called after sections within an
    274   /// object have been relocated using mapSectionAddress.  When this method is
    275   /// called the MCJIT execution engine will reapply relocations for a loaded
    276   /// object.  This method has no effect for the interpeter.
    277   virtual void finalizeObject() {}
    278 
    279   /// runStaticConstructorsDestructors - This method is used to execute all of
    280   /// the static constructors or destructors for a program.
    281   ///
    282   /// \param isDtors - Run the destructors instead of constructors.
    283   virtual void runStaticConstructorsDestructors(bool isDtors);
    284 
    285   /// This method is used to execute all of the static constructors or
    286   /// destructors for a particular module.
    287   ///
    288   /// \param isDtors - Run the destructors instead of constructors.
    289   void runStaticConstructorsDestructors(Module &module, bool isDtors);
    290 
    291 
    292   /// runFunctionAsMain - This is a helper function which wraps runFunction to
    293   /// handle the common task of starting up main with the specified argc, argv,
    294   /// and envp parameters.
    295   int runFunctionAsMain(Function *Fn, const std::vector<std::string> &argv,
    296                         const char * const * envp);
    297 
    298 
    299   /// addGlobalMapping - Tell the execution engine that the specified global is
    300   /// at the specified location.  This is used internally as functions are JIT'd
    301   /// and as global variables are laid out in memory.  It can and should also be
    302   /// used by clients of the EE that want to have an LLVM global overlay
    303   /// existing data in memory. Values to be mapped should be named, and have
    304   /// external or weak linkage. Mappings are automatically removed when their
    305   /// GlobalValue is destroyed.
    306   void addGlobalMapping(const GlobalValue *GV, void *Addr);
    307   void addGlobalMapping(StringRef Name, uint64_t Addr);
    308 
    309   /// clearAllGlobalMappings - Clear all global mappings and start over again,
    310   /// for use in dynamic compilation scenarios to move globals.
    311   void clearAllGlobalMappings();
    312 
    313   /// clearGlobalMappingsFromModule - Clear all global mappings that came from a
    314   /// particular module, because it has been removed from the JIT.
    315   void clearGlobalMappingsFromModule(Module *M);
    316 
    317   /// updateGlobalMapping - Replace an existing mapping for GV with a new
    318   /// address.  This updates both maps as required.  If "Addr" is null, the
    319   /// entry for the global is removed from the mappings.  This returns the old
    320   /// value of the pointer, or null if it was not in the map.
    321   uint64_t updateGlobalMapping(const GlobalValue *GV, void *Addr);
    322   uint64_t updateGlobalMapping(StringRef Name, uint64_t Addr);
    323 
    324   /// getAddressToGlobalIfAvailable - This returns the address of the specified
    325   /// global symbol.
    326   uint64_t getAddressToGlobalIfAvailable(StringRef S);
    327 
    328   /// getPointerToGlobalIfAvailable - This returns the address of the specified
    329   /// global value if it is has already been codegen'd, otherwise it returns
    330   /// null.
    331   void *getPointerToGlobalIfAvailable(StringRef S);
    332   void *getPointerToGlobalIfAvailable(const GlobalValue *GV);
    333 
    334   /// getPointerToGlobal - This returns the address of the specified global
    335   /// value. This may involve code generation if it's a function.
    336   ///
    337   /// This function is deprecated for the MCJIT execution engine.  Use
    338   /// getGlobalValueAddress instead.
    339   void *getPointerToGlobal(const GlobalValue *GV);
    340 
    341   /// getPointerToFunction - The different EE's represent function bodies in
    342   /// different ways.  They should each implement this to say what a function
    343   /// pointer should look like.  When F is destroyed, the ExecutionEngine will
    344   /// remove its global mapping and free any machine code.  Be sure no threads
    345   /// are running inside F when that happens.
    346   ///
    347   /// This function is deprecated for the MCJIT execution engine.  Use
    348   /// getFunctionAddress instead.
    349   virtual void *getPointerToFunction(Function *F) = 0;
    350 
    351   /// getPointerToFunctionOrStub - If the specified function has been
    352   /// code-gen'd, return a pointer to the function.  If not, compile it, or use
    353   /// a stub to implement lazy compilation if available.  See
    354   /// getPointerToFunction for the requirements on destroying F.
    355   ///
    356   /// This function is deprecated for the MCJIT execution engine.  Use
    357   /// getFunctionAddress instead.
    358   virtual void *getPointerToFunctionOrStub(Function *F) {
    359     // Default implementation, just codegen the function.
    360     return getPointerToFunction(F);
    361   }
    362 
    363   /// getGlobalValueAddress - Return the address of the specified global
    364   /// value. This may involve code generation.
    365   ///
    366   /// This function should not be called with the interpreter engine.
    367   virtual uint64_t getGlobalValueAddress(const std::string &Name) {
    368     // Default implementation for the interpreter.  MCJIT will override this.
    369     // JIT and interpreter clients should use getPointerToGlobal instead.
    370     return 0;
    371   }
    372 
    373   /// getFunctionAddress - Return the address of the specified function.
    374   /// This may involve code generation.
    375   virtual uint64_t getFunctionAddress(const std::string &Name) {
    376     // Default implementation for the interpreter.  MCJIT will override this.
    377     // Interpreter clients should use getPointerToFunction instead.
    378     return 0;
    379   }
    380 
    381   /// getGlobalValueAtAddress - Return the LLVM global value object that starts
    382   /// at the specified address.
    383   ///
    384   const GlobalValue *getGlobalValueAtAddress(void *Addr);
    385 
    386   /// StoreValueToMemory - Stores the data in Val of type Ty at address Ptr.
    387   /// Ptr is the address of the memory at which to store Val, cast to
    388   /// GenericValue *.  It is not a pointer to a GenericValue containing the
    389   /// address at which to store Val.
    390   void StoreValueToMemory(const GenericValue &Val, GenericValue *Ptr,
    391                           Type *Ty);
    392 
    393   void InitializeMemory(const Constant *Init, void *Addr);
    394 
    395   /// getOrEmitGlobalVariable - Return the address of the specified global
    396   /// variable, possibly emitting it to memory if needed.  This is used by the
    397   /// Emitter.
    398   ///
    399   /// This function is deprecated for the MCJIT execution engine.  Use
    400   /// getGlobalValueAddress instead.
    401   virtual void *getOrEmitGlobalVariable(const GlobalVariable *GV) {
    402     return getPointerToGlobal((const GlobalValue *)GV);
    403   }
    404 
    405   /// Registers a listener to be called back on various events within
    406   /// the JIT.  See JITEventListener.h for more details.  Does not
    407   /// take ownership of the argument.  The argument may be NULL, in
    408   /// which case these functions do nothing.
    409   virtual void RegisterJITEventListener(JITEventListener *) {}
    410   virtual void UnregisterJITEventListener(JITEventListener *) {}
    411 
    412   /// Sets the pre-compiled object cache.  The ownership of the ObjectCache is
    413   /// not changed.  Supported by MCJIT but not the interpreter.
    414   virtual void setObjectCache(ObjectCache *) {
    415     llvm_unreachable("No support for an object cache");
    416   }
    417 
    418   /// setProcessAllSections (MCJIT Only): By default, only sections that are
    419   /// "required for execution" are passed to the RTDyldMemoryManager, and other
    420   /// sections are discarded. Passing 'true' to this method will cause
    421   /// RuntimeDyld to pass all sections to its RTDyldMemoryManager regardless
    422   /// of whether they are "required to execute" in the usual sense.
    423   ///
    424   /// Rationale: Some MCJIT clients want to be able to inspect metadata
    425   /// sections (e.g. Dwarf, Stack-maps) to enable functionality or analyze
    426   /// performance. Passing these sections to the memory manager allows the
    427   /// client to make policy about the relevant sections, rather than having
    428   /// MCJIT do it.
    429   virtual void setProcessAllSections(bool ProcessAllSections) {
    430     llvm_unreachable("No support for ProcessAllSections option");
    431   }
    432 
    433   /// Return the target machine (if available).
    434   virtual TargetMachine *getTargetMachine() { return nullptr; }
    435 
    436   /// DisableLazyCompilation - When lazy compilation is off (the default), the
    437   /// JIT will eagerly compile every function reachable from the argument to
    438   /// getPointerToFunction.  If lazy compilation is turned on, the JIT will only
    439   /// compile the one function and emit stubs to compile the rest when they're
    440   /// first called.  If lazy compilation is turned off again while some lazy
    441   /// stubs are still around, and one of those stubs is called, the program will
    442   /// abort.
    443   ///
    444   /// In order to safely compile lazily in a threaded program, the user must
    445   /// ensure that 1) only one thread at a time can call any particular lazy
    446   /// stub, and 2) any thread modifying LLVM IR must hold the JIT's lock
    447   /// (ExecutionEngine::lock) or otherwise ensure that no other thread calls a
    448   /// lazy stub.  See http://llvm.org/PR5184 for details.
    449   void DisableLazyCompilation(bool Disabled = true) {
    450     CompilingLazily = !Disabled;
    451   }
    452   bool isCompilingLazily() const {
    453     return CompilingLazily;
    454   }
    455 
    456   /// DisableGVCompilation - If called, the JIT will abort if it's asked to
    457   /// allocate space and populate a GlobalVariable that is not internal to
    458   /// the module.
    459   void DisableGVCompilation(bool Disabled = true) {
    460     GVCompilationDisabled = Disabled;
    461   }
    462   bool isGVCompilationDisabled() const {
    463     return GVCompilationDisabled;
    464   }
    465 
    466   /// DisableSymbolSearching - If called, the JIT will not try to lookup unknown
    467   /// symbols with dlsym.  A client can still use InstallLazyFunctionCreator to
    468   /// resolve symbols in a custom way.
    469   void DisableSymbolSearching(bool Disabled = true) {
    470     SymbolSearchingDisabled = Disabled;
    471   }
    472   bool isSymbolSearchingDisabled() const {
    473     return SymbolSearchingDisabled;
    474   }
    475 
    476   /// Enable/Disable IR module verification.
    477   ///
    478   /// Note: Module verification is enabled by default in Debug builds, and
    479   /// disabled by default in Release. Use this method to override the default.
    480   void setVerifyModules(bool Verify) {
    481     VerifyModules = Verify;
    482   }
    483   bool getVerifyModules() const {
    484     return VerifyModules;
    485   }
    486 
    487   /// InstallLazyFunctionCreator - If an unknown function is needed, the
    488   /// specified function pointer is invoked to create it.  If it returns null,
    489   /// the JIT will abort.
    490   void InstallLazyFunctionCreator(FunctionCreator C) {
    491     LazyFunctionCreator = std::move(C);
    492   }
    493 
    494 protected:
    495   ExecutionEngine(DataLayout DL) : DL(std::move(DL)) {}
    496   explicit ExecutionEngine(DataLayout DL, std::unique_ptr<Module> M);
    497   explicit ExecutionEngine(std::unique_ptr<Module> M);
    498 
    499   void emitGlobals();
    500 
    501   void EmitGlobalVariable(const GlobalVariable *GV);
    502 
    503   GenericValue getConstantValue(const Constant *C);
    504   void LoadValueFromMemory(GenericValue &Result, GenericValue *Ptr,
    505                            Type *Ty);
    506 
    507 private:
    508   void Init(std::unique_ptr<Module> M);
    509 };
    510 
    511 namespace EngineKind {
    512   // These are actually bitmasks that get or-ed together.
    513   enum Kind {
    514     JIT         = 0x1,
    515     Interpreter = 0x2
    516   };
    517   const static Kind Either = (Kind)(JIT | Interpreter);
    518 }
    519 
    520 /// Builder class for ExecutionEngines. Use this by stack-allocating a builder,
    521 /// chaining the various set* methods, and terminating it with a .create()
    522 /// call.
    523 class EngineBuilder {
    524 private:
    525   std::unique_ptr<Module> M;
    526   EngineKind::Kind WhichEngine;
    527   std::string *ErrorStr;
    528   CodeGenOpt::Level OptLevel;
    529   std::shared_ptr<MCJITMemoryManager> MemMgr;
    530   std::shared_ptr<JITSymbolResolver> Resolver;
    531   TargetOptions Options;
    532   Optional<Reloc::Model> RelocModel;
    533   CodeModel::Model CMModel;
    534   std::string MArch;
    535   std::string MCPU;
    536   SmallVector<std::string, 4> MAttrs;
    537   bool VerifyModules;
    538   bool UseOrcMCJITReplacement;
    539 
    540 public:
    541   /// Default constructor for EngineBuilder.
    542   EngineBuilder();
    543 
    544   /// Constructor for EngineBuilder.
    545   EngineBuilder(std::unique_ptr<Module> M);
    546 
    547   // Out-of-line since we don't have the def'n of RTDyldMemoryManager here.
    548   ~EngineBuilder();
    549 
    550   /// setEngineKind - Controls whether the user wants the interpreter, the JIT,
    551   /// or whichever engine works.  This option defaults to EngineKind::Either.
    552   EngineBuilder &setEngineKind(EngineKind::Kind w) {
    553     WhichEngine = w;
    554     return *this;
    555   }
    556 
    557   /// setMCJITMemoryManager - Sets the MCJIT memory manager to use. This allows
    558   /// clients to customize their memory allocation policies for the MCJIT. This
    559   /// is only appropriate for the MCJIT; setting this and configuring the builder
    560   /// to create anything other than MCJIT will cause a runtime error. If create()
    561   /// is called and is successful, the created engine takes ownership of the
    562   /// memory manager. This option defaults to NULL.
    563   EngineBuilder &setMCJITMemoryManager(std::unique_ptr<RTDyldMemoryManager> mcjmm);
    564 
    565   EngineBuilder&
    566   setMemoryManager(std::unique_ptr<MCJITMemoryManager> MM);
    567 
    568   EngineBuilder&
    569   setSymbolResolver(std::unique_ptr<JITSymbolResolver> SR);
    570 
    571   /// setErrorStr - Set the error string to write to on error.  This option
    572   /// defaults to NULL.
    573   EngineBuilder &setErrorStr(std::string *e) {
    574     ErrorStr = e;
    575     return *this;
    576   }
    577 
    578   /// setOptLevel - Set the optimization level for the JIT.  This option
    579   /// defaults to CodeGenOpt::Default.
    580   EngineBuilder &setOptLevel(CodeGenOpt::Level l) {
    581     OptLevel = l;
    582     return *this;
    583   }
    584 
    585   /// setTargetOptions - Set the target options that the ExecutionEngine
    586   /// target is using. Defaults to TargetOptions().
    587   EngineBuilder &setTargetOptions(const TargetOptions &Opts) {
    588     Options = Opts;
    589     return *this;
    590   }
    591 
    592   /// setRelocationModel - Set the relocation model that the ExecutionEngine
    593   /// target is using. Defaults to target specific default "Reloc::Default".
    594   EngineBuilder &setRelocationModel(Reloc::Model RM) {
    595     RelocModel = RM;
    596     return *this;
    597   }
    598 
    599   /// setCodeModel - Set the CodeModel that the ExecutionEngine target
    600   /// data is using. Defaults to target specific default
    601   /// "CodeModel::JITDefault".
    602   EngineBuilder &setCodeModel(CodeModel::Model M) {
    603     CMModel = M;
    604     return *this;
    605   }
    606 
    607   /// setMArch - Override the architecture set by the Module's triple.
    608   EngineBuilder &setMArch(StringRef march) {
    609     MArch.assign(march.begin(), march.end());
    610     return *this;
    611   }
    612 
    613   /// setMCPU - Target a specific cpu type.
    614   EngineBuilder &setMCPU(StringRef mcpu) {
    615     MCPU.assign(mcpu.begin(), mcpu.end());
    616     return *this;
    617   }
    618 
    619   /// setVerifyModules - Set whether the JIT implementation should verify
    620   /// IR modules during compilation.
    621   EngineBuilder &setVerifyModules(bool Verify) {
    622     VerifyModules = Verify;
    623     return *this;
    624   }
    625 
    626   /// setMAttrs - Set cpu-specific attributes.
    627   template<typename StringSequence>
    628   EngineBuilder &setMAttrs(const StringSequence &mattrs) {
    629     MAttrs.clear();
    630     MAttrs.append(mattrs.begin(), mattrs.end());
    631     return *this;
    632   }
    633 
    634   // \brief Use OrcMCJITReplacement instead of MCJIT. Off by default.
    635   void setUseOrcMCJITReplacement(bool UseOrcMCJITReplacement) {
    636     this->UseOrcMCJITReplacement = UseOrcMCJITReplacement;
    637   }
    638 
    639   TargetMachine *selectTarget();
    640 
    641   /// selectTarget - Pick a target either via -march or by guessing the native
    642   /// arch.  Add any CPU features specified via -mcpu or -mattr.
    643   TargetMachine *selectTarget(const Triple &TargetTriple,
    644                               StringRef MArch,
    645                               StringRef MCPU,
    646                               const SmallVectorImpl<std::string>& MAttrs);
    647 
    648   ExecutionEngine *create() {
    649     return create(selectTarget());
    650   }
    651 
    652   ExecutionEngine *create(TargetMachine *TM);
    653 };
    654 
    655 // Create wrappers for C Binding types (see CBindingWrapping.h).
    656 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ExecutionEngine, LLVMExecutionEngineRef)
    657 
    658 } // End llvm namespace
    659 
    660 #endif
    661