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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 "llvm-c/ExecutionEngine.h"
     19 #include "llvm/ADT/ArrayRef.h"
     20 #include "llvm/ADT/Optional.h"
     21 #include "llvm/ADT/SmallVector.h"
     22 #include "llvm/ADT/StringMap.h"
     23 #include "llvm/ADT/StringRef.h"
     24 #include "llvm/ExecutionEngine/JITSymbol.h"
     25 #include "llvm/IR/DataLayout.h"
     26 #include "llvm/IR/Module.h"
     27 #include "llvm/Object/Binary.h"
     28 #include "llvm/Support/CBindingWrapping.h"
     29 #include "llvm/Support/CodeGen.h"
     30 #include "llvm/Support/ErrorHandling.h"
     31 #include "llvm/Support/Mutex.h"
     32 #include "llvm/Target/TargetMachine.h"
     33 #include "llvm/Target/TargetOptions.h"
     34 #include <algorithm>
     35 #include <cstdint>
     36 #include <functional>
     37 #include <map>
     38 #include <memory>
     39 #include <string>
     40 #include <vector>
     41 
     42 namespace llvm {
     43 
     44 class Constant;
     45 class Function;
     46 struct GenericValue;
     47 class GlobalValue;
     48 class GlobalVariable;
     49 class JITEventListener;
     50 class MCJITMemoryManager;
     51 class ObjectCache;
     52 class RTDyldMemoryManager;
     53 class Triple;
     54 class Type;
     55 
     56 namespace object {
     57 
     58 class Archive;
     59 class ObjectFile;
     60 
     61 } // end namespace object
     62 
     63 /// Helper class for helping synchronize access to the global address map
     64 /// table.  Access to this class should be serialized under a mutex.
     65 class ExecutionEngineState {
     66 public:
     67   using GlobalAddressMapTy = StringMap<uint64_t>;
     68 
     69 private:
     70   /// GlobalAddressMap - A mapping between LLVM global symbol names values and
     71   /// their actualized version...
     72   GlobalAddressMapTy GlobalAddressMap;
     73 
     74   /// GlobalAddressReverseMap - This is the reverse mapping of GlobalAddressMap,
     75   /// used to convert raw addresses into the LLVM global value that is emitted
     76   /// at the address.  This map is not computed unless getGlobalValueAtAddress
     77   /// is called at some point.
     78   std::map<uint64_t, std::string> GlobalAddressReverseMap;
     79 
     80 public:
     81   GlobalAddressMapTy &getGlobalAddressMap() {
     82     return GlobalAddressMap;
     83   }
     84 
     85   std::map<uint64_t, std::string> &getGlobalAddressReverseMap() {
     86     return GlobalAddressReverseMap;
     87   }
     88 
     89   /// Erase an entry from the mapping table.
     90   ///
     91   /// \returns The address that \p ToUnmap was happed to.
     92   uint64_t RemoveMapping(StringRef Name);
     93 };
     94 
     95 using FunctionCreator = std::function<void *(const std::string &)>;
     96 
     97 /// Abstract interface for implementation execution of LLVM modules,
     98 /// designed to support both interpreter and just-in-time (JIT) compiler
     99 /// implementations.
    100 class ExecutionEngine {
    101   /// The state object holding the global address mapping, which must be
    102   /// accessed synchronously.
    103   //
    104   // FIXME: There is no particular need the entire map needs to be
    105   // synchronized.  Wouldn't a reader-writer design be better here?
    106   ExecutionEngineState EEState;
    107 
    108   /// The target data for the platform for which execution is being performed.
    109   ///
    110   /// Note: the DataLayout is LLVMContext specific because it has an
    111   /// internal cache based on type pointers. It makes unsafe to reuse the
    112   /// ExecutionEngine across context, we don't enforce this rule but undefined
    113   /// behavior can occurs if the user tries to do it.
    114   const DataLayout DL;
    115 
    116   /// Whether lazy JIT compilation is enabled.
    117   bool CompilingLazily;
    118 
    119   /// Whether JIT compilation of external global variables is allowed.
    120   bool GVCompilationDisabled;
    121 
    122   /// Whether the JIT should perform lookups of external symbols (e.g.,
    123   /// using dlsym).
    124   bool SymbolSearchingDisabled;
    125 
    126   /// Whether the JIT should verify IR modules during compilation.
    127   bool VerifyModules;
    128 
    129   friend class EngineBuilder;  // To allow access to JITCtor and InterpCtor.
    130 
    131 protected:
    132   /// The list of Modules that we are JIT'ing from.  We use a SmallVector to
    133   /// optimize for the case where there is only one module.
    134   SmallVector<std::unique_ptr<Module>, 1> Modules;
    135 
    136   /// getMemoryforGV - Allocate memory for a global variable.
    137   virtual char *getMemoryForGV(const GlobalVariable *GV);
    138 
    139   static ExecutionEngine *(*MCJITCtor)(
    140       std::unique_ptr<Module> M, std::string *ErrorStr,
    141       std::shared_ptr<MCJITMemoryManager> MM,
    142       std::shared_ptr<LegacyJITSymbolResolver> SR,
    143       std::unique_ptr<TargetMachine> TM);
    144 
    145   static ExecutionEngine *(*OrcMCJITReplacementCtor)(
    146       std::string *ErrorStr, std::shared_ptr<MCJITMemoryManager> MM,
    147       std::shared_ptr<LegacyJITSymbolResolver> SR,
    148       std::unique_ptr<TargetMachine> TM);
    149 
    150   static ExecutionEngine *(*InterpCtor)(std::unique_ptr<Module> M,
    151                                         std::string *ErrorStr);
    152 
    153   /// LazyFunctionCreator - If an unknown function is needed, this function
    154   /// pointer is invoked to create it.  If this returns null, the JIT will
    155   /// abort.
    156   FunctionCreator LazyFunctionCreator;
    157 
    158   /// getMangledName - Get mangled name.
    159   std::string getMangledName(const GlobalValue *GV);
    160 
    161 public:
    162   /// lock - This lock protects the ExecutionEngine and MCJIT classes. It must
    163   /// be held while changing the internal state of any of those classes.
    164   sys::Mutex lock;
    165 
    166   //===--------------------------------------------------------------------===//
    167   //  ExecutionEngine Startup
    168   //===--------------------------------------------------------------------===//
    169 
    170   virtual ~ExecutionEngine();
    171 
    172   /// Add a Module to the list of modules that we can JIT from.
    173   virtual void addModule(std::unique_ptr<Module> M) {
    174     Modules.push_back(std::move(M));
    175   }
    176 
    177   /// addObjectFile - Add an ObjectFile to the execution engine.
    178   ///
    179   /// This method is only supported by MCJIT.  MCJIT will immediately load the
    180   /// object into memory and adds its symbols to the list used to resolve
    181   /// external symbols while preparing other objects for execution.
    182   ///
    183   /// Objects added using this function will not be made executable until
    184   /// needed by another object.
    185   ///
    186   /// MCJIT will take ownership of the ObjectFile.
    187   virtual void addObjectFile(std::unique_ptr<object::ObjectFile> O);
    188   virtual void addObjectFile(object::OwningBinary<object::ObjectFile> O);
    189 
    190   /// addArchive - Add an Archive to the execution engine.
    191   ///
    192   /// This method is only supported by MCJIT.  MCJIT will use the archive to
    193   /// resolve external symbols in objects it is loading.  If a symbol is found
    194   /// in the Archive the contained object file will be extracted (in memory)
    195   /// and loaded for possible execution.
    196   virtual void addArchive(object::OwningBinary<object::Archive> A);
    197 
    198   //===--------------------------------------------------------------------===//
    199 
    200   const DataLayout &getDataLayout() const { return DL; }
    201 
    202   /// removeModule - Removes a Module from the list of modules, but does not
    203   /// free the module's memory. Returns true if M is found, in which case the
    204   /// caller assumes responsibility for deleting the module.
    205   //
    206   // FIXME: This stealth ownership transfer is horrible. This will probably be
    207   //        fixed by deleting ExecutionEngine.
    208   virtual bool removeModule(Module *M);
    209 
    210   /// FindFunctionNamed - Search all of the active modules to find the function that
    211   /// defines FnName.  This is very slow operation and shouldn't be used for
    212   /// general code.
    213   virtual Function *FindFunctionNamed(StringRef FnName);
    214 
    215   /// FindGlobalVariableNamed - Search all of the active modules to find the global variable
    216   /// that defines Name.  This is very slow operation and shouldn't be used for
    217   /// general code.
    218   virtual GlobalVariable *FindGlobalVariableNamed(StringRef Name, bool AllowInternal = false);
    219 
    220   /// runFunction - Execute the specified function with the specified arguments,
    221   /// and return the result.
    222   ///
    223   /// For MCJIT execution engines, clients are encouraged to use the
    224   /// "GetFunctionAddress" method (rather than runFunction) and cast the
    225   /// returned uint64_t to the desired function pointer type. However, for
    226   /// backwards compatibility MCJIT's implementation can execute 'main-like'
    227   /// function (i.e. those returning void or int, and taking either no
    228   /// arguments or (int, char*[])).
    229   virtual GenericValue runFunction(Function *F,
    230                                    ArrayRef<GenericValue> ArgValues) = 0;
    231 
    232   /// getPointerToNamedFunction - This method returns the address of the
    233   /// specified function by using the dlsym function call.  As such it is only
    234   /// useful for resolving library symbols, not code generated symbols.
    235   ///
    236   /// If AbortOnFailure is false and no function with the given name is
    237   /// found, this function silently returns a null pointer. Otherwise,
    238   /// it prints a message to stderr and aborts.
    239   ///
    240   /// This function is deprecated for the MCJIT execution engine.
    241   virtual void *getPointerToNamedFunction(StringRef Name,
    242                                           bool AbortOnFailure = true) = 0;
    243 
    244   /// mapSectionAddress - map a section to its target address space value.
    245   /// Map the address of a JIT section as returned from the memory manager
    246   /// to the address in the target process as the running code will see it.
    247   /// This is the address which will be used for relocation resolution.
    248   virtual void mapSectionAddress(const void *LocalAddress,
    249                                  uint64_t TargetAddress) {
    250     llvm_unreachable("Re-mapping of section addresses not supported with this "
    251                      "EE!");
    252   }
    253 
    254   /// generateCodeForModule - Run code generation for the specified module and
    255   /// load it into memory.
    256   ///
    257   /// When this function has completed, all code and data for the specified
    258   /// module, and any module on which this module depends, will be generated
    259   /// and loaded into memory, but relocations will not yet have been applied
    260   /// and all memory will be readable and writable but not executable.
    261   ///
    262   /// This function is primarily useful when generating code for an external
    263   /// target, allowing the client an opportunity to remap section addresses
    264   /// before relocations are applied.  Clients that intend to execute code
    265   /// locally can use the getFunctionAddress call, which will generate code
    266   /// and apply final preparations all in one step.
    267   ///
    268   /// This method has no effect for the interpeter.
    269   virtual void generateCodeForModule(Module *M) {}
    270 
    271   /// finalizeObject - ensure the module is fully processed and is usable.
    272   ///
    273   /// It is the user-level function for completing the process of making the
    274   /// object usable for execution.  It should be called after sections within an
    275   /// object have been relocated using mapSectionAddress.  When this method is
    276   /// called the MCJIT execution engine will reapply relocations for a loaded
    277   /// object.  This method has no effect for the interpeter.
    278   virtual void finalizeObject() {}
    279 
    280   /// runStaticConstructorsDestructors - This method is used to execute all of
    281   /// the static constructors or destructors for a program.
    282   ///
    283   /// \param isDtors - Run the destructors instead of constructors.
    284   virtual void runStaticConstructorsDestructors(bool isDtors);
    285 
    286   /// This method is used to execute all of the static constructors or
    287   /// destructors for a particular module.
    288   ///
    289   /// \param isDtors - Run the destructors instead of constructors.
    290   void runStaticConstructorsDestructors(Module &module, bool isDtors);
    291 
    292 
    293   /// runFunctionAsMain - This is a helper function which wraps runFunction to
    294   /// handle the common task of starting up main with the specified argc, argv,
    295   /// and envp parameters.
    296   int runFunctionAsMain(Function *Fn, const std::vector<std::string> &argv,
    297                         const char * const * envp);
    298 
    299 
    300   /// addGlobalMapping - Tell the execution engine that the specified global is
    301   /// at the specified location.  This is used internally as functions are JIT'd
    302   /// and as global variables are laid out in memory.  It can and should also be
    303   /// used by clients of the EE that want to have an LLVM global overlay
    304   /// existing data in memory. Values to be mapped should be named, and have
    305   /// external or weak linkage. Mappings are automatically removed when their
    306   /// GlobalValue is destroyed.
    307   void addGlobalMapping(const GlobalValue *GV, void *Addr);
    308   void addGlobalMapping(StringRef Name, uint64_t Addr);
    309 
    310   /// clearAllGlobalMappings - Clear all global mappings and start over again,
    311   /// for use in dynamic compilation scenarios to move globals.
    312   void clearAllGlobalMappings();
    313 
    314   /// clearGlobalMappingsFromModule - Clear all global mappings that came from a
    315   /// particular module, because it has been removed from the JIT.
    316   void clearGlobalMappingsFromModule(Module *M);
    317 
    318   /// updateGlobalMapping - Replace an existing mapping for GV with a new
    319   /// address.  This updates both maps as required.  If "Addr" is null, the
    320   /// entry for the global is removed from the mappings.  This returns the old
    321   /// value of the pointer, or null if it was not in the map.
    322   uint64_t updateGlobalMapping(const GlobalValue *GV, void *Addr);
    323   uint64_t updateGlobalMapping(StringRef Name, uint64_t Addr);
    324 
    325   /// getAddressToGlobalIfAvailable - This returns the address of the specified
    326   /// global symbol.
    327   uint64_t getAddressToGlobalIfAvailable(StringRef S);
    328 
    329   /// getPointerToGlobalIfAvailable - This returns the address of the specified
    330   /// global value if it is has already been codegen'd, otherwise it returns
    331   /// null.
    332   void *getPointerToGlobalIfAvailable(StringRef S);
    333   void *getPointerToGlobalIfAvailable(const GlobalValue *GV);
    334 
    335   /// getPointerToGlobal - This returns the address of the specified global
    336   /// value. This may involve code generation if it's a function.
    337   ///
    338   /// This function is deprecated for the MCJIT execution engine.  Use
    339   /// getGlobalValueAddress instead.
    340   void *getPointerToGlobal(const GlobalValue *GV);
    341 
    342   /// getPointerToFunction - The different EE's represent function bodies in
    343   /// different ways.  They should each implement this to say what a function
    344   /// pointer should look like.  When F is destroyed, the ExecutionEngine will
    345   /// remove its global mapping and free any machine code.  Be sure no threads
    346   /// are running inside F when that happens.
    347   ///
    348   /// This function is deprecated for the MCJIT execution engine.  Use
    349   /// getFunctionAddress instead.
    350   virtual void *getPointerToFunction(Function *F) = 0;
    351 
    352   /// getPointerToFunctionOrStub - If the specified function has been
    353   /// code-gen'd, return a pointer to the function.  If not, compile it, or use
    354   /// a stub to implement lazy compilation if available.  See
    355   /// getPointerToFunction for the requirements on destroying F.
    356   ///
    357   /// This function is deprecated for the MCJIT execution engine.  Use
    358   /// getFunctionAddress instead.
    359   virtual void *getPointerToFunctionOrStub(Function *F) {
    360     // Default implementation, just codegen the function.
    361     return getPointerToFunction(F);
    362   }
    363 
    364   /// getGlobalValueAddress - Return the address of the specified global
    365   /// value. This may involve code generation.
    366   ///
    367   /// This function should not be called with the interpreter engine.
    368   virtual uint64_t getGlobalValueAddress(const std::string &Name) {
    369     // Default implementation for the interpreter.  MCJIT will override this.
    370     // JIT and interpreter clients should use getPointerToGlobal instead.
    371     return 0;
    372   }
    373 
    374   /// getFunctionAddress - Return the address of the specified function.
    375   /// This may involve code generation.
    376   virtual uint64_t getFunctionAddress(const std::string &Name) {
    377     // Default implementation for the interpreter.  MCJIT will override this.
    378     // Interpreter clients should use getPointerToFunction instead.
    379     return 0;
    380   }
    381 
    382   /// getGlobalValueAtAddress - Return the LLVM global value object that starts
    383   /// at the specified address.
    384   ///
    385   const GlobalValue *getGlobalValueAtAddress(void *Addr);
    386 
    387   /// StoreValueToMemory - Stores the data in Val of type Ty at address Ptr.
    388   /// Ptr is the address of the memory at which to store Val, cast to
    389   /// GenericValue *.  It is not a pointer to a GenericValue containing the
    390   /// address at which to store Val.
    391   void StoreValueToMemory(const GenericValue &Val, GenericValue *Ptr,
    392                           Type *Ty);
    393 
    394   void InitializeMemory(const Constant *Init, void *Addr);
    395 
    396   /// getOrEmitGlobalVariable - Return the address of the specified global
    397   /// variable, possibly emitting it to memory if needed.  This is used by the
    398   /// Emitter.
    399   ///
    400   /// This function is deprecated for the MCJIT execution engine.  Use
    401   /// getGlobalValueAddress instead.
    402   virtual void *getOrEmitGlobalVariable(const GlobalVariable *GV) {
    403     return getPointerToGlobal((const GlobalValue *)GV);
    404   }
    405 
    406   /// Registers a listener to be called back on various events within
    407   /// the JIT.  See JITEventListener.h for more details.  Does not
    408   /// take ownership of the argument.  The argument may be NULL, in
    409   /// which case these functions do nothing.
    410   virtual void RegisterJITEventListener(JITEventListener *) {}
    411   virtual void UnregisterJITEventListener(JITEventListener *) {}
    412 
    413   /// Sets the pre-compiled object cache.  The ownership of the ObjectCache is
    414   /// not changed.  Supported by MCJIT but not the interpreter.
    415   virtual void setObjectCache(ObjectCache *) {
    416     llvm_unreachable("No support for an object cache");
    417   }
    418 
    419   /// setProcessAllSections (MCJIT Only): By default, only sections that are
    420   /// "required for execution" are passed to the RTDyldMemoryManager, and other
    421   /// sections are discarded. Passing 'true' to this method will cause
    422   /// RuntimeDyld to pass all sections to its RTDyldMemoryManager regardless
    423   /// of whether they are "required to execute" in the usual sense.
    424   ///
    425   /// Rationale: Some MCJIT clients want to be able to inspect metadata
    426   /// sections (e.g. Dwarf, Stack-maps) to enable functionality or analyze
    427   /// performance. Passing these sections to the memory manager allows the
    428   /// client to make policy about the relevant sections, rather than having
    429   /// MCJIT do it.
    430   virtual void setProcessAllSections(bool ProcessAllSections) {
    431     llvm_unreachable("No support for ProcessAllSections option");
    432   }
    433 
    434   /// Return the target machine (if available).
    435   virtual TargetMachine *getTargetMachine() { return nullptr; }
    436 
    437   /// DisableLazyCompilation - When lazy compilation is off (the default), the
    438   /// JIT will eagerly compile every function reachable from the argument to
    439   /// getPointerToFunction.  If lazy compilation is turned on, the JIT will only
    440   /// compile the one function and emit stubs to compile the rest when they're
    441   /// first called.  If lazy compilation is turned off again while some lazy
    442   /// stubs are still around, and one of those stubs is called, the program will
    443   /// abort.
    444   ///
    445   /// In order to safely compile lazily in a threaded program, the user must
    446   /// ensure that 1) only one thread at a time can call any particular lazy
    447   /// stub, and 2) any thread modifying LLVM IR must hold the JIT's lock
    448   /// (ExecutionEngine::lock) or otherwise ensure that no other thread calls a
    449   /// lazy stub.  See http://llvm.org/PR5184 for details.
    450   void DisableLazyCompilation(bool Disabled = true) {
    451     CompilingLazily = !Disabled;
    452   }
    453   bool isCompilingLazily() const {
    454     return CompilingLazily;
    455   }
    456 
    457   /// DisableGVCompilation - If called, the JIT will abort if it's asked to
    458   /// allocate space and populate a GlobalVariable that is not internal to
    459   /// the module.
    460   void DisableGVCompilation(bool Disabled = true) {
    461     GVCompilationDisabled = Disabled;
    462   }
    463   bool isGVCompilationDisabled() const {
    464     return GVCompilationDisabled;
    465   }
    466 
    467   /// DisableSymbolSearching - If called, the JIT will not try to lookup unknown
    468   /// symbols with dlsym.  A client can still use InstallLazyFunctionCreator to
    469   /// resolve symbols in a custom way.
    470   void DisableSymbolSearching(bool Disabled = true) {
    471     SymbolSearchingDisabled = Disabled;
    472   }
    473   bool isSymbolSearchingDisabled() const {
    474     return SymbolSearchingDisabled;
    475   }
    476 
    477   /// Enable/Disable IR module verification.
    478   ///
    479   /// Note: Module verification is enabled by default in Debug builds, and
    480   /// disabled by default in Release. Use this method to override the default.
    481   void setVerifyModules(bool Verify) {
    482     VerifyModules = Verify;
    483   }
    484   bool getVerifyModules() const {
    485     return VerifyModules;
    486   }
    487 
    488   /// InstallLazyFunctionCreator - If an unknown function is needed, the
    489   /// specified function pointer is invoked to create it.  If it returns null,
    490   /// the JIT will abort.
    491   void InstallLazyFunctionCreator(FunctionCreator C) {
    492     LazyFunctionCreator = std::move(C);
    493   }
    494 
    495 protected:
    496   ExecutionEngine(DataLayout DL) : DL(std::move(DL)) {}
    497   explicit ExecutionEngine(DataLayout DL, std::unique_ptr<Module> M);
    498   explicit ExecutionEngine(std::unique_ptr<Module> M);
    499 
    500   void emitGlobals();
    501 
    502   void EmitGlobalVariable(const GlobalVariable *GV);
    503 
    504   GenericValue getConstantValue(const Constant *C);
    505   void LoadValueFromMemory(GenericValue &Result, GenericValue *Ptr,
    506                            Type *Ty);
    507 
    508 private:
    509   void Init(std::unique_ptr<Module> M);
    510 };
    511 
    512 namespace EngineKind {
    513 
    514   // These are actually bitmasks that get or-ed together.
    515   enum Kind {
    516     JIT         = 0x1,
    517     Interpreter = 0x2
    518   };
    519   const static Kind Either = (Kind)(JIT | Interpreter);
    520 
    521 } // end namespace EngineKind
    522 
    523 /// Builder class for ExecutionEngines. Use this by stack-allocating a builder,
    524 /// chaining the various set* methods, and terminating it with a .create()
    525 /// call.
    526 class EngineBuilder {
    527 private:
    528   std::unique_ptr<Module> M;
    529   EngineKind::Kind WhichEngine;
    530   std::string *ErrorStr;
    531   CodeGenOpt::Level OptLevel;
    532   std::shared_ptr<MCJITMemoryManager> MemMgr;
    533   std::shared_ptr<LegacyJITSymbolResolver> Resolver;
    534   TargetOptions Options;
    535   Optional<Reloc::Model> RelocModel;
    536   Optional<CodeModel::Model> CMModel;
    537   std::string MArch;
    538   std::string MCPU;
    539   SmallVector<std::string, 4> MAttrs;
    540   bool VerifyModules;
    541   bool UseOrcMCJITReplacement;
    542   bool EmulatedTLS = true;
    543 
    544 public:
    545   /// Default constructor for EngineBuilder.
    546   EngineBuilder();
    547 
    548   /// Constructor for EngineBuilder.
    549   EngineBuilder(std::unique_ptr<Module> M);
    550 
    551   // Out-of-line since we don't have the def'n of RTDyldMemoryManager here.
    552   ~EngineBuilder();
    553 
    554   /// setEngineKind - Controls whether the user wants the interpreter, the JIT,
    555   /// or whichever engine works.  This option defaults to EngineKind::Either.
    556   EngineBuilder &setEngineKind(EngineKind::Kind w) {
    557     WhichEngine = w;
    558     return *this;
    559   }
    560 
    561   /// setMCJITMemoryManager - Sets the MCJIT memory manager to use. This allows
    562   /// clients to customize their memory allocation policies for the MCJIT. This
    563   /// is only appropriate for the MCJIT; setting this and configuring the builder
    564   /// to create anything other than MCJIT will cause a runtime error. If create()
    565   /// is called and is successful, the created engine takes ownership of the
    566   /// memory manager. This option defaults to NULL.
    567   EngineBuilder &setMCJITMemoryManager(std::unique_ptr<RTDyldMemoryManager> mcjmm);
    568 
    569   EngineBuilder&
    570   setMemoryManager(std::unique_ptr<MCJITMemoryManager> MM);
    571 
    572   EngineBuilder &setSymbolResolver(std::unique_ptr<LegacyJITSymbolResolver> SR);
    573 
    574   /// setErrorStr - Set the error string to write to on error.  This option
    575   /// defaults to NULL.
    576   EngineBuilder &setErrorStr(std::string *e) {
    577     ErrorStr = e;
    578     return *this;
    579   }
    580 
    581   /// setOptLevel - Set the optimization level for the JIT.  This option
    582   /// defaults to CodeGenOpt::Default.
    583   EngineBuilder &setOptLevel(CodeGenOpt::Level l) {
    584     OptLevel = l;
    585     return *this;
    586   }
    587 
    588   /// setTargetOptions - Set the target options that the ExecutionEngine
    589   /// target is using. Defaults to TargetOptions().
    590   EngineBuilder &setTargetOptions(const TargetOptions &Opts) {
    591     Options = Opts;
    592     return *this;
    593   }
    594 
    595   /// setRelocationModel - Set the relocation model that the ExecutionEngine
    596   /// target is using. Defaults to target specific default "Reloc::Default".
    597   EngineBuilder &setRelocationModel(Reloc::Model RM) {
    598     RelocModel = RM;
    599     return *this;
    600   }
    601 
    602   /// setCodeModel - Set the CodeModel that the ExecutionEngine target
    603   /// data is using. Defaults to target specific default
    604   /// "CodeModel::JITDefault".
    605   EngineBuilder &setCodeModel(CodeModel::Model M) {
    606     CMModel = M;
    607     return *this;
    608   }
    609 
    610   /// setMArch - Override the architecture set by the Module's triple.
    611   EngineBuilder &setMArch(StringRef march) {
    612     MArch.assign(march.begin(), march.end());
    613     return *this;
    614   }
    615 
    616   /// setMCPU - Target a specific cpu type.
    617   EngineBuilder &setMCPU(StringRef mcpu) {
    618     MCPU.assign(mcpu.begin(), mcpu.end());
    619     return *this;
    620   }
    621 
    622   /// setVerifyModules - Set whether the JIT implementation should verify
    623   /// IR modules during compilation.
    624   EngineBuilder &setVerifyModules(bool Verify) {
    625     VerifyModules = Verify;
    626     return *this;
    627   }
    628 
    629   /// setMAttrs - Set cpu-specific attributes.
    630   template<typename StringSequence>
    631   EngineBuilder &setMAttrs(const StringSequence &mattrs) {
    632     MAttrs.clear();
    633     MAttrs.append(mattrs.begin(), mattrs.end());
    634     return *this;
    635   }
    636 
    637   // Use OrcMCJITReplacement instead of MCJIT. Off by default.
    638   void setUseOrcMCJITReplacement(bool UseOrcMCJITReplacement) {
    639     this->UseOrcMCJITReplacement = UseOrcMCJITReplacement;
    640   }
    641 
    642   void setEmulatedTLS(bool EmulatedTLS) {
    643     this->EmulatedTLS = EmulatedTLS;
    644   }
    645 
    646   TargetMachine *selectTarget();
    647 
    648   /// selectTarget - Pick a target either via -march or by guessing the native
    649   /// arch.  Add any CPU features specified via -mcpu or -mattr.
    650   TargetMachine *selectTarget(const Triple &TargetTriple,
    651                               StringRef MArch,
    652                               StringRef MCPU,
    653                               const SmallVectorImpl<std::string>& MAttrs);
    654 
    655   ExecutionEngine *create() {
    656     return create(selectTarget());
    657   }
    658 
    659   ExecutionEngine *create(TargetMachine *TM);
    660 };
    661 
    662 // Create wrappers for C Binding types (see CBindingWrapping.h).
    663 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ExecutionEngine, LLVMExecutionEngineRef)
    664 
    665 } // end namespace llvm
    666 
    667 #endif // LLVM_EXECUTIONENGINE_EXECUTIONENGINE_H
    668