Home | History | Annotate | Download | only in ExecutionEngine
      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/DenseMap.h"
     20 #include "llvm/ADT/SmallVector.h"
     21 #include "llvm/ADT/StringRef.h"
     22 #include "llvm/ADT/ValueMap.h"
     23 #include "llvm/MC/MCCodeGenInfo.h"
     24 #include "llvm/Support/ErrorHandling.h"
     25 #include "llvm/Support/Mutex.h"
     26 #include "llvm/Support/ValueHandle.h"
     27 #include "llvm/Target/TargetMachine.h"
     28 #include "llvm/Target/TargetOptions.h"
     29 #include <map>
     30 #include <string>
     31 #include <vector>
     32 
     33 namespace llvm {
     34 
     35 struct GenericValue;
     36 class Constant;
     37 class DataLayout;
     38 class ExecutionEngine;
     39 class Function;
     40 class GlobalVariable;
     41 class GlobalValue;
     42 class JITEventListener;
     43 class JITMemoryManager;
     44 class MachineCodeInfo;
     45 class Module;
     46 class MutexGuard;
     47 class ObjectCache;
     48 class RTDyldMemoryManager;
     49 class Triple;
     50 class Type;
     51 
     52 /// \brief Helper class for helping synchronize access to the global address map
     53 /// table.
     54 class ExecutionEngineState {
     55 public:
     56   struct AddressMapConfig : public ValueMapConfig<const GlobalValue*> {
     57     typedef ExecutionEngineState *ExtraData;
     58     static sys::Mutex *getMutex(ExecutionEngineState *EES);
     59     static void onDelete(ExecutionEngineState *EES, const GlobalValue *Old);
     60     static void onRAUW(ExecutionEngineState *, const GlobalValue *,
     61                        const GlobalValue *);
     62   };
     63 
     64   typedef ValueMap<const GlobalValue *, void *, AddressMapConfig>
     65       GlobalAddressMapTy;
     66 
     67 private:
     68   ExecutionEngine &EE;
     69 
     70   /// GlobalAddressMap - A mapping between LLVM global values and their
     71   /// 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<void *, AssertingVH<const GlobalValue> > GlobalAddressReverseMap;
     79 
     80 public:
     81   ExecutionEngineState(ExecutionEngine &EE);
     82 
     83   GlobalAddressMapTy &getGlobalAddressMap(const MutexGuard &) {
     84     return GlobalAddressMap;
     85   }
     86 
     87   std::map<void*, AssertingVH<const GlobalValue> > &
     88   getGlobalAddressReverseMap(const MutexGuard &) {
     89     return GlobalAddressReverseMap;
     90   }
     91 
     92   /// \brief Erase an entry from the mapping table.
     93   ///
     94   /// \returns The address that \p ToUnmap was happed to.
     95   void *RemoveMapping(const MutexGuard &, const GlobalValue *ToUnmap);
     96 };
     97 
     98 /// \brief Abstract interface for implementation execution of LLVM modules,
     99 /// designed to support both interpreter and just-in-time (JIT) compiler
    100 /// implementations.
    101 class ExecutionEngine {
    102   /// The state object holding the global address mapping, which must be
    103   /// accessed synchronously.
    104   //
    105   // FIXME: There is no particular need the entire map needs to be
    106   // synchronized.  Wouldn't a reader-writer design be better here?
    107   ExecutionEngineState EEState;
    108 
    109   /// The target data for the platform for which execution is being performed.
    110   const DataLayout *TD;
    111 
    112   /// Whether lazy JIT compilation is enabled.
    113   bool CompilingLazily;
    114 
    115   /// Whether JIT compilation of external global variables is allowed.
    116   bool GVCompilationDisabled;
    117 
    118   /// Whether the JIT should perform lookups of external symbols (e.g.,
    119   /// using dlsym).
    120   bool SymbolSearchingDisabled;
    121 
    122   friend class EngineBuilder;  // To allow access to JITCtor and InterpCtor.
    123 
    124 protected:
    125   /// The list of Modules that we are JIT'ing from.  We use a SmallVector to
    126   /// optimize for the case where there is only one module.
    127   SmallVector<Module*, 1> Modules;
    128 
    129   void setDataLayout(const DataLayout *td) { TD = td; }
    130 
    131   /// getMemoryforGV - Allocate memory for a global variable.
    132   virtual char *getMemoryForGV(const GlobalVariable *GV);
    133 
    134   // To avoid having libexecutionengine depend on the JIT and interpreter
    135   // libraries, the execution engine implementations set these functions to ctor
    136   // pointers at startup time if they are linked in.
    137   static ExecutionEngine *(*JITCtor)(
    138     Module *M,
    139     std::string *ErrorStr,
    140     JITMemoryManager *JMM,
    141     bool GVsWithCode,
    142     TargetMachine *TM);
    143   static ExecutionEngine *(*MCJITCtor)(
    144     Module *M,
    145     std::string *ErrorStr,
    146     RTDyldMemoryManager *MCJMM,
    147     bool GVsWithCode,
    148     TargetMachine *TM);
    149   static ExecutionEngine *(*InterpCtor)(Module *M, std::string *ErrorStr);
    150 
    151   /// LazyFunctionCreator - If an unknown function is needed, this function
    152   /// pointer is invoked to create it.  If this returns null, the JIT will
    153   /// abort.
    154   void *(*LazyFunctionCreator)(const std::string &);
    155 
    156   /// ExceptionTableRegister - If Exception Handling is set, the JIT will
    157   /// register dwarf tables with this function.
    158   typedef void (*EERegisterFn)(void*);
    159   EERegisterFn ExceptionTableRegister;
    160   EERegisterFn ExceptionTableDeregister;
    161   /// This maps functions to their exception tables frames.
    162   DenseMap<const Function*, void*> AllExceptionTables;
    163 
    164 
    165 public:
    166   /// lock - This lock protects the ExecutionEngine, JIT, JITResolver and
    167   /// JITEmitter classes.  It must be held while changing the internal state of
    168   /// any of those classes.
    169   sys::Mutex lock;
    170 
    171   //===--------------------------------------------------------------------===//
    172   //  ExecutionEngine Startup
    173   //===--------------------------------------------------------------------===//
    174 
    175   virtual ~ExecutionEngine();
    176 
    177   /// create - This is the factory method for creating an execution engine which
    178   /// is appropriate for the current machine.  This takes ownership of the
    179   /// module.
    180   ///
    181   /// \param GVsWithCode - Allocating globals with code breaks
    182   /// freeMachineCodeForFunction and is probably unsafe and bad for performance.
    183   /// However, we have clients who depend on this behavior, so we must support
    184   /// it.  Eventually, when we're willing to break some backwards compatibility,
    185   /// this flag should be flipped to false, so that by default
    186   /// freeMachineCodeForFunction works.
    187   static ExecutionEngine *create(Module *M,
    188                                  bool ForceInterpreter = false,
    189                                  std::string *ErrorStr = 0,
    190                                  CodeGenOpt::Level OptLevel =
    191                                  CodeGenOpt::Default,
    192                                  bool GVsWithCode = true);
    193 
    194   /// createJIT - This is the factory method for creating a JIT for the current
    195   /// machine, it does not fall back to the interpreter.  This takes ownership
    196   /// of the Module and JITMemoryManager if successful.
    197   ///
    198   /// Clients should make sure to initialize targets prior to calling this
    199   /// function.
    200   static ExecutionEngine *createJIT(Module *M,
    201                                     std::string *ErrorStr = 0,
    202                                     JITMemoryManager *JMM = 0,
    203                                     CodeGenOpt::Level OptLevel =
    204                                     CodeGenOpt::Default,
    205                                     bool GVsWithCode = true,
    206                                     Reloc::Model RM = Reloc::Default,
    207                                     CodeModel::Model CMM =
    208                                     CodeModel::JITDefault);
    209 
    210   /// addModule - Add a Module to the list of modules that we can JIT from.
    211   /// Note that this takes ownership of the Module: when the ExecutionEngine is
    212   /// destroyed, it destroys the Module as well.
    213   virtual void addModule(Module *M) {
    214     Modules.push_back(M);
    215   }
    216 
    217   //===--------------------------------------------------------------------===//
    218 
    219   const DataLayout *getDataLayout() const { return TD; }
    220 
    221   /// removeModule - Remove a Module from the list of modules.  Returns true if
    222   /// M is found.
    223   virtual bool removeModule(Module *M);
    224 
    225   /// FindFunctionNamed - Search all of the active modules to find the one that
    226   /// defines FnName.  This is very slow operation and shouldn't be used for
    227   /// general code.
    228   Function *FindFunctionNamed(const char *FnName);
    229 
    230   /// runFunction - Execute the specified function with the specified arguments,
    231   /// and return the result.
    232   virtual GenericValue runFunction(Function *F,
    233                                 const std::vector<GenericValue> &ArgValues) = 0;
    234 
    235   /// getPointerToNamedFunction - This method returns the address of the
    236   /// specified function by using the dlsym function call.  As such it is only
    237   /// useful for resolving library symbols, not code generated symbols.
    238   ///
    239   /// If AbortOnFailure is false and no function with the given name is
    240   /// found, this function silently returns a null pointer. Otherwise,
    241   /// it prints a message to stderr and aborts.
    242   ///
    243   virtual void *getPointerToNamedFunction(const std::string &Name,
    244                                           bool AbortOnFailure = true) = 0;
    245 
    246   /// mapSectionAddress - map a section to its target address space value.
    247   /// Map the address of a JIT section as returned from the memory manager
    248   /// to the address in the target process as the running code will see it.
    249   /// This is the address which will be used for relocation resolution.
    250   virtual void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress) {
    251     llvm_unreachable("Re-mapping of section addresses not supported with this "
    252                      "EE!");
    253   }
    254 
    255   /// finalizeObject - ensure the module is fully processed and is usable.
    256   ///
    257   /// It is the user-level function for completing the process of making the
    258   /// object usable for execution.  It should be called after sections within an
    259   /// object have been relocated using mapSectionAddress.  When this method is
    260   /// called the MCJIT execution engine will reapply relocations for a loaded
    261   /// object.  This method has no effect for the legacy JIT engine or the
    262   /// interpeter.
    263   virtual void finalizeObject() {}
    264 
    265   /// runStaticConstructorsDestructors - This method is used to execute all of
    266   /// the static constructors or destructors for a program.
    267   ///
    268   /// \param isDtors - Run the destructors instead of constructors.
    269   void runStaticConstructorsDestructors(bool isDtors);
    270 
    271   /// runStaticConstructorsDestructors - This method is used to execute all of
    272   /// the static constructors or destructors for a particular module.
    273   ///
    274   /// \param isDtors - Run the destructors instead of constructors.
    275   void runStaticConstructorsDestructors(Module *module, bool isDtors);
    276 
    277 
    278   /// runFunctionAsMain - This is a helper function which wraps runFunction to
    279   /// handle the common task of starting up main with the specified argc, argv,
    280   /// and envp parameters.
    281   int runFunctionAsMain(Function *Fn, const std::vector<std::string> &argv,
    282                         const char * const * envp);
    283 
    284 
    285   /// addGlobalMapping - Tell the execution engine that the specified global is
    286   /// at the specified location.  This is used internally as functions are JIT'd
    287   /// and as global variables are laid out in memory.  It can and should also be
    288   /// used by clients of the EE that want to have an LLVM global overlay
    289   /// existing data in memory.  Mappings are automatically removed when their
    290   /// GlobalValue is destroyed.
    291   void addGlobalMapping(const GlobalValue *GV, void *Addr);
    292 
    293   /// clearAllGlobalMappings - Clear all global mappings and start over again,
    294   /// for use in dynamic compilation scenarios to move globals.
    295   void clearAllGlobalMappings();
    296 
    297   /// clearGlobalMappingsFromModule - Clear all global mappings that came from a
    298   /// particular module, because it has been removed from the JIT.
    299   void clearGlobalMappingsFromModule(Module *M);
    300 
    301   /// updateGlobalMapping - Replace an existing mapping for GV with a new
    302   /// address.  This updates both maps as required.  If "Addr" is null, the
    303   /// entry for the global is removed from the mappings.  This returns the old
    304   /// value of the pointer, or null if it was not in the map.
    305   void *updateGlobalMapping(const GlobalValue *GV, void *Addr);
    306 
    307   /// getPointerToGlobalIfAvailable - This returns the address of the specified
    308   /// global value if it is has already been codegen'd, otherwise it returns
    309   /// null.
    310   void *getPointerToGlobalIfAvailable(const GlobalValue *GV);
    311 
    312   /// getPointerToGlobal - This returns the address of the specified global
    313   /// value. This may involve code generation if it's a function.
    314   void *getPointerToGlobal(const GlobalValue *GV);
    315 
    316   /// getPointerToFunction - The different EE's represent function bodies in
    317   /// different ways.  They should each implement this to say what a function
    318   /// pointer should look like.  When F is destroyed, the ExecutionEngine will
    319   /// remove its global mapping and free any machine code.  Be sure no threads
    320   /// are running inside F when that happens.
    321   virtual void *getPointerToFunction(Function *F) = 0;
    322 
    323   /// getPointerToBasicBlock - The different EE's represent basic blocks in
    324   /// different ways.  Return the representation for a blockaddress of the
    325   /// specified block.
    326   virtual void *getPointerToBasicBlock(BasicBlock *BB) = 0;
    327 
    328   /// getPointerToFunctionOrStub - If the specified function has been
    329   /// code-gen'd, return a pointer to the function.  If not, compile it, or use
    330   /// a stub to implement lazy compilation if available.  See
    331   /// getPointerToFunction for the requirements on destroying F.
    332   virtual void *getPointerToFunctionOrStub(Function *F) {
    333     // Default implementation, just codegen the function.
    334     return getPointerToFunction(F);
    335   }
    336 
    337   // The JIT overrides a version that actually does this.
    338   virtual void runJITOnFunction(Function *, MachineCodeInfo * = 0) { }
    339 
    340   /// getGlobalValueAtAddress - Return the LLVM global value object that starts
    341   /// at the specified address.
    342   ///
    343   const GlobalValue *getGlobalValueAtAddress(void *Addr);
    344 
    345   /// StoreValueToMemory - Stores the data in Val of type Ty at address Ptr.
    346   /// Ptr is the address of the memory at which to store Val, cast to
    347   /// GenericValue *.  It is not a pointer to a GenericValue containing the
    348   /// address at which to store Val.
    349   void StoreValueToMemory(const GenericValue &Val, GenericValue *Ptr,
    350                           Type *Ty);
    351 
    352   void InitializeMemory(const Constant *Init, void *Addr);
    353 
    354   /// recompileAndRelinkFunction - This method is used to force a function which
    355   /// has already been compiled to be compiled again, possibly after it has been
    356   /// modified.  Then the entry to the old copy is overwritten with a branch to
    357   /// the new copy.  If there was no old copy, this acts just like
    358   /// VM::getPointerToFunction().
    359   virtual void *recompileAndRelinkFunction(Function *F) = 0;
    360 
    361   /// freeMachineCodeForFunction - Release memory in the ExecutionEngine
    362   /// corresponding to the machine code emitted to execute this function, useful
    363   /// for garbage-collecting generated code.
    364   virtual void freeMachineCodeForFunction(Function *F) = 0;
    365 
    366   /// getOrEmitGlobalVariable - Return the address of the specified global
    367   /// variable, possibly emitting it to memory if needed.  This is used by the
    368   /// Emitter.
    369   virtual void *getOrEmitGlobalVariable(const GlobalVariable *GV) {
    370     return getPointerToGlobal((const GlobalValue *)GV);
    371   }
    372 
    373   /// Registers a listener to be called back on various events within
    374   /// the JIT.  See JITEventListener.h for more details.  Does not
    375   /// take ownership of the argument.  The argument may be NULL, in
    376   /// which case these functions do nothing.
    377   virtual void RegisterJITEventListener(JITEventListener *) {}
    378   virtual void UnregisterJITEventListener(JITEventListener *) {}
    379 
    380   /// Sets the pre-compiled object cache.  The ownership of the ObjectCache is
    381   /// not changed.  Supported by MCJIT but not JIT.
    382   virtual void setObjectCache(ObjectCache *) {
    383     llvm_unreachable("No support for an object cache");
    384   }
    385 
    386   /// DisableLazyCompilation - When lazy compilation is off (the default), the
    387   /// JIT will eagerly compile every function reachable from the argument to
    388   /// getPointerToFunction.  If lazy compilation is turned on, the JIT will only
    389   /// compile the one function and emit stubs to compile the rest when they're
    390   /// first called.  If lazy compilation is turned off again while some lazy
    391   /// stubs are still around, and one of those stubs is called, the program will
    392   /// abort.
    393   ///
    394   /// In order to safely compile lazily in a threaded program, the user must
    395   /// ensure that 1) only one thread at a time can call any particular lazy
    396   /// stub, and 2) any thread modifying LLVM IR must hold the JIT's lock
    397   /// (ExecutionEngine::lock) or otherwise ensure that no other thread calls a
    398   /// lazy stub.  See http://llvm.org/PR5184 for details.
    399   void DisableLazyCompilation(bool Disabled = true) {
    400     CompilingLazily = !Disabled;
    401   }
    402   bool isCompilingLazily() const {
    403     return CompilingLazily;
    404   }
    405   // Deprecated in favor of isCompilingLazily (to reduce double-negatives).
    406   // Remove this in LLVM 2.8.
    407   bool isLazyCompilationDisabled() const {
    408     return !CompilingLazily;
    409   }
    410 
    411   /// DisableGVCompilation - If called, the JIT will abort if it's asked to
    412   /// allocate space and populate a GlobalVariable that is not internal to
    413   /// the module.
    414   void DisableGVCompilation(bool Disabled = true) {
    415     GVCompilationDisabled = Disabled;
    416   }
    417   bool isGVCompilationDisabled() const {
    418     return GVCompilationDisabled;
    419   }
    420 
    421   /// DisableSymbolSearching - If called, the JIT will not try to lookup unknown
    422   /// symbols with dlsym.  A client can still use InstallLazyFunctionCreator to
    423   /// resolve symbols in a custom way.
    424   void DisableSymbolSearching(bool Disabled = true) {
    425     SymbolSearchingDisabled = Disabled;
    426   }
    427   bool isSymbolSearchingDisabled() const {
    428     return SymbolSearchingDisabled;
    429   }
    430 
    431   /// InstallLazyFunctionCreator - If an unknown function is needed, the
    432   /// specified function pointer is invoked to create it.  If it returns null,
    433   /// the JIT will abort.
    434   void InstallLazyFunctionCreator(void* (*P)(const std::string &)) {
    435     LazyFunctionCreator = P;
    436   }
    437 
    438   /// InstallExceptionTableRegister - The JIT will use the given function
    439   /// to register the exception tables it generates.
    440   void InstallExceptionTableRegister(EERegisterFn F) {
    441     ExceptionTableRegister = F;
    442   }
    443   void InstallExceptionTableDeregister(EERegisterFn F) {
    444     ExceptionTableDeregister = F;
    445   }
    446 
    447   /// RegisterTable - Registers the given pointer as an exception table.  It
    448   /// uses the ExceptionTableRegister function.
    449   void RegisterTable(const Function *fn, void* res) {
    450     if (ExceptionTableRegister) {
    451       ExceptionTableRegister(res);
    452       AllExceptionTables[fn] = res;
    453     }
    454   }
    455 
    456   /// DeregisterTable - Deregisters the exception frame previously registered
    457   /// for the given function.
    458   void DeregisterTable(const Function *Fn) {
    459     if (ExceptionTableDeregister) {
    460       DenseMap<const Function*, void*>::iterator frame =
    461         AllExceptionTables.find(Fn);
    462       if(frame != AllExceptionTables.end()) {
    463         ExceptionTableDeregister(frame->second);
    464         AllExceptionTables.erase(frame);
    465       }
    466     }
    467   }
    468 
    469   /// DeregisterAllTables - Deregisters all previously registered pointers to an
    470   /// exception tables.  It uses the ExceptionTableoDeregister function.
    471   void DeregisterAllTables();
    472 
    473 protected:
    474   explicit ExecutionEngine(Module *M);
    475 
    476   void emitGlobals();
    477 
    478   void EmitGlobalVariable(const GlobalVariable *GV);
    479 
    480   GenericValue getConstantValue(const Constant *C);
    481   void LoadValueFromMemory(GenericValue &Result, GenericValue *Ptr,
    482                            Type *Ty);
    483 };
    484 
    485 namespace EngineKind {
    486   // These are actually bitmasks that get or-ed together.
    487   enum Kind {
    488     JIT         = 0x1,
    489     Interpreter = 0x2
    490   };
    491   const static Kind Either = (Kind)(JIT | Interpreter);
    492 }
    493 
    494 /// EngineBuilder - Builder class for ExecutionEngines.  Use this by
    495 /// stack-allocating a builder, chaining the various set* methods, and
    496 /// terminating it with a .create() call.
    497 class EngineBuilder {
    498 private:
    499   Module *M;
    500   EngineKind::Kind WhichEngine;
    501   std::string *ErrorStr;
    502   CodeGenOpt::Level OptLevel;
    503   RTDyldMemoryManager *MCJMM;
    504   JITMemoryManager *JMM;
    505   bool AllocateGVsWithCode;
    506   TargetOptions Options;
    507   Reloc::Model RelocModel;
    508   CodeModel::Model CMModel;
    509   std::string MArch;
    510   std::string MCPU;
    511   SmallVector<std::string, 4> MAttrs;
    512   bool UseMCJIT;
    513 
    514   /// InitEngine - Does the common initialization of default options.
    515   void InitEngine() {
    516     WhichEngine = EngineKind::Either;
    517     ErrorStr = NULL;
    518     OptLevel = CodeGenOpt::Default;
    519     MCJMM = NULL;
    520     JMM = NULL;
    521     Options = TargetOptions();
    522     AllocateGVsWithCode = false;
    523     RelocModel = Reloc::Default;
    524     CMModel = CodeModel::JITDefault;
    525     UseMCJIT = false;
    526   }
    527 
    528 public:
    529   /// EngineBuilder - Constructor for EngineBuilder.  If create() is called and
    530   /// is successful, the created engine takes ownership of the module.
    531   EngineBuilder(Module *m) : M(m) {
    532     InitEngine();
    533   }
    534 
    535   /// setEngineKind - Controls whether the user wants the interpreter, the JIT,
    536   /// or whichever engine works.  This option defaults to EngineKind::Either.
    537   EngineBuilder &setEngineKind(EngineKind::Kind w) {
    538     WhichEngine = w;
    539     return *this;
    540   }
    541 
    542   /// setMCJITMemoryManager - Sets the MCJIT memory manager to use. This allows
    543   /// clients to customize their memory allocation policies for the MCJIT. This
    544   /// is only appropriate for the MCJIT; setting this and configuring the builder
    545   /// to create anything other than MCJIT will cause a runtime error. If create()
    546   /// is called and is successful, the created engine takes ownership of the
    547   /// memory manager. This option defaults to NULL. Using this option nullifies
    548   /// the setJITMemoryManager() option.
    549   EngineBuilder &setMCJITMemoryManager(RTDyldMemoryManager *mcjmm) {
    550     MCJMM = mcjmm;
    551     JMM = NULL;
    552     return *this;
    553   }
    554 
    555   /// setJITMemoryManager - Sets the JIT memory manager to use.  This allows
    556   /// clients to customize their memory allocation policies.  This is only
    557   /// appropriate for either JIT or MCJIT; setting this and configuring the
    558   /// builder to create an interpreter will cause a runtime error. If create()
    559   /// is called and is successful, the created engine takes ownership of the
    560   /// memory manager.  This option defaults to NULL. This option overrides
    561   /// setMCJITMemoryManager() as well.
    562   EngineBuilder &setJITMemoryManager(JITMemoryManager *jmm) {
    563     MCJMM = NULL;
    564     JMM = jmm;
    565     return *this;
    566   }
    567 
    568   /// setErrorStr - Set the error string to write to on error.  This option
    569   /// defaults to NULL.
    570   EngineBuilder &setErrorStr(std::string *e) {
    571     ErrorStr = e;
    572     return *this;
    573   }
    574 
    575   /// setOptLevel - Set the optimization level for the JIT.  This option
    576   /// defaults to CodeGenOpt::Default.
    577   EngineBuilder &setOptLevel(CodeGenOpt::Level l) {
    578     OptLevel = l;
    579     return *this;
    580   }
    581 
    582   /// setTargetOptions - Set the target options that the ExecutionEngine
    583   /// target is using. Defaults to TargetOptions().
    584   EngineBuilder &setTargetOptions(const TargetOptions &Opts) {
    585     Options = Opts;
    586     return *this;
    587   }
    588 
    589   /// setRelocationModel - Set the relocation model that the ExecutionEngine
    590   /// target is using. Defaults to target specific default "Reloc::Default".
    591   EngineBuilder &setRelocationModel(Reloc::Model RM) {
    592     RelocModel = RM;
    593     return *this;
    594   }
    595 
    596   /// setCodeModel - Set the CodeModel that the ExecutionEngine target
    597   /// data is using. Defaults to target specific default
    598   /// "CodeModel::JITDefault".
    599   EngineBuilder &setCodeModel(CodeModel::Model M) {
    600     CMModel = M;
    601     return *this;
    602   }
    603 
    604   /// setAllocateGVsWithCode - Sets whether global values should be allocated
    605   /// into the same buffer as code.  For most applications this should be set
    606   /// to false.  Allocating globals with code breaks freeMachineCodeForFunction
    607   /// and is probably unsafe and bad for performance.  However, we have clients
    608   /// who depend on this behavior, so we must support it.  This option defaults
    609   /// to false so that users of the new API can safely use the new memory
    610   /// manager and free machine code.
    611   EngineBuilder &setAllocateGVsWithCode(bool a) {
    612     AllocateGVsWithCode = a;
    613     return *this;
    614   }
    615 
    616   /// setMArch - Override the architecture set by the Module's triple.
    617   EngineBuilder &setMArch(StringRef march) {
    618     MArch.assign(march.begin(), march.end());
    619     return *this;
    620   }
    621 
    622   /// setMCPU - Target a specific cpu type.
    623   EngineBuilder &setMCPU(StringRef mcpu) {
    624     MCPU.assign(mcpu.begin(), mcpu.end());
    625     return *this;
    626   }
    627 
    628   /// setUseMCJIT - Set whether the MC-JIT implementation should be used
    629   /// (experimental).
    630   EngineBuilder &setUseMCJIT(bool Value) {
    631     UseMCJIT = Value;
    632     return *this;
    633   }
    634 
    635   /// setMAttrs - Set cpu-specific attributes.
    636   template<typename StringSequence>
    637   EngineBuilder &setMAttrs(const StringSequence &mattrs) {
    638     MAttrs.clear();
    639     MAttrs.append(mattrs.begin(), mattrs.end());
    640     return *this;
    641   }
    642 
    643   TargetMachine *selectTarget();
    644 
    645   /// selectTarget - Pick a target either via -march or by guessing the native
    646   /// arch.  Add any CPU features specified via -mcpu or -mattr.
    647   TargetMachine *selectTarget(const Triple &TargetTriple,
    648                               StringRef MArch,
    649                               StringRef MCPU,
    650                               const SmallVectorImpl<std::string>& MAttrs);
    651 
    652   ExecutionEngine *create() {
    653     return create(selectTarget());
    654   }
    655 
    656   ExecutionEngine *create(TargetMachine *TM);
    657 };
    658 
    659 // Create wrappers for C Binding types (see CBindingWrapping.h).
    660 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ExecutionEngine, LLVMExecutionEngineRef)
    661 
    662 } // End llvm namespace
    663 
    664 #endif
    665