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ExecutionEngine.cpp

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00001 //===-- ExecutionEngine.cpp - Common Implementation shared by EEs ---------===//
00002 // 
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 // 
00008 //===----------------------------------------------------------------------===//
00009 // 
00010 // This file defines the common interface used by the various execution engine
00011 // subclasses.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #define DEBUG_TYPE "jit"
00016 #include "Interpreter/Interpreter.h"
00017 #include "JIT/JIT.h"
00018 #include "llvm/Constants.h"
00019 #include "llvm/DerivedTypes.h"
00020 #include "llvm/Module.h"
00021 #include "llvm/ModuleProvider.h"
00022 #include "llvm/ADT/Statistic.h"
00023 #include "llvm/CodeGen/IntrinsicLowering.h"
00024 #include "llvm/ExecutionEngine/ExecutionEngine.h"
00025 #include "llvm/ExecutionEngine/GenericValue.h"
00026 #include "llvm/Support/Debug.h"
00027 #include "llvm/System/DynamicLibrary.h"
00028 #include "llvm/Target/TargetData.h"
00029 using namespace llvm;
00030 
00031 namespace {
00032   Statistic<> NumInitBytes("lli", "Number of bytes of global vars initialized");
00033   Statistic<> NumGlobals  ("lli", "Number of global vars initialized");
00034 }
00035 
00036 ExecutionEngine::ExecutionEngine(ModuleProvider *P) : 
00037   CurMod(*P->getModule()), MP(P) {
00038   assert(P && "ModuleProvider is null?");
00039 }
00040 
00041 ExecutionEngine::ExecutionEngine(Module *M) : CurMod(*M), MP(0) {
00042   assert(M && "Module is null?");
00043 }
00044 
00045 ExecutionEngine::~ExecutionEngine() {
00046   delete MP;
00047 }
00048 
00049 /// getGlobalValueAtAddress - Return the LLVM global value object that starts
00050 /// at the specified address.
00051 ///
00052 const GlobalValue *ExecutionEngine::getGlobalValueAtAddress(void *Addr) {
00053   // If we haven't computed the reverse mapping yet, do so first.
00054   if (GlobalAddressReverseMap.empty()) {
00055     for (std::map<const GlobalValue*, void *>::iterator I = 
00056            GlobalAddressMap.begin(), E = GlobalAddressMap.end(); I != E; ++I)
00057       GlobalAddressReverseMap.insert(std::make_pair(I->second, I->first));
00058   }
00059 
00060   std::map<void *, const GlobalValue*>::iterator I =
00061     GlobalAddressReverseMap.find(Addr);
00062   return I != GlobalAddressReverseMap.end() ? I->second : 0;
00063 }
00064 
00065 // CreateArgv - Turn a vector of strings into a nice argv style array of
00066 // pointers to null terminated strings.
00067 //
00068 static void *CreateArgv(ExecutionEngine *EE,
00069                         const std::vector<std::string> &InputArgv) {
00070   unsigned PtrSize = EE->getTargetData().getPointerSize();
00071   char *Result = new char[(InputArgv.size()+1)*PtrSize];
00072 
00073   DEBUG(std::cerr << "ARGV = " << (void*)Result << "\n");
00074   const Type *SBytePtr = PointerType::get(Type::SByteTy);
00075 
00076   for (unsigned i = 0; i != InputArgv.size(); ++i) {
00077     unsigned Size = InputArgv[i].size()+1;
00078     char *Dest = new char[Size];
00079     DEBUG(std::cerr << "ARGV[" << i << "] = " << (void*)Dest << "\n");
00080       
00081     std::copy(InputArgv[i].begin(), InputArgv[i].end(), Dest);
00082     Dest[Size-1] = 0;
00083       
00084     // Endian safe: Result[i] = (PointerTy)Dest;
00085     EE->StoreValueToMemory(PTOGV(Dest), (GenericValue*)(Result+i*PtrSize),
00086                            SBytePtr);
00087   }
00088 
00089   // Null terminate it
00090   EE->StoreValueToMemory(PTOGV(0),
00091                          (GenericValue*)(Result+InputArgv.size()*PtrSize),
00092                          SBytePtr);
00093   return Result;
00094 }
00095 
00096 /// runFunctionAsMain - This is a helper function which wraps runFunction to
00097 /// handle the common task of starting up main with the specified argc, argv,
00098 /// and envp parameters.
00099 int ExecutionEngine::runFunctionAsMain(Function *Fn,
00100                                        const std::vector<std::string> &argv,
00101                                        const char * const * envp) {
00102   std::vector<GenericValue> GVArgs;
00103   GenericValue GVArgc;
00104   GVArgc.IntVal = argv.size();
00105   unsigned NumArgs = Fn->getFunctionType()->getNumParams();
00106   if (NumArgs) {
00107     GVArgs.push_back(GVArgc); // Arg #0 = argc.
00108     if (NumArgs > 1) {
00109       GVArgs.push_back(PTOGV(CreateArgv(this, argv))); // Arg #1 = argv.
00110       assert(((char **)GVTOP(GVArgs[1]))[0] &&
00111              "argv[0] was null after CreateArgv");
00112       if (NumArgs > 2) {
00113         std::vector<std::string> EnvVars;
00114         for (unsigned i = 0; envp[i]; ++i)
00115           EnvVars.push_back(envp[i]);
00116         GVArgs.push_back(PTOGV(CreateArgv(this, EnvVars))); // Arg #2 = envp.
00117       }
00118     }
00119   }
00120   return runFunction(Fn, GVArgs).IntVal;
00121 }
00122 
00123 
00124 
00125 /// If possible, create a JIT, unless the caller specifically requests an
00126 /// Interpreter or there's an error. If even an Interpreter cannot be created,
00127 /// NULL is returned. 
00128 ///
00129 ExecutionEngine *ExecutionEngine::create(ModuleProvider *MP, 
00130                                          bool ForceInterpreter,
00131                                          IntrinsicLowering *IL) {
00132   ExecutionEngine *EE = 0;
00133 
00134   // Unless the interpreter was explicitly selected, try making a JIT.
00135   if (!ForceInterpreter)
00136     EE = JIT::create(MP, IL);
00137 
00138   // If we can't make a JIT, make an interpreter instead.
00139   if (EE == 0) {
00140     try {
00141       Module *M = MP->materializeModule();
00142       try {
00143         EE = Interpreter::create(M, IL);
00144       } catch (...) {
00145         std::cerr << "Error creating the interpreter!\n";
00146       }
00147     } catch (std::string& errmsg) {
00148       std::cerr << "Error reading the bytecode file: " << errmsg << "\n";
00149     } catch (...) {
00150       std::cerr << "Error reading the bytecode file!\n";
00151     }
00152   }
00153 
00154   if (EE == 0) 
00155     delete IL;
00156   else
00157     // Make sure we can resolve symbols in the program as well. The zero arg 
00158     // to the function tells DynamicLibrary to load the program, not a library.
00159     sys::DynamicLibrary::LoadLibraryPermanently(0);
00160 
00161   return EE;
00162 }
00163 
00164 /// getPointerToGlobal - This returns the address of the specified global
00165 /// value.  This may involve code generation if it's a function.
00166 ///
00167 void *ExecutionEngine::getPointerToGlobal(const GlobalValue *GV) {
00168   if (Function *F = const_cast<Function*>(dyn_cast<Function>(GV)))
00169     return getPointerToFunction(F);
00170 
00171   assert(GlobalAddressMap[GV] && "Global hasn't had an address allocated yet?");
00172   return GlobalAddressMap[GV];
00173 }
00174 
00175 /// FIXME: document
00176 /// 
00177 GenericValue ExecutionEngine::getConstantValue(const Constant *C) {
00178   GenericValue Result;
00179   if (isa<UndefValue>(C)) return Result;
00180 
00181   if (ConstantExpr *CE = const_cast<ConstantExpr*>(dyn_cast<ConstantExpr>(C))) {
00182     switch (CE->getOpcode()) {
00183     case Instruction::GetElementPtr: {
00184       Result = getConstantValue(CE->getOperand(0));
00185       std::vector<Value*> Indexes(CE->op_begin()+1, CE->op_end());
00186       uint64_t Offset =
00187         TD->getIndexedOffset(CE->getOperand(0)->getType(), Indexes);
00188                              
00189       Result.LongVal += Offset;
00190       return Result;
00191     }
00192     case Instruction::Cast: {
00193       // We only need to handle a few cases here.  Almost all casts will
00194       // automatically fold, just the ones involving pointers won't.
00195       //
00196       Constant *Op = CE->getOperand(0);
00197       GenericValue GV = getConstantValue(Op);
00198 
00199       // Handle cast of pointer to pointer...
00200       if (Op->getType()->getTypeID() == C->getType()->getTypeID())
00201         return GV;
00202 
00203       // Handle a cast of pointer to any integral type...
00204       if (isa<PointerType>(Op->getType()) && C->getType()->isIntegral())
00205         return GV;
00206         
00207       // Handle cast of integer to a pointer...
00208       if (isa<PointerType>(C->getType()) && Op->getType()->isIntegral())
00209         switch (Op->getType()->getTypeID()) {
00210         case Type::BoolTyID:    return PTOGV((void*)(uintptr_t)GV.BoolVal);
00211         case Type::SByteTyID:   return PTOGV((void*)( intptr_t)GV.SByteVal);
00212         case Type::UByteTyID:   return PTOGV((void*)(uintptr_t)GV.UByteVal);
00213         case Type::ShortTyID:   return PTOGV((void*)( intptr_t)GV.ShortVal);
00214         case Type::UShortTyID:  return PTOGV((void*)(uintptr_t)GV.UShortVal);
00215         case Type::IntTyID:     return PTOGV((void*)( intptr_t)GV.IntVal);
00216         case Type::UIntTyID:    return PTOGV((void*)(uintptr_t)GV.UIntVal);
00217         case Type::LongTyID:    return PTOGV((void*)( intptr_t)GV.LongVal);
00218         case Type::ULongTyID:   return PTOGV((void*)(uintptr_t)GV.ULongVal);
00219         default: assert(0 && "Unknown integral type!");
00220         }
00221       break;
00222     }
00223 
00224     case Instruction::Add:
00225       switch (CE->getOperand(0)->getType()->getTypeID()) {
00226       default: assert(0 && "Bad add type!"); abort();
00227       case Type::LongTyID:
00228       case Type::ULongTyID:
00229         Result.LongVal = getConstantValue(CE->getOperand(0)).LongVal +
00230                          getConstantValue(CE->getOperand(1)).LongVal;
00231         break;
00232       case Type::IntTyID:
00233       case Type::UIntTyID:
00234         Result.IntVal = getConstantValue(CE->getOperand(0)).IntVal +
00235                         getConstantValue(CE->getOperand(1)).IntVal;
00236         break;
00237       case Type::ShortTyID:
00238       case Type::UShortTyID:
00239         Result.ShortVal = getConstantValue(CE->getOperand(0)).ShortVal +
00240                           getConstantValue(CE->getOperand(1)).ShortVal;
00241         break;
00242       case Type::SByteTyID:
00243       case Type::UByteTyID:
00244         Result.SByteVal = getConstantValue(CE->getOperand(0)).SByteVal +
00245                           getConstantValue(CE->getOperand(1)).SByteVal;
00246         break;
00247       case Type::FloatTyID:
00248         Result.FloatVal = getConstantValue(CE->getOperand(0)).FloatVal +
00249                           getConstantValue(CE->getOperand(1)).FloatVal;
00250         break;
00251       case Type::DoubleTyID:
00252         Result.DoubleVal = getConstantValue(CE->getOperand(0)).DoubleVal +
00253                            getConstantValue(CE->getOperand(1)).DoubleVal;
00254         break;
00255       }
00256       return Result;
00257     default:
00258       break;
00259     }
00260     std::cerr << "ConstantExpr not handled as global var init: " << *CE << "\n";
00261     abort();
00262   }
00263   
00264   switch (C->getType()->getTypeID()) {
00265 #define GET_CONST_VAL(TY, CLASS) \
00266   case Type::TY##TyID: Result.TY##Val = cast<CLASS>(C)->getValue(); break
00267     GET_CONST_VAL(Bool   , ConstantBool);
00268     GET_CONST_VAL(UByte  , ConstantUInt);
00269     GET_CONST_VAL(SByte  , ConstantSInt);
00270     GET_CONST_VAL(UShort , ConstantUInt);
00271     GET_CONST_VAL(Short  , ConstantSInt);
00272     GET_CONST_VAL(UInt   , ConstantUInt);
00273     GET_CONST_VAL(Int    , ConstantSInt);
00274     GET_CONST_VAL(ULong  , ConstantUInt);
00275     GET_CONST_VAL(Long   , ConstantSInt);
00276     GET_CONST_VAL(Float  , ConstantFP);
00277     GET_CONST_VAL(Double , ConstantFP);
00278 #undef GET_CONST_VAL
00279   case Type::PointerTyID:
00280     if (isa<ConstantPointerNull>(C))
00281       Result.PointerVal = 0;
00282     else if (const Function *F = dyn_cast<Function>(C))
00283       Result = PTOGV(getPointerToFunctionOrStub(const_cast<Function*>(F)));
00284     else if (const GlobalVariable* GV = dyn_cast<GlobalVariable>(C))
00285       Result = PTOGV(getOrEmitGlobalVariable(const_cast<GlobalVariable*>(GV)));
00286     else
00287       assert(0 && "Unknown constant pointer type!");
00288     break;
00289   default:
00290     std::cout << "ERROR: Constant unimp for type: " << *C->getType() << "\n";
00291     abort();
00292   }
00293   return Result;
00294 }
00295 
00296 /// FIXME: document
00297 ///
00298 void ExecutionEngine::StoreValueToMemory(GenericValue Val, GenericValue *Ptr,
00299                                          const Type *Ty) {
00300   if (getTargetData().isLittleEndian()) {
00301     switch (Ty->getTypeID()) {
00302     case Type::BoolTyID:
00303     case Type::UByteTyID:
00304     case Type::SByteTyID:   Ptr->Untyped[0] = Val.UByteVal; break;
00305     case Type::UShortTyID:
00306     case Type::ShortTyID:   Ptr->Untyped[0] = Val.UShortVal & 255;
00307                             Ptr->Untyped[1] = (Val.UShortVal >> 8) & 255;
00308                             break;
00309     Store4BytesLittleEndian:
00310     case Type::FloatTyID:
00311     case Type::UIntTyID:
00312     case Type::IntTyID:     Ptr->Untyped[0] =  Val.UIntVal        & 255;
00313                             Ptr->Untyped[1] = (Val.UIntVal >>  8) & 255;
00314                             Ptr->Untyped[2] = (Val.UIntVal >> 16) & 255;
00315                             Ptr->Untyped[3] = (Val.UIntVal >> 24) & 255;
00316                             break;
00317     case Type::PointerTyID: if (getTargetData().getPointerSize() == 4)
00318                               goto Store4BytesLittleEndian;
00319     case Type::DoubleTyID:
00320     case Type::ULongTyID:
00321     case Type::LongTyID:    Ptr->Untyped[0] =  Val.ULongVal        & 255;
00322                             Ptr->Untyped[1] = (Val.ULongVal >>  8) & 255;
00323                             Ptr->Untyped[2] = (Val.ULongVal >> 16) & 255;
00324                             Ptr->Untyped[3] = (Val.ULongVal >> 24) & 255;
00325                             Ptr->Untyped[4] = (Val.ULongVal >> 32) & 255;
00326                             Ptr->Untyped[5] = (Val.ULongVal >> 40) & 255;
00327                             Ptr->Untyped[6] = (Val.ULongVal >> 48) & 255;
00328                             Ptr->Untyped[7] = (Val.ULongVal >> 56) & 255;
00329                             break;
00330     default:
00331       std::cout << "Cannot store value of type " << *Ty << "!\n";
00332     }
00333   } else {
00334     switch (Ty->getTypeID()) {
00335     case Type::BoolTyID:
00336     case Type::UByteTyID:
00337     case Type::SByteTyID:   Ptr->Untyped[0] = Val.UByteVal; break;
00338     case Type::UShortTyID:
00339     case Type::ShortTyID:   Ptr->Untyped[1] = Val.UShortVal & 255;
00340                             Ptr->Untyped[0] = (Val.UShortVal >> 8) & 255;
00341                             break;
00342     Store4BytesBigEndian:
00343     case Type::FloatTyID:
00344     case Type::UIntTyID:
00345     case Type::IntTyID:     Ptr->Untyped[3] =  Val.UIntVal        & 255;
00346                             Ptr->Untyped[2] = (Val.UIntVal >>  8) & 255;
00347                             Ptr->Untyped[1] = (Val.UIntVal >> 16) & 255;
00348                             Ptr->Untyped[0] = (Val.UIntVal >> 24) & 255;
00349                             break;
00350     case Type::PointerTyID: if (getTargetData().getPointerSize() == 4)
00351                               goto Store4BytesBigEndian;
00352     case Type::DoubleTyID:
00353     case Type::ULongTyID:
00354     case Type::LongTyID:    Ptr->Untyped[7] =  Val.ULongVal        & 255;
00355                             Ptr->Untyped[6] = (Val.ULongVal >>  8) & 255;
00356                             Ptr->Untyped[5] = (Val.ULongVal >> 16) & 255;
00357                             Ptr->Untyped[4] = (Val.ULongVal >> 24) & 255;
00358                             Ptr->Untyped[3] = (Val.ULongVal >> 32) & 255;
00359                             Ptr->Untyped[2] = (Val.ULongVal >> 40) & 255;
00360                             Ptr->Untyped[1] = (Val.ULongVal >> 48) & 255;
00361                             Ptr->Untyped[0] = (Val.ULongVal >> 56) & 255;
00362                             break;
00363     default:
00364       std::cout << "Cannot store value of type " << *Ty << "!\n";
00365     }
00366   }
00367 }
00368 
00369 /// FIXME: document
00370 ///
00371 GenericValue ExecutionEngine::LoadValueFromMemory(GenericValue *Ptr,
00372                                                   const Type *Ty) {
00373   GenericValue Result;
00374   if (getTargetData().isLittleEndian()) {
00375     switch (Ty->getTypeID()) {
00376     case Type::BoolTyID:
00377     case Type::UByteTyID:
00378     case Type::SByteTyID:   Result.UByteVal = Ptr->Untyped[0]; break;
00379     case Type::UShortTyID:
00380     case Type::ShortTyID:   Result.UShortVal = (unsigned)Ptr->Untyped[0] |
00381                                               ((unsigned)Ptr->Untyped[1] << 8);
00382                             break;
00383     Load4BytesLittleEndian:                            
00384     case Type::FloatTyID:
00385     case Type::UIntTyID:
00386     case Type::IntTyID:     Result.UIntVal = (unsigned)Ptr->Untyped[0] |
00387                                             ((unsigned)Ptr->Untyped[1] <<  8) |
00388                                             ((unsigned)Ptr->Untyped[2] << 16) |
00389                                             ((unsigned)Ptr->Untyped[3] << 24);
00390                             break;
00391     case Type::PointerTyID: if (getTargetData().getPointerSize() == 4)
00392                               goto Load4BytesLittleEndian;
00393     case Type::DoubleTyID:
00394     case Type::ULongTyID:
00395     case Type::LongTyID:    Result.ULongVal = (uint64_t)Ptr->Untyped[0] |
00396                                              ((uint64_t)Ptr->Untyped[1] <<  8) |
00397                                              ((uint64_t)Ptr->Untyped[2] << 16) |
00398                                              ((uint64_t)Ptr->Untyped[3] << 24) |
00399                                              ((uint64_t)Ptr->Untyped[4] << 32) |
00400                                              ((uint64_t)Ptr->Untyped[5] << 40) |
00401                                              ((uint64_t)Ptr->Untyped[6] << 48) |
00402                                              ((uint64_t)Ptr->Untyped[7] << 56);
00403                             break;
00404     default:
00405       std::cout << "Cannot load value of type " << *Ty << "!\n";
00406       abort();
00407     }
00408   } else {
00409     switch (Ty->getTypeID()) {
00410     case Type::BoolTyID:
00411     case Type::UByteTyID:
00412     case Type::SByteTyID:   Result.UByteVal = Ptr->Untyped[0]; break;
00413     case Type::UShortTyID:
00414     case Type::ShortTyID:   Result.UShortVal = (unsigned)Ptr->Untyped[1] |
00415                                               ((unsigned)Ptr->Untyped[0] << 8);
00416                             break;
00417     Load4BytesBigEndian:
00418     case Type::FloatTyID:
00419     case Type::UIntTyID:
00420     case Type::IntTyID:     Result.UIntVal = (unsigned)Ptr->Untyped[3] |
00421                                             ((unsigned)Ptr->Untyped[2] <<  8) |
00422                                             ((unsigned)Ptr->Untyped[1] << 16) |
00423                                             ((unsigned)Ptr->Untyped[0] << 24);
00424                             break;
00425     case Type::PointerTyID: if (getTargetData().getPointerSize() == 4)
00426                               goto Load4BytesBigEndian;
00427     case Type::DoubleTyID:
00428     case Type::ULongTyID:
00429     case Type::LongTyID:    Result.ULongVal = (uint64_t)Ptr->Untyped[7] |
00430                                              ((uint64_t)Ptr->Untyped[6] <<  8) |
00431                                              ((uint64_t)Ptr->Untyped[5] << 16) |
00432                                              ((uint64_t)Ptr->Untyped[4] << 24) |
00433                                              ((uint64_t)Ptr->Untyped[3] << 32) |
00434                                              ((uint64_t)Ptr->Untyped[2] << 40) |
00435                                              ((uint64_t)Ptr->Untyped[1] << 48) |
00436                                              ((uint64_t)Ptr->Untyped[0] << 56);
00437                             break;
00438     default:
00439       std::cout << "Cannot load value of type " << *Ty << "!\n";
00440       abort();
00441     }
00442   }
00443   return Result;
00444 }
00445 
00446 // InitializeMemory - Recursive function to apply a Constant value into the
00447 // specified memory location...
00448 //
00449 void ExecutionEngine::InitializeMemory(const Constant *Init, void *Addr) {
00450   if (isa<UndefValue>(Init)) {
00451     // FIXME: THIS SHOULD NOT BE NEEDED.
00452     unsigned Size = getTargetData().getTypeSize(Init->getType());
00453     memset(Addr, 0, Size);
00454     return;
00455   } else if (Init->getType()->isFirstClassType()) {
00456     GenericValue Val = getConstantValue(Init);
00457     StoreValueToMemory(Val, (GenericValue*)Addr, Init->getType());
00458     return;
00459   } else if (isa<ConstantAggregateZero>(Init)) {
00460     unsigned Size = getTargetData().getTypeSize(Init->getType());
00461     memset(Addr, 0, Size);
00462     return;
00463   }
00464 
00465   switch (Init->getType()->getTypeID()) {
00466   case Type::ArrayTyID: {
00467     const ConstantArray *CPA = cast<ConstantArray>(Init);
00468     unsigned ElementSize = 
00469       getTargetData().getTypeSize(cast<ArrayType>(CPA->getType())->getElementType());
00470     for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
00471       InitializeMemory(CPA->getOperand(i), (char*)Addr+i*ElementSize);
00472     return;
00473   }
00474 
00475   case Type::StructTyID: {
00476     const ConstantStruct *CPS = cast<ConstantStruct>(Init);
00477     const StructLayout *SL =
00478       getTargetData().getStructLayout(cast<StructType>(CPS->getType()));
00479     for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
00480       InitializeMemory(CPS->getOperand(i), (char*)Addr+SL->MemberOffsets[i]);
00481     return;
00482   }
00483 
00484   default:
00485     std::cerr << "Bad Type: " << *Init->getType() << "\n";
00486     assert(0 && "Unknown constant type to initialize memory with!");
00487   }
00488 }
00489 
00490 /// EmitGlobals - Emit all of the global variables to memory, storing their
00491 /// addresses into GlobalAddress.  This must make sure to copy the contents of
00492 /// their initializers into the memory.
00493 ///
00494 void ExecutionEngine::emitGlobals() {
00495   const TargetData &TD = getTargetData();
00496   
00497   // Loop over all of the global variables in the program, allocating the memory
00498   // to hold them.
00499   for (Module::giterator I = getModule().gbegin(), E = getModule().gend();
00500        I != E; ++I)
00501     if (!I->isExternal()) {
00502       // Get the type of the global...
00503       const Type *Ty = I->getType()->getElementType();
00504       
00505       // Allocate some memory for it!
00506       unsigned Size = TD.getTypeSize(Ty);
00507       addGlobalMapping(I, new char[Size]);
00508     } else {
00509       // External variable reference. Try to use the dynamic loader to
00510       // get a pointer to it.
00511       if (void *SymAddr = sys::DynamicLibrary::SearchForAddressOfSymbol(
00512                             I->getName().c_str()))
00513         addGlobalMapping(I, SymAddr);
00514       else {
00515         std::cerr << "Could not resolve external global address: "
00516                   << I->getName() << "\n";
00517         abort();
00518       }
00519     }
00520   
00521   // Now that all of the globals are set up in memory, loop through them all and
00522   // initialize their contents.
00523   for (Module::giterator I = getModule().gbegin(), E = getModule().gend();
00524        I != E; ++I)
00525     if (!I->isExternal())
00526       EmitGlobalVariable(I);
00527 }
00528 
00529 // EmitGlobalVariable - This method emits the specified global variable to the
00530 // address specified in GlobalAddresses, or allocates new memory if it's not
00531 // already in the map.
00532 void ExecutionEngine::EmitGlobalVariable(const GlobalVariable *GV) {
00533   void *GA = getPointerToGlobalIfAvailable(GV);
00534   DEBUG(std::cerr << "Global '" << GV->getName() << "' -> " << GA << "\n");
00535 
00536   const Type *ElTy = GV->getType()->getElementType();
00537   unsigned GVSize = getTargetData().getTypeSize(ElTy);
00538   if (GA == 0) {
00539     // If it's not already specified, allocate memory for the global.
00540     GA = new char[GVSize];
00541     addGlobalMapping(GV, GA);
00542   }
00543 
00544   InitializeMemory(GV->getInitializer(), GA);
00545   NumInitBytes += GVSize;
00546   ++NumGlobals;
00547 }