ExecutionEngine.cpp revision 88216af3ea4bb1c68a8793ed1d3b30308b64ab0e 
1//===-- ExecutionEngine.cpp - Common Implementation shared by EEs ---------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the common interface used by the various execution engine
11// subclasses.
12//
13//===----------------------------------------------------------------------===//
14
15#define DEBUG_TYPE "jit"
16#include "llvm/Constants.h"
17#include "llvm/DerivedTypes.h"
18#include "llvm/Module.h"
19#include "llvm/ModuleProvider.h"
20#include "llvm/ADT/Statistic.h"
21#include "llvm/ExecutionEngine/ExecutionEngine.h"
22#include "llvm/ExecutionEngine/GenericValue.h"
23#include "llvm/Support/Debug.h"
24#include "llvm/Support/MutexGuard.h"
25#include "llvm/System/DynamicLibrary.h"
26#include "llvm/Target/TargetData.h"
27#include <math.h>
28using namespace llvm;
29
30STATISTIC(NumInitBytes, "Number of bytes of global vars initialized");
31STATISTIC(NumGlobals  , "Number of global vars initialized");
32
33ExecutionEngine::EECtorFn ExecutionEngine::JITCtor = 0;
34ExecutionEngine::EECtorFn ExecutionEngine::InterpCtor = 0;
35
36ExecutionEngine::ExecutionEngine(ModuleProvider *P) {
37  LazyCompilationDisabled = false;
38  Modules.push_back(P);
39  assert(P && "ModuleProvider is null?");
40}
41
42ExecutionEngine::ExecutionEngine(Module *M) {
43  LazyCompilationDisabled = false;
44  assert(M && "Module is null?");
45  Modules.push_back(new ExistingModuleProvider(M));
46}
47
48ExecutionEngine::~ExecutionEngine() {
49  clearAllGlobalMappings();
50  for (unsigned i = 0, e = Modules.size(); i != e; ++i)
51    delete Modules[i];
52}
53
54/// FindFunctionNamed - Search all of the active modules to find the one that
55/// defines FnName.  This is very slow operation and shouldn't be used for
56/// general code.
57Function *ExecutionEngine::FindFunctionNamed(const char *FnName) {
58  for (unsigned i = 0, e = Modules.size(); i != e; ++i) {
59    if (Function *F = Modules[i]->getModule()->getFunction(FnName))
60      return F;
61  }
62  return 0;
63}
64
65
66/// addGlobalMapping - Tell the execution engine that the specified global is
67/// at the specified location.  This is used internally as functions are JIT'd
68/// and as global variables are laid out in memory.  It can and should also be
69/// used by clients of the EE that want to have an LLVM global overlay
70/// existing data in memory.
71void ExecutionEngine::addGlobalMapping(const GlobalValue *GV, void *Addr) {
72  MutexGuard locked(lock);
73
74  void *&CurVal = state.getGlobalAddressMap(locked)[GV];
75  assert((CurVal == 0 || Addr == 0) && "GlobalMapping already established!");
76  CurVal = Addr;
77
78  // If we are using the reverse mapping, add it too
79  if (!state.getGlobalAddressReverseMap(locked).empty()) {
80    const GlobalValue *&V = state.getGlobalAddressReverseMap(locked)[Addr];
81    assert((V == 0 || GV == 0) && "GlobalMapping already established!");
82    V = GV;
83  }
84}
85
86/// clearAllGlobalMappings - Clear all global mappings and start over again
87/// use in dynamic compilation scenarios when you want to move globals
88void ExecutionEngine::clearAllGlobalMappings() {
89  MutexGuard locked(lock);
90
91  state.getGlobalAddressMap(locked).clear();
92  state.getGlobalAddressReverseMap(locked).clear();
93}
94
95/// updateGlobalMapping - Replace an existing mapping for GV with a new
96/// address.  This updates both maps as required.  If "Addr" is null, the
97/// entry for the global is removed from the mappings.
98void ExecutionEngine::updateGlobalMapping(const GlobalValue *GV, void *Addr) {
99  MutexGuard locked(lock);
100
101  // Deleting from the mapping?
102  if (Addr == 0) {
103    state.getGlobalAddressMap(locked).erase(GV);
104    if (!state.getGlobalAddressReverseMap(locked).empty())
105      state.getGlobalAddressReverseMap(locked).erase(Addr);
106    return;
107  }
108
109  void *&CurVal = state.getGlobalAddressMap(locked)[GV];
110  if (CurVal && !state.getGlobalAddressReverseMap(locked).empty())
111    state.getGlobalAddressReverseMap(locked).erase(CurVal);
112  CurVal = Addr;
113
114  // If we are using the reverse mapping, add it too
115  if (!state.getGlobalAddressReverseMap(locked).empty()) {
116    const GlobalValue *&V = state.getGlobalAddressReverseMap(locked)[Addr];
117    assert((V == 0 || GV == 0) && "GlobalMapping already established!");
118    V = GV;
119  }
120}
121
122/// getPointerToGlobalIfAvailable - This returns the address of the specified
123/// global value if it is has already been codegen'd, otherwise it returns null.
124///
125void *ExecutionEngine::getPointerToGlobalIfAvailable(const GlobalValue *GV) {
126  MutexGuard locked(lock);
127
128  std::map<const GlobalValue*, void*>::iterator I =
129  state.getGlobalAddressMap(locked).find(GV);
130  return I != state.getGlobalAddressMap(locked).end() ? I->second : 0;
131}
132
133/// getGlobalValueAtAddress - Return the LLVM global value object that starts
134/// at the specified address.
135///
136const GlobalValue *ExecutionEngine::getGlobalValueAtAddress(void *Addr) {
137  MutexGuard locked(lock);
138
139  // If we haven't computed the reverse mapping yet, do so first.
140  if (state.getGlobalAddressReverseMap(locked).empty()) {
141    for (std::map<const GlobalValue*, void *>::iterator
142         I = state.getGlobalAddressMap(locked).begin(),
143         E = state.getGlobalAddressMap(locked).end(); I != E; ++I)
144      state.getGlobalAddressReverseMap(locked).insert(std::make_pair(I->second,
145                                                                     I->first));
146  }
147
148  std::map<void *, const GlobalValue*>::iterator I =
149    state.getGlobalAddressReverseMap(locked).find(Addr);
150  return I != state.getGlobalAddressReverseMap(locked).end() ? I->second : 0;
151}
152
153// CreateArgv - Turn a vector of strings into a nice argv style array of
154// pointers to null terminated strings.
155//
156static void *CreateArgv(ExecutionEngine *EE,
157                        const std::vector<std::string> &InputArgv) {
158  unsigned PtrSize = EE->getTargetData()->getPointerSize();
159  char *Result = new char[(InputArgv.size()+1)*PtrSize];
160
161  DOUT << "ARGV = " << (void*)Result << "\n";
162  const Type *SBytePtr = PointerType::get(Type::Int8Ty);
163
164  for (unsigned i = 0; i != InputArgv.size(); ++i) {
165    unsigned Size = InputArgv[i].size()+1;
166    char *Dest = new char[Size];
167    DOUT << "ARGV[" << i << "] = " << (void*)Dest << "\n";
168
169    std::copy(InputArgv[i].begin(), InputArgv[i].end(), Dest);
170    Dest[Size-1] = 0;
171
172    // Endian safe: Result[i] = (PointerTy)Dest;
173    EE->StoreValueToMemory(PTOGV(Dest), (GenericValue*)(Result+i*PtrSize),
174                           SBytePtr);
175  }
176
177  // Null terminate it
178  EE->StoreValueToMemory(PTOGV(0),
179                         (GenericValue*)(Result+InputArgv.size()*PtrSize),
180                         SBytePtr);
181  return Result;
182}
183
184
185/// runStaticConstructorsDestructors - This method is used to execute all of
186/// the static constructors or destructors for a program, depending on the
187/// value of isDtors.
188void ExecutionEngine::runStaticConstructorsDestructors(bool isDtors) {
189  const char *Name = isDtors ? "llvm.global_dtors" : "llvm.global_ctors";
190
191  // Execute global ctors/dtors for each module in the program.
192  for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
193    GlobalVariable *GV = Modules[m]->getModule()->getNamedGlobal(Name);
194
195    // If this global has internal linkage, or if it has a use, then it must be
196    // an old-style (llvmgcc3) static ctor with __main linked in and in use.  If
197    // this is the case, don't execute any of the global ctors, __main will do
198    // it.
199    if (!GV || GV->isDeclaration() || GV->hasInternalLinkage()) continue;
200
201    // Should be an array of '{ int, void ()* }' structs.  The first value is
202    // the init priority, which we ignore.
203    ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
204    if (!InitList) continue;
205    for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
206      if (ConstantStruct *CS =
207          dyn_cast<ConstantStruct>(InitList->getOperand(i))) {
208        if (CS->getNumOperands() != 2) break; // Not array of 2-element structs.
209
210        Constant *FP = CS->getOperand(1);
211        if (FP->isNullValue())
212          break;  // Found a null terminator, exit.
213
214        if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
215          if (CE->isCast())
216            FP = CE->getOperand(0);
217        if (Function *F = dyn_cast<Function>(FP)) {
218          // Execute the ctor/dtor function!
219          runFunction(F, std::vector<GenericValue>());
220        }
221      }
222  }
223}
224
225/// runFunctionAsMain - This is a helper function which wraps runFunction to
226/// handle the common task of starting up main with the specified argc, argv,
227/// and envp parameters.
228int ExecutionEngine::runFunctionAsMain(Function *Fn,
229                                       const std::vector<std::string> &argv,
230                                       const char * const * envp) {
231  std::vector<GenericValue> GVArgs;
232  GenericValue GVArgc;
233  GVArgc.IntVal = APInt(32, argv.size());
234
235  // Check main() type
236  unsigned NumArgs = Fn->getFunctionType()->getNumParams();
237  const FunctionType *FTy = Fn->getFunctionType();
238  const Type* PPInt8Ty = PointerType::get(PointerType::get(Type::Int8Ty));
239  switch (NumArgs) {
240  case 3:
241   if (FTy->getParamType(2) != PPInt8Ty) {
242     cerr << "Invalid type for third argument of main() supplied\n";
243     abort();
244   }
245   // FALLS THROUGH
246  case 2:
247   if (FTy->getParamType(1) != PPInt8Ty) {
248     cerr << "Invalid type for second argument of main() supplied\n";
249     abort();
250   }
251   // FALLS THROUGH
252  case 1:
253   if (FTy->getParamType(0) != Type::Int32Ty) {
254     cerr << "Invalid type for first argument of main() supplied\n";
255     abort();
256   }
257   // FALLS THROUGH
258  case 0:
259   if (FTy->getReturnType() != Type::Int32Ty &&
260       FTy->getReturnType() != Type::VoidTy) {
261     cerr << "Invalid return type of main() supplied\n";
262     abort();
263   }
264   break;
265  default:
266   cerr << "Invalid number of arguments of main() supplied\n";
267   abort();
268  }
269
270  if (NumArgs) {
271    GVArgs.push_back(GVArgc); // Arg #0 = argc.
272    if (NumArgs > 1) {
273      GVArgs.push_back(PTOGV(CreateArgv(this, argv))); // Arg #1 = argv.
274      assert(((char **)GVTOP(GVArgs[1]))[0] &&
275             "argv[0] was null after CreateArgv");
276      if (NumArgs > 2) {
277        std::vector<std::string> EnvVars;
278        for (unsigned i = 0; envp[i]; ++i)
279          EnvVars.push_back(envp[i]);
280        GVArgs.push_back(PTOGV(CreateArgv(this, EnvVars))); // Arg #2 = envp.
281      }
282    }
283  }
284  return runFunction(Fn, GVArgs).IntVal.getZExtValue();
285}
286
287/// If possible, create a JIT, unless the caller specifically requests an
288/// Interpreter or there's an error. If even an Interpreter cannot be created,
289/// NULL is returned.
290///
291ExecutionEngine *ExecutionEngine::create(ModuleProvider *MP,
292                                         bool ForceInterpreter,
293                                         std::string *ErrorStr) {
294  ExecutionEngine *EE = 0;
295
296  // Unless the interpreter was explicitly selected, try making a JIT.
297  if (!ForceInterpreter && JITCtor)
298    EE = JITCtor(MP, ErrorStr);
299
300  // If we can't make a JIT, make an interpreter instead.
301  if (EE == 0 && InterpCtor)
302    EE = InterpCtor(MP, ErrorStr);
303
304  if (EE) {
305    // Make sure we can resolve symbols in the program as well. The zero arg
306    // to the function tells DynamicLibrary to load the program, not a library.
307    try {
308      sys::DynamicLibrary::LoadLibraryPermanently(0);
309    } catch (...) {
310    }
311  }
312
313  return EE;
314}
315
316/// getPointerToGlobal - This returns the address of the specified global
317/// value.  This may involve code generation if it's a function.
318///
319void *ExecutionEngine::getPointerToGlobal(const GlobalValue *GV) {
320  if (Function *F = const_cast<Function*>(dyn_cast<Function>(GV)))
321    return getPointerToFunction(F);
322
323  MutexGuard locked(lock);
324  void *p = state.getGlobalAddressMap(locked)[GV];
325  if (p)
326    return p;
327
328  // Global variable might have been added since interpreter started.
329  if (GlobalVariable *GVar =
330          const_cast<GlobalVariable *>(dyn_cast<GlobalVariable>(GV)))
331    EmitGlobalVariable(GVar);
332  else
333    assert(0 && "Global hasn't had an address allocated yet!");
334  return state.getGlobalAddressMap(locked)[GV];
335}
336
337/// This function converts a Constant* into a GenericValue. The interesting
338/// part is if C is a ConstantExpr.
339/// @brief Get a GenericValue for a Constant*
340GenericValue ExecutionEngine::getConstantValue(const Constant *C) {
341  // If its undefined, return the garbage.
342  if (isa<UndefValue>(C))
343    return GenericValue();
344
345  // If the value is a ConstantExpr
346  if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
347    Constant *Op0 = CE->getOperand(0);
348    switch (CE->getOpcode()) {
349    case Instruction::GetElementPtr: {
350      // Compute the index
351      GenericValue Result = getConstantValue(Op0);
352      SmallVector<Value*, 8> Indices(CE->op_begin()+1, CE->op_end());
353      uint64_t Offset =
354        TD->getIndexedOffset(Op0->getType(), &Indices[0], Indices.size());
355
356      char* tmp = (char*) Result.PointerVal;
357      Result = PTOGV(tmp + Offset);
358      return Result;
359    }
360    case Instruction::Trunc: {
361      GenericValue GV = getConstantValue(Op0);
362      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
363      GV.IntVal = GV.IntVal.trunc(BitWidth);
364      return GV;
365    }
366    case Instruction::ZExt: {
367      GenericValue GV = getConstantValue(Op0);
368      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
369      GV.IntVal = GV.IntVal.zext(BitWidth);
370      return GV;
371    }
372    case Instruction::SExt: {
373      GenericValue GV = getConstantValue(Op0);
374      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
375      GV.IntVal = GV.IntVal.sext(BitWidth);
376      return GV;
377    }
378    case Instruction::FPTrunc: {
379      // FIXME long double
380      GenericValue GV = getConstantValue(Op0);
381      GV.FloatVal = float(GV.DoubleVal);
382      return GV;
383    }
384    case Instruction::FPExt:{
385      // FIXME long double
386      GenericValue GV = getConstantValue(Op0);
387      GV.DoubleVal = double(GV.FloatVal);
388      return GV;
389    }
390    case Instruction::UIToFP: {
391      GenericValue GV = getConstantValue(Op0);
392      if (CE->getType() == Type::FloatTy)
393        GV.FloatVal = float(GV.IntVal.roundToDouble());
394      else if (CE->getType() == Type::DoubleTy)
395        GV.DoubleVal = GV.IntVal.roundToDouble();
396      else if (CE->getType() == Type::X86_FP80Ty) {
397        const uint64_t zero[] = {0, 0};
398        APFloat apf = APFloat(APInt(80, 2, zero));
399        (void)apf.convertFromInteger(GV.IntVal.getRawData(),
400                               GV.IntVal.getBitWidth(), false,
401                               APFloat::rmNearestTiesToEven);
402        GV.IntVal = apf.convertToAPInt();
403      }
404      return GV;
405    }
406    case Instruction::SIToFP: {
407      GenericValue GV = getConstantValue(Op0);
408      if (CE->getType() == Type::FloatTy)
409        GV.FloatVal = float(GV.IntVal.signedRoundToDouble());
410      else if (CE->getType() == Type::DoubleTy)
411        GV.DoubleVal = GV.IntVal.signedRoundToDouble();
412      else if (CE->getType() == Type::X86_FP80Ty) {
413        const uint64_t zero[] = { 0, 0};
414        APFloat apf = APFloat(APInt(80, 2, zero));
415        (void)apf.convertFromInteger(GV.IntVal.getRawData(),
416                               GV.IntVal.getBitWidth(), true,
417                               APFloat::rmNearestTiesToEven);
418        GV.IntVal = apf.convertToAPInt();
419      }
420      return GV;
421    }
422    case Instruction::FPToUI: // double->APInt conversion handles sign
423    case Instruction::FPToSI: {
424      GenericValue GV = getConstantValue(Op0);
425      uint32_t BitWidth = cast<IntegerType>(CE->getType())->getBitWidth();
426      if (Op0->getType() == Type::FloatTy)
427        GV.IntVal = APIntOps::RoundFloatToAPInt(GV.FloatVal, BitWidth);
428      else if (Op0->getType() == Type::DoubleTy)
429        GV.IntVal = APIntOps::RoundDoubleToAPInt(GV.DoubleVal, BitWidth);
430      else if (Op0->getType() == Type::X86_FP80Ty) {
431        APFloat apf = APFloat(GV.IntVal);
432        uint64_t v;
433        (void)apf.convertToInteger(&v, BitWidth,
434                                   CE->getOpcode()==Instruction::FPToSI,
435                                   APFloat::rmTowardZero);
436        GV.IntVal = v; // endian?
437      }
438      return GV;
439    }
440    case Instruction::PtrToInt: {
441      GenericValue GV = getConstantValue(Op0);
442      uint32_t PtrWidth = TD->getPointerSizeInBits();
443      GV.IntVal = APInt(PtrWidth, uintptr_t(GV.PointerVal));
444      return GV;
445    }
446    case Instruction::IntToPtr: {
447      GenericValue GV = getConstantValue(Op0);
448      uint32_t PtrWidth = TD->getPointerSizeInBits();
449      if (PtrWidth != GV.IntVal.getBitWidth())
450        GV.IntVal = GV.IntVal.zextOrTrunc(PtrWidth);
451      assert(GV.IntVal.getBitWidth() <= 64 && "Bad pointer width");
452      GV.PointerVal = PointerTy(uintptr_t(GV.IntVal.getZExtValue()));
453      return GV;
454    }
455    case Instruction::BitCast: {
456      GenericValue GV = getConstantValue(Op0);
457      const Type* DestTy = CE->getType();
458      switch (Op0->getType()->getTypeID()) {
459        default: assert(0 && "Invalid bitcast operand");
460        case Type::IntegerTyID:
461          assert(DestTy->isFloatingPoint() && "invalid bitcast");
462          if (DestTy == Type::FloatTy)
463            GV.FloatVal = GV.IntVal.bitsToFloat();
464          else if (DestTy == Type::DoubleTy)
465            GV.DoubleVal = GV.IntVal.bitsToDouble();
466          break;
467        case Type::FloatTyID:
468          assert(DestTy == Type::Int32Ty && "Invalid bitcast");
469          GV.IntVal.floatToBits(GV.FloatVal);
470          break;
471        case Type::DoubleTyID:
472          assert(DestTy == Type::Int64Ty && "Invalid bitcast");
473          GV.IntVal.doubleToBits(GV.DoubleVal);
474          break;
475        case Type::PointerTyID:
476          assert(isa<PointerType>(DestTy) && "Invalid bitcast");
477          break; // getConstantValue(Op0)  above already converted it
478      }
479      return GV;
480    }
481    case Instruction::Add:
482    case Instruction::Sub:
483    case Instruction::Mul:
484    case Instruction::UDiv:
485    case Instruction::SDiv:
486    case Instruction::URem:
487    case Instruction::SRem:
488    case Instruction::And:
489    case Instruction::Or:
490    case Instruction::Xor: {
491      GenericValue LHS = getConstantValue(Op0);
492      GenericValue RHS = getConstantValue(CE->getOperand(1));
493      GenericValue GV;
494      switch (CE->getOperand(0)->getType()->getTypeID()) {
495      default: assert(0 && "Bad add type!"); abort();
496      case Type::IntegerTyID:
497        switch (CE->getOpcode()) {
498          default: assert(0 && "Invalid integer opcode");
499          case Instruction::Add: GV.IntVal = LHS.IntVal + RHS.IntVal; break;
500          case Instruction::Sub: GV.IntVal = LHS.IntVal - RHS.IntVal; break;
501          case Instruction::Mul: GV.IntVal = LHS.IntVal * RHS.IntVal; break;
502          case Instruction::UDiv:GV.IntVal = LHS.IntVal.udiv(RHS.IntVal); break;
503          case Instruction::SDiv:GV.IntVal = LHS.IntVal.sdiv(RHS.IntVal); break;
504          case Instruction::URem:GV.IntVal = LHS.IntVal.urem(RHS.IntVal); break;
505          case Instruction::SRem:GV.IntVal = LHS.IntVal.srem(RHS.IntVal); break;
506          case Instruction::And: GV.IntVal = LHS.IntVal & RHS.IntVal; break;
507          case Instruction::Or:  GV.IntVal = LHS.IntVal | RHS.IntVal; break;
508          case Instruction::Xor: GV.IntVal = LHS.IntVal ^ RHS.IntVal; break;
509        }
510        break;
511      case Type::FloatTyID:
512        switch (CE->getOpcode()) {
513          default: assert(0 && "Invalid float opcode"); abort();
514          case Instruction::Add:
515            GV.FloatVal = LHS.FloatVal + RHS.FloatVal; break;
516          case Instruction::Sub:
517            GV.FloatVal = LHS.FloatVal - RHS.FloatVal; break;
518          case Instruction::Mul:
519            GV.FloatVal = LHS.FloatVal * RHS.FloatVal; break;
520          case Instruction::FDiv:
521            GV.FloatVal = LHS.FloatVal / RHS.FloatVal; break;
522          case Instruction::FRem:
523            GV.FloatVal = ::fmodf(LHS.FloatVal,RHS.FloatVal); break;
524        }
525        break;
526      case Type::DoubleTyID:
527        switch (CE->getOpcode()) {
528          default: assert(0 && "Invalid double opcode"); abort();
529          case Instruction::Add:
530            GV.DoubleVal = LHS.DoubleVal + RHS.DoubleVal; break;
531          case Instruction::Sub:
532            GV.DoubleVal = LHS.DoubleVal - RHS.DoubleVal; break;
533          case Instruction::Mul:
534            GV.DoubleVal = LHS.DoubleVal * RHS.DoubleVal; break;
535          case Instruction::FDiv:
536            GV.DoubleVal = LHS.DoubleVal / RHS.DoubleVal; break;
537          case Instruction::FRem:
538            GV.DoubleVal = ::fmod(LHS.DoubleVal,RHS.DoubleVal); break;
539        }
540        break;
541      case Type::X86_FP80TyID:
542      case Type::PPC_FP128TyID:
543      case Type::FP128TyID: {
544        APFloat apfLHS = APFloat(LHS.IntVal);
545        switch (CE->getOpcode()) {
546          default: assert(0 && "Invalid long double opcode"); abort();
547          case Instruction::Add:
548            apfLHS.add(APFloat(RHS.IntVal), APFloat::rmNearestTiesToEven);
549            GV.IntVal = apfLHS.convertToAPInt();
550            break;
551          case Instruction::Sub:
552            apfLHS.subtract(APFloat(RHS.IntVal), APFloat::rmNearestTiesToEven);
553            GV.IntVal = apfLHS.convertToAPInt();
554            break;
555          case Instruction::Mul:
556            apfLHS.multiply(APFloat(RHS.IntVal), APFloat::rmNearestTiesToEven);
557            GV.IntVal = apfLHS.convertToAPInt();
558            break;
559          case Instruction::FDiv:
560            apfLHS.divide(APFloat(RHS.IntVal), APFloat::rmNearestTiesToEven);
561            GV.IntVal = apfLHS.convertToAPInt();
562            break;
563          case Instruction::FRem:
564            apfLHS.mod(APFloat(RHS.IntVal), APFloat::rmNearestTiesToEven);
565            GV.IntVal = apfLHS.convertToAPInt();
566            break;
567          }
568        }
569        break;
570      }
571      return GV;
572    }
573    default:
574      break;
575    }
576    cerr << "ConstantExpr not handled: " << *CE << "\n";
577    abort();
578  }
579
580  GenericValue Result;
581  switch (C->getType()->getTypeID()) {
582  case Type::FloatTyID:
583    Result.FloatVal = cast<ConstantFP>(C)->getValueAPF().convertToFloat();
584    break;
585  case Type::DoubleTyID:
586    Result.DoubleVal = cast<ConstantFP>(C)->getValueAPF().convertToDouble();
587    break;
588  case Type::X86_FP80TyID:
589  case Type::FP128TyID:
590  case Type::PPC_FP128TyID:
591    Result.IntVal = cast <ConstantFP>(C)->getValueAPF().convertToAPInt();
592    break;
593  case Type::IntegerTyID:
594    Result.IntVal = cast<ConstantInt>(C)->getValue();
595    break;
596  case Type::PointerTyID:
597    if (isa<ConstantPointerNull>(C))
598      Result.PointerVal = 0;
599    else if (const Function *F = dyn_cast<Function>(C))
600      Result = PTOGV(getPointerToFunctionOrStub(const_cast<Function*>(F)));
601    else if (const GlobalVariable* GV = dyn_cast<GlobalVariable>(C))
602      Result = PTOGV(getOrEmitGlobalVariable(const_cast<GlobalVariable*>(GV)));
603    else
604      assert(0 && "Unknown constant pointer type!");
605    break;
606  default:
607    cerr << "ERROR: Constant unimplemented for type: " << *C->getType() << "\n";
608    abort();
609  }
610  return Result;
611}
612
613/// StoreValueToMemory - Stores the data in Val of type Ty at address Ptr.  Ptr
614/// is the address of the memory at which to store Val, cast to GenericValue *.
615/// It is not a pointer to a GenericValue containing the address at which to
616/// store Val.
617///
618void ExecutionEngine::StoreValueToMemory(const GenericValue &Val, GenericValue *Ptr,
619                                         const Type *Ty) {
620  switch (Ty->getTypeID()) {
621  case Type::IntegerTyID: {
622    unsigned BitWidth = cast<IntegerType>(Ty)->getBitWidth();
623    GenericValue TmpVal = Val;
624    if (BitWidth <= 8)
625      *((uint8_t*)Ptr) = uint8_t(Val.IntVal.getZExtValue());
626    else if (BitWidth <= 16) {
627      *((uint16_t*)Ptr) = uint16_t(Val.IntVal.getZExtValue());
628    } else if (BitWidth <= 32) {
629      *((uint32_t*)Ptr) = uint32_t(Val.IntVal.getZExtValue());
630    } else if (BitWidth <= 64) {
631      *((uint64_t*)Ptr) = uint64_t(Val.IntVal.getZExtValue());
632    } else {
633      uint64_t *Dest = (uint64_t*)Ptr;
634      const uint64_t *Src = Val.IntVal.getRawData();
635      for (uint32_t i = 0; i < Val.IntVal.getNumWords(); ++i)
636        Dest[i] = Src[i];
637    }
638    break;
639  }
640  case Type::FloatTyID:
641    *((float*)Ptr) = Val.FloatVal;
642    break;
643  case Type::DoubleTyID:
644    *((double*)Ptr) = Val.DoubleVal;
645    break;
646  case Type::X86_FP80TyID: {
647      uint16_t *Dest = (uint16_t*)Ptr;
648      const uint16_t *Src = (uint16_t*)Val.IntVal.getRawData();
649      // This is endian dependent, but it will only work on x86 anyway.
650      Dest[0] = Src[4];
651      Dest[1] = Src[0];
652      Dest[2] = Src[1];
653      Dest[3] = Src[2];
654      Dest[4] = Src[3];
655      break;
656    }
657  case Type::PointerTyID:
658    *((PointerTy*)Ptr) = Val.PointerVal;
659    break;
660  default:
661    cerr << "Cannot store value of type " << *Ty << "!\n";
662  }
663}
664
665/// FIXME: document
666///
667void ExecutionEngine::LoadValueFromMemory(GenericValue &Result,
668                                                  GenericValue *Ptr,
669                                                  const Type *Ty) {
670  switch (Ty->getTypeID()) {
671  case Type::IntegerTyID: {
672    unsigned BitWidth = cast<IntegerType>(Ty)->getBitWidth();
673    if (BitWidth <= 8)
674      Result.IntVal = APInt(BitWidth, *((uint8_t*)Ptr));
675    else if (BitWidth <= 16) {
676      Result.IntVal = APInt(BitWidth, *((uint16_t*)Ptr));
677    } else if (BitWidth <= 32) {
678      Result.IntVal = APInt(BitWidth, *((uint32_t*)Ptr));
679    } else if (BitWidth <= 64) {
680      Result.IntVal = APInt(BitWidth, *((uint64_t*)Ptr));
681    } else
682      Result.IntVal = APInt(BitWidth, (BitWidth+63)/64, (uint64_t*)Ptr);
683    break;
684  }
685  case Type::FloatTyID:
686    Result.FloatVal = *((float*)Ptr);
687    break;
688  case Type::DoubleTyID:
689    Result.DoubleVal = *((double*)Ptr);
690    break;
691  case Type::PointerTyID:
692    Result.PointerVal = *((PointerTy*)Ptr);
693    break;
694  case Type::X86_FP80TyID: {
695    // This is endian dependent, but it will only work on x86 anyway.
696    uint16_t x[8], *p = (uint16_t*)Ptr;
697    x[0] = p[1];
698    x[1] = p[2];
699    x[2] = p[3];
700    x[3] = p[4];
701    x[4] = p[0];
702    Result.IntVal = APInt(80, 2, x);
703    break;
704  }
705  default:
706    cerr << "Cannot load value of type " << *Ty << "!\n";
707    abort();
708  }
709}
710
711// InitializeMemory - Recursive function to apply a Constant value into the
712// specified memory location...
713//
714void ExecutionEngine::InitializeMemory(const Constant *Init, void *Addr) {
715  if (isa<UndefValue>(Init)) {
716    return;
717  } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(Init)) {
718    unsigned ElementSize =
719      getTargetData()->getTypeSize(CP->getType()->getElementType());
720    for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
721      InitializeMemory(CP->getOperand(i), (char*)Addr+i*ElementSize);
722    return;
723  } else if (Init->getType()->isFirstClassType()) {
724    GenericValue Val = getConstantValue(Init);
725    StoreValueToMemory(Val, (GenericValue*)Addr, Init->getType());
726    return;
727  } else if (isa<ConstantAggregateZero>(Init)) {
728    memset(Addr, 0, (size_t)getTargetData()->getTypeSize(Init->getType()));
729    return;
730  }
731
732  switch (Init->getType()->getTypeID()) {
733  case Type::ArrayTyID: {
734    const ConstantArray *CPA = cast<ConstantArray>(Init);
735    unsigned ElementSize =
736      getTargetData()->getTypeSize(CPA->getType()->getElementType());
737    for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
738      InitializeMemory(CPA->getOperand(i), (char*)Addr+i*ElementSize);
739    return;
740  }
741
742  case Type::StructTyID: {
743    const ConstantStruct *CPS = cast<ConstantStruct>(Init);
744    const StructLayout *SL =
745      getTargetData()->getStructLayout(cast<StructType>(CPS->getType()));
746    for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
747      InitializeMemory(CPS->getOperand(i), (char*)Addr+SL->getElementOffset(i));
748    return;
749  }
750
751  default:
752    cerr << "Bad Type: " << *Init->getType() << "\n";
753    assert(0 && "Unknown constant type to initialize memory with!");
754  }
755}
756
757/// EmitGlobals - Emit all of the global variables to memory, storing their
758/// addresses into GlobalAddress.  This must make sure to copy the contents of
759/// their initializers into the memory.
760///
761void ExecutionEngine::emitGlobals() {
762  const TargetData *TD = getTargetData();
763
764  // Loop over all of the global variables in the program, allocating the memory
765  // to hold them.  If there is more than one module, do a prepass over globals
766  // to figure out how the different modules should link together.
767  //
768  std::map<std::pair<std::string, const Type*>,
769           const GlobalValue*> LinkedGlobalsMap;
770
771  if (Modules.size() != 1) {
772    for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
773      Module &M = *Modules[m]->getModule();
774      for (Module::const_global_iterator I = M.global_begin(),
775           E = M.global_end(); I != E; ++I) {
776        const GlobalValue *GV = I;
777        if (GV->hasInternalLinkage() || GV->isDeclaration() ||
778            GV->hasAppendingLinkage() || !GV->hasName())
779          continue;// Ignore external globals and globals with internal linkage.
780
781        const GlobalValue *&GVEntry =
782          LinkedGlobalsMap[std::make_pair(GV->getName(), GV->getType())];
783
784        // If this is the first time we've seen this global, it is the canonical
785        // version.
786        if (!GVEntry) {
787          GVEntry = GV;
788          continue;
789        }
790
791        // If the existing global is strong, never replace it.
792        if (GVEntry->hasExternalLinkage() ||
793            GVEntry->hasDLLImportLinkage() ||
794            GVEntry->hasDLLExportLinkage())
795          continue;
796
797        // Otherwise, we know it's linkonce/weak, replace it if this is a strong
798        // symbol.
799        if (GV->hasExternalLinkage() || GVEntry->hasExternalWeakLinkage())
800          GVEntry = GV;
801      }
802    }
803  }
804
805  std::vector<const GlobalValue*> NonCanonicalGlobals;
806  for (unsigned m = 0, e = Modules.size(); m != e; ++m) {
807    Module &M = *Modules[m]->getModule();
808    for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
809         I != E; ++I) {
810      // In the multi-module case, see what this global maps to.
811      if (!LinkedGlobalsMap.empty()) {
812        if (const GlobalValue *GVEntry =
813              LinkedGlobalsMap[std::make_pair(I->getName(), I->getType())]) {
814          // If something else is the canonical global, ignore this one.
815          if (GVEntry != &*I) {
816            NonCanonicalGlobals.push_back(I);
817            continue;
818          }
819        }
820      }
821
822      if (!I->isDeclaration()) {
823        // Get the type of the global.
824        const Type *Ty = I->getType()->getElementType();
825
826        // Allocate some memory for it!
827        unsigned Size = TD->getTypeSize(Ty);
828        addGlobalMapping(I, new char[Size]);
829      } else {
830        // External variable reference. Try to use the dynamic loader to
831        // get a pointer to it.
832        if (void *SymAddr =
833            sys::DynamicLibrary::SearchForAddressOfSymbol(I->getName().c_str()))
834          addGlobalMapping(I, SymAddr);
835        else {
836          cerr << "Could not resolve external global address: "
837               << I->getName() << "\n";
838          abort();
839        }
840      }
841    }
842
843    // If there are multiple modules, map the non-canonical globals to their
844    // canonical location.
845    if (!NonCanonicalGlobals.empty()) {
846      for (unsigned i = 0, e = NonCanonicalGlobals.size(); i != e; ++i) {
847        const GlobalValue *GV = NonCanonicalGlobals[i];
848        const GlobalValue *CGV =
849          LinkedGlobalsMap[std::make_pair(GV->getName(), GV->getType())];
850        void *Ptr = getPointerToGlobalIfAvailable(CGV);
851        assert(Ptr && "Canonical global wasn't codegen'd!");
852        addGlobalMapping(GV, getPointerToGlobalIfAvailable(CGV));
853      }
854    }
855
856    // Now that all of the globals are set up in memory, loop through them all
857    // and initialize their contents.
858    for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
859         I != E; ++I) {
860      if (!I->isDeclaration()) {
861        if (!LinkedGlobalsMap.empty()) {
862          if (const GlobalValue *GVEntry =
863                LinkedGlobalsMap[std::make_pair(I->getName(), I->getType())])
864            if (GVEntry != &*I)  // Not the canonical variable.
865              continue;
866        }
867        EmitGlobalVariable(I);
868      }
869    }
870  }
871}
872
873// EmitGlobalVariable - This method emits the specified global variable to the
874// address specified in GlobalAddresses, or allocates new memory if it's not
875// already in the map.
876void ExecutionEngine::EmitGlobalVariable(const GlobalVariable *GV) {
877  void *GA = getPointerToGlobalIfAvailable(GV);
878  DOUT << "Global '" << GV->getName() << "' -> " << GA << "\n";
879
880  const Type *ElTy = GV->getType()->getElementType();
881  size_t GVSize = (size_t)getTargetData()->getTypeSize(ElTy);
882  if (GA == 0) {
883    // If it's not already specified, allocate memory for the global.
884    GA = new char[GVSize];
885    addGlobalMapping(GV, GA);
886  }
887
888  InitializeMemory(GV->getInitializer(), GA);
889  NumInitBytes += (unsigned)GVSize;
890  ++NumGlobals;
891}
892