lib/VMCore/ConstantsContext.h

   1 //===-- ConstantsContext.h - Constants-related Context Interals -----------===//
   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 various helper methods and classes used by
  11 // LLVMContextImpl for creating and managing constants.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_CONSTANTSCONTEXT_H
  16 #define LLVM_CONSTANTSCONTEXT_H
  17
  18 #include "llvm/Instructions.h"
  19 #include "llvm/Operator.h"
  20 #include "llvm/Support/Debug.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include "llvm/Support/raw_ostream.h"
  23 #include "llvm/System/Mutex.h"
  24 #include "llvm/System/RWMutex.h"
  25 #include <map>
  26
  27 namespace llvm {
  28 template<class ValType>
  29 struct ConstantTraits;
  30
  31 /// UnaryConstantExpr - This class is private to Constants.cpp, and is used
  32 /// behind the scenes to implement unary constant exprs.
  33 class UnaryConstantExpr : public ConstantExpr {
  34   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
  35 public:
  36   // allocate space for exactly one operand
  37   void *operator new(size_t s) {
  38     return User::operator new(s, 1);
  39   }
  40   UnaryConstantExpr(unsigned Opcode, Constant *C, const Type *Ty)
  41     : ConstantExpr(Ty, Opcode, &Op<0>(), 1) {
  42     Op<0>() = C;
  43   }
  44   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
  45 };
  46
  47 /// BinaryConstantExpr - This class is private to Constants.cpp, and is used
  48 /// behind the scenes to implement binary constant exprs.
  49 class BinaryConstantExpr : public ConstantExpr {
  50   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
  51 public:
  52   // allocate space for exactly two operands
  53   void *operator new(size_t s) {
  54     return User::operator new(s, 2);
  55   }
  56   BinaryConstantExpr(unsigned Opcode, Constant *C1, Constant *C2,
  57                      unsigned Flags)
  58     : ConstantExpr(C1->getType(), Opcode, &Op<0>(), 2) {
  59     Op<0>() = C1;
  60     Op<1>() = C2;
  61     SubclassOptionalData = Flags;
  62   }
  63   /// Transparently provide more efficient getOperand methods.
  64   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
  65 };
  66
  67 /// SelectConstantExpr - This class is private to Constants.cpp, and is used
  68 /// behind the scenes to implement select constant exprs.
  69 class SelectConstantExpr : public ConstantExpr {
  70   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
  71 public:
  72   // allocate space for exactly three operands
  73   void *operator new(size_t s) {
  74     return User::operator new(s, 3);
  75   }
  76   SelectConstantExpr(Constant *C1, Constant *C2, Constant *C3)
  77     : ConstantExpr(C2->getType(), Instruction::Select, &Op<0>(), 3) {
  78     Op<0>() = C1;
  79     Op<1>() = C2;
  80     Op<2>() = C3;
  81   }
  82   /// Transparently provide more efficient getOperand methods.
  83   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
  84 };
  85
  86 /// ExtractElementConstantExpr - This class is private to
  87 /// Constants.cpp, and is used behind the scenes to implement
  88 /// extractelement constant exprs.
  89 class ExtractElementConstantExpr : public ConstantExpr {
  90   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
  91 public:
  92   // allocate space for exactly two operands
  93   void *operator new(size_t s) {
  94     return User::operator new(s, 2);
  95   }
  96   ExtractElementConstantExpr(Constant *C1, Constant *C2)
  97     : ConstantExpr(cast<VectorType>(C1->getType())->getElementType(),
  98                    Instruction::ExtractElement, &Op<0>(), 2) {
  99     Op<0>() = C1;
 100     Op<1>() = C2;
 101   }
 102   /// Transparently provide more efficient getOperand methods.
 103   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 104 };
 105
 106 /// InsertElementConstantExpr - This class is private to
 107 /// Constants.cpp, and is used behind the scenes to implement
 108 /// insertelement constant exprs.
 109 class InsertElementConstantExpr : public ConstantExpr {
 110   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
 111 public:
 112   // allocate space for exactly three operands
 113   void *operator new(size_t s) {
 114     return User::operator new(s, 3);
 115   }
 116   InsertElementConstantExpr(Constant *C1, Constant *C2, Constant *C3)
 117     : ConstantExpr(C1->getType(), Instruction::InsertElement,
 118                    &Op<0>(), 3) {
 119     Op<0>() = C1;
 120     Op<1>() = C2;
 121     Op<2>() = C3;
 122   }
 123   /// Transparently provide more efficient getOperand methods.
 124   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 125 };
 126
 127 /// ShuffleVectorConstantExpr - This class is private to
 128 /// Constants.cpp, and is used behind the scenes to implement
 129 /// shufflevector constant exprs.
 130 class ShuffleVectorConstantExpr : public ConstantExpr {
 131   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
 132 public:
 133   // allocate space for exactly three operands
 134   void *operator new(size_t s) {
 135     return User::operator new(s, 3);
 136   }
 137   ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3)
 138   : ConstantExpr(VectorType::get(
 139                    cast<VectorType>(C1->getType())->getElementType(),
 140                    cast<VectorType>(C3->getType())->getNumElements()),
 141                  Instruction::ShuffleVector,
 142                  &Op<0>(), 3) {
 143     Op<0>() = C1;
 144     Op<1>() = C2;
 145     Op<2>() = C3;
 146   }
 147   /// Transparently provide more efficient getOperand methods.
 148   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 149 };
 150
 151 /// ExtractValueConstantExpr - This class is private to
 152 /// Constants.cpp, and is used behind the scenes to implement
 153 /// extractvalue constant exprs.
 154 class ExtractValueConstantExpr : public ConstantExpr {
 155   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
 156 public:
 157   // allocate space for exactly one operand
 158   void *operator new(size_t s) {
 159     return User::operator new(s, 1);
 160   }
 161   ExtractValueConstantExpr(Constant *Agg,
 162                            const SmallVector<unsigned, 4> &IdxList,
 163                            const Type *DestTy)
 164     : ConstantExpr(DestTy, Instruction::ExtractValue, &Op<0>(), 1),
 165       Indices(IdxList) {
 166     Op<0>() = Agg;
 167   }
 168
 169   /// Indices - These identify which value to extract.
 170   const SmallVector<unsigned, 4> Indices;
 171
 172   /// Transparently provide more efficient getOperand methods.
 173   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 174 };
 175
 176 /// InsertValueConstantExpr - This class is private to
 177 /// Constants.cpp, and is used behind the scenes to implement
 178 /// insertvalue constant exprs.
 179 class InsertValueConstantExpr : public ConstantExpr {
 180   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
 181 public:
 182   // allocate space for exactly one operand
 183   void *operator new(size_t s) {
 184     return User::operator new(s, 2);
 185   }
 186   InsertValueConstantExpr(Constant *Agg, Constant *Val,
 187                           const SmallVector<unsigned, 4> &IdxList,
 188                           const Type *DestTy)
 189     : ConstantExpr(DestTy, Instruction::InsertValue, &Op<0>(), 2),
 190       Indices(IdxList) {
 191     Op<0>() = Agg;
 192     Op<1>() = Val;
 193   }
 194
 195   /// Indices - These identify the position for the insertion.
 196   const SmallVector<unsigned, 4> Indices;
 197
 198   /// Transparently provide more efficient getOperand methods.
 199   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 200 };
 201
 202
 203 /// GetElementPtrConstantExpr - This class is private to Constants.cpp, and is
 204 /// used behind the scenes to implement getelementpr constant exprs.
 205 class GetElementPtrConstantExpr : public ConstantExpr {
 206   GetElementPtrConstantExpr(Constant *C, const std::vector<Constant*> &IdxList,
 207                             const Type *DestTy);
 208 public:
 209   static GetElementPtrConstantExpr *Create(Constant *C,
 210                                            const std::vector<Constant*>&IdxList,
 211                                            const Type *DestTy,
 212                                            unsigned Flags) {
 213     GetElementPtrConstantExpr *Result =
 214       new(IdxList.size() + 1) GetElementPtrConstantExpr(C, IdxList, DestTy);
 215     Result->SubclassOptionalData = Flags;
 216     return Result;
 217   }
 218   /// Transparently provide more efficient getOperand methods.
 219   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 220 };
 221
 222 // CompareConstantExpr - This class is private to Constants.cpp, and is used
 223 // behind the scenes to implement ICmp and FCmp constant expressions. This is
 224 // needed in order to store the predicate value for these instructions.
 225 struct CompareConstantExpr : public ConstantExpr {
 226   void *operator new(size_t, unsigned);  // DO NOT IMPLEMENT
 227   // allocate space for exactly two operands
 228   void *operator new(size_t s) {
 229     return User::operator new(s, 2);
 230   }
 231   unsigned short predicate;
 232   CompareConstantExpr(const Type *ty, Instruction::OtherOps opc,
 233                       unsigned short pred,  Constant* LHS, Constant* RHS)
 234     : ConstantExpr(ty, opc, &Op<0>(), 2), predicate(pred) {
 235     Op<0>() = LHS;
 236     Op<1>() = RHS;
 237   }
 238   /// Transparently provide more efficient getOperand methods.
 239   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 240 };
 241
 242 template <>
 243 struct OperandTraits<UnaryConstantExpr> : public FixedNumOperandTraits<1> {
 244 };
 245 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(UnaryConstantExpr, Value)
 246
 247 template <>
 248 struct OperandTraits<BinaryConstantExpr> : public FixedNumOperandTraits<2> {
 249 };
 250 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(BinaryConstantExpr, Value)
 251
 252 template <>
 253 struct OperandTraits<SelectConstantExpr> : public FixedNumOperandTraits<3> {
 254 };
 255 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(SelectConstantExpr, Value)
 256
 257 template <>
 258 struct OperandTraits<ExtractElementConstantExpr> : public FixedNumOperandTraits<2> {
 259 };
 260 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ExtractElementConstantExpr, Value)
 261
 262 template <>
 263 struct OperandTraits<InsertElementConstantExpr> : public FixedNumOperandTraits<3> {
 264 };
 265 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(InsertElementConstantExpr, Value)
 266
 267 template <>
 268 struct OperandTraits<ShuffleVectorConstantExpr> : public FixedNumOperandTraits<3> {
 269 };
 270 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ShuffleVectorConstantExpr, Value)
 271
 272 template <>
 273 struct OperandTraits<ExtractValueConstantExpr> : public FixedNumOperandTraits<1> {
 274 };
 275 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ExtractValueConstantExpr, Value)
 276
 277 template <>
 278 struct OperandTraits<InsertValueConstantExpr> : public FixedNumOperandTraits<2> {
 279 };
 280 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(InsertValueConstantExpr, Value)
 281
 282 template <>
 283 struct OperandTraits<GetElementPtrConstantExpr> : public VariadicOperandTraits<1> {
 284 };
 285
 286 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GetElementPtrConstantExpr, Value)
 287
 288
 289 template <>
 290 struct OperandTraits<CompareConstantExpr> : public FixedNumOperandTraits<2> {
 291 };
 292 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(CompareConstantExpr, Value)
 293
 294 struct ExprMapKeyType {
 295   typedef SmallVector<unsigned, 4> IndexList;
 296
 297   ExprMapKeyType(unsigned opc,
 298       const std::vector<Constant*> &ops,
 299       unsigned short flags = 0,
 300       unsigned short optionalflags = 0,
 301       const IndexList &inds = IndexList())
 302         : opcode(opc), subclassoptionaldata(optionalflags), subclassdata(flags),
 303         operands(ops), indices(inds) {}
 304   uint8_t opcode;
 305   uint8_t subclassoptionaldata;
 306   uint16_t subclassdata;
 307   std::vector<Constant*> operands;
 308   IndexList indices;
 309   bool operator==(const ExprMapKeyType& that) const {
 310     return this->opcode == that.opcode &&
 311            this->subclassdata == that.subclassdata &&
 312            this->subclassoptionaldata == that.subclassoptionaldata &&
 313            this->operands == that.operands &&
 314            this->indices == that.indices;
 315   }
 316   bool operator<(const ExprMapKeyType & that) const {
 317     if (this->opcode != that.opcode) return this->opcode < that.opcode;
 318     if (this->operands != that.operands) return this->operands < that.operands;
 319     if (this->subclassdata != that.subclassdata)
 320       return this->subclassdata < that.subclassdata;
 321     if (this->subclassoptionaldata != that.subclassoptionaldata)
 322       return this->subclassoptionaldata < that.subclassoptionaldata;
 323     if (this->indices != that.indices) return this->indices < that.indices;
 324     return false;
 325   }
 326
 327   bool operator!=(const ExprMapKeyType& that) const {
 328     return !(*this == that);
 329   }
 330 };
 331
 332 // The number of operands for each ConstantCreator::create method is
 333 // determined by the ConstantTraits template.
 334 // ConstantCreator - A class that is used to create constants by
 335 // ValueMap*.  This class should be partially specialized if there is
 336 // something strange that needs to be done to interface to the ctor for the
 337 // constant.
 338 //
 339 template<typename T, typename Alloc>
 340 struct ConstantTraits< std::vector<T, Alloc> > {
 341   static unsigned uses(const std::vector<T, Alloc>& v) {
 342     return v.size();
 343   }
 344 };
 345
 346 template<class ConstantClass, class TypeClass, class ValType>
 347 struct ConstantCreator {
 348   static ConstantClass *create(const TypeClass *Ty, const ValType &V) {
 349     return new(ConstantTraits<ValType>::uses(V)) ConstantClass(Ty, V);
 350   }
 351 };
 352
 353 template<class ConstantClass, class TypeClass>
 354 struct ConvertConstantType {
 355   static void convert(ConstantClass *OldC, const TypeClass *NewTy) {
 356     llvm_unreachable("This type cannot be converted!");
 357   }
 358 };
 359
 360 template<>
 361 struct ConstantCreator<ConstantExpr, Type, ExprMapKeyType> {
 362   static ConstantExpr *create(const Type *Ty, const ExprMapKeyType &V,
 363       unsigned short pred = 0) {
 364     if (Instruction::isCast(V.opcode))
 365       return new UnaryConstantExpr(V.opcode, V.operands[0], Ty);
 366     if ((V.opcode >= Instruction::BinaryOpsBegin &&
 367          V.opcode < Instruction::BinaryOpsEnd))
 368       return new BinaryConstantExpr(V.opcode, V.operands[0], V.operands[1],
 369                                     V.subclassoptionaldata);
 370     if (V.opcode == Instruction::Select)
 371       return new SelectConstantExpr(V.operands[0], V.operands[1],
 372                                     V.operands[2]);
 373     if (V.opcode == Instruction::ExtractElement)
 374       return new ExtractElementConstantExpr(V.operands[0], V.operands[1]);
 375     if (V.opcode == Instruction::InsertElement)
 376       return new InsertElementConstantExpr(V.operands[0], V.operands[1],
 377                                            V.operands[2]);
 378     if (V.opcode == Instruction::ShuffleVector)
 379       return new ShuffleVectorConstantExpr(V.operands[0], V.operands[1],
 380                                            V.operands[2]);
 381     if (V.opcode == Instruction::InsertValue)
 382       return new InsertValueConstantExpr(V.operands[0], V.operands[1],
 383                                          V.indices, Ty);
 384     if (V.opcode == Instruction::ExtractValue)
 385       return new ExtractValueConstantExpr(V.operands[0], V.indices, Ty);
 386     if (V.opcode == Instruction::GetElementPtr) {
 387       std::vector<Constant*> IdxList(V.operands.begin()+1, V.operands.end());
 388       return GetElementPtrConstantExpr::Create(V.operands[0], IdxList, Ty,
 389                                                V.subclassoptionaldata);
 390     }
 391
 392     // The compare instructions are weird. We have to encode the predicate
 393     // value and it is combined with the instruction opcode by multiplying
 394     // the opcode by one hundred. We must decode this to get the predicate.
 395     if (V.opcode == Instruction::ICmp)
 396       return new CompareConstantExpr(Ty, Instruction::ICmp, V.subclassdata,
 397                                      V.operands[0], V.operands[1]);
 398     if (V.opcode == Instruction::FCmp)
 399       return new CompareConstantExpr(Ty, Instruction::FCmp, V.subclassdata,
 400                                      V.operands[0], V.operands[1]);
 401     llvm_unreachable("Invalid ConstantExpr!");
 402     return 0;
 403   }
 404 };
 405
 406 template<>
 407 struct ConvertConstantType<ConstantExpr, Type> {
 408   static void convert(ConstantExpr *OldC, const Type *NewTy) {
 409     Constant *New;
 410     switch (OldC->getOpcode()) {
 411     case Instruction::Trunc:
 412     case Instruction::ZExt:
 413     case Instruction::SExt:
 414     case Instruction::FPTrunc:
 415     case Instruction::FPExt:
 416     case Instruction::UIToFP:
 417     case Instruction::SIToFP:
 418     case Instruction::FPToUI:
 419     case Instruction::FPToSI:
 420     case Instruction::PtrToInt:
 421     case Instruction::IntToPtr:
 422     case Instruction::BitCast:
 423       New = ConstantExpr::getCast(OldC->getOpcode(), OldC->getOperand(0),
 424                                   NewTy);
 425       break;
 426     case Instruction::Select:
 427       New = ConstantExpr::getSelectTy(NewTy, OldC->getOperand(0),
 428                                       OldC->getOperand(1),
 429                                       OldC->getOperand(2));
 430       break;
 431     default:
 432       assert(OldC->getOpcode() >= Instruction::BinaryOpsBegin &&
 433              OldC->getOpcode() <  Instruction::BinaryOpsEnd);
 434       New = ConstantExpr::getTy(NewTy, OldC->getOpcode(), OldC->getOperand(0),
 435                                 OldC->getOperand(1));
 436       break;
 437     case Instruction::GetElementPtr:
 438       // Make everyone now use a constant of the new type...
 439       std::vector<Value*> Idx(OldC->op_begin()+1, OldC->op_end());
 440       New = cast<GEPOperator>(OldC)->isInBounds() ?
 441         ConstantExpr::getInBoundsGetElementPtrTy(NewTy, OldC->getOperand(0),
 442                                                  &Idx[0], Idx.size()) :
 443         ConstantExpr::getGetElementPtrTy(NewTy, OldC->getOperand(0),
 444                                          &Idx[0], Idx.size());
 445       break;
 446     }
 447
 448     assert(New != OldC && "Didn't replace constant??");
 449     OldC->uncheckedReplaceAllUsesWith(New);
 450     OldC->destroyConstant();    // This constant is now dead, destroy it.
 451   }
 452 };
 453
 454 // ConstantAggregateZero does not take extra "value" argument...
 455 template<class ValType>
 456 struct ConstantCreator<ConstantAggregateZero, Type, ValType> {
 457   static ConstantAggregateZero *create(const Type *Ty, const ValType &V){
 458     return new ConstantAggregateZero(Ty);
 459   }
 460 };
 461
 462 template<>
 463 struct ConvertConstantType<ConstantVector, VectorType> {
 464   static void convert(ConstantVector *OldC, const VectorType *NewTy) {
 465     // Make everyone now use a constant of the new type...
 466     std::vector<Constant*> C;
 467     for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
 468       C.push_back(cast<Constant>(OldC->getOperand(i)));
 469     Constant *New = ConstantVector::get(NewTy, C);
 470     assert(New != OldC && "Didn't replace constant??");
 471     OldC->uncheckedReplaceAllUsesWith(New);
 472     OldC->destroyConstant();    // This constant is now dead, destroy it.
 473   }
 474 };
 475
 476 template<>
 477 struct ConvertConstantType<ConstantAggregateZero, Type> {
 478   static void convert(ConstantAggregateZero *OldC, const Type *NewTy) {
 479     // Make everyone now use a constant of the new type...
 480     Constant *New = ConstantAggregateZero::get(NewTy);
 481     assert(New != OldC && "Didn't replace constant??");
 482     OldC->uncheckedReplaceAllUsesWith(New);
 483     OldC->destroyConstant();     // This constant is now dead, destroy it.
 484   }
 485 };
 486
 487 template<>
 488 struct ConvertConstantType<ConstantArray, ArrayType> {
 489   static void convert(ConstantArray *OldC, const ArrayType *NewTy) {
 490     // Make everyone now use a constant of the new type...
 491     std::vector<Constant*> C;
 492     for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
 493       C.push_back(cast<Constant>(OldC->getOperand(i)));
 494     Constant *New = ConstantArray::get(NewTy, C);
 495     assert(New != OldC && "Didn't replace constant??");
 496     OldC->uncheckedReplaceAllUsesWith(New);
 497     OldC->destroyConstant();    // This constant is now dead, destroy it.
 498   }
 499 };
 500
 501 template<>
 502 struct ConvertConstantType<ConstantStruct, StructType> {
 503   static void convert(ConstantStruct *OldC, const StructType *NewTy) {
 504     // Make everyone now use a constant of the new type...
 505     std::vector<Constant*> C;
 506     for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
 507       C.push_back(cast<Constant>(OldC->getOperand(i)));
 508     Constant *New = ConstantStruct::get(NewTy, C);
 509     assert(New != OldC && "Didn't replace constant??");
 510
 511     OldC->uncheckedReplaceAllUsesWith(New);
 512     OldC->destroyConstant();    // This constant is now dead, destroy it.
 513   }
 514 };
 515
 516 // ConstantPointerNull does not take extra "value" argument...
 517 template<class ValType>
 518 struct ConstantCreator<ConstantPointerNull, PointerType, ValType> {
 519   static ConstantPointerNull *create(const PointerType *Ty, const ValType &V){
 520     return new ConstantPointerNull(Ty);
 521   }
 522 };
 523
 524 template<>
 525 struct ConvertConstantType<ConstantPointerNull, PointerType> {
 526   static void convert(ConstantPointerNull *OldC, const PointerType *NewTy) {
 527     // Make everyone now use a constant of the new type...
 528     Constant *New = ConstantPointerNull::get(NewTy);
 529     assert(New != OldC && "Didn't replace constant??");
 530     OldC->uncheckedReplaceAllUsesWith(New);
 531     OldC->destroyConstant();     // This constant is now dead, destroy it.
 532   }
 533 };
 534
 535 // UndefValue does not take extra "value" argument...
 536 template<class ValType>
 537 struct ConstantCreator<UndefValue, Type, ValType> {
 538   static UndefValue *create(const Type *Ty, const ValType &V) {
 539     return new UndefValue(Ty);
 540   }
 541 };
 542
 543 template<>
 544 struct ConvertConstantType<UndefValue, Type> {
 545   static void convert(UndefValue *OldC, const Type *NewTy) {
 546     // Make everyone now use a constant of the new type.
 547     Constant *New = UndefValue::get(NewTy);
 548     assert(New != OldC && "Didn't replace constant??");
 549     OldC->uncheckedReplaceAllUsesWith(New);
 550     OldC->destroyConstant();     // This constant is now dead, destroy it.
 551   }
 552 };
 553
 554 template<class ValType, class TypeClass, class ConstantClass,
 555          bool HasLargeKey = false /*true for arrays and structs*/ >
 556 class ValueMap : public AbstractTypeUser {
 557 public:
 558   typedef std::pair<const Type*, ValType> MapKey;
 559   typedef std::map<MapKey, Constant *> MapTy;
 560   typedef std::map<Constant*, typename MapTy::iterator> InverseMapTy;
 561   typedef std::map<const Type*, typename MapTy::iterator> AbstractTypeMapTy;
 562 private:
 563   /// Map - This is the main map from the element descriptor to the Constants.
 564   /// This is the primary way we avoid creating two of the same shape
 565   /// constant.
 566   MapTy Map;
 567
 568   /// InverseMap - If "HasLargeKey" is true, this contains an inverse mapping
 569   /// from the constants to their element in Map.  This is important for
 570   /// removal of constants from the array, which would otherwise have to scan
 571   /// through the map with very large keys.
 572   InverseMapTy InverseMap;
 573
 574   /// AbstractTypeMap - Map for abstract type constants.
 575   ///
 576   AbstractTypeMapTy AbstractTypeMap;
 577
 578   /// ValueMapLock - Mutex for this map.
 579   sys::SmartMutex<true> ValueMapLock;
 580
 581 public:
 582   // NOTE: This function is not locked.  It is the caller's responsibility
 583   // to enforce proper synchronization.
 584   typename MapTy::iterator map_begin() { return Map.begin(); }
 585   typename MapTy::iterator map_end() { return Map.end(); }
 586
 587   void freeConstants() {
 588     for (typename MapTy::iterator I=Map.begin(), E=Map.end();
 589          I != E; ++I) {
 590       if (I->second->use_empty())
 591         delete I->second;
 592     }
 593   }
 594
 595   /// InsertOrGetItem - Return an iterator for the specified element.
 596   /// If the element exists in the map, the returned iterator points to the
 597   /// entry and Exists=true.  If not, the iterator points to the newly
 598   /// inserted entry and returns Exists=false.  Newly inserted entries have
 599   /// I->second == 0, and should be filled in.
 600   /// NOTE: This function is not locked.  It is the caller's responsibility
 601   // to enforce proper synchronization.
 602   typename MapTy::iterator InsertOrGetItem(std::pair<MapKey, Constant *>
 603                                  &InsertVal,
 604                                  bool &Exists) {
 605     std::pair<typename MapTy::iterator, bool> IP = Map.insert(InsertVal);
 606     Exists = !IP.second;
 607     return IP.first;
 608   }
 609
 610 private:
 611   typename MapTy::iterator FindExistingElement(ConstantClass *CP) {
 612     if (HasLargeKey) {
 613       typename InverseMapTy::iterator IMI = InverseMap.find(CP);
 614       assert(IMI != InverseMap.end() && IMI->second != Map.end() &&
 615              IMI->second->second == CP &&
 616              "InverseMap corrupt!");
 617       return IMI->second;
 618     }
 619
 620     typename MapTy::iterator I =
 621       Map.find(MapKey(static_cast<const TypeClass*>(CP->getRawType()),
 622                       getValType(CP)));
 623     if (I == Map.end() || I->second != CP) {
 624       // FIXME: This should not use a linear scan.  If this gets to be a
 625       // performance problem, someone should look at this.
 626       for (I = Map.begin(); I != Map.end() && I->second != CP; ++I)
 627         /* empty */;
 628     }
 629     return I;
 630   }
 631
 632   ConstantClass* Create(const TypeClass *Ty, const ValType &V,
 633                         typename MapTy::iterator I) {
 634     ConstantClass* Result =
 635       ConstantCreator<ConstantClass,TypeClass,ValType>::create(Ty, V);
 636
 637     assert(Result->getType() == Ty && "Type specified is not correct!");
 638     I = Map.insert(I, std::make_pair(MapKey(Ty, V), Result));
 639
 640     if (HasLargeKey)  // Remember the reverse mapping if needed.
 641       InverseMap.insert(std::make_pair(Result, I));
 642
 643     // If the type of the constant is abstract, make sure that an entry
 644     // exists for it in the AbstractTypeMap.
 645     if (Ty->isAbstract()) {
 646       typename AbstractTypeMapTy::iterator TI =
 647                                                AbstractTypeMap.find(Ty);
 648
 649       if (TI == AbstractTypeMap.end()) {
 650         // Add ourselves to the ATU list of the type.
 651         cast<DerivedType>(Ty)->addAbstractTypeUser(this);
 652
 653         AbstractTypeMap.insert(TI, std::make_pair(Ty, I));
 654       }
 655     }
 656
 657     return Result;
 658   }
 659 public:
 660
 661   /// getOrCreate - Return the specified constant from the map, creating it if
 662   /// necessary.
 663   ConstantClass *getOrCreate(const TypeClass *Ty, const ValType &V) {
 664     sys::SmartScopedLock<true> Lock(ValueMapLock);
 665     MapKey Lookup(Ty, V);
 666     ConstantClass* Result = 0;
 667
 668     typename MapTy::iterator I = Map.find(Lookup);
 669     // Is it in the map?
 670     if (I != Map.end())
 671       Result = static_cast<ConstantClass *>(I->second);
 672
 673     if (!Result) {
 674       // If no preexisting value, create one now...
 675       Result = Create(Ty, V, I);
 676     }
 677
 678     return Result;
 679   }
 680
 681   void remove(ConstantClass *CP) {
 682     sys::SmartScopedLock<true> Lock(ValueMapLock);
 683     typename MapTy::iterator I = FindExistingElement(CP);
 684     assert(I != Map.end() && "Constant not found in constant table!");
 685     assert(I->second == CP && "Didn't find correct element?");
 686
 687     if (HasLargeKey)  // Remember the reverse mapping if needed.
 688       InverseMap.erase(CP);
 689
 690     // Now that we found the entry, make sure this isn't the entry that
 691     // the AbstractTypeMap points to.
 692     const TypeClass *Ty = static_cast<const TypeClass *>(I->first.first);
 693     if (Ty->isAbstract()) {
 694       assert(AbstractTypeMap.count(Ty) &&
 695              "Abstract type not in AbstractTypeMap?");
 696       typename MapTy::iterator &ATMEntryIt = AbstractTypeMap[Ty];
 697       if (ATMEntryIt == I) {
 698         // Yes, we are removing the representative entry for this type.
 699         // See if there are any other entries of the same type.
 700         typename MapTy::iterator TmpIt = ATMEntryIt;
 701
 702         // First check the entry before this one...
 703         if (TmpIt != Map.begin()) {
 704           --TmpIt;
 705           if (TmpIt->first.first != Ty) // Not the same type, move back...
 706             ++TmpIt;
 707         }
 708
 709         // If we didn't find the same type, try to move forward...
 710         if (TmpIt == ATMEntryIt) {
 711           ++TmpIt;
 712           if (TmpIt == Map.end() || TmpIt->first.first != Ty)
 713             --TmpIt;   // No entry afterwards with the same type
 714         }
 715
 716         // If there is another entry in the map of the same abstract type,
 717         // update the AbstractTypeMap entry now.
 718         if (TmpIt != ATMEntryIt) {
 719           ATMEntryIt = TmpIt;
 720         } else {
 721           // Otherwise, we are removing the last instance of this type
 722           // from the table.  Remove from the ATM, and from user list.
 723           cast<DerivedType>(Ty)->removeAbstractTypeUser(this);
 724           AbstractTypeMap.erase(Ty);
 725         }
 726       }
 727     }
 728
 729     Map.erase(I);
 730   }
 731
 732
 733   /// MoveConstantToNewSlot - If we are about to change C to be the element
 734   /// specified by I, update our internal data structures to reflect this
 735   /// fact.
 736   /// NOTE: This function is not locked. It is the responsibility of the
 737   /// caller to enforce proper synchronization if using this method.
 738   void MoveConstantToNewSlot(ConstantClass *C, typename MapTy::iterator I) {
 739     // First, remove the old location of the specified constant in the map.
 740     typename MapTy::iterator OldI = FindExistingElement(C);
 741     assert(OldI != Map.end() && "Constant not found in constant table!");
 742     assert(OldI->second == C && "Didn't find correct element?");
 743
 744     // If this constant is the representative element for its abstract type,
 745     // update the AbstractTypeMap so that the representative element is I.
 746     if (C->getType()->isAbstract()) {
 747       typename AbstractTypeMapTy::iterator ATI =
 748           AbstractTypeMap.find(C->getType());
 749       assert(ATI != AbstractTypeMap.end() &&
 750              "Abstract type not in AbstractTypeMap?");
 751       if (ATI->second == OldI)
 752         ATI->second = I;
 753     }
 754
 755     // Remove the old entry from the map.
 756     Map.erase(OldI);
 757
 758     // Update the inverse map so that we know that this constant is now
 759     // located at descriptor I.
 760     if (HasLargeKey) {
 761       assert(I->second == C && "Bad inversemap entry!");
 762       InverseMap[C] = I;
 763     }
 764   }
 765
 766   void refineAbstractType(const DerivedType *OldTy, const Type *NewTy) {
 767     sys::SmartScopedLock<true> Lock(ValueMapLock);
 768     typename AbstractTypeMapTy::iterator I =
 769       AbstractTypeMap.find(cast<Type>(OldTy));
 770
 771     assert(I != AbstractTypeMap.end() &&
 772            "Abstract type not in AbstractTypeMap?");
 773
 774     // Convert a constant at a time until the last one is gone.  The last one
 775     // leaving will remove() itself, causing the AbstractTypeMapEntry to be
 776     // eliminated eventually.
 777     do {
 778       ConvertConstantType<ConstantClass,
 779                           TypeClass>::convert(
 780                               static_cast<ConstantClass *>(I->second->second),
 781                                               cast<TypeClass>(NewTy));
 782
 783       I = AbstractTypeMap.find(cast<Type>(OldTy));
 784     } while (I != AbstractTypeMap.end());
 785   }
 786
 787   // If the type became concrete without being refined to any other existing
 788   // type, we just remove ourselves from the ATU list.
 789   void typeBecameConcrete(const DerivedType *AbsTy) {
 790     AbsTy->removeAbstractTypeUser(this);
 791   }
 792
 793   void dump() const {
 794     DEBUG(errs() << "Constant.cpp: ValueMap\n");
 795   }
 796 };
 797
 798 }
 799
 800 #endif