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      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/ADT/DenseMap.h"
     19 #include "llvm/ADT/Hashing.h"
     20 #include "llvm/IR/InlineAsm.h"
     21 #include "llvm/IR/Instructions.h"
     22 #include "llvm/IR/Operator.h"
     23 #include "llvm/Support/Debug.h"
     24 #include "llvm/Support/ErrorHandling.h"
     25 #include "llvm/Support/raw_ostream.h"
     26 #include <map>
     27 
     28 namespace llvm {
     29 template<class ValType>
     30 struct ConstantTraits;
     31 
     32 /// UnaryConstantExpr - This class is private to Constants.cpp, and is used
     33 /// behind the scenes to implement unary constant exprs.
     34 class UnaryConstantExpr : public ConstantExpr {
     35   virtual void anchor();
     36   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
     37 public:
     38   // allocate space for exactly one operand
     39   void *operator new(size_t s) {
     40     return User::operator new(s, 1);
     41   }
     42   UnaryConstantExpr(unsigned Opcode, Constant *C, Type *Ty)
     43     : ConstantExpr(Ty, Opcode, &Op<0>(), 1) {
     44     Op<0>() = C;
     45   }
     46   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
     47 };
     48 
     49 /// BinaryConstantExpr - This class is private to Constants.cpp, and is used
     50 /// behind the scenes to implement binary constant exprs.
     51 class BinaryConstantExpr : public ConstantExpr {
     52   virtual void anchor();
     53   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
     54 public:
     55   // allocate space for exactly two operands
     56   void *operator new(size_t s) {
     57     return User::operator new(s, 2);
     58   }
     59   BinaryConstantExpr(unsigned Opcode, Constant *C1, Constant *C2,
     60                      unsigned Flags)
     61     : ConstantExpr(C1->getType(), Opcode, &Op<0>(), 2) {
     62     Op<0>() = C1;
     63     Op<1>() = C2;
     64     SubclassOptionalData = Flags;
     65   }
     66   /// Transparently provide more efficient getOperand methods.
     67   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
     68 };
     69 
     70 /// SelectConstantExpr - This class is private to Constants.cpp, and is used
     71 /// behind the scenes to implement select constant exprs.
     72 class SelectConstantExpr : public ConstantExpr {
     73   virtual void anchor();
     74   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
     75 public:
     76   // allocate space for exactly three operands
     77   void *operator new(size_t s) {
     78     return User::operator new(s, 3);
     79   }
     80   SelectConstantExpr(Constant *C1, Constant *C2, Constant *C3)
     81     : ConstantExpr(C2->getType(), Instruction::Select, &Op<0>(), 3) {
     82     Op<0>() = C1;
     83     Op<1>() = C2;
     84     Op<2>() = C3;
     85   }
     86   /// Transparently provide more efficient getOperand methods.
     87   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
     88 };
     89 
     90 /// ExtractElementConstantExpr - This class is private to
     91 /// Constants.cpp, and is used behind the scenes to implement
     92 /// extractelement constant exprs.
     93 class ExtractElementConstantExpr : public ConstantExpr {
     94   virtual void anchor();
     95   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
     96 public:
     97   // allocate space for exactly two operands
     98   void *operator new(size_t s) {
     99     return User::operator new(s, 2);
    100   }
    101   ExtractElementConstantExpr(Constant *C1, Constant *C2)
    102     : ConstantExpr(cast<VectorType>(C1->getType())->getElementType(),
    103                    Instruction::ExtractElement, &Op<0>(), 2) {
    104     Op<0>() = C1;
    105     Op<1>() = C2;
    106   }
    107   /// Transparently provide more efficient getOperand methods.
    108   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    109 };
    110 
    111 /// InsertElementConstantExpr - This class is private to
    112 /// Constants.cpp, and is used behind the scenes to implement
    113 /// insertelement constant exprs.
    114 class InsertElementConstantExpr : public ConstantExpr {
    115   virtual void anchor();
    116   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
    117 public:
    118   // allocate space for exactly three operands
    119   void *operator new(size_t s) {
    120     return User::operator new(s, 3);
    121   }
    122   InsertElementConstantExpr(Constant *C1, Constant *C2, Constant *C3)
    123     : ConstantExpr(C1->getType(), Instruction::InsertElement,
    124                    &Op<0>(), 3) {
    125     Op<0>() = C1;
    126     Op<1>() = C2;
    127     Op<2>() = C3;
    128   }
    129   /// Transparently provide more efficient getOperand methods.
    130   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    131 };
    132 
    133 /// ShuffleVectorConstantExpr - This class is private to
    134 /// Constants.cpp, and is used behind the scenes to implement
    135 /// shufflevector constant exprs.
    136 class ShuffleVectorConstantExpr : public ConstantExpr {
    137   virtual void anchor();
    138   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
    139 public:
    140   // allocate space for exactly three operands
    141   void *operator new(size_t s) {
    142     return User::operator new(s, 3);
    143   }
    144   ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3)
    145   : ConstantExpr(VectorType::get(
    146                    cast<VectorType>(C1->getType())->getElementType(),
    147                    cast<VectorType>(C3->getType())->getNumElements()),
    148                  Instruction::ShuffleVector,
    149                  &Op<0>(), 3) {
    150     Op<0>() = C1;
    151     Op<1>() = C2;
    152     Op<2>() = C3;
    153   }
    154   /// Transparently provide more efficient getOperand methods.
    155   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    156 };
    157 
    158 /// ExtractValueConstantExpr - This class is private to
    159 /// Constants.cpp, and is used behind the scenes to implement
    160 /// extractvalue constant exprs.
    161 class ExtractValueConstantExpr : public ConstantExpr {
    162   virtual void anchor();
    163   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
    164 public:
    165   // allocate space for exactly one operand
    166   void *operator new(size_t s) {
    167     return User::operator new(s, 1);
    168   }
    169   ExtractValueConstantExpr(Constant *Agg,
    170                            const SmallVector<unsigned, 4> &IdxList,
    171                            Type *DestTy)
    172     : ConstantExpr(DestTy, Instruction::ExtractValue, &Op<0>(), 1),
    173       Indices(IdxList) {
    174     Op<0>() = Agg;
    175   }
    176 
    177   /// Indices - These identify which value to extract.
    178   const SmallVector<unsigned, 4> Indices;
    179 
    180   /// Transparently provide more efficient getOperand methods.
    181   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    182 };
    183 
    184 /// InsertValueConstantExpr - This class is private to
    185 /// Constants.cpp, and is used behind the scenes to implement
    186 /// insertvalue constant exprs.
    187 class InsertValueConstantExpr : public ConstantExpr {
    188   virtual void anchor();
    189   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
    190 public:
    191   // allocate space for exactly one operand
    192   void *operator new(size_t s) {
    193     return User::operator new(s, 2);
    194   }
    195   InsertValueConstantExpr(Constant *Agg, Constant *Val,
    196                           const SmallVector<unsigned, 4> &IdxList,
    197                           Type *DestTy)
    198     : ConstantExpr(DestTy, Instruction::InsertValue, &Op<0>(), 2),
    199       Indices(IdxList) {
    200     Op<0>() = Agg;
    201     Op<1>() = Val;
    202   }
    203 
    204   /// Indices - These identify the position for the insertion.
    205   const SmallVector<unsigned, 4> Indices;
    206 
    207   /// Transparently provide more efficient getOperand methods.
    208   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    209 };
    210 
    211 
    212 /// GetElementPtrConstantExpr - This class is private to Constants.cpp, and is
    213 /// used behind the scenes to implement getelementpr constant exprs.
    214 class GetElementPtrConstantExpr : public ConstantExpr {
    215   virtual void anchor();
    216   GetElementPtrConstantExpr(Constant *C, ArrayRef<Constant*> IdxList,
    217                             Type *DestTy);
    218 public:
    219   static GetElementPtrConstantExpr *Create(Constant *C,
    220                                            ArrayRef<Constant*> IdxList,
    221                                            Type *DestTy,
    222                                            unsigned Flags) {
    223     GetElementPtrConstantExpr *Result =
    224       new(IdxList.size() + 1) GetElementPtrConstantExpr(C, IdxList, DestTy);
    225     Result->SubclassOptionalData = Flags;
    226     return Result;
    227   }
    228   /// Transparently provide more efficient getOperand methods.
    229   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    230 };
    231 
    232 // CompareConstantExpr - This class is private to Constants.cpp, and is used
    233 // behind the scenes to implement ICmp and FCmp constant expressions. This is
    234 // needed in order to store the predicate value for these instructions.
    235 class CompareConstantExpr : public ConstantExpr {
    236   virtual void anchor();
    237   void *operator new(size_t, unsigned) LLVM_DELETED_FUNCTION;
    238 public:
    239   // allocate space for exactly two operands
    240   void *operator new(size_t s) {
    241     return User::operator new(s, 2);
    242   }
    243   unsigned short predicate;
    244   CompareConstantExpr(Type *ty, Instruction::OtherOps opc,
    245                       unsigned short pred,  Constant* LHS, Constant* RHS)
    246     : ConstantExpr(ty, opc, &Op<0>(), 2), predicate(pred) {
    247     Op<0>() = LHS;
    248     Op<1>() = RHS;
    249   }
    250   /// Transparently provide more efficient getOperand methods.
    251   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
    252 };
    253 
    254 template <>
    255 struct OperandTraits<UnaryConstantExpr> :
    256   public FixedNumOperandTraits<UnaryConstantExpr, 1> {
    257 };
    258 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(UnaryConstantExpr, Value)
    259 
    260 template <>
    261 struct OperandTraits<BinaryConstantExpr> :
    262   public FixedNumOperandTraits<BinaryConstantExpr, 2> {
    263 };
    264 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(BinaryConstantExpr, Value)
    265 
    266 template <>
    267 struct OperandTraits<SelectConstantExpr> :
    268   public FixedNumOperandTraits<SelectConstantExpr, 3> {
    269 };
    270 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(SelectConstantExpr, Value)
    271 
    272 template <>
    273 struct OperandTraits<ExtractElementConstantExpr> :
    274   public FixedNumOperandTraits<ExtractElementConstantExpr, 2> {
    275 };
    276 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ExtractElementConstantExpr, Value)
    277 
    278 template <>
    279 struct OperandTraits<InsertElementConstantExpr> :
    280   public FixedNumOperandTraits<InsertElementConstantExpr, 3> {
    281 };
    282 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(InsertElementConstantExpr, Value)
    283 
    284 template <>
    285 struct OperandTraits<ShuffleVectorConstantExpr> :
    286     public FixedNumOperandTraits<ShuffleVectorConstantExpr, 3> {
    287 };
    288 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ShuffleVectorConstantExpr, Value)
    289 
    290 template <>
    291 struct OperandTraits<ExtractValueConstantExpr> :
    292   public FixedNumOperandTraits<ExtractValueConstantExpr, 1> {
    293 };
    294 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ExtractValueConstantExpr, Value)
    295 
    296 template <>
    297 struct OperandTraits<InsertValueConstantExpr> :
    298   public FixedNumOperandTraits<InsertValueConstantExpr, 2> {
    299 };
    300 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(InsertValueConstantExpr, Value)
    301 
    302 template <>
    303 struct OperandTraits<GetElementPtrConstantExpr> :
    304   public VariadicOperandTraits<GetElementPtrConstantExpr, 1> {
    305 };
    306 
    307 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GetElementPtrConstantExpr, Value)
    308 
    309 
    310 template <>
    311 struct OperandTraits<CompareConstantExpr> :
    312   public FixedNumOperandTraits<CompareConstantExpr, 2> {
    313 };
    314 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(CompareConstantExpr, Value)
    315 
    316 struct ExprMapKeyType {
    317   ExprMapKeyType(unsigned opc,
    318       ArrayRef<Constant*> ops,
    319       unsigned short flags = 0,
    320       unsigned short optionalflags = 0,
    321       ArrayRef<unsigned> inds = None)
    322         : opcode(opc), subclassoptionaldata(optionalflags), subclassdata(flags),
    323         operands(ops.begin(), ops.end()), indices(inds.begin(), inds.end()) {}
    324   uint8_t opcode;
    325   uint8_t subclassoptionaldata;
    326   uint16_t subclassdata;
    327   std::vector<Constant*> operands;
    328   SmallVector<unsigned, 4> indices;
    329   bool operator==(const ExprMapKeyType& that) const {
    330     return this->opcode == that.opcode &&
    331            this->subclassdata == that.subclassdata &&
    332            this->subclassoptionaldata == that.subclassoptionaldata &&
    333            this->operands == that.operands &&
    334            this->indices == that.indices;
    335   }
    336   bool operator<(const ExprMapKeyType & that) const {
    337     if (this->opcode != that.opcode) return this->opcode < that.opcode;
    338     if (this->operands != that.operands) return this->operands < that.operands;
    339     if (this->subclassdata != that.subclassdata)
    340       return this->subclassdata < that.subclassdata;
    341     if (this->subclassoptionaldata != that.subclassoptionaldata)
    342       return this->subclassoptionaldata < that.subclassoptionaldata;
    343     if (this->indices != that.indices) return this->indices < that.indices;
    344     return false;
    345   }
    346 
    347   bool operator!=(const ExprMapKeyType& that) const {
    348     return !(*this == that);
    349   }
    350 };
    351 
    352 struct InlineAsmKeyType {
    353   InlineAsmKeyType(StringRef AsmString,
    354                    StringRef Constraints, bool hasSideEffects,
    355                    bool isAlignStack, InlineAsm::AsmDialect asmDialect)
    356     : asm_string(AsmString), constraints(Constraints),
    357       has_side_effects(hasSideEffects), is_align_stack(isAlignStack),
    358       asm_dialect(asmDialect) {}
    359   std::string asm_string;
    360   std::string constraints;
    361   bool has_side_effects;
    362   bool is_align_stack;
    363   InlineAsm::AsmDialect asm_dialect;
    364   bool operator==(const InlineAsmKeyType& that) const {
    365     return this->asm_string == that.asm_string &&
    366            this->constraints == that.constraints &&
    367            this->has_side_effects == that.has_side_effects &&
    368            this->is_align_stack == that.is_align_stack &&
    369            this->asm_dialect == that.asm_dialect;
    370   }
    371   bool operator<(const InlineAsmKeyType& that) const {
    372     if (this->asm_string != that.asm_string)
    373       return this->asm_string < that.asm_string;
    374     if (this->constraints != that.constraints)
    375       return this->constraints < that.constraints;
    376     if (this->has_side_effects != that.has_side_effects)
    377       return this->has_side_effects < that.has_side_effects;
    378     if (this->is_align_stack != that.is_align_stack)
    379       return this->is_align_stack < that.is_align_stack;
    380     if (this->asm_dialect != that.asm_dialect)
    381       return this->asm_dialect < that.asm_dialect;
    382     return false;
    383   }
    384 
    385   bool operator!=(const InlineAsmKeyType& that) const {
    386     return !(*this == that);
    387   }
    388 };
    389 
    390 // The number of operands for each ConstantCreator::create method is
    391 // determined by the ConstantTraits template.
    392 // ConstantCreator - A class that is used to create constants by
    393 // ConstantUniqueMap*.  This class should be partially specialized if there is
    394 // something strange that needs to be done to interface to the ctor for the
    395 // constant.
    396 //
    397 template<typename T, typename Alloc>
    398 struct ConstantTraits< std::vector<T, Alloc> > {
    399   static unsigned uses(const std::vector<T, Alloc>& v) {
    400     return v.size();
    401   }
    402 };
    403 
    404 template<>
    405 struct ConstantTraits<Constant *> {
    406   static unsigned uses(Constant * const & v) {
    407     return 1;
    408   }
    409 };
    410 
    411 template<class ConstantClass, class TypeClass, class ValType>
    412 struct ConstantCreator {
    413   static ConstantClass *create(TypeClass *Ty, const ValType &V) {
    414     return new(ConstantTraits<ValType>::uses(V)) ConstantClass(Ty, V);
    415   }
    416 };
    417 
    418 template<class ConstantClass, class TypeClass>
    419 struct ConstantArrayCreator {
    420   static ConstantClass *create(TypeClass *Ty, ArrayRef<Constant*> V) {
    421     return new(V.size()) ConstantClass(Ty, V);
    422   }
    423 };
    424 
    425 template<class ConstantClass>
    426 struct ConstantKeyData {
    427   typedef void ValType;
    428   static ValType getValType(ConstantClass *C) {
    429     llvm_unreachable("Unknown Constant type!");
    430   }
    431 };
    432 
    433 template<>
    434 struct ConstantCreator<ConstantExpr, Type, ExprMapKeyType> {
    435   static ConstantExpr *create(Type *Ty, const ExprMapKeyType &V,
    436       unsigned short pred = 0) {
    437     if (Instruction::isCast(V.opcode))
    438       return new UnaryConstantExpr(V.opcode, V.operands[0], Ty);
    439     if ((V.opcode >= Instruction::BinaryOpsBegin &&
    440          V.opcode < Instruction::BinaryOpsEnd))
    441       return new BinaryConstantExpr(V.opcode, V.operands[0], V.operands[1],
    442                                     V.subclassoptionaldata);
    443     if (V.opcode == Instruction::Select)
    444       return new SelectConstantExpr(V.operands[0], V.operands[1],
    445                                     V.operands[2]);
    446     if (V.opcode == Instruction::ExtractElement)
    447       return new ExtractElementConstantExpr(V.operands[0], V.operands[1]);
    448     if (V.opcode == Instruction::InsertElement)
    449       return new InsertElementConstantExpr(V.operands[0], V.operands[1],
    450                                            V.operands[2]);
    451     if (V.opcode == Instruction::ShuffleVector)
    452       return new ShuffleVectorConstantExpr(V.operands[0], V.operands[1],
    453                                            V.operands[2]);
    454     if (V.opcode == Instruction::InsertValue)
    455       return new InsertValueConstantExpr(V.operands[0], V.operands[1],
    456                                          V.indices, Ty);
    457     if (V.opcode == Instruction::ExtractValue)
    458       return new ExtractValueConstantExpr(V.operands[0], V.indices, Ty);
    459     if (V.opcode == Instruction::GetElementPtr) {
    460       std::vector<Constant*> IdxList(V.operands.begin()+1, V.operands.end());
    461       return GetElementPtrConstantExpr::Create(V.operands[0], IdxList, Ty,
    462                                                V.subclassoptionaldata);
    463     }
    464 
    465     // The compare instructions are weird. We have to encode the predicate
    466     // value and it is combined with the instruction opcode by multiplying
    467     // the opcode by one hundred. We must decode this to get the predicate.
    468     if (V.opcode == Instruction::ICmp)
    469       return new CompareConstantExpr(Ty, Instruction::ICmp, V.subclassdata,
    470                                      V.operands[0], V.operands[1]);
    471     if (V.opcode == Instruction::FCmp)
    472       return new CompareConstantExpr(Ty, Instruction::FCmp, V.subclassdata,
    473                                      V.operands[0], V.operands[1]);
    474     llvm_unreachable("Invalid ConstantExpr!");
    475   }
    476 };
    477 
    478 template<>
    479 struct ConstantKeyData<ConstantExpr> {
    480   typedef ExprMapKeyType ValType;
    481   static ValType getValType(ConstantExpr *CE) {
    482     std::vector<Constant*> Operands;
    483     Operands.reserve(CE->getNumOperands());
    484     for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
    485       Operands.push_back(cast<Constant>(CE->getOperand(i)));
    486     return ExprMapKeyType(CE->getOpcode(), Operands,
    487         CE->isCompare() ? CE->getPredicate() : 0,
    488         CE->getRawSubclassOptionalData(),
    489         CE->hasIndices() ?
    490           CE->getIndices() : ArrayRef<unsigned>());
    491   }
    492 };
    493 
    494 template<>
    495 struct ConstantCreator<InlineAsm, PointerType, InlineAsmKeyType> {
    496   static InlineAsm *create(PointerType *Ty, const InlineAsmKeyType &Key) {
    497     return new InlineAsm(Ty, Key.asm_string, Key.constraints,
    498                          Key.has_side_effects, Key.is_align_stack,
    499                          Key.asm_dialect);
    500   }
    501 };
    502 
    503 template<>
    504 struct ConstantKeyData<InlineAsm> {
    505   typedef InlineAsmKeyType ValType;
    506   static ValType getValType(InlineAsm *Asm) {
    507     return InlineAsmKeyType(Asm->getAsmString(), Asm->getConstraintString(),
    508                             Asm->hasSideEffects(), Asm->isAlignStack(),
    509                             Asm->getDialect());
    510   }
    511 };
    512 
    513 template<class ValType, class ValRefType, class TypeClass, class ConstantClass,
    514          bool HasLargeKey = false /*true for arrays and structs*/ >
    515 class ConstantUniqueMap {
    516 public:
    517   typedef std::pair<TypeClass*, ValType> MapKey;
    518   typedef std::map<MapKey, ConstantClass *> MapTy;
    519   typedef std::map<ConstantClass *, typename MapTy::iterator> InverseMapTy;
    520 private:
    521   /// Map - This is the main map from the element descriptor to the Constants.
    522   /// This is the primary way we avoid creating two of the same shape
    523   /// constant.
    524   MapTy Map;
    525 
    526   /// InverseMap - If "HasLargeKey" is true, this contains an inverse mapping
    527   /// from the constants to their element in Map.  This is important for
    528   /// removal of constants from the array, which would otherwise have to scan
    529   /// through the map with very large keys.
    530   InverseMapTy InverseMap;
    531 
    532 public:
    533   typename MapTy::iterator map_begin() { return Map.begin(); }
    534   typename MapTy::iterator map_end() { return Map.end(); }
    535 
    536   void freeConstants() {
    537     for (typename MapTy::iterator I=Map.begin(), E=Map.end();
    538          I != E; ++I) {
    539       // Asserts that use_empty().
    540       delete I->second;
    541     }
    542   }
    543 
    544   /// InsertOrGetItem - Return an iterator for the specified element.
    545   /// If the element exists in the map, the returned iterator points to the
    546   /// entry and Exists=true.  If not, the iterator points to the newly
    547   /// inserted entry and returns Exists=false.  Newly inserted entries have
    548   /// I->second == 0, and should be filled in.
    549   typename MapTy::iterator InsertOrGetItem(std::pair<MapKey, ConstantClass *>
    550                                  &InsertVal,
    551                                  bool &Exists) {
    552     std::pair<typename MapTy::iterator, bool> IP = Map.insert(InsertVal);
    553     Exists = !IP.second;
    554     return IP.first;
    555   }
    556 
    557 private:
    558   typename MapTy::iterator FindExistingElement(ConstantClass *CP) {
    559     if (HasLargeKey) {
    560       typename InverseMapTy::iterator IMI = InverseMap.find(CP);
    561       assert(IMI != InverseMap.end() && IMI->second != Map.end() &&
    562              IMI->second->second == CP &&
    563              "InverseMap corrupt!");
    564       return IMI->second;
    565     }
    566 
    567     typename MapTy::iterator I =
    568       Map.find(MapKey(static_cast<TypeClass*>(CP->getType()),
    569                       ConstantKeyData<ConstantClass>::getValType(CP)));
    570     if (I == Map.end() || I->second != CP) {
    571       // FIXME: This should not use a linear scan.  If this gets to be a
    572       // performance problem, someone should look at this.
    573       for (I = Map.begin(); I != Map.end() && I->second != CP; ++I)
    574         /* empty */;
    575     }
    576     return I;
    577   }
    578 
    579   ConstantClass *Create(TypeClass *Ty, ValRefType V,
    580                         typename MapTy::iterator I) {
    581     ConstantClass* Result =
    582       ConstantCreator<ConstantClass,TypeClass,ValType>::create(Ty, V);
    583 
    584     assert(Result->getType() == Ty && "Type specified is not correct!");
    585     I = Map.insert(I, std::make_pair(MapKey(Ty, V), Result));
    586 
    587     if (HasLargeKey)  // Remember the reverse mapping if needed.
    588       InverseMap.insert(std::make_pair(Result, I));
    589 
    590     return Result;
    591   }
    592 public:
    593 
    594   /// getOrCreate - Return the specified constant from the map, creating it if
    595   /// necessary.
    596   ConstantClass *getOrCreate(TypeClass *Ty, ValRefType V) {
    597     MapKey Lookup(Ty, V);
    598     ConstantClass* Result = 0;
    599 
    600     typename MapTy::iterator I = Map.find(Lookup);
    601     // Is it in the map?
    602     if (I != Map.end())
    603       Result = I->second;
    604 
    605     if (!Result) {
    606       // If no preexisting value, create one now...
    607       Result = Create(Ty, V, I);
    608     }
    609 
    610     return Result;
    611   }
    612 
    613   void remove(ConstantClass *CP) {
    614     typename MapTy::iterator I = FindExistingElement(CP);
    615     assert(I != Map.end() && "Constant not found in constant table!");
    616     assert(I->second == CP && "Didn't find correct element?");
    617 
    618     if (HasLargeKey)  // Remember the reverse mapping if needed.
    619       InverseMap.erase(CP);
    620 
    621     Map.erase(I);
    622   }
    623 
    624   /// MoveConstantToNewSlot - If we are about to change C to be the element
    625   /// specified by I, update our internal data structures to reflect this
    626   /// fact.
    627   void MoveConstantToNewSlot(ConstantClass *C, typename MapTy::iterator I) {
    628     // First, remove the old location of the specified constant in the map.
    629     typename MapTy::iterator OldI = FindExistingElement(C);
    630     assert(OldI != Map.end() && "Constant not found in constant table!");
    631     assert(OldI->second == C && "Didn't find correct element?");
    632 
    633      // Remove the old entry from the map.
    634     Map.erase(OldI);
    635 
    636     // Update the inverse map so that we know that this constant is now
    637     // located at descriptor I.
    638     if (HasLargeKey) {
    639       assert(I->second == C && "Bad inversemap entry!");
    640       InverseMap[C] = I;
    641     }
    642   }
    643 
    644   void dump() const {
    645     DEBUG(dbgs() << "Constant.cpp: ConstantUniqueMap\n");
    646   }
    647 };
    648 
    649 // Unique map for aggregate constants
    650 template<class TypeClass, class ConstantClass>
    651 class ConstantAggrUniqueMap {
    652 public:
    653   typedef ArrayRef<Constant*> Operands;
    654   typedef std::pair<TypeClass*, Operands> LookupKey;
    655 private:
    656   struct MapInfo {
    657     typedef DenseMapInfo<ConstantClass*> ConstantClassInfo;
    658     typedef DenseMapInfo<Constant*> ConstantInfo;
    659     typedef DenseMapInfo<TypeClass*> TypeClassInfo;
    660     static inline ConstantClass* getEmptyKey() {
    661       return ConstantClassInfo::getEmptyKey();
    662     }
    663     static inline ConstantClass* getTombstoneKey() {
    664       return ConstantClassInfo::getTombstoneKey();
    665     }
    666     static unsigned getHashValue(const ConstantClass *CP) {
    667       SmallVector<Constant*, 8> CPOperands;
    668       CPOperands.reserve(CP->getNumOperands());
    669       for (unsigned I = 0, E = CP->getNumOperands(); I < E; ++I)
    670         CPOperands.push_back(CP->getOperand(I));
    671       return getHashValue(LookupKey(CP->getType(), CPOperands));
    672     }
    673     static bool isEqual(const ConstantClass *LHS, const ConstantClass *RHS) {
    674       return LHS == RHS;
    675     }
    676     static unsigned getHashValue(const LookupKey &Val) {
    677       return hash_combine(Val.first, hash_combine_range(Val.second.begin(),
    678                                                         Val.second.end()));
    679     }
    680     static bool isEqual(const LookupKey &LHS, const ConstantClass *RHS) {
    681       if (RHS == getEmptyKey() || RHS == getTombstoneKey())
    682         return false;
    683       if (LHS.first != RHS->getType()
    684           || LHS.second.size() != RHS->getNumOperands())
    685         return false;
    686       for (unsigned I = 0, E = RHS->getNumOperands(); I < E; ++I) {
    687         if (LHS.second[I] != RHS->getOperand(I))
    688           return false;
    689       }
    690       return true;
    691     }
    692   };
    693 public:
    694   typedef DenseMap<ConstantClass *, char, MapInfo> MapTy;
    695 
    696 private:
    697   /// Map - This is the main map from the element descriptor to the Constants.
    698   /// This is the primary way we avoid creating two of the same shape
    699   /// constant.
    700   MapTy Map;
    701 
    702 public:
    703   typename MapTy::iterator map_begin() { return Map.begin(); }
    704   typename MapTy::iterator map_end() { return Map.end(); }
    705 
    706   void freeConstants() {
    707     for (typename MapTy::iterator I=Map.begin(), E=Map.end();
    708          I != E; ++I) {
    709       // Asserts that use_empty().
    710       delete I->first;
    711     }
    712   }
    713 
    714 private:
    715   typename MapTy::iterator findExistingElement(ConstantClass *CP) {
    716     return Map.find(CP);
    717   }
    718 
    719   ConstantClass *Create(TypeClass *Ty, Operands V, typename MapTy::iterator I) {
    720     ConstantClass* Result =
    721       ConstantArrayCreator<ConstantClass,TypeClass>::create(Ty, V);
    722 
    723     assert(Result->getType() == Ty && "Type specified is not correct!");
    724     Map[Result] = '\0';
    725 
    726     return Result;
    727   }
    728 public:
    729 
    730   /// getOrCreate - Return the specified constant from the map, creating it if
    731   /// necessary.
    732   ConstantClass *getOrCreate(TypeClass *Ty, Operands V) {
    733     LookupKey Lookup(Ty, V);
    734     ConstantClass* Result = 0;
    735 
    736     typename MapTy::iterator I = Map.find_as(Lookup);
    737     // Is it in the map?
    738     if (I != Map.end())
    739       Result = I->first;
    740 
    741     if (!Result) {
    742       // If no preexisting value, create one now...
    743       Result = Create(Ty, V, I);
    744     }
    745 
    746     return Result;
    747   }
    748 
    749   /// Find the constant by lookup key.
    750   typename MapTy::iterator find(LookupKey Lookup) {
    751     return Map.find_as(Lookup);
    752   }
    753 
    754   /// Insert the constant into its proper slot.
    755   void insert(ConstantClass *CP) {
    756     Map[CP] = '\0';
    757   }
    758 
    759   /// Remove this constant from the map
    760   void remove(ConstantClass *CP) {
    761     typename MapTy::iterator I = findExistingElement(CP);
    762     assert(I != Map.end() && "Constant not found in constant table!");
    763     assert(I->first == CP && "Didn't find correct element?");
    764     Map.erase(I);
    765   }
    766 
    767   void dump() const {
    768     DEBUG(dbgs() << "Constant.cpp: ConstantUniqueMap\n");
    769   }
    770 };
    771 
    772 }
    773 
    774 #endif
    775