1 files changed, 708 insertions, 0 deletions

diff --git a/llvm/lib/IR/ConstantsContext.h b/llvm/lib/IR/ConstantsContext.h
new file mode 100644
index 0000000000000..1ec9087551f86
--- /dev/null
+++ b/llvm/lib/IR/ConstantsContext.h
@@ -0,0 +1,708 @@
+//===-- ConstantsContext.h - Constants-related Context Interals -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines various helper methods and classes used by
+// LLVMContextImpl for creating and managing constants.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_IR_CONSTANTSCONTEXT_H
+#define LLVM_LIB_IR_CONSTANTSCONTEXT_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Hashing.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/OperandTraits.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <utility>
+
+#define DEBUG_TYPE "ir"
+
+namespace llvm {
+
+/// UnaryConstantExpr - This class is private to Constants.cpp, and is used
+/// behind the scenes to implement unary constant exprs.
+class UnaryConstantExpr : public ConstantExpr {
+public:
+  UnaryConstantExpr(unsigned Opcode, Constant *C, Type *Ty)
+    : ConstantExpr(Ty, Opcode, &Op<0>(), 1) {
+    Op<0>() = C;
+  }
+
+  // allocate space for exactly one operand
+  void *operator new(size_t s) {
+    return User::operator new(s, 1);
+  }
+
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+};
+
+/// BinaryConstantExpr - This class is private to Constants.cpp, and is used
+/// behind the scenes to implement binary constant exprs.
+class BinaryConstantExpr : public ConstantExpr {
+public:
+  BinaryConstantExpr(unsigned Opcode, Constant *C1, Constant *C2,
+                     unsigned Flags)
+    : ConstantExpr(C1->getType(), Opcode, &Op<0>(), 2) {
+    Op<0>() = C1;
+    Op<1>() = C2;
+    SubclassOptionalData = Flags;
+  }
+
+  // allocate space for exactly two operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 2);
+  }
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+};
+
+/// SelectConstantExpr - This class is private to Constants.cpp, and is used
+/// behind the scenes to implement select constant exprs.
+class SelectConstantExpr : public ConstantExpr {
+public:
+  SelectConstantExpr(Constant *C1, Constant *C2, Constant *C3)
+    : ConstantExpr(C2->getType(), Instruction::Select, &Op<0>(), 3) {
+    Op<0>() = C1;
+    Op<1>() = C2;
+    Op<2>() = C3;
+  }
+
+  // allocate space for exactly three operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 3);
+  }
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+};
+
+/// ExtractElementConstantExpr - This class is private to
+/// Constants.cpp, and is used behind the scenes to implement
+/// extractelement constant exprs.
+class ExtractElementConstantExpr : public ConstantExpr {
+public:
+  ExtractElementConstantExpr(Constant *C1, Constant *C2)
+    : ConstantExpr(cast<VectorType>(C1->getType())->getElementType(),
+                   Instruction::ExtractElement, &Op<0>(), 2) {
+    Op<0>() = C1;
+    Op<1>() = C2;
+  }
+
+  // allocate space for exactly two operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 2);
+  }
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+};
+
+/// InsertElementConstantExpr - This class is private to
+/// Constants.cpp, and is used behind the scenes to implement
+/// insertelement constant exprs.
+class InsertElementConstantExpr : public ConstantExpr {
+public:
+  InsertElementConstantExpr(Constant *C1, Constant *C2, Constant *C3)
+    : ConstantExpr(C1->getType(), Instruction::InsertElement,
+                   &Op<0>(), 3) {
+    Op<0>() = C1;
+    Op<1>() = C2;
+    Op<2>() = C3;
+  }
+
+  // allocate space for exactly three operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 3);
+  }
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+};
+
+/// ShuffleVectorConstantExpr - This class is private to
+/// Constants.cpp, and is used behind the scenes to implement
+/// shufflevector constant exprs.
+class ShuffleVectorConstantExpr : public ConstantExpr {
+public:
+  ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3)
+  : ConstantExpr(VectorType::get(
+                   cast<VectorType>(C1->getType())->getElementType(),
+                   cast<VectorType>(C3->getType())->getNumElements()),
+                 Instruction::ShuffleVector,
+                 &Op<0>(), 3) {
+    Op<0>() = C1;
+    Op<1>() = C2;
+    Op<2>() = C3;
+  }
+
+  // allocate space for exactly three operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 3);
+  }
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+};
+
+/// ExtractValueConstantExpr - This class is private to
+/// Constants.cpp, and is used behind the scenes to implement
+/// extractvalue constant exprs.
+class ExtractValueConstantExpr : public ConstantExpr {
+public:
+  ExtractValueConstantExpr(Constant *Agg, ArrayRef<unsigned> IdxList,
+                           Type *DestTy)
+      : ConstantExpr(DestTy, Instruction::ExtractValue, &Op<0>(), 1),
+        Indices(IdxList.begin(), IdxList.end()) {
+    Op<0>() = Agg;
+  }
+
+  // allocate space for exactly one operand
+  void *operator new(size_t s) {
+    return User::operator new(s, 1);
+  }
+
+  /// Indices - These identify which value to extract.
+  const SmallVector<unsigned, 4> Indices;
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+
+  static bool classof(const ConstantExpr *CE) {
+    return CE->getOpcode() == Instruction::ExtractValue;
+  }
+  static bool classof(const Value *V) {
+    return isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V));
+  }
+};
+
+/// InsertValueConstantExpr - This class is private to
+/// Constants.cpp, and is used behind the scenes to implement
+/// insertvalue constant exprs.
+class InsertValueConstantExpr : public ConstantExpr {
+public:
+  InsertValueConstantExpr(Constant *Agg, Constant *Val,
+                          ArrayRef<unsigned> IdxList, Type *DestTy)
+      : ConstantExpr(DestTy, Instruction::InsertValue, &Op<0>(), 2),
+        Indices(IdxList.begin(), IdxList.end()) {
+    Op<0>() = Agg;
+    Op<1>() = Val;
+  }
+
+  // allocate space for exactly one operand
+  void *operator new(size_t s) {
+    return User::operator new(s, 2);
+  }
+
+  /// Indices - These identify the position for the insertion.
+  const SmallVector<unsigned, 4> Indices;
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+
+  static bool classof(const ConstantExpr *CE) {
+    return CE->getOpcode() == Instruction::InsertValue;
+  }
+  static bool classof(const Value *V) {
+    return isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V));
+  }
+};
+
+/// GetElementPtrConstantExpr - This class is private to Constants.cpp, and is
+/// used behind the scenes to implement getelementpr constant exprs.
+class GetElementPtrConstantExpr : public ConstantExpr {
+  Type *SrcElementTy;
+  Type *ResElementTy;
+
+  GetElementPtrConstantExpr(Type *SrcElementTy, Constant *C,
+                            ArrayRef<Constant *> IdxList, Type *DestTy);
+
+public:
+  static GetElementPtrConstantExpr *Create(Type *SrcElementTy, Constant *C,
+                                           ArrayRef<Constant *> IdxList,
+                                           Type *DestTy, unsigned Flags) {
+    GetElementPtrConstantExpr *Result = new (IdxList.size() + 1)
+        GetElementPtrConstantExpr(SrcElementTy, C, IdxList, DestTy);
+    Result->SubclassOptionalData = Flags;
+    return Result;
+  }
+
+  Type *getSourceElementType() const;
+  Type *getResultElementType() const;
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+
+  static bool classof(const ConstantExpr *CE) {
+    return CE->getOpcode() == Instruction::GetElementPtr;
+  }
+  static bool classof(const Value *V) {
+    return isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V));
+  }
+};
+
+// CompareConstantExpr - This class is private to Constants.cpp, and is used
+// behind the scenes to implement ICmp and FCmp constant expressions. This is
+// needed in order to store the predicate value for these instructions.
+class CompareConstantExpr : public ConstantExpr {
+public:
+  unsigned short predicate;
+  CompareConstantExpr(Type *ty, Instruction::OtherOps opc,
+                      unsigned short pred,  Constant* LHS, Constant* RHS)
+    : ConstantExpr(ty, opc, &Op<0>(), 2), predicate(pred) {
+    Op<0>() = LHS;
+    Op<1>() = RHS;
+  }
+
+  // allocate space for exactly two operands
+  void *operator new(size_t s) {
+    return User::operator new(s, 2);
+  }
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+
+  static bool classof(const ConstantExpr *CE) {
+    return CE->getOpcode() == Instruction::ICmp ||
+           CE->getOpcode() == Instruction::FCmp;
+  }
+  static bool classof(const Value *V) {
+    return isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V));
+  }
+};
+
+template <>
+struct OperandTraits<UnaryConstantExpr>
+    : public FixedNumOperandTraits<UnaryConstantExpr, 1> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(UnaryConstantExpr, Value)
+
+template <>
+struct OperandTraits<BinaryConstantExpr>
+    : public FixedNumOperandTraits<BinaryConstantExpr, 2> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(BinaryConstantExpr, Value)
+
+template <>
+struct OperandTraits<SelectConstantExpr>
+    : public FixedNumOperandTraits<SelectConstantExpr, 3> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(SelectConstantExpr, Value)
+
+template <>
+struct OperandTraits<ExtractElementConstantExpr>
+    : public FixedNumOperandTraits<ExtractElementConstantExpr, 2> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ExtractElementConstantExpr, Value)
+
+template <>
+struct OperandTraits<InsertElementConstantExpr>
+    : public FixedNumOperandTraits<InsertElementConstantExpr, 3> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(InsertElementConstantExpr, Value)
+
+template <>
+struct OperandTraits<ShuffleVectorConstantExpr>
+    : public FixedNumOperandTraits<ShuffleVectorConstantExpr, 3> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ShuffleVectorConstantExpr, Value)
+
+template <>
+struct OperandTraits<ExtractValueConstantExpr>
+    : public FixedNumOperandTraits<ExtractValueConstantExpr, 1> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(ExtractValueConstantExpr, Value)
+
+template <>
+struct OperandTraits<InsertValueConstantExpr>
+    : public FixedNumOperandTraits<InsertValueConstantExpr, 2> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(InsertValueConstantExpr, Value)
+
+template <>
+struct OperandTraits<GetElementPtrConstantExpr>
+    : public VariadicOperandTraits<GetElementPtrConstantExpr, 1> {};
+
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GetElementPtrConstantExpr, Value)
+
+template <>
+struct OperandTraits<CompareConstantExpr>
+    : public FixedNumOperandTraits<CompareConstantExpr, 2> {};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(CompareConstantExpr, Value)
+
+template <class ConstantClass> struct ConstantAggrKeyType;
+struct InlineAsmKeyType;
+struct ConstantExprKeyType;
+
+template <class ConstantClass> struct ConstantInfo;
+template <> struct ConstantInfo<ConstantExpr> {
+  using ValType = ConstantExprKeyType;
+  using TypeClass = Type;
+};
+template <> struct ConstantInfo<InlineAsm> {
+  using ValType = InlineAsmKeyType;
+  using TypeClass = PointerType;
+};
+template <> struct ConstantInfo<ConstantArray> {
+  using ValType = ConstantAggrKeyType<ConstantArray>;
+  using TypeClass = ArrayType;
+};
+template <> struct ConstantInfo<ConstantStruct> {
+  using ValType = ConstantAggrKeyType<ConstantStruct>;
+  using TypeClass = StructType;
+};
+template <> struct ConstantInfo<ConstantVector> {
+  using ValType = ConstantAggrKeyType<ConstantVector>;
+  using TypeClass = VectorType;
+};
+
+template <class ConstantClass> struct ConstantAggrKeyType {
+  ArrayRef<Constant *> Operands;
+
+  ConstantAggrKeyType(ArrayRef<Constant *> Operands) : Operands(Operands) {}
+
+  ConstantAggrKeyType(ArrayRef<Constant *> Operands, const ConstantClass *)
+      : Operands(Operands) {}
+
+  ConstantAggrKeyType(const ConstantClass *C,
+                      SmallVectorImpl<Constant *> &Storage) {
+    assert(Storage.empty() && "Expected empty storage");
+    for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I)
+      Storage.push_back(C->getOperand(I));
+    Operands = Storage;
+  }
+
+  bool operator==(const ConstantAggrKeyType &X) const {
+    return Operands == X.Operands;
+  }
+
+  bool operator==(const ConstantClass *C) const {
+    if (Operands.size() != C->getNumOperands())
+      return false;
+    for (unsigned I = 0, E = Operands.size(); I != E; ++I)
+      if (Operands[I] != C->getOperand(I))
+        return false;
+    return true;
+  }
+
+  unsigned getHash() const {
+    return hash_combine_range(Operands.begin(), Operands.end());
+  }
+
+  using TypeClass = typename ConstantInfo<ConstantClass>::TypeClass;
+
+  ConstantClass *create(TypeClass *Ty) const {
+    return new (Operands.size()) ConstantClass(Ty, Operands);
+  }
+};
+
+struct InlineAsmKeyType {
+  StringRef AsmString;
+  StringRef Constraints;
+  FunctionType *FTy;
+  bool HasSideEffects;
+  bool IsAlignStack;
+  InlineAsm::AsmDialect AsmDialect;
+
+  InlineAsmKeyType(StringRef AsmString, StringRef Constraints,
+                   FunctionType *FTy, bool HasSideEffects, bool IsAlignStack,
+                   InlineAsm::AsmDialect AsmDialect)
+      : AsmString(AsmString), Constraints(Constraints), FTy(FTy),
+        HasSideEffects(HasSideEffects), IsAlignStack(IsAlignStack),
+        AsmDialect(AsmDialect) {}
+
+  InlineAsmKeyType(const InlineAsm *Asm, SmallVectorImpl<Constant *> &)
+      : AsmString(Asm->getAsmString()), Constraints(Asm->getConstraintString()),
+        FTy(Asm->getFunctionType()), HasSideEffects(Asm->hasSideEffects()),
+        IsAlignStack(Asm->isAlignStack()), AsmDialect(Asm->getDialect()) {}
+
+  bool operator==(const InlineAsmKeyType &X) const {
+    return HasSideEffects == X.HasSideEffects &&
+           IsAlignStack == X.IsAlignStack && AsmDialect == X.AsmDialect &&
+           AsmString == X.AsmString && Constraints == X.Constraints &&
+           FTy == X.FTy;
+  }
+
+  bool operator==(const InlineAsm *Asm) const {
+    return HasSideEffects == Asm->hasSideEffects() &&
+           IsAlignStack == Asm->isAlignStack() &&
+           AsmDialect == Asm->getDialect() &&
+           AsmString == Asm->getAsmString() &&
+           Constraints == Asm->getConstraintString() &&
+           FTy == Asm->getFunctionType();
+  }
+
+  unsigned getHash() const {
+    return hash_combine(AsmString, Constraints, HasSideEffects, IsAlignStack,
+                        AsmDialect, FTy);
+  }
+
+  using TypeClass = ConstantInfo<InlineAsm>::TypeClass;
+
+  InlineAsm *create(TypeClass *Ty) const {
+    assert(PointerType::getUnqual(FTy) == Ty);
+    return new InlineAsm(FTy, AsmString, Constraints, HasSideEffects,
+                         IsAlignStack, AsmDialect);
+  }
+};
+
+struct ConstantExprKeyType {
+  uint8_t Opcode;
+  uint8_t SubclassOptionalData;
+  uint16_t SubclassData;
+  ArrayRef<Constant *> Ops;
+  ArrayRef<unsigned> Indexes;
+  Type *ExplicitTy;
+
+  ConstantExprKeyType(unsigned Opcode, ArrayRef<Constant *> Ops,
+                      unsigned short SubclassData = 0,
+                      unsigned short SubclassOptionalData = 0,
+                      ArrayRef<unsigned> Indexes = None,
+                      Type *ExplicitTy = nullptr)
+      : Opcode(Opcode), SubclassOptionalData(SubclassOptionalData),
+        SubclassData(SubclassData), Ops(Ops), Indexes(Indexes),
+        ExplicitTy(ExplicitTy) {}
+
+  ConstantExprKeyType(ArrayRef<Constant *> Operands, const ConstantExpr *CE)
+      : Opcode(CE->getOpcode()),
+        SubclassOptionalData(CE->getRawSubclassOptionalData()),
+        SubclassData(CE->isCompare() ? CE->getPredicate() : 0), Ops(Operands),
+        Indexes(CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()),
+        ExplicitTy(nullptr) {}
+
+  ConstantExprKeyType(const ConstantExpr *CE,
+                      SmallVectorImpl<Constant *> &Storage)
+      : Opcode(CE->getOpcode()),
+        SubclassOptionalData(CE->getRawSubclassOptionalData()),
+        SubclassData(CE->isCompare() ? CE->getPredicate() : 0),
+        Indexes(CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()),
+        ExplicitTy(nullptr) {
+    assert(Storage.empty() && "Expected empty storage");
+    for (unsigned I = 0, E = CE->getNumOperands(); I != E; ++I)
+      Storage.push_back(CE->getOperand(I));
+    Ops = Storage;
+  }
+
+  bool operator==(const ConstantExprKeyType &X) const {
+    return Opcode == X.Opcode && SubclassData == X.SubclassData &&
+           SubclassOptionalData == X.SubclassOptionalData && Ops == X.Ops &&
+           Indexes == X.Indexes;
+  }
+
+  bool operator==(const ConstantExpr *CE) const {
+    if (Opcode != CE->getOpcode())
+      return false;
+    if (SubclassOptionalData != CE->getRawSubclassOptionalData())
+      return false;
+    if (Ops.size() != CE->getNumOperands())
+      return false;
+    if (SubclassData != (CE->isCompare() ? CE->getPredicate() : 0))
+      return false;
+    for (unsigned I = 0, E = Ops.size(); I != E; ++I)
+      if (Ops[I] != CE->getOperand(I))
+        return false;
+    if (Indexes != (CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()))
+      return false;
+    return true;
+  }
+
+  unsigned getHash() const {
+    return hash_combine(Opcode, SubclassOptionalData, SubclassData,
+                        hash_combine_range(Ops.begin(), Ops.end()),
+                        hash_combine_range(Indexes.begin(), Indexes.end()));
+  }
+
+  using TypeClass = ConstantInfo<ConstantExpr>::TypeClass;
+
+  ConstantExpr *create(TypeClass *Ty) const {
+    switch (Opcode) {
+    default:
+      if (Instruction::isCast(Opcode) ||
+          (Opcode >= Instruction::UnaryOpsBegin &&
+           Opcode < Instruction::UnaryOpsEnd))
+        return new UnaryConstantExpr(Opcode, Ops[0], Ty);
+      if ((Opcode >= Instruction::BinaryOpsBegin &&
+           Opcode < Instruction::BinaryOpsEnd))
+        return new BinaryConstantExpr(Opcode, Ops[0], Ops[1],
+                                      SubclassOptionalData);
+      llvm_unreachable("Invalid ConstantExpr!");
+    case Instruction::Select:
+      return new SelectConstantExpr(Ops[0], Ops[1], Ops[2]);
+    case Instruction::ExtractElement:
+      return new ExtractElementConstantExpr(Ops[0], Ops[1]);
+    case Instruction::InsertElement:
+      return new InsertElementConstantExpr(Ops[0], Ops[1], Ops[2]);
+    case Instruction::ShuffleVector:
+      return new ShuffleVectorConstantExpr(Ops[0], Ops[1], Ops[2]);
+    case Instruction::InsertValue:
+      return new InsertValueConstantExpr(Ops[0], Ops[1], Indexes, Ty);
+    case Instruction::ExtractValue:
+      return new ExtractValueConstantExpr(Ops[0], Indexes, Ty);
+    case Instruction::GetElementPtr:
+      return GetElementPtrConstantExpr::Create(
+          ExplicitTy ? ExplicitTy
+                     : cast<PointerType>(Ops[0]->getType()->getScalarType())
+                           ->getElementType(),
+          Ops[0], Ops.slice(1), Ty, SubclassOptionalData);
+    case Instruction::ICmp:
+      return new CompareConstantExpr(Ty, Instruction::ICmp, SubclassData,
+                                     Ops[0], Ops[1]);
+    case Instruction::FCmp:
+      return new CompareConstantExpr(Ty, Instruction::FCmp, SubclassData,
+                                     Ops[0], Ops[1]);
+    }
+  }
+};
+
+template <class ConstantClass> class ConstantUniqueMap {
+public:
+  using ValType = typename ConstantInfo<ConstantClass>::ValType;
+  using TypeClass = typename ConstantInfo<ConstantClass>::TypeClass;
+  using LookupKey = std::pair<TypeClass *, ValType>;
+
+  /// Key and hash together, so that we compute the hash only once and reuse it.
+  using LookupKeyHashed = std::pair<unsigned, LookupKey>;
+
+private:
+  struct MapInfo {
+    using ConstantClassInfo = DenseMapInfo<ConstantClass *>;
+
+    static inline ConstantClass *getEmptyKey() {
+      return ConstantClassInfo::getEmptyKey();
+    }
+
+    static inline ConstantClass *getTombstoneKey() {
+      return ConstantClassInfo::getTombstoneKey();
+    }
+
+    static unsigned getHashValue(const ConstantClass *CP) {
+      SmallVector<Constant *, 32> Storage;
+      return getHashValue(LookupKey(CP->getType(), ValType(CP, Storage)));
+    }
+
+    static bool isEqual(const ConstantClass *LHS, const ConstantClass *RHS) {
+      return LHS == RHS;
+    }
+
+    static unsigned getHashValue(const LookupKey &Val) {
+      return hash_combine(Val.first, Val.second.getHash());
+    }
+
+    static unsigned getHashValue(const LookupKeyHashed &Val) {
+      return Val.first;
+    }
+
+    static bool isEqual(const LookupKey &LHS, const ConstantClass *RHS) {
+      if (RHS == getEmptyKey() || RHS == getTombstoneKey())
+        return false;
+      if (LHS.first != RHS->getType())
+        return false;
+      return LHS.second == RHS;
+    }
+
+    static bool isEqual(const LookupKeyHashed &LHS, const ConstantClass *RHS) {
+      return isEqual(LHS.second, RHS);
+    }
+  };
+
+public:
+  using MapTy = DenseSet<ConstantClass *, MapInfo>;
+
+private:
+  MapTy Map;
+
+public:
+  typename MapTy::iterator begin() { return Map.begin(); }
+  typename MapTy::iterator end() { return Map.end(); }
+
+  void freeConstants() {
+    for (auto &I : Map)
+      delete I; // Asserts that use_empty().
+  }
+
+private:
+  ConstantClass *create(TypeClass *Ty, ValType V, LookupKeyHashed &HashKey) {
+    ConstantClass *Result = V.create(Ty);
+
+    assert(Result->getType() == Ty && "Type specified is not correct!");
+    Map.insert_as(Result, HashKey);
+
+    return Result;
+  }
+
+public:
+  /// Return the specified constant from the map, creating it if necessary.
+  ConstantClass *getOrCreate(TypeClass *Ty, ValType V) {
+    LookupKey Key(Ty, V);
+    /// Hash once, and reuse it for the lookup and the insertion if needed.
+    LookupKeyHashed Lookup(MapInfo::getHashValue(Key), Key);
+
+    ConstantClass *Result = nullptr;
+
+    auto I = Map.find_as(Lookup);
+    if (I == Map.end())
+      Result = create(Ty, V, Lookup);
+    else
+      Result = *I;
+    assert(Result && "Unexpected nullptr");
+
+    return Result;
+  }
+
+  /// Remove this constant from the map
+  void remove(ConstantClass *CP) {
+    typename MapTy::iterator I = Map.find(CP);
+    assert(I != Map.end() && "Constant not found in constant table!");
+    assert(*I == CP && "Didn't find correct element?");
+    Map.erase(I);
+  }
+
+  ConstantClass *replaceOperandsInPlace(ArrayRef<Constant *> Operands,
+                                        ConstantClass *CP, Value *From,
+                                        Constant *To, unsigned NumUpdated = 0,
+                                        unsigned OperandNo = ~0u) {
+    LookupKey Key(CP->getType(), ValType(Operands, CP));
+    /// Hash once, and reuse it for the lookup and the insertion if needed.
+    LookupKeyHashed Lookup(MapInfo::getHashValue(Key), Key);
+
+    auto ItMap = Map.find_as(Lookup);
+    if (ItMap != Map.end())
+      return *ItMap;
+
+    // Update to the new value.  Optimize for the case when we have a single
+    // operand that we're changing, but handle bulk updates efficiently.
+    remove(CP);
+    if (NumUpdated == 1) {
+      assert(OperandNo < CP->getNumOperands() && "Invalid index");
+      assert(CP->getOperand(OperandNo) != To && "I didn't contain From!");
+      CP->setOperand(OperandNo, To);
+    } else {
+      for (unsigned I = 0, E = CP->getNumOperands(); I != E; ++I)
+        if (CP->getOperand(I) == From)
+          CP->setOperand(I, To);
+    }
+    Map.insert_as(CP, Lookup);
+    return nullptr;
+  }
+
+  void dump() const {
+    LLVM_DEBUG(dbgs() << "Constant.cpp: ConstantUniqueMap\n");
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_LIB_IR_CONSTANTSCONTEXT_H