//===-- Constants.cpp - Implement Constant nodes --------------------------===// // // The LLVM Compiler Infrastructure // // This file was developed by the LLVM research group and is distributed under // the University of Illinois Open Source License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the Constant* classes... // //===----------------------------------------------------------------------===// #include "llvm/Constants.h" #include "ConstantFold.h" #include "llvm/DerivedTypes.h" #include "llvm/GlobalValue.h" #include "llvm/Instructions.h" #include "llvm/Module.h" #include "llvm/ADT/StringExtras.h" #include "llvm/Support/Compiler.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ManagedStatic.h" #include "llvm/Support/MathExtras.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/SmallVector.h" #include #include using namespace llvm; //===----------------------------------------------------------------------===// // Constant Class //===----------------------------------------------------------------------===// void Constant::destroyConstantImpl() { // When a Constant is destroyed, there may be lingering // references to the constant by other constants in the constant pool. These // constants are implicitly dependent on the module that is being deleted, // but they don't know that. Because we only find out when the CPV is // deleted, we must now notify all of our users (that should only be // Constants) that they are, in fact, invalid now and should be deleted. // while (!use_empty()) { Value *V = use_back(); #ifndef NDEBUG // Only in -g mode... if (!isa(V)) DOUT << "While deleting: " << *this << "\n\nUse still stuck around after Def is destroyed: " << *V << "\n\n"; #endif assert(isa(V) && "References remain to Constant being destroyed"); Constant *CV = cast(V); CV->destroyConstant(); // The constant should remove itself from our use list... assert((use_empty() || use_back() != V) && "Constant not removed!"); } // Value has no outstanding references it is safe to delete it now... delete this; } /// canTrap - Return true if evaluation of this constant could trap. This is /// true for things like constant expressions that could divide by zero. bool Constant::canTrap() const { assert(getType()->isFirstClassType() && "Cannot evaluate aggregate vals!"); // The only thing that could possibly trap are constant exprs. const ConstantExpr *CE = dyn_cast(this); if (!CE) return false; // ConstantExpr traps if any operands can trap. for (unsigned i = 0, e = getNumOperands(); i != e; ++i) if (getOperand(i)->canTrap()) return true; // Otherwise, only specific operations can trap. switch (CE->getOpcode()) { default: return false; case Instruction::UDiv: case Instruction::SDiv: case Instruction::FDiv: case Instruction::URem: case Instruction::SRem: case Instruction::FRem: // Div and rem can trap if the RHS is not known to be non-zero. if (!isa(getOperand(1)) || getOperand(1)->isNullValue()) return true; return false; } } // Static constructor to create a '0' constant of arbitrary type... Constant *Constant::getNullValue(const Type *Ty) { switch (Ty->getTypeID()) { case Type::IntegerTyID: return ConstantInt::get(Ty, 0); case Type::FloatTyID: case Type::DoubleTyID: return ConstantFP::get(Ty, 0.0); case Type::PointerTyID: return ConstantPointerNull::get(cast(Ty)); case Type::StructTyID: case Type::ArrayTyID: case Type::VectorTyID: return ConstantAggregateZero::get(Ty); default: // Function, Label, or Opaque type? assert(!"Cannot create a null constant of that type!"); return 0; } } // Static constructor to create an integral constant with all bits set ConstantInt *ConstantInt::getAllOnesValue(const Type *Ty) { if (const IntegerType* ITy = dyn_cast(Ty)) return ConstantInt::get(APInt::getAllOnesValue(ITy->getBitWidth())); return 0; } /// @returns the value for an packed integer constant of the given type that /// has all its bits set to true. /// @brief Get the all ones value ConstantVector *ConstantVector::getAllOnesValue(const VectorType *Ty) { std::vector Elts; Elts.resize(Ty->getNumElements(), ConstantInt::getAllOnesValue(Ty->getElementType())); assert(Elts[0] && "Not a packed integer type!"); return cast(ConstantVector::get(Elts)); } //===----------------------------------------------------------------------===// // ConstantInt //===----------------------------------------------------------------------===// ConstantInt::ConstantInt(const IntegerType *Ty, const APInt& V) : Constant(Ty, ConstantIntVal, 0, 0), Val(V) { assert(V.getBitWidth() == Ty->getBitWidth() && "Invalid constant for type"); } ConstantInt *ConstantInt::TheTrueVal = 0; ConstantInt *ConstantInt::TheFalseVal = 0; namespace llvm { void CleanupTrueFalse(void *) { ConstantInt::ResetTrueFalse(); } } static ManagedCleanup TrueFalseCleanup; ConstantInt *ConstantInt::CreateTrueFalseVals(bool WhichOne) { assert(TheTrueVal == 0 && TheFalseVal == 0); TheTrueVal = get(Type::Int1Ty, 1); TheFalseVal = get(Type::Int1Ty, 0); // Ensure that llvm_shutdown nulls out TheTrueVal/TheFalseVal. TrueFalseCleanup.Register(); return WhichOne ? TheTrueVal : TheFalseVal; } namespace { struct DenseMapAPIntKeyInfo { struct KeyTy { APInt val; const Type* type; KeyTy(const APInt& V, const Type* Ty) : val(V), type(Ty) {} KeyTy(const KeyTy& that) : val(that.val), type(that.type) {} bool operator==(const KeyTy& that) const { return type == that.type && this->val == that.val; } bool operator!=(const KeyTy& that) const { return !this->operator==(that); } }; static inline KeyTy getEmptyKey() { return KeyTy(APInt(1,0), 0); } static inline KeyTy getTombstoneKey() { return KeyTy(APInt(1,1), 0); } static unsigned getHashValue(const KeyTy &Key) { return DenseMapKeyInfo::getHashValue(Key.type) ^ Key.val.getHashValue(); } static bool isPod() { return true; } }; } typedef DenseMap IntMapTy; static ManagedStatic IntConstants; ConstantInt *ConstantInt::get(const Type *Ty, uint64_t V) { const IntegerType *ITy = cast(Ty); return get(APInt(ITy->getBitWidth(), V)); } // Get a ConstantInt from an APInt. Note that the value stored in the DenseMap // as the key, is a DensMapAPIntKeyInfo::KeyTy which has provided the // operator== and operator!= to ensure that the DenseMap doesn't attempt to // compare APInt's of different widths, which would violate an APInt class // invariant which generates an assertion. ConstantInt *ConstantInt::get(const APInt& V) { // Get the corresponding integer type for the bit width of the value. const IntegerType *ITy = IntegerType::get(V.getBitWidth()); // get an existing value or the insertion position DenseMapAPIntKeyInfo::KeyTy Key(V, ITy); ConstantInt *&Slot = (*IntConstants)[Key]; // if it exists, return it. if (Slot) return Slot; // otherwise create a new one, insert it, and return it. return Slot = new ConstantInt(ITy, V); } //===----------------------------------------------------------------------===// // ConstantFP //===----------------------------------------------------------------------===// ConstantFP::ConstantFP(const Type *Ty, double V) : Constant(Ty, ConstantFPVal, 0, 0) { Val = V; } bool ConstantFP::isNullValue() const { return DoubleToBits(Val) == 0; } bool ConstantFP::isExactlyValue(double V) const { return DoubleToBits(V) == DoubleToBits(Val); } namespace { struct DenseMapInt64KeyInfo { typedef std::pair KeyTy; static inline KeyTy getEmptyKey() { return KeyTy(0, 0); } static inline KeyTy getTombstoneKey() { return KeyTy(1, 0); } static unsigned getHashValue(const KeyTy &Key) { return DenseMapKeyInfo::getHashValue(Key.second) ^ Key.first; } static bool isPod() { return true; } }; struct DenseMapInt32KeyInfo { typedef std::pair KeyTy; static inline KeyTy getEmptyKey() { return KeyTy(0, 0); } static inline KeyTy getTombstoneKey() { return KeyTy(1, 0); } static unsigned getHashValue(const KeyTy &Key) { return DenseMapKeyInfo::getHashValue(Key.second) ^ Key.first; } static bool isPod() { return true; } }; } //---- ConstantFP::get() implementation... // typedef DenseMap FloatMapTy; typedef DenseMap DoubleMapTy; static ManagedStatic FloatConstants; static ManagedStatic DoubleConstants; ConstantFP *ConstantFP::get(const Type *Ty, double V) { if (Ty == Type::FloatTy) { uint32_t IntVal = FloatToBits((float)V); ConstantFP *&Slot = (*FloatConstants)[std::make_pair(IntVal, Ty)]; if (Slot) return Slot; return Slot = new ConstantFP(Ty, (float)V); } else { assert(Ty == Type::DoubleTy); uint64_t IntVal = DoubleToBits(V); ConstantFP *&Slot = (*DoubleConstants)[std::make_pair(IntVal, Ty)]; if (Slot) return Slot; return Slot = new ConstantFP(Ty, V); } } //===----------------------------------------------------------------------===// // ConstantXXX Classes //===----------------------------------------------------------------------===// ConstantArray::ConstantArray(const ArrayType *T, const std::vector &V) : Constant(T, ConstantArrayVal, new Use[V.size()], V.size()) { assert(V.size() == T->getNumElements() && "Invalid initializer vector for constant array"); Use *OL = OperandList; for (std::vector::const_iterator I = V.begin(), E = V.end(); I != E; ++I, ++OL) { Constant *C = *I; assert((C->getType() == T->getElementType() || (T->isAbstract() && C->getType()->getTypeID() == T->getElementType()->getTypeID())) && "Initializer for array element doesn't match array element type!"); OL->init(C, this); } } ConstantArray::~ConstantArray() { delete [] OperandList; } ConstantStruct::ConstantStruct(const StructType *T, const std::vector &V) : Constant(T, ConstantStructVal, new Use[V.size()], V.size()) { assert(V.size() == T->getNumElements() && "Invalid initializer vector for constant structure"); Use *OL = OperandList; for (std::vector::const_iterator I = V.begin(), E = V.end(); I != E; ++I, ++OL) { Constant *C = *I; assert((C->getType() == T->getElementType(I-V.begin()) || ((T->getElementType(I-V.begin())->isAbstract() || C->getType()->isAbstract()) && T->getElementType(I-V.begin())->getTypeID() == C->getType()->getTypeID())) && "Initializer for struct element doesn't match struct element type!"); OL->init(C, this); } } ConstantStruct::~ConstantStruct() { delete [] OperandList; } ConstantVector::ConstantVector(const VectorType *T, const std::vector &V) : Constant(T, ConstantVectorVal, new Use[V.size()], V.size()) { Use *OL = OperandList; for (std::vector::const_iterator I = V.begin(), E = V.end(); I != E; ++I, ++OL) { Constant *C = *I; assert((C->getType() == T->getElementType() || (T->isAbstract() && C->getType()->getTypeID() == T->getElementType()->getTypeID())) && "Initializer for packed element doesn't match packed element type!"); OL->init(C, this); } } ConstantVector::~ConstantVector() { delete [] OperandList; } // We declare several classes private to this file, so use an anonymous // namespace namespace { /// UnaryConstantExpr - This class is private to Constants.cpp, and is used /// behind the scenes to implement unary constant exprs. class VISIBILITY_HIDDEN UnaryConstantExpr : public ConstantExpr { Use Op; public: UnaryConstantExpr(unsigned Opcode, Constant *C, const Type *Ty) : ConstantExpr(Ty, Opcode, &Op, 1), Op(C, this) {} }; /// BinaryConstantExpr - This class is private to Constants.cpp, and is used /// behind the scenes to implement binary constant exprs. class VISIBILITY_HIDDEN BinaryConstantExpr : public ConstantExpr { Use Ops[2]; public: BinaryConstantExpr(unsigned Opcode, Constant *C1, Constant *C2) : ConstantExpr(C1->getType(), Opcode, Ops, 2) { Ops[0].init(C1, this); Ops[1].init(C2, this); } }; /// SelectConstantExpr - This class is private to Constants.cpp, and is used /// behind the scenes to implement select constant exprs. class VISIBILITY_HIDDEN SelectConstantExpr : public ConstantExpr { Use Ops[3]; public: SelectConstantExpr(Constant *C1, Constant *C2, Constant *C3) : ConstantExpr(C2->getType(), Instruction::Select, Ops, 3) { Ops[0].init(C1, this); Ops[1].init(C2, this); Ops[2].init(C3, this); } }; /// ExtractElementConstantExpr - This class is private to /// Constants.cpp, and is used behind the scenes to implement /// extractelement constant exprs. class VISIBILITY_HIDDEN ExtractElementConstantExpr : public ConstantExpr { Use Ops[2]; public: ExtractElementConstantExpr(Constant *C1, Constant *C2) : ConstantExpr(cast(C1->getType())->getElementType(), Instruction::ExtractElement, Ops, 2) { Ops[0].init(C1, this); Ops[1].init(C2, this); } }; /// InsertElementConstantExpr - This class is private to /// Constants.cpp, and is used behind the scenes to implement /// insertelement constant exprs. class VISIBILITY_HIDDEN InsertElementConstantExpr : public ConstantExpr { Use Ops[3]; public: InsertElementConstantExpr(Constant *C1, Constant *C2, Constant *C3) : ConstantExpr(C1->getType(), Instruction::InsertElement, Ops, 3) { Ops[0].init(C1, this); Ops[1].init(C2, this); Ops[2].init(C3, this); } }; /// ShuffleVectorConstantExpr - This class is private to /// Constants.cpp, and is used behind the scenes to implement /// shufflevector constant exprs. class VISIBILITY_HIDDEN ShuffleVectorConstantExpr : public ConstantExpr { Use Ops[3]; public: ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3) : ConstantExpr(C1->getType(), Instruction::ShuffleVector, Ops, 3) { Ops[0].init(C1, this); Ops[1].init(C2, this); Ops[2].init(C3, this); } }; /// GetElementPtrConstantExpr - This class is private to Constants.cpp, and is /// used behind the scenes to implement getelementpr constant exprs. struct VISIBILITY_HIDDEN GetElementPtrConstantExpr : public ConstantExpr { GetElementPtrConstantExpr(Constant *C, const std::vector &IdxList, const Type *DestTy) : ConstantExpr(DestTy, Instruction::GetElementPtr, new Use[IdxList.size()+1], IdxList.size()+1) { OperandList[0].init(C, this); for (unsigned i = 0, E = IdxList.size(); i != E; ++i) OperandList[i+1].init(IdxList[i], this); } ~GetElementPtrConstantExpr() { delete [] OperandList; } }; // 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. struct VISIBILITY_HIDDEN CompareConstantExpr : public ConstantExpr { unsigned short predicate; Use Ops[2]; CompareConstantExpr(Instruction::OtherOps opc, unsigned short pred, Constant* LHS, Constant* RHS) : ConstantExpr(Type::Int1Ty, opc, Ops, 2), predicate(pred) { OperandList[0].init(LHS, this); OperandList[1].init(RHS, this); } }; } // end anonymous namespace // Utility function for determining if a ConstantExpr is a CastOp or not. This // can't be inline because we don't want to #include Instruction.h into // Constant.h bool ConstantExpr::isCast() const { return Instruction::isCast(getOpcode()); } bool ConstantExpr::isCompare() const { return getOpcode() == Instruction::ICmp || getOpcode() == Instruction::FCmp; } /// ConstantExpr::get* - Return some common constants without having to /// specify the full Instruction::OPCODE identifier. /// Constant *ConstantExpr::getNeg(Constant *C) { return get(Instruction::Sub, ConstantExpr::getZeroValueForNegationExpr(C->getType()), C); } Constant *ConstantExpr::getNot(Constant *C) { assert(isa(C) && "Cannot NOT a nonintegral type!"); return get(Instruction::Xor, C, ConstantInt::getAllOnesValue(C->getType())); } Constant *ConstantExpr::getAdd(Constant *C1, Constant *C2) { return get(Instruction::Add, C1, C2); } Constant *ConstantExpr::getSub(Constant *C1, Constant *C2) { return get(Instruction::Sub, C1, C2); } Constant *ConstantExpr::getMul(Constant *C1, Constant *C2) { return get(Instruction::Mul, C1, C2); } Constant *ConstantExpr::getUDiv(Constant *C1, Constant *C2) { return get(Instruction::UDiv, C1, C2); } Constant *ConstantExpr::getSDiv(Constant *C1, Constant *C2) { return get(Instruction::SDiv, C1, C2); } Constant *ConstantExpr::getFDiv(Constant *C1, Constant *C2) { return get(Instruction::FDiv, C1, C2); } Constant *ConstantExpr::getURem(Constant *C1, Constant *C2) { return get(Instruction::URem, C1, C2); } Constant *ConstantExpr::getSRem(Constant *C1, Constant *C2) { return get(Instruction::SRem, C1, C2); } Constant *ConstantExpr::getFRem(Constant *C1, Constant *C2) { return get(Instruction::FRem, C1, C2); } Constant *ConstantExpr::getAnd(Constant *C1, Constant *C2) { return get(Instruction::And, C1, C2); } Constant *ConstantExpr::getOr(Constant *C1, Constant *C2) { return get(Instruction::Or, C1, C2); } Constant *ConstantExpr::getXor(Constant *C1, Constant *C2) { return get(Instruction::Xor, C1, C2); } unsigned ConstantExpr::getPredicate() const { assert(getOpcode() == Instruction::FCmp || getOpcode() == Instruction::ICmp); return dynamic_cast(this)->predicate; } Constant *ConstantExpr::getShl(Constant *C1, Constant *C2) { return get(Instruction::Shl, C1, C2); } Constant *ConstantExpr::getLShr(Constant *C1, Constant *C2) { return get(Instruction::LShr, C1, C2); } Constant *ConstantExpr::getAShr(Constant *C1, Constant *C2) { return get(Instruction::AShr, C1, C2); } /// getWithOperandReplaced - Return a constant expression identical to this /// one, but with the specified operand set to the specified value. Constant * ConstantExpr::getWithOperandReplaced(unsigned OpNo, Constant *Op) const { assert(OpNo < getNumOperands() && "Operand num is out of range!"); assert(Op->getType() == getOperand(OpNo)->getType() && "Replacing operand with value of different type!"); if (getOperand(OpNo) == Op) return const_cast(this); Constant *Op0, *Op1, *Op2; switch (getOpcode()) { case Instruction::Trunc: case Instruction::ZExt: case Instruction::SExt: case Instruction::FPTrunc: case Instruction::FPExt: case Instruction::UIToFP: case Instruction::SIToFP: case Instruction::FPToUI: case Instruction::FPToSI: case Instruction::PtrToInt: case Instruction::IntToPtr: case Instruction::BitCast: return ConstantExpr::getCast(getOpcode(), Op, getType()); case Instruction::Select: Op0 = (OpNo == 0) ? Op : getOperand(0); Op1 = (OpNo == 1) ? Op : getOperand(1); Op2 = (OpNo == 2) ? Op : getOperand(2); return ConstantExpr::getSelect(Op0, Op1, Op2); case Instruction::InsertElement: Op0 = (OpNo == 0) ? Op : getOperand(0); Op1 = (OpNo == 1) ? Op : getOperand(1); Op2 = (OpNo == 2) ? Op : getOperand(2); return ConstantExpr::getInsertElement(Op0, Op1, Op2); case Instruction::ExtractElement: Op0 = (OpNo == 0) ? Op : getOperand(0); Op1 = (OpNo == 1) ? Op : getOperand(1); return ConstantExpr::getExtractElement(Op0, Op1); case Instruction::ShuffleVector: Op0 = (OpNo == 0) ? Op : getOperand(0); Op1 = (OpNo == 1) ? Op : getOperand(1); Op2 = (OpNo == 2) ? Op : getOperand(2); return ConstantExpr::getShuffleVector(Op0, Op1, Op2); case Instruction::GetElementPtr: { SmallVector Ops; Ops.resize(getNumOperands()); for (unsigned i = 1, e = getNumOperands(); i != e; ++i) Ops[i] = getOperand(i); if (OpNo == 0) return ConstantExpr::getGetElementPtr(Op, &Ops[0], Ops.size()); Ops[OpNo-1] = Op; return ConstantExpr::getGetElementPtr(getOperand(0), &Ops[0], Ops.size()); } default: assert(getNumOperands() == 2 && "Must be binary operator?"); Op0 = (OpNo == 0) ? Op : getOperand(0); Op1 = (OpNo == 1) ? Op : getOperand(1); return ConstantExpr::get(getOpcode(), Op0, Op1); } } /// getWithOperands - This returns the current constant expression with the /// operands replaced with the specified values. The specified operands must /// match count and type with the existing ones. Constant *ConstantExpr:: getWithOperands(const std::vector &Ops) const { assert(Ops.size() == getNumOperands() && "Operand count mismatch!"); bool AnyChange = false; for (unsigned i = 0, e = Ops.size(); i != e; ++i) { assert(Ops[i]->getType() == getOperand(i)->getType() && "Operand type mismatch!"); AnyChange |= Ops[i] != getOperand(i); } if (!AnyChange) // No operands changed, return self. return const_cast(this); switch (getOpcode()) { case Instruction::Trunc: case Instruction::ZExt: case Instruction::SExt: case Instruction::FPTrunc: case Instruction::FPExt: case Instruction::UIToFP: case Instruction::SIToFP: case Instruction::FPToUI: case Instruction::FPToSI: case Instruction::PtrToInt: case Instruction::IntToPtr: case Instruction::BitCast: return ConstantExpr::getCast(getOpcode(), Ops[0], getType()); case Instruction::Select: return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]); case Instruction::InsertElement: return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]); case Instruction::ExtractElement: return ConstantExpr::getExtractElement(Ops[0], Ops[1]); case Instruction::ShuffleVector: return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]); case Instruction::GetElementPtr: return ConstantExpr::getGetElementPtr(Ops[0], &Ops[1], Ops.size()-1); case Instruction::ICmp: case Instruction::FCmp: return ConstantExpr::getCompare(getPredicate(), Ops[0], Ops[1]); default: assert(getNumOperands() == 2 && "Must be binary operator?"); return ConstantExpr::get(getOpcode(), Ops[0], Ops[1]); } } //===----------------------------------------------------------------------===// // isValueValidForType implementations bool ConstantInt::isValueValidForType(const Type *Ty, uint64_t Val) { unsigned NumBits = cast(Ty)->getBitWidth(); // assert okay if (Ty == Type::Int1Ty) return Val == 0 || Val == 1; if (NumBits >= 64) return true; // always true, has to fit in largest type uint64_t Max = (1ll << NumBits) - 1; return Val <= Max; } bool ConstantInt::isValueValidForType(const Type *Ty, int64_t Val) { unsigned NumBits = cast(Ty)->getBitWidth(); // assert okay if (Ty == Type::Int1Ty) return Val == 0 || Val == 1 || Val == -1; if (NumBits >= 64) return true; // always true, has to fit in largest type int64_t Min = -(1ll << (NumBits-1)); int64_t Max = (1ll << (NumBits-1)) - 1; return (Val >= Min && Val <= Max); } bool ConstantFP::isValueValidForType(const Type *Ty, double Val) { switch (Ty->getTypeID()) { default: return false; // These can't be represented as floating point! // TODO: Figure out how to test if a double can be cast to a float! case Type::FloatTyID: case Type::DoubleTyID: return true; // This is the largest type... } } //===----------------------------------------------------------------------===// // Factory Function Implementation // ConstantCreator - A class that is used to create constants by // ValueMap*. This class should be partially specialized if there is // something strange that needs to be done to interface to the ctor for the // constant. // namespace llvm { template struct VISIBILITY_HIDDEN ConstantCreator { static ConstantClass *create(const TypeClass *Ty, const ValType &V) { return new ConstantClass(Ty, V); } }; template struct VISIBILITY_HIDDEN ConvertConstantType { static void convert(ConstantClass *OldC, const TypeClass *NewTy) { assert(0 && "This type cannot be converted!\n"); abort(); } }; template class VISIBILITY_HIDDEN ValueMap : public AbstractTypeUser { public: typedef std::pair MapKey; typedef std::map MapTy; typedef std::map InverseMapTy; typedef std::map AbstractTypeMapTy; private: /// Map - This is the main map from the element descriptor to the Constants. /// This is the primary way we avoid creating two of the same shape /// constant. MapTy Map; /// InverseMap - If "HasLargeKey" is true, this contains an inverse mapping /// from the constants to their element in Map. This is important for /// removal of constants from the array, which would otherwise have to scan /// through the map with very large keys. InverseMapTy InverseMap; /// AbstractTypeMap - Map for abstract type constants. /// AbstractTypeMapTy AbstractTypeMap; public: typename MapTy::iterator map_end() { return Map.end(); } /// InsertOrGetItem - Return an iterator for the specified element. /// If the element exists in the map, the returned iterator points to the /// entry and Exists=true. If not, the iterator points to the newly /// inserted entry and returns Exists=false. Newly inserted entries have /// I->second == 0, and should be filled in. typename MapTy::iterator InsertOrGetItem(std::pair &InsertVal, bool &Exists) { std::pair IP = Map.insert(InsertVal); Exists = !IP.second; return IP.first; } private: typename MapTy::iterator FindExistingElement(ConstantClass *CP) { if (HasLargeKey) { typename InverseMapTy::iterator IMI = InverseMap.find(CP); assert(IMI != InverseMap.end() && IMI->second != Map.end() && IMI->second->second == CP && "InverseMap corrupt!"); return IMI->second; } typename MapTy::iterator I = Map.find(MapKey((TypeClass*)CP->getRawType(), getValType(CP))); if (I == Map.end() || I->second != CP) { // FIXME: This should not use a linear scan. If this gets to be a // performance problem, someone should look at this. for (I = Map.begin(); I != Map.end() && I->second != CP; ++I) /* empty */; } return I; } public: /// getOrCreate - Return the specified constant from the map, creating it if /// necessary. ConstantClass *getOrCreate(const TypeClass *Ty, const ValType &V) { MapKey Lookup(Ty, V); typename MapTy::iterator I = Map.lower_bound(Lookup); // Is it in the map? if (I != Map.end() && I->first == Lookup) return static_cast(I->second); // If no preexisting value, create one now... ConstantClass *Result = ConstantCreator::create(Ty, V); /// FIXME: why does this assert fail when loading 176.gcc? //assert(Result->getType() == Ty && "Type specified is not correct!"); I = Map.insert(I, std::make_pair(MapKey(Ty, V), Result)); if (HasLargeKey) // Remember the reverse mapping if needed. InverseMap.insert(std::make_pair(Result, I)); // If the type of the constant is abstract, make sure that an entry exists // for it in the AbstractTypeMap. if (Ty->isAbstract()) { typename AbstractTypeMapTy::iterator TI = AbstractTypeMap.lower_bound(Ty); if (TI == AbstractTypeMap.end() || TI->first != Ty) { // Add ourselves to the ATU list of the type. cast(Ty)->addAbstractTypeUser(this); AbstractTypeMap.insert(TI, std::make_pair(Ty, I)); } } return Result; } void remove(ConstantClass *CP) { typename MapTy::iterator I = FindExistingElement(CP); assert(I != Map.end() && "Constant not found in constant table!"); assert(I->second == CP && "Didn't find correct element?"); if (HasLargeKey) // Remember the reverse mapping if needed. InverseMap.erase(CP); // Now that we found the entry, make sure this isn't the entry that // the AbstractTypeMap points to. const TypeClass *Ty = static_cast(I->first.first); if (Ty->isAbstract()) { assert(AbstractTypeMap.count(Ty) && "Abstract type not in AbstractTypeMap?"); typename MapTy::iterator &ATMEntryIt = AbstractTypeMap[Ty]; if (ATMEntryIt == I) { // Yes, we are removing the representative entry for this type. // See if there are any other entries of the same type. typename MapTy::iterator TmpIt = ATMEntryIt; // First check the entry before this one... if (TmpIt != Map.begin()) { --TmpIt; if (TmpIt->first.first != Ty) // Not the same type, move back... ++TmpIt; } // If we didn't find the same type, try to move forward... if (TmpIt == ATMEntryIt) { ++TmpIt; if (TmpIt == Map.end() || TmpIt->first.first != Ty) --TmpIt; // No entry afterwards with the same type } // If there is another entry in the map of the same abstract type, // update the AbstractTypeMap entry now. if (TmpIt != ATMEntryIt) { ATMEntryIt = TmpIt; } else { // Otherwise, we are removing the last instance of this type // from the table. Remove from the ATM, and from user list. cast(Ty)->removeAbstractTypeUser(this); AbstractTypeMap.erase(Ty); } } } Map.erase(I); } /// MoveConstantToNewSlot - If we are about to change C to be the element /// specified by I, update our internal data structures to reflect this /// fact. void MoveConstantToNewSlot(ConstantClass *C, typename MapTy::iterator I) { // First, remove the old location of the specified constant in the map. typename MapTy::iterator OldI = FindExistingElement(C); assert(OldI != Map.end() && "Constant not found in constant table!"); assert(OldI->second == C && "Didn't find correct element?"); // If this constant is the representative element for its abstract type, // update the AbstractTypeMap so that the representative element is I. if (C->getType()->isAbstract()) { typename AbstractTypeMapTy::iterator ATI = AbstractTypeMap.find(C->getType()); assert(ATI != AbstractTypeMap.end() && "Abstract type not in AbstractTypeMap?"); if (ATI->second == OldI) ATI->second = I; } // Remove the old entry from the map. Map.erase(OldI); // Update the inverse map so that we know that this constant is now // located at descriptor I. if (HasLargeKey) { assert(I->second == C && "Bad inversemap entry!"); InverseMap[C] = I; } } void refineAbstractType(const DerivedType *OldTy, const Type *NewTy) { typename AbstractTypeMapTy::iterator I = AbstractTypeMap.find(cast(OldTy)); assert(I != AbstractTypeMap.end() && "Abstract type not in AbstractTypeMap?"); // Convert a constant at a time until the last one is gone. The last one // leaving will remove() itself, causing the AbstractTypeMapEntry to be // eliminated eventually. do { ConvertConstantType::convert( static_cast(I->second->second), cast(NewTy)); I = AbstractTypeMap.find(cast(OldTy)); } while (I != AbstractTypeMap.end()); } // If the type became concrete without being refined to any other existing // type, we just remove ourselves from the ATU list. void typeBecameConcrete(const DerivedType *AbsTy) { AbsTy->removeAbstractTypeUser(this); } void dump() const { DOUT << "Constant.cpp: ValueMap\n"; } }; } //---- ConstantAggregateZero::get() implementation... // namespace llvm { // ConstantAggregateZero does not take extra "value" argument... template struct ConstantCreator { static ConstantAggregateZero *create(const Type *Ty, const ValType &V){ return new ConstantAggregateZero(Ty); } }; template<> struct ConvertConstantType { static void convert(ConstantAggregateZero *OldC, const Type *NewTy) { // Make everyone now use a constant of the new type... Constant *New = ConstantAggregateZero::get(NewTy); assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } static ManagedStatic > AggZeroConstants; static char getValType(ConstantAggregateZero *CPZ) { return 0; } Constant *ConstantAggregateZero::get(const Type *Ty) { assert((isa(Ty) || isa(Ty) || isa(Ty)) && "Cannot create an aggregate zero of non-aggregate type!"); return AggZeroConstants->getOrCreate(Ty, 0); } // destroyConstant - Remove the constant from the constant table... // void ConstantAggregateZero::destroyConstant() { AggZeroConstants->remove(this); destroyConstantImpl(); } //---- ConstantArray::get() implementation... // namespace llvm { template<> struct ConvertConstantType { static void convert(ConstantArray *OldC, const ArrayType *NewTy) { // Make everyone now use a constant of the new type... std::vector C; for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i) C.push_back(cast(OldC->getOperand(i))); Constant *New = ConstantArray::get(NewTy, C); assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } static std::vector getValType(ConstantArray *CA) { std::vector Elements; Elements.reserve(CA->getNumOperands()); for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) Elements.push_back(cast(CA->getOperand(i))); return Elements; } typedef ValueMap, ArrayType, ConstantArray, true /*largekey*/> ArrayConstantsTy; static ManagedStatic ArrayConstants; Constant *ConstantArray::get(const ArrayType *Ty, const std::vector &V) { // If this is an all-zero array, return a ConstantAggregateZero object if (!V.empty()) { Constant *C = V[0]; if (!C->isNullValue()) return ArrayConstants->getOrCreate(Ty, V); for (unsigned i = 1, e = V.size(); i != e; ++i) if (V[i] != C) return ArrayConstants->getOrCreate(Ty, V); } return ConstantAggregateZero::get(Ty); } // destroyConstant - Remove the constant from the constant table... // void ConstantArray::destroyConstant() { ArrayConstants->remove(this); destroyConstantImpl(); } /// ConstantArray::get(const string&) - Return an array that is initialized to /// contain the specified string. If length is zero then a null terminator is /// added to the specified string so that it may be used in a natural way. /// Otherwise, the length parameter specifies how much of the string to use /// and it won't be null terminated. /// Constant *ConstantArray::get(const std::string &Str, bool AddNull) { std::vector ElementVals; for (unsigned i = 0; i < Str.length(); ++i) ElementVals.push_back(ConstantInt::get(Type::Int8Ty, Str[i])); // Add a null terminator to the string... if (AddNull) { ElementVals.push_back(ConstantInt::get(Type::Int8Ty, 0)); } ArrayType *ATy = ArrayType::get(Type::Int8Ty, ElementVals.size()); return ConstantArray::get(ATy, ElementVals); } /// isString - This method returns true if the array is an array of i8, and /// if the elements of the array are all ConstantInt's. bool ConstantArray::isString() const { // Check the element type for i8... if (getType()->getElementType() != Type::Int8Ty) return false; // Check the elements to make sure they are all integers, not constant // expressions. for (unsigned i = 0, e = getNumOperands(); i != e; ++i) if (!isa(getOperand(i))) return false; return true; } /// isCString - This method returns true if the array is a string (see /// isString) and it ends in a null byte \0 and does not contains any other /// null bytes except its terminator. bool ConstantArray::isCString() const { // Check the element type for i8... if (getType()->getElementType() != Type::Int8Ty) return false; Constant *Zero = Constant::getNullValue(getOperand(0)->getType()); // Last element must be a null. if (getOperand(getNumOperands()-1) != Zero) return false; // Other elements must be non-null integers. for (unsigned i = 0, e = getNumOperands()-1; i != e; ++i) { if (!isa(getOperand(i))) return false; if (getOperand(i) == Zero) return false; } return true; } // getAsString - If the sub-element type of this array is i8 // then this method converts the array to an std::string and returns it. // Otherwise, it asserts out. // std::string ConstantArray::getAsString() const { assert(isString() && "Not a string!"); std::string Result; for (unsigned i = 0, e = getNumOperands(); i != e; ++i) Result += (char)cast(getOperand(i))->getZExtValue(); return Result; } //---- ConstantStruct::get() implementation... // namespace llvm { template<> struct ConvertConstantType { static void convert(ConstantStruct *OldC, const StructType *NewTy) { // Make everyone now use a constant of the new type... std::vector C; for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i) C.push_back(cast(OldC->getOperand(i))); Constant *New = ConstantStruct::get(NewTy, C); assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } typedef ValueMap, StructType, ConstantStruct, true /*largekey*/> StructConstantsTy; static ManagedStatic StructConstants; static std::vector getValType(ConstantStruct *CS) { std::vector Elements; Elements.reserve(CS->getNumOperands()); for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) Elements.push_back(cast(CS->getOperand(i))); return Elements; } Constant *ConstantStruct::get(const StructType *Ty, const std::vector &V) { // Create a ConstantAggregateZero value if all elements are zeros... for (unsigned i = 0, e = V.size(); i != e; ++i) if (!V[i]->isNullValue()) return StructConstants->getOrCreate(Ty, V); return ConstantAggregateZero::get(Ty); } Constant *ConstantStruct::get(const std::vector &V, bool packed) { std::vector StructEls; StructEls.reserve(V.size()); for (unsigned i = 0, e = V.size(); i != e; ++i) StructEls.push_back(V[i]->getType()); return get(StructType::get(StructEls, packed), V); } // destroyConstant - Remove the constant from the constant table... // void ConstantStruct::destroyConstant() { StructConstants->remove(this); destroyConstantImpl(); } //---- ConstantVector::get() implementation... // namespace llvm { template<> struct ConvertConstantType { static void convert(ConstantVector *OldC, const VectorType *NewTy) { // Make everyone now use a constant of the new type... std::vector C; for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i) C.push_back(cast(OldC->getOperand(i))); Constant *New = ConstantVector::get(NewTy, C); assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } static std::vector getValType(ConstantVector *CP) { std::vector Elements; Elements.reserve(CP->getNumOperands()); for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) Elements.push_back(CP->getOperand(i)); return Elements; } static ManagedStatic, VectorType, ConstantVector> > VectorConstants; Constant *ConstantVector::get(const VectorType *Ty, const std::vector &V) { // If this is an all-zero packed, return a ConstantAggregateZero object if (!V.empty()) { Constant *C = V[0]; if (!C->isNullValue()) return VectorConstants->getOrCreate(Ty, V); for (unsigned i = 1, e = V.size(); i != e; ++i) if (V[i] != C) return VectorConstants->getOrCreate(Ty, V); } return ConstantAggregateZero::get(Ty); } Constant *ConstantVector::get(const std::vector &V) { assert(!V.empty() && "Cannot infer type if V is empty"); return get(VectorType::get(V.front()->getType(),V.size()), V); } // destroyConstant - Remove the constant from the constant table... // void ConstantVector::destroyConstant() { VectorConstants->remove(this); destroyConstantImpl(); } /// This function will return true iff every element in this packed constant /// is set to all ones. /// @returns true iff this constant's emements are all set to all ones. /// @brief Determine if the value is all ones. bool ConstantVector::isAllOnesValue() const { // Check out first element. const Constant *Elt = getOperand(0); const ConstantInt *CI = dyn_cast(Elt); if (!CI || !CI->isAllOnesValue()) return false; // Then make sure all remaining elements point to the same value. for (unsigned I = 1, E = getNumOperands(); I < E; ++I) { if (getOperand(I) != Elt) return false; } return true; } //---- ConstantPointerNull::get() implementation... // namespace llvm { // ConstantPointerNull does not take extra "value" argument... template struct ConstantCreator { static ConstantPointerNull *create(const PointerType *Ty, const ValType &V){ return new ConstantPointerNull(Ty); } }; template<> struct ConvertConstantType { static void convert(ConstantPointerNull *OldC, const PointerType *NewTy) { // Make everyone now use a constant of the new type... Constant *New = ConstantPointerNull::get(NewTy); assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } static ManagedStatic > NullPtrConstants; static char getValType(ConstantPointerNull *) { return 0; } ConstantPointerNull *ConstantPointerNull::get(const PointerType *Ty) { return NullPtrConstants->getOrCreate(Ty, 0); } // destroyConstant - Remove the constant from the constant table... // void ConstantPointerNull::destroyConstant() { NullPtrConstants->remove(this); destroyConstantImpl(); } //---- UndefValue::get() implementation... // namespace llvm { // UndefValue does not take extra "value" argument... template struct ConstantCreator { static UndefValue *create(const Type *Ty, const ValType &V) { return new UndefValue(Ty); } }; template<> struct ConvertConstantType { static void convert(UndefValue *OldC, const Type *NewTy) { // Make everyone now use a constant of the new type. Constant *New = UndefValue::get(NewTy); assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } static ManagedStatic > UndefValueConstants; static char getValType(UndefValue *) { return 0; } UndefValue *UndefValue::get(const Type *Ty) { return UndefValueConstants->getOrCreate(Ty, 0); } // destroyConstant - Remove the constant from the constant table. // void UndefValue::destroyConstant() { UndefValueConstants->remove(this); destroyConstantImpl(); } //---- ConstantExpr::get() implementations... // struct ExprMapKeyType { explicit ExprMapKeyType(unsigned opc, std::vector ops, unsigned short pred = 0) : opcode(opc), predicate(pred), operands(ops) { } uint16_t opcode; uint16_t predicate; std::vector operands; bool operator==(const ExprMapKeyType& that) const { return this->opcode == that.opcode && this->predicate == that.predicate && this->operands == that.operands; } bool operator<(const ExprMapKeyType & that) const { return this->opcode < that.opcode || (this->opcode == that.opcode && this->predicate < that.predicate) || (this->opcode == that.opcode && this->predicate == that.predicate && this->operands < that.operands); } bool operator!=(const ExprMapKeyType& that) const { return !(*this == that); } }; namespace llvm { template<> struct ConstantCreator { static ConstantExpr *create(const Type *Ty, const ExprMapKeyType &V, unsigned short pred = 0) { if (Instruction::isCast(V.opcode)) return new UnaryConstantExpr(V.opcode, V.operands[0], Ty); if ((V.opcode >= Instruction::BinaryOpsBegin && V.opcode < Instruction::BinaryOpsEnd)) return new BinaryConstantExpr(V.opcode, V.operands[0], V.operands[1]); if (V.opcode == Instruction::Select) return new SelectConstantExpr(V.operands[0], V.operands[1], V.operands[2]); if (V.opcode == Instruction::ExtractElement) return new ExtractElementConstantExpr(V.operands[0], V.operands[1]); if (V.opcode == Instruction::InsertElement) return new InsertElementConstantExpr(V.operands[0], V.operands[1], V.operands[2]); if (V.opcode == Instruction::ShuffleVector) return new ShuffleVectorConstantExpr(V.operands[0], V.operands[1], V.operands[2]); if (V.opcode == Instruction::GetElementPtr) { std::vector IdxList(V.operands.begin()+1, V.operands.end()); return new GetElementPtrConstantExpr(V.operands[0], IdxList, Ty); } // The compare instructions are weird. We have to encode the predicate // value and it is combined with the instruction opcode by multiplying // the opcode by one hundred. We must decode this to get the predicate. if (V.opcode == Instruction::ICmp) return new CompareConstantExpr(Instruction::ICmp, V.predicate, V.operands[0], V.operands[1]); if (V.opcode == Instruction::FCmp) return new CompareConstantExpr(Instruction::FCmp, V.predicate, V.operands[0], V.operands[1]); assert(0 && "Invalid ConstantExpr!"); return 0; } }; template<> struct ConvertConstantType { static void convert(ConstantExpr *OldC, const Type *NewTy) { Constant *New; switch (OldC->getOpcode()) { case Instruction::Trunc: case Instruction::ZExt: case Instruction::SExt: case Instruction::FPTrunc: case Instruction::FPExt: case Instruction::UIToFP: case Instruction::SIToFP: case Instruction::FPToUI: case Instruction::FPToSI: case Instruction::PtrToInt: case Instruction::IntToPtr: case Instruction::BitCast: New = ConstantExpr::getCast(OldC->getOpcode(), OldC->getOperand(0), NewTy); break; case Instruction::Select: New = ConstantExpr::getSelectTy(NewTy, OldC->getOperand(0), OldC->getOperand(1), OldC->getOperand(2)); break; default: assert(OldC->getOpcode() >= Instruction::BinaryOpsBegin && OldC->getOpcode() < Instruction::BinaryOpsEnd); New = ConstantExpr::getTy(NewTy, OldC->getOpcode(), OldC->getOperand(0), OldC->getOperand(1)); break; case Instruction::GetElementPtr: // Make everyone now use a constant of the new type... std::vector Idx(OldC->op_begin()+1, OldC->op_end()); New = ConstantExpr::getGetElementPtrTy(NewTy, OldC->getOperand(0), &Idx[0], Idx.size()); break; } assert(New != OldC && "Didn't replace constant??"); OldC->uncheckedReplaceAllUsesWith(New); OldC->destroyConstant(); // This constant is now dead, destroy it. } }; } // end namespace llvm static ExprMapKeyType getValType(ConstantExpr *CE) { std::vector Operands; Operands.reserve(CE->getNumOperands()); for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) Operands.push_back(cast(CE->getOperand(i))); return ExprMapKeyType(CE->getOpcode(), Operands, CE->isCompare() ? CE->getPredicate() : 0); } static ManagedStatic > ExprConstants; /// This is a utility function to handle folding of casts and lookup of the /// cast in the ExprConstants map. It is usedby the various get* methods below. static inline Constant *getFoldedCast( Instruction::CastOps opc, Constant *C, const Type *Ty) { assert(Ty->isFirstClassType() && "Cannot cast to an aggregate type!"); // Fold a few common cases if (Constant *FC = ConstantFoldCastInstruction(opc, C, Ty)) return FC; // Look up the constant in the table first to ensure uniqueness std::vector argVec(1, C); ExprMapKeyType Key(opc, argVec); return ExprConstants->getOrCreate(Ty, Key); } Constant *ConstantExpr::getCast(unsigned oc, Constant *C, const Type *Ty) { Instruction::CastOps opc = Instruction::CastOps(oc); assert(Instruction::isCast(opc) && "opcode out of range"); assert(C && Ty && "Null arguments to getCast"); assert(Ty->isFirstClassType() && "Cannot cast to an aggregate type!"); switch (opc) { default: assert(0 && "Invalid cast opcode"); break; case Instruction::Trunc: return getTrunc(C, Ty); case Instruction::ZExt: return getZExt(C, Ty); case Instruction::SExt: return getSExt(C, Ty); case Instruction::FPTrunc: return getFPTrunc(C, Ty); case Instruction::FPExt: return getFPExtend(C, Ty); case Instruction::UIToFP: return getUIToFP(C, Ty); case Instruction::SIToFP: return getSIToFP(C, Ty); case Instruction::FPToUI: return getFPToUI(C, Ty); case Instruction::FPToSI: return getFPToSI(C, Ty); case Instruction::PtrToInt: return getPtrToInt(C, Ty); case Instruction::IntToPtr: return getIntToPtr(C, Ty); case Instruction::BitCast: return getBitCast(C, Ty); } return 0; } Constant *ConstantExpr::getZExtOrBitCast(Constant *C, const Type *Ty) { if (C->getType()->getPrimitiveSizeInBits() == Ty->getPrimitiveSizeInBits()) return getCast(Instruction::BitCast, C, Ty); return getCast(Instruction::ZExt, C, Ty); } Constant *ConstantExpr::getSExtOrBitCast(Constant *C, const Type *Ty) { if (C->getType()->getPrimitiveSizeInBits() == Ty->getPrimitiveSizeInBits()) return getCast(Instruction::BitCast, C, Ty); return getCast(Instruction::SExt, C, Ty); } Constant *ConstantExpr::getTruncOrBitCast(Constant *C, const Type *Ty) { if (C->getType()->getPrimitiveSizeInBits() == Ty->getPrimitiveSizeInBits()) return getCast(Instruction::BitCast, C, Ty); return getCast(Instruction::Trunc, C, Ty); } Constant *ConstantExpr::getPointerCast(Constant *S, const Type *Ty) { assert(isa(S->getType()) && "Invalid cast"); assert((Ty->isInteger() || isa(Ty)) && "Invalid cast"); if (Ty->isInteger()) return getCast(Instruction::PtrToInt, S, Ty); return getCast(Instruction::BitCast, S, Ty); } Constant *ConstantExpr::getIntegerCast(Constant *C, const Type *Ty, bool isSigned) { assert(C->getType()->isInteger() && Ty->isInteger() && "Invalid cast"); unsigned SrcBits = C->getType()->getPrimitiveSizeInBits(); unsigned DstBits = Ty->getPrimitiveSizeInBits(); Instruction::CastOps opcode = (SrcBits == DstBits ? Instruction::BitCast : (SrcBits > DstBits ? Instruction::Trunc : (isSigned ? Instruction::SExt : Instruction::ZExt))); return getCast(opcode, C, Ty); } Constant *ConstantExpr::getFPCast(Constant *C, const Type *Ty) { assert(C->getType()->isFloatingPoint() && Ty->isFloatingPoint() && "Invalid cast"); unsigned SrcBits = C->getType()->getPrimitiveSizeInBits(); unsigned DstBits = Ty->getPrimitiveSizeInBits(); if (SrcBits == DstBits) return C; // Avoid a useless cast Instruction::CastOps opcode = (SrcBits > DstBits ? Instruction::FPTrunc : Instruction::FPExt); return getCast(opcode, C, Ty); } Constant *ConstantExpr::getTrunc(Constant *C, const Type *Ty) { assert(C->getType()->isInteger() && "Trunc operand must be integer"); assert(Ty->isInteger() && "Trunc produces only integral"); assert(C->getType()->getPrimitiveSizeInBits() > Ty->getPrimitiveSizeInBits()&& "SrcTy must be larger than DestTy for Trunc!"); return getFoldedCast(Instruction::Trunc, C, Ty); } Constant *ConstantExpr::getSExt(Constant *C, const Type *Ty) { assert(C->getType()->isInteger() && "SEXt operand must be integral"); assert(Ty->isInteger() && "SExt produces only integer"); assert(C->getType()->getPrimitiveSizeInBits() < Ty->getPrimitiveSizeInBits()&& "SrcTy must be smaller than DestTy for SExt!"); return getFoldedCast(Instruction::SExt, C, Ty); } Constant *ConstantExpr::getZExt(Constant *C, const Type *Ty) { assert(C->getType()->isInteger() && "ZEXt operand must be integral"); assert(Ty->isInteger() && "ZExt produces only integer"); assert(C->getType()->getPrimitiveSizeInBits() < Ty->getPrimitiveSizeInBits()&& "SrcTy must be smaller than DestTy for ZExt!"); return getFoldedCast(Instruction::ZExt, C, Ty); } Constant *ConstantExpr::getFPTrunc(Constant *C, const Type *Ty) { assert(C->getType()->isFloatingPoint() && Ty->isFloatingPoint() && C->getType()->getPrimitiveSizeInBits() > Ty->getPrimitiveSizeInBits()&& "This is an illegal floating point truncation!"); return getFoldedCast(Instruction::FPTrunc, C, Ty); } Constant *ConstantExpr::getFPExtend(Constant *C, const Type *Ty) { assert(C->getType()->isFloatingPoint() && Ty->isFloatingPoint() && C->getType()->getPrimitiveSizeInBits() < Ty->getPrimitiveSizeInBits()&& "This is an illegal floating point extension!"); return getFoldedCast(Instruction::FPExt, C, Ty); } Constant *ConstantExpr::getUIToFP(Constant *C, const Type *Ty) { assert(C->getType()->isInteger() && Ty->isFloatingPoint() && "This is an illegal i32 to floating point cast!"); return getFoldedCast(Instruction::UIToFP, C, Ty); } Constant *ConstantExpr::getSIToFP(Constant *C, const Type *Ty) { assert(C->getType()->isInteger() && Ty->isFloatingPoint() && "This is an illegal sint to floating point cast!"); return getFoldedCast(Instruction::SIToFP, C, Ty); } Constant *ConstantExpr::getFPToUI(Constant *C, const Type *Ty) { assert(C->getType()->isFloatingPoint() && Ty->isInteger() && "This is an illegal floating point to i32 cast!"); return getFoldedCast(Instruction::FPToUI, C, Ty); } Constant *ConstantExpr::getFPToSI(Constant *C, const Type *Ty) { assert(C->getType()->isFloatingPoint() && Ty->isInteger() && "This is an illegal floating point to i32 cast!"); return getFoldedCast(Instruction::FPToSI, C, Ty); } Constant *ConstantExpr::getPtrToInt(Constant *C, const Type *DstTy) { assert(isa(C->getType()) && "PtrToInt source must be pointer"); assert(DstTy->isInteger() && "PtrToInt destination must be integral"); return getFoldedCast(Instruction::PtrToInt, C, DstTy); } Constant *ConstantExpr::getIntToPtr(Constant *C, const Type *DstTy) { assert(C->getType()->isInteger() && "IntToPtr source must be integral"); assert(isa(DstTy) && "IntToPtr destination must be a pointer"); return getFoldedCast(Instruction::IntToPtr, C, DstTy); } Constant *ConstantExpr::getBitCast(Constant *C, const Type *DstTy) { // BitCast implies a no-op cast of type only. No bits change. However, you // can't cast pointers to anything but pointers. const Type *SrcTy = C->getType(); assert((isa(SrcTy) == isa(DstTy)) && "BitCast cannot cast pointer to non-pointer and vice versa"); // Now we know we're not dealing with mismatched pointer casts (ptr->nonptr // or nonptr->ptr). For all the other types, the cast is okay if source and // destination bit widths are identical. unsigned SrcBitSize = SrcTy->getPrimitiveSizeInBits(); unsigned DstBitSize = DstTy->getPrimitiveSizeInBits(); assert(SrcBitSize == DstBitSize && "BitCast requies types of same width"); return getFoldedCast(Instruction::BitCast, C, DstTy); } Constant *ConstantExpr::getSizeOf(const Type *Ty) { // sizeof is implemented as: (ulong) gep (Ty*)null, 1 Constant *GEPIdx = ConstantInt::get(Type::Int32Ty, 1); Constant *GEP = getGetElementPtr(getNullValue(PointerType::get(Ty)), &GEPIdx, 1); return getCast(Instruction::PtrToInt, GEP, Type::Int64Ty); } Constant *ConstantExpr::getTy(const Type *ReqTy, unsigned Opcode, Constant *C1, Constant *C2) { // Check the operands for consistency first assert(Opcode >= Instruction::BinaryOpsBegin && Opcode < Instruction::BinaryOpsEnd && "Invalid opcode in binary constant expression"); assert(C1->getType() == C2->getType() && "Operand types in binary constant expression should match"); if (ReqTy == C1->getType() || ReqTy == Type::Int1Ty) if (Constant *FC = ConstantFoldBinaryInstruction(Opcode, C1, C2)) return FC; // Fold a few common cases... std::vector argVec(1, C1); argVec.push_back(C2); ExprMapKeyType Key(Opcode, argVec); return ExprConstants->getOrCreate(ReqTy, Key); } Constant *ConstantExpr::getCompareTy(unsigned short predicate, Constant *C1, Constant *C2) { switch (predicate) { default: assert(0 && "Invalid CmpInst predicate"); case FCmpInst::FCMP_FALSE: case FCmpInst::FCMP_OEQ: case FCmpInst::FCMP_OGT: case FCmpInst::FCMP_OGE: case FCmpInst::FCMP_OLT: case FCmpInst::FCMP_OLE: case FCmpInst::FCMP_ONE: case FCmpInst::FCMP_ORD: case FCmpInst::FCMP_UNO: case FCmpInst::FCMP_UEQ: case FCmpInst::FCMP_UGT: case FCmpInst::FCMP_UGE: case FCmpInst::FCMP_ULT: case FCmpInst::FCMP_ULE: case FCmpInst::FCMP_UNE: case FCmpInst::FCMP_TRUE: return getFCmp(predicate, C1, C2); case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_UGE: case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_ULE: case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_SGE: case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_SLE: return getICmp(predicate, C1, C2); } } Constant *ConstantExpr::get(unsigned Opcode, Constant *C1, Constant *C2) { #ifndef NDEBUG switch (Opcode) { case Instruction::Add: case Instruction::Sub: case Instruction::Mul: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert((C1->getType()->isInteger() || C1->getType()->isFloatingPoint() || isa(C1->getType())) && "Tried to create an arithmetic operation on a non-arithmetic type!"); break; case Instruction::UDiv: case Instruction::SDiv: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert((C1->getType()->isInteger() || (isa(C1->getType()) && cast(C1->getType())->getElementType()->isInteger())) && "Tried to create an arithmetic operation on a non-arithmetic type!"); break; case Instruction::FDiv: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert((C1->getType()->isFloatingPoint() || (isa(C1->getType()) && cast(C1->getType())->getElementType()->isFloatingPoint())) && "Tried to create an arithmetic operation on a non-arithmetic type!"); break; case Instruction::URem: case Instruction::SRem: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert((C1->getType()->isInteger() || (isa(C1->getType()) && cast(C1->getType())->getElementType()->isInteger())) && "Tried to create an arithmetic operation on a non-arithmetic type!"); break; case Instruction::FRem: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert((C1->getType()->isFloatingPoint() || (isa(C1->getType()) && cast(C1->getType())->getElementType()->isFloatingPoint())) && "Tried to create an arithmetic operation on a non-arithmetic type!"); break; case Instruction::And: case Instruction::Or: case Instruction::Xor: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert((C1->getType()->isInteger() || isa(C1->getType())) && "Tried to create a logical operation on a non-integral type!"); break; case Instruction::Shl: case Instruction::LShr: case Instruction::AShr: assert(C1->getType() == C2->getType() && "Op types should be identical!"); assert(C1->getType()->isInteger() && "Tried to create a shift operation on a non-integer type!"); break; default: break; } #endif return getTy(C1->getType(), Opcode, C1, C2); } Constant *ConstantExpr::getCompare(unsigned short pred, Constant *C1, Constant *C2) { assert(C1->getType() == C2->getType() && "Op types should be identical!"); return getCompareTy(pred, C1, C2); } Constant *ConstantExpr::getSelectTy(const Type *ReqTy, Constant *C, Constant *V1, Constant *V2) { assert(C->getType() == Type::Int1Ty && "Select condition must be i1!"); assert(V1->getType() == V2->getType() && "Select value types must match!"); assert(V1->getType()->isFirstClassType() && "Cannot select aggregate type!"); if (ReqTy == V1->getType()) if (Constant *SC = ConstantFoldSelectInstruction(C, V1, V2)) return SC; // Fold common cases std::vector argVec(3, C); argVec[1] = V1; argVec[2] = V2; ExprMapKeyType Key(Instruction::Select, argVec); return ExprConstants->getOrCreate(ReqTy, Key); } Constant *ConstantExpr::getGetElementPtrTy(const Type *ReqTy, Constant *C, Value* const *Idxs, unsigned NumIdx) { assert(GetElementPtrInst::getIndexedType(C->getType(), Idxs, NumIdx, true) && "GEP indices invalid!"); if (Constant *FC = ConstantFoldGetElementPtr(C, (Constant**)Idxs, NumIdx)) return FC; // Fold a few common cases... assert(isa(C->getType()) && "Non-pointer type for constant GetElementPtr expression"); // Look up the constant in the table first to ensure uniqueness std::vector ArgVec; ArgVec.reserve(NumIdx+1); ArgVec.push_back(C); for (unsigned i = 0; i != NumIdx; ++i) ArgVec.push_back(cast(Idxs[i])); const ExprMapKeyType Key(Instruction::GetElementPtr, ArgVec); return ExprConstants->getOrCreate(ReqTy, Key); } Constant *ConstantExpr::getGetElementPtr(Constant *C, Value* const *Idxs, unsigned NumIdx) { // Get the result type of the getelementptr! const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), Idxs, NumIdx, true); assert(Ty && "GEP indices invalid!"); return getGetElementPtrTy(PointerType::get(Ty), C, Idxs, NumIdx); } Constant *ConstantExpr::getGetElementPtr(Constant *C, Constant* const *Idxs, unsigned NumIdx) { return getGetElementPtr(C, (Value* const *)Idxs, NumIdx); } Constant * ConstantExpr::getICmp(unsigned short pred, Constant* LHS, Constant* RHS) { assert(LHS->getType() == RHS->getType()); assert(pred >= ICmpInst::FIRST_ICMP_PREDICATE && pred <= ICmpInst::LAST_ICMP_PREDICATE && "Invalid ICmp Predicate"); if (Constant *FC = ConstantFoldCompareInstruction(pred, LHS, RHS)) return FC; // Fold a few common cases... // Look up the constant in the table first to ensure uniqueness std::vector ArgVec; ArgVec.push_back(LHS); ArgVec.push_back(RHS); // Get the key type with both the opcode and predicate const ExprMapKeyType Key(Instruction::ICmp, ArgVec, pred); return ExprConstants->getOrCreate(Type::Int1Ty, Key); } Constant * ConstantExpr::getFCmp(unsigned short pred, Constant* LHS, Constant* RHS) { assert(LHS->getType() == RHS->getType()); assert(pred <= FCmpInst::LAST_FCMP_PREDICATE && "Invalid FCmp Predicate"); if (Constant *FC = ConstantFoldCompareInstruction(pred, LHS, RHS)) return FC; // Fold a few common cases... // Look up the constant in the table first to ensure uniqueness std::vector ArgVec; ArgVec.push_back(LHS); ArgVec.push_back(RHS); // Get the key type with both the opcode and predicate const ExprMapKeyType Key(Instruction::FCmp, ArgVec, pred); return ExprConstants->getOrCreate(Type::Int1Ty, Key); } Constant *ConstantExpr::getExtractElementTy(const Type *ReqTy, Constant *Val, Constant *Idx) { if (Constant *FC = ConstantFoldExtractElementInstruction(Val, Idx)) return FC; // Fold a few common cases... // Look up the constant in the table first to ensure uniqueness std::vector ArgVec(1, Val); ArgVec.push_back(Idx); const ExprMapKeyType Key(Instruction::ExtractElement,ArgVec); return ExprConstants->getOrCreate(ReqTy, Key); } Constant *ConstantExpr::getExtractElement(Constant *Val, Constant *Idx) { assert(isa(Val->getType()) && "Tried to create extractelement operation on non-vector type!"); assert(Idx->getType() == Type::Int32Ty && "Extractelement index must be i32 type!"); return getExtractElementTy(cast(Val->getType())->getElementType(), Val, Idx); } Constant *ConstantExpr::getInsertElementTy(const Type *ReqTy, Constant *Val, Constant *Elt, Constant *Idx) { if (Constant *FC = ConstantFoldInsertElementInstruction(Val, Elt, Idx)) return FC; // Fold a few common cases... // Look up the constant in the table first to ensure uniqueness std::vector ArgVec(1, Val); ArgVec.push_back(Elt); ArgVec.push_back(Idx); const ExprMapKeyType Key(Instruction::InsertElement,ArgVec); return ExprConstants->getOrCreate(ReqTy, Key); } Constant *ConstantExpr::getInsertElement(Constant *Val, Constant *Elt, Constant *Idx) { assert(isa(Val->getType()) && "Tried to create insertelement operation on non-vector type!"); assert(Elt->getType() == cast(Val->getType())->getElementType() && "Insertelement types must match!"); assert(Idx->getType() == Type::Int32Ty && "Insertelement index must be i32 type!"); return getInsertElementTy(cast(Val->getType())->getElementType(), Val, Elt, Idx); } Constant *ConstantExpr::getShuffleVectorTy(const Type *ReqTy, Constant *V1, Constant *V2, Constant *Mask) { if (Constant *FC = ConstantFoldShuffleVectorInstruction(V1, V2, Mask)) return FC; // Fold a few common cases... // Look up the constant in the table first to ensure uniqueness std::vector ArgVec(1, V1); ArgVec.push_back(V2); ArgVec.push_back(Mask); const ExprMapKeyType Key(Instruction::ShuffleVector,ArgVec); return ExprConstants->getOrCreate(ReqTy, Key); } Constant *ConstantExpr::getShuffleVector(Constant *V1, Constant *V2, Constant *Mask) { assert(ShuffleVectorInst::isValidOperands(V1, V2, Mask) && "Invalid shuffle vector constant expr operands!"); return getShuffleVectorTy(V1->getType(), V1, V2, Mask); } Constant *ConstantExpr::getZeroValueForNegationExpr(const Type *Ty) { if (const VectorType *PTy = dyn_cast(Ty)) if (PTy->getElementType()->isFloatingPoint()) { std::vector zeros(PTy->getNumElements(), ConstantFP::get(PTy->getElementType(),-0.0)); return ConstantVector::get(PTy, zeros); } if (Ty->isFloatingPoint()) return ConstantFP::get(Ty, -0.0); return Constant::getNullValue(Ty); } // destroyConstant - Remove the constant from the constant table... // void ConstantExpr::destroyConstant() { ExprConstants->remove(this); destroyConstantImpl(); } const char *ConstantExpr::getOpcodeName() const { return Instruction::getOpcodeName(getOpcode()); } //===----------------------------------------------------------------------===// // replaceUsesOfWithOnConstant implementations void ConstantArray::replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) { assert(isa(To) && "Cannot make Constant refer to non-constant!"); Constant *ToC = cast(To); unsigned OperandToUpdate = U-OperandList; assert(getOperand(OperandToUpdate) == From && "ReplaceAllUsesWith broken!"); std::pair Lookup; Lookup.first.first = getType(); Lookup.second = this; std::vector &Values = Lookup.first.second; Values.reserve(getNumOperands()); // Build replacement array. // Fill values with the modified operands of the constant array. Also, // compute whether this turns into an all-zeros array. bool isAllZeros = false; if (!ToC->isNullValue()) { for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O) Values.push_back(cast(O->get())); } else { isAllZeros = true; for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O) { Constant *Val = cast(O->get()); Values.push_back(Val); if (isAllZeros) isAllZeros = Val->isNullValue(); } } Values[OperandToUpdate] = ToC; Constant *Replacement = 0; if (isAllZeros) { Replacement = ConstantAggregateZero::get(getType()); } else { // Check to see if we have this array type already. bool Exists; ArrayConstantsTy::MapTy::iterator I = ArrayConstants->InsertOrGetItem(Lookup, Exists); if (Exists) { Replacement = I->second; } else { // Okay, the new shape doesn't exist in the system yet. Instead of // creating a new constant array, inserting it, replaceallusesof'ing the // old with the new, then deleting the old... just update the current one // in place! ArrayConstants->MoveConstantToNewSlot(this, I); // Update to the new value. setOperand(OperandToUpdate, ToC); return; } } // Otherwise, I do need to replace this with an existing value. assert(Replacement != this && "I didn't contain From!"); // Everyone using this now uses the replacement. uncheckedReplaceAllUsesWith(Replacement); // Delete the old constant! destroyConstant(); } void ConstantStruct::replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) { assert(isa(To) && "Cannot make Constant refer to non-constant!"); Constant *ToC = cast(To); unsigned OperandToUpdate = U-OperandList; assert(getOperand(OperandToUpdate) == From && "ReplaceAllUsesWith broken!"); std::pair Lookup; Lookup.first.first = getType(); Lookup.second = this; std::vector &Values = Lookup.first.second; Values.reserve(getNumOperands()); // Build replacement struct. // Fill values with the modified operands of the constant struct. Also, // compute whether this turns into an all-zeros struct. bool isAllZeros = false; if (!ToC->isNullValue()) { for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O) Values.push_back(cast(O->get())); } else { isAllZeros = true; for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O) { Constant *Val = cast(O->get()); Values.push_back(Val); if (isAllZeros) isAllZeros = Val->isNullValue(); } } Values[OperandToUpdate] = ToC; Constant *Replacement = 0; if (isAllZeros) { Replacement = ConstantAggregateZero::get(getType()); } else { // Check to see if we have this array type already. bool Exists; StructConstantsTy::MapTy::iterator I = StructConstants->InsertOrGetItem(Lookup, Exists); if (Exists) { Replacement = I->second; } else { // Okay, the new shape doesn't exist in the system yet. Instead of // creating a new constant struct, inserting it, replaceallusesof'ing the // old with the new, then deleting the old... just update the current one // in place! StructConstants->MoveConstantToNewSlot(this, I); // Update to the new value. setOperand(OperandToUpdate, ToC); return; } } assert(Replacement != this && "I didn't contain From!"); // Everyone using this now uses the replacement. uncheckedReplaceAllUsesWith(Replacement); // Delete the old constant! destroyConstant(); } void ConstantVector::replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) { assert(isa(To) && "Cannot make Constant refer to non-constant!"); std::vector Values; Values.reserve(getNumOperands()); // Build replacement array... for (unsigned i = 0, e = getNumOperands(); i != e; ++i) { Constant *Val = getOperand(i); if (Val == From) Val = cast(To); Values.push_back(Val); } Constant *Replacement = ConstantVector::get(getType(), Values); assert(Replacement != this && "I didn't contain From!"); // Everyone using this now uses the replacement. uncheckedReplaceAllUsesWith(Replacement); // Delete the old constant! destroyConstant(); } void ConstantExpr::replaceUsesOfWithOnConstant(Value *From, Value *ToV, Use *U) { assert(isa(ToV) && "Cannot make Constant refer to non-constant!"); Constant *To = cast(ToV); Constant *Replacement = 0; if (getOpcode() == Instruction::GetElementPtr) { SmallVector Indices; Constant *Pointer = getOperand(0); Indices.reserve(getNumOperands()-1); if (Pointer == From) Pointer = To; for (unsigned i = 1, e = getNumOperands(); i != e; ++i) { Constant *Val = getOperand(i); if (Val == From) Val = To; Indices.push_back(Val); } Replacement = ConstantExpr::getGetElementPtr(Pointer, &Indices[0], Indices.size()); } else if (isCast()) { assert(getOperand(0) == From && "Cast only has one use!"); Replacement = ConstantExpr::getCast(getOpcode(), To, getType()); } else if (getOpcode() == Instruction::Select) { Constant *C1 = getOperand(0); Constant *C2 = getOperand(1); Constant *C3 = getOperand(2); if (C1 == From) C1 = To; if (C2 == From) C2 = To; if (C3 == From) C3 = To; Replacement = ConstantExpr::getSelect(C1, C2, C3); } else if (getOpcode() == Instruction::ExtractElement) { Constant *C1 = getOperand(0); Constant *C2 = getOperand(1); if (C1 == From) C1 = To; if (C2 == From) C2 = To; Replacement = ConstantExpr::getExtractElement(C1, C2); } else if (getOpcode() == Instruction::InsertElement) { Constant *C1 = getOperand(0); Constant *C2 = getOperand(1); Constant *C3 = getOperand(1); if (C1 == From) C1 = To; if (C2 == From) C2 = To; if (C3 == From) C3 = To; Replacement = ConstantExpr::getInsertElement(C1, C2, C3); } else if (getOpcode() == Instruction::ShuffleVector) { Constant *C1 = getOperand(0); Constant *C2 = getOperand(1); Constant *C3 = getOperand(2); if (C1 == From) C1 = To; if (C2 == From) C2 = To; if (C3 == From) C3 = To; Replacement = ConstantExpr::getShuffleVector(C1, C2, C3); } else if (isCompare()) { Constant *C1 = getOperand(0); Constant *C2 = getOperand(1); if (C1 == From) C1 = To; if (C2 == From) C2 = To; if (getOpcode() == Instruction::ICmp) Replacement = ConstantExpr::getICmp(getPredicate(), C1, C2); else Replacement = ConstantExpr::getFCmp(getPredicate(), C1, C2); } else if (getNumOperands() == 2) { Constant *C1 = getOperand(0); Constant *C2 = getOperand(1); if (C1 == From) C1 = To; if (C2 == From) C2 = To; Replacement = ConstantExpr::get(getOpcode(), C1, C2); } else { assert(0 && "Unknown ConstantExpr type!"); return; } assert(Replacement != this && "I didn't contain From!"); // Everyone using this now uses the replacement. uncheckedReplaceAllUsesWith(Replacement); // Delete the old constant! destroyConstant(); } /// getStringValue - Turn an LLVM constant pointer that eventually points to a /// global into a string value. Return an empty string if we can't do it. /// Parameter Chop determines if the result is chopped at the first null /// terminator. /// std::string Constant::getStringValue(bool Chop, unsigned Offset) { if (GlobalVariable *GV = dyn_cast(this)) { if (GV->hasInitializer() && isa(GV->getInitializer())) { ConstantArray *Init = cast(GV->getInitializer()); if (Init->isString()) { std::string Result = Init->getAsString(); if (Offset < Result.size()) { // If we are pointing INTO The string, erase the beginning... Result.erase(Result.begin(), Result.begin()+Offset); // Take off the null terminator, and any string fragments after it. if (Chop) { std::string::size_type NullPos = Result.find_first_of((char)0); if (NullPos != std::string::npos) Result.erase(Result.begin()+NullPos, Result.end()); } return Result; } } } } else if (Constant *C = dyn_cast(this)) { if (GlobalValue *GV = dyn_cast(C)) return GV->getStringValue(Chop, Offset); else if (ConstantExpr *CE = dyn_cast(C)) { if (CE->getOpcode() == Instruction::GetElementPtr) { // Turn a gep into the specified offset. if (CE->getNumOperands() == 3 && cast(CE->getOperand(1))->isNullValue() && isa(CE->getOperand(2))) { Offset += cast(CE->getOperand(2))->getZExtValue(); return CE->getOperand(0)->getStringValue(Chop, Offset); } } } } return ""; }