1 //===-- CodeGen/MachineConstantPool.h - Abstract Constant Pool --*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 /// @file 11 /// This file declares the MachineConstantPool class which is an abstract 12 /// constant pool to keep track of constants referenced by a function. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H 17 #define LLVM_CODEGEN_MACHINECONSTANTPOOL_H 18 19 #include "llvm/ADT/DenseSet.h" 20 #include "llvm/MC/SectionKind.h" 21 #include <cassert> 22 #include <climits> 23 #include <vector> 24 25 namespace llvm { 26 27 class Constant; 28 class FoldingSetNodeID; 29 class DataLayout; 30 class TargetMachine; 31 class Type; 32 class MachineConstantPool; 33 class raw_ostream; 34 35 /// Abstract base class for all machine specific constantpool value subclasses. 36 /// 37 class MachineConstantPoolValue { 38 virtual void anchor(); 39 Type *Ty; 40 41 public: 42 explicit MachineConstantPoolValue(Type *ty) : Ty(ty) {} 43 virtual ~MachineConstantPoolValue() {} 44 45 /// getType - get type of this MachineConstantPoolValue. 46 /// 47 Type *getType() const { return Ty; } 48 49 50 /// getRelocationInfo - This method classifies the entry according to 51 /// whether or not it may generate a relocation entry. This must be 52 /// conservative, so if it might codegen to a relocatable entry, it should say 53 /// so. The return values are the same as Constant::getRelocationInfo(). 54 virtual unsigned getRelocationInfo() const = 0; 55 56 virtual int getExistingMachineCPValue(MachineConstantPool *CP, 57 unsigned Alignment) = 0; 58 59 virtual void addSelectionDAGCSEId(FoldingSetNodeID &ID) = 0; 60 61 /// print - Implement operator<< 62 virtual void print(raw_ostream &O) const = 0; 63 }; 64 65 inline raw_ostream &operator<<(raw_ostream &OS, 66 const MachineConstantPoolValue &V) { 67 V.print(OS); 68 return OS; 69 } 70 71 72 /// This class is a data container for one entry in a MachineConstantPool. 73 /// It contains a pointer to the value and an offset from the start of 74 /// the constant pool. 75 /// @brief An entry in a MachineConstantPool 76 class MachineConstantPoolEntry { 77 public: 78 /// The constant itself. 79 union { 80 const Constant *ConstVal; 81 MachineConstantPoolValue *MachineCPVal; 82 } Val; 83 84 /// The required alignment for this entry. The top bit is set when Val is 85 /// a target specific MachineConstantPoolValue. 86 unsigned Alignment; 87 88 MachineConstantPoolEntry(const Constant *V, unsigned A) 89 : Alignment(A) { 90 Val.ConstVal = V; 91 } 92 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned A) 93 : Alignment(A) { 94 Val.MachineCPVal = V; 95 Alignment |= 1U << (sizeof(unsigned)*CHAR_BIT-1); 96 } 97 98 /// isMachineConstantPoolEntry - Return true if the MachineConstantPoolEntry 99 /// is indeed a target specific constantpool entry, not a wrapper over a 100 /// Constant. 101 bool isMachineConstantPoolEntry() const { 102 return (int)Alignment < 0; 103 } 104 105 int getAlignment() const { 106 return Alignment & ~(1 << (sizeof(unsigned)*CHAR_BIT-1)); 107 } 108 109 Type *getType() const; 110 111 /// getRelocationInfo - This method classifies the entry according to 112 /// whether or not it may generate a relocation entry. This must be 113 /// conservative, so if it might codegen to a relocatable entry, it should say 114 /// so. The return values are: 115 /// 116 /// 0: This constant pool entry is guaranteed to never have a relocation 117 /// applied to it (because it holds a simple constant like '4'). 118 /// 1: This entry has relocations, but the entries are guaranteed to be 119 /// resolvable by the static linker, so the dynamic linker will never see 120 /// them. 121 /// 2: This entry may have arbitrary relocations. 122 unsigned getRelocationInfo() const; 123 124 SectionKind getSectionKind(const DataLayout *DL) const; 125 }; 126 127 /// The MachineConstantPool class keeps track of constants referenced by a 128 /// function which must be spilled to memory. This is used for constants which 129 /// are unable to be used directly as operands to instructions, which typically 130 /// include floating point and large integer constants. 131 /// 132 /// Instructions reference the address of these constant pool constants through 133 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine 134 /// code, these virtual address references are converted to refer to the 135 /// address of the function constant pool values. 136 /// @brief The machine constant pool. 137 class MachineConstantPool { 138 const TargetMachine &TM; ///< The target machine. 139 unsigned PoolAlignment; ///< The alignment for the pool. 140 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants. 141 /// MachineConstantPoolValues that use an existing MachineConstantPoolEntry. 142 DenseSet<MachineConstantPoolValue*> MachineCPVsSharingEntries; 143 144 const DataLayout *getDataLayout() const; 145 public: 146 /// @brief The only constructor. 147 explicit MachineConstantPool(const TargetMachine &TM) 148 : TM(TM), PoolAlignment(1) {} 149 ~MachineConstantPool(); 150 151 /// getConstantPoolAlignment - Return the alignment required by 152 /// the whole constant pool, of which the first element must be aligned. 153 unsigned getConstantPoolAlignment() const { return PoolAlignment; } 154 155 /// getConstantPoolIndex - Create a new entry in the constant pool or return 156 /// an existing one. User must specify the minimum required alignment for 157 /// the object. 158 unsigned getConstantPoolIndex(const Constant *C, unsigned Alignment); 159 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment); 160 161 /// isEmpty - Return true if this constant pool contains no constants. 162 bool isEmpty() const { return Constants.empty(); } 163 164 const std::vector<MachineConstantPoolEntry> &getConstants() const { 165 return Constants; 166 } 167 168 /// print - Used by the MachineFunction printer to print information about 169 /// constant pool objects. Implemented in MachineFunction.cpp 170 /// 171 void print(raw_ostream &OS) const; 172 173 /// dump - Call print(cerr) to be called from the debugger. 174 void dump() const; 175 }; 176 177 } // End llvm namespace 178 179 #endif 180
