1 //===-- CodeGen/MachineConstantPool.h - Abstract Constant Pool --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// This file declares the MachineConstantPool class which is an abstract
12 /// constant pool to keep track of constants referenced by a function.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H
17 #define LLVM_CODEGEN_MACHINECONSTANTPOOL_H
26 class FoldingSetNodeID;
30 class MachineConstantPool;
33 /// Abstract base class for all machine specific constantpool value subclasses.
35 class MachineConstantPoolValue {
39 explicit MachineConstantPoolValue(const Type *ty) : Ty(ty) {}
40 virtual ~MachineConstantPoolValue() {}
42 /// getType - get type of this MachineConstantPoolValue.
44 const Type *getType() const { return Ty; }
47 /// getRelocatationInfo - This method classifies the entry according to
48 /// whether or not it may generate a relocation entry. This must be
49 /// conservative, so if it might codegen to a relocatable entry, it should say
50 /// so. The return values are:
52 /// 0: This constant pool entry is guaranteed to never have a relocation
53 /// applied to it (because it holds a simple constant like '4').
54 /// 1: This entry has relocations, but the entries are guaranteed to be
55 /// resolvable by the static linker, so the dynamic linker will never see
57 /// 2: This entry may have arbitrary relocations.
58 virtual unsigned getRelocatationInfo() const = 0;
60 virtual int getExistingMachineCPValue(MachineConstantPool *CP,
61 unsigned Alignment) = 0;
63 virtual void AddSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;
65 /// print - Implement operator<<
66 virtual void print(raw_ostream &O) const = 0;
69 inline raw_ostream &operator<<(raw_ostream &OS,
70 const MachineConstantPoolValue &V) {
76 /// This class is a data container for one entry in a MachineConstantPool.
77 /// It contains a pointer to the value and an offset from the start of
78 /// the constant pool.
79 /// @brief An entry in a MachineConstantPool
80 class MachineConstantPoolEntry {
82 /// The constant itself.
85 MachineConstantPoolValue *MachineCPVal;
88 /// The required alignment for this entry. The top bit is set when Val is
89 /// a MachineConstantPoolValue.
92 MachineConstantPoolEntry(Constant *V, unsigned A)
96 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned A)
99 Alignment |= 1 << (sizeof(unsigned)*CHAR_BIT-1);
102 bool isMachineConstantPoolEntry() const {
103 return (int)Alignment < 0;
106 int getAlignment() const {
107 return Alignment & ~(1 << (sizeof(unsigned)*CHAR_BIT-1));
110 const Type *getType() const;
112 /// getRelocatationInfo - This method classifies the entry according to
113 /// whether or not it may generate a relocation entry. This must be
114 /// conservative, so if it might codegen to a relocatable entry, it should say
115 /// so. The return values are:
117 /// 0: This constant pool entry is guaranteed to never have a relocation
118 /// applied to it (because it holds a simple constant like '4').
119 /// 1: This entry has relocations, but the entries are guaranteed to be
120 /// resolvable by the static linker, so the dynamic linker will never see
122 /// 2: This entry may have arbitrary relocations.
123 unsigned getRelocatationInfo() const;
126 /// The MachineConstantPool class keeps track of constants referenced by a
127 /// function which must be spilled to memory. This is used for constants which
128 /// are unable to be used directly as operands to instructions, which typically
129 /// include floating point and large integer constants.
131 /// Instructions reference the address of these constant pool constants through
132 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
133 /// code, these virtual address references are converted to refer to the
134 /// address of the function constant pool values.
135 /// @brief The machine constant pool.
136 class MachineConstantPool {
137 const TargetData *TD; ///< The machine's TargetData.
138 unsigned PoolAlignment; ///< The alignment for the pool.
139 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
141 /// @brief The only constructor.
142 explicit MachineConstantPool(const TargetData *td)
143 : TD(td), PoolAlignment(1) {}
144 ~MachineConstantPool();
146 /// getConstantPoolAlignment - Return the the alignment required by
147 /// the whole constant pool, of which the first element must be aligned.
148 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
150 /// getConstantPoolIndex - Create a new entry in the constant pool or return
151 /// an existing one. User must specify the minimum required alignment for
153 unsigned getConstantPoolIndex(Constant *C, unsigned Alignment);
154 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment);
156 /// isEmpty - Return true if this constant pool contains no constants.
157 bool isEmpty() const { return Constants.empty(); }
159 const std::vector<MachineConstantPoolEntry> &getConstants() const {
163 /// print - Used by the MachineFunction printer to print information about
164 /// constant pool objects. Implemented in MachineFunction.cpp
166 void print(raw_ostream &OS) const;
168 /// dump - Call print(cerr) to be called from the debugger.
172 } // End llvm namespace