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 inline const Type *getType() const { return Ty; }
46 virtual int getExistingMachineCPValue(MachineConstantPool *CP,
47 unsigned Alignment) = 0;
49 virtual void AddSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;
51 /// print - Implement operator<<
52 virtual void print(raw_ostream &O) const = 0;
55 inline raw_ostream &operator<<(raw_ostream &OS,
56 const MachineConstantPoolValue &V) {
62 /// This class is a data container for one entry in a MachineConstantPool.
63 /// It contains a pointer to the value and an offset from the start of
64 /// the constant pool.
65 /// @brief An entry in a MachineConstantPool
66 class MachineConstantPoolEntry {
68 /// The constant itself.
71 MachineConstantPoolValue *MachineCPVal;
74 /// The required alignment for this entry. The top bit is set when Val is
75 /// a MachineConstantPoolValue.
78 MachineConstantPoolEntry(Constant *V, unsigned A)
82 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned A)
85 Alignment |= 1 << (sizeof(unsigned)*CHAR_BIT-1);
88 bool isMachineConstantPoolEntry() const {
89 return (int)Alignment < 0;
92 int getAlignment() const {
93 return Alignment & ~(1 << (sizeof(unsigned)*CHAR_BIT-1));
96 const Type *getType() const;
99 /// The MachineConstantPool class keeps track of constants referenced by a
100 /// function which must be spilled to memory. This is used for constants which
101 /// are unable to be used directly as operands to instructions, which typically
102 /// include floating point and large integer constants.
104 /// Instructions reference the address of these constant pool constants through
105 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
106 /// code, these virtual address references are converted to refer to the
107 /// address of the function constant pool values.
108 /// @brief The machine constant pool.
109 class MachineConstantPool {
110 const TargetData *TD; ///< The machine's TargetData.
111 unsigned PoolAlignment; ///< The alignment for the pool.
112 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
114 /// @brief The only constructor.
115 explicit MachineConstantPool(const TargetData *td)
116 : TD(td), PoolAlignment(1) {}
117 ~MachineConstantPool();
119 /// getConstantPoolAlignment - Return the the alignment required by
120 /// the whole constant pool, of which the first element must be aligned.
121 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
123 /// getConstantPoolIndex - Create a new entry in the constant pool or return
124 /// an existing one. User must specify the minimum required alignment for
126 unsigned getConstantPoolIndex(Constant *C, unsigned Alignment);
127 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment);
129 /// isEmpty - Return true if this constant pool contains no constants.
130 bool isEmpty() const { return Constants.empty(); }
132 const std::vector<MachineConstantPoolEntry> &getConstants() const {
136 /// print - Used by the MachineFunction printer to print information about
137 /// constant pool objects. Implemented in MachineFunction.cpp
139 void print(raw_ostream &OS) const;
141 /// dump - Call print(cerr) to be called from the debugger.
145 } // End llvm namespace