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 //===----------------------------------------------------------------------===//
10 /// @file This file declares the MachineConstantPool class which is an abstract
11 /// constant pool to keep track of constants referenced by a function.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H
16 #define LLVM_CODEGEN_MACHINECONSTANTPOOL_H
18 #include "llvm/ADT/FoldingSet.h"
29 class MachineConstantPool;
32 /// Abstract base class for all machine specific constantpool value subclasses.
34 class MachineConstantPoolValue {
38 explicit MachineConstantPoolValue(const Type *ty) : Ty(ty) {}
39 virtual ~MachineConstantPoolValue() {}
41 /// getType - get type of this MachineConstantPoolValue.
43 inline const Type *getType() const { return Ty; }
45 virtual int getExistingMachineCPValue(MachineConstantPool *CP,
46 unsigned Alignment) = 0;
48 virtual void AddSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;
50 /// print - Implement operator<<
51 virtual void print(raw_ostream &O) const = 0;
54 inline raw_ostream &operator<<(raw_ostream &OS,
55 const MachineConstantPoolValue &V) {
61 /// This class is a data container for one entry in a MachineConstantPool.
62 /// It contains a pointer to the value and an offset from the start of
63 /// the constant pool.
64 /// @brief An entry in a MachineConstantPool
65 class MachineConstantPoolEntry {
67 /// The constant itself.
70 MachineConstantPoolValue *MachineCPVal;
73 /// The offset of the constant from the start of the pool. The top bit is set
74 /// when Val is a MachineConstantPoolValue.
77 MachineConstantPoolEntry(Constant *V, unsigned O)
79 assert((int)Offset >= 0 && "Offset is too large");
82 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned O)
84 assert((int)Offset >= 0 && "Offset is too large");
86 Offset |= 1 << (sizeof(unsigned)*8-1);
89 bool isMachineConstantPoolEntry() const {
90 return (int)Offset < 0;
93 int getOffset() const {
94 return Offset & ~(1 << (sizeof(unsigned)*8-1));
97 const Type *getType() const;
100 /// The MachineConstantPool class keeps track of constants referenced by a
101 /// function which must be spilled to memory. This is used for constants which
102 /// are unable to be used directly as operands to instructions, which typically
103 /// include floating point and large integer constants.
105 /// Instructions reference the address of these constant pool constants through
106 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
107 /// code, these virtual address references are converted to refer to the
108 /// address of the function constant pool values.
109 /// @brief The machine constant pool.
110 class MachineConstantPool {
111 const TargetData *TD; ///< The machine's TargetData.
112 unsigned PoolAlignment; ///< The alignment for the pool.
113 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
115 /// @brief The only constructor.
116 explicit MachineConstantPool(const TargetData *td)
117 : TD(td), PoolAlignment(1) {}
118 ~MachineConstantPool();
120 /// getConstantPoolAlignment - Return the log2 of the alignment required by
121 /// the whole constant pool, of which the first element must be aligned.
122 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
124 /// getConstantPoolIndex - Create a new entry in the constant pool or return
125 /// an existing one. User must specify the log2 of the minimum required
126 /// alignment for the object.
127 unsigned getConstantPoolIndex(Constant *C, unsigned Alignment);
128 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment);
130 /// isEmpty - Return true if this constant pool contains no constants.
131 bool isEmpty() const { return Constants.empty(); }
133 const std::vector<MachineConstantPoolEntry> &getConstants() const {
137 /// print - Used by the MachineFunction printer to print information about
138 /// constant pool objects. Implemented in MachineFunction.cpp
140 void print(raw_ostream &OS) const;
142 /// dump - Call print(cerr) to be called from the debugger.
146 } // End llvm namespace