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"
19 #include "llvm/CodeGen/SelectionDAGNodes.h"
20 #include "llvm/Support/Streams.h"
30 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<<...
52 virtual void print(std::ostream &O) const = 0;
53 void print(std::ostream *O) const { if (O) print(*O); }
56 inline std::ostream &operator<<(std::ostream &OS,
57 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 offset of the constant from the start of the pool. The top bit is set
75 /// when Val is a MachineConstantPoolValue.
78 MachineConstantPoolEntry(Constant *V, unsigned O)
80 assert((int)Offset >= 0 && "Offset is too large");
83 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned O)
85 assert((int)Offset >= 0 && "Offset is too large");
87 Offset |= 1 << (sizeof(unsigned)*8-1);
90 bool isMachineConstantPoolEntry() const {
91 return (int)Offset < 0;
94 int getOffset() const {
95 return Offset & ~(1 << (sizeof(unsigned)*8-1));
98 const Type *getType() const;
101 /// The MachineConstantPool class keeps track of constants referenced by a
102 /// function which must be spilled to memory. This is used for constants which
103 /// are unable to be used directly as operands to instructions, which typically
104 /// include floating point and large integer constants.
106 /// Instructions reference the address of these constant pool constants through
107 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
108 /// code, these virtual address references are converted to refer to the
109 /// address of the function constant pool values.
110 /// @brief The machine constant pool.
111 class MachineConstantPool {
112 const TargetData *TD; ///< The machine's TargetData.
113 unsigned PoolAlignment; ///< The alignment for the pool.
114 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
116 /// @brief The only constructor.
117 explicit MachineConstantPool(const TargetData *td)
118 : TD(td), PoolAlignment(1) {}
119 ~MachineConstantPool();
121 /// getConstantPoolAlignment - Return the log2 of the alignment required by
122 /// the whole constant pool, of which the first element must be aligned.
123 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
125 /// getConstantPoolIndex - Create a new entry in the constant pool or return
126 /// an existing one. User must specify an alignment in bytes 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(std::ostream &OS) const;
141 void print(std::ostream *OS) const { if (OS) print(*OS); }
143 /// dump - Call print(std::cerr) to be called from the debugger.
148 } // End llvm namespace