1 //===-- CodeGen/MachineConstantPool.h - Abstract Constant Pool --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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"
29 class MachineConstantPool;
31 /// Abstract base class for all machine specific constantpool value subclasses.
33 class MachineConstantPoolValue {
37 MachineConstantPoolValue(const Type *ty) : Ty(ty) {}
38 virtual ~MachineConstantPoolValue() {};
40 /// getType - get type of this MachineConstantPoolValue.
42 inline const Type *getType() const { return Ty; }
44 virtual int getExistingMachineCPValue(MachineConstantPool *CP,
45 unsigned Alignment) = 0;
47 virtual void AddSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;
49 /// print - Implement operator<<...
51 virtual void print(std::ostream &O) const = 0;
54 inline std::ostream &operator<<(std::ostream &OS,
55 const MachineConstantPoolValue &V) {
60 /// This class is a data container for one entry in a MachineConstantPool.
61 /// It contains a pointer to the value and an offset from the start of
62 /// the constant pool.
63 /// @brief An entry in a MachineConstantPool
64 struct MachineConstantPoolEntry {
65 /// The constant itself.
68 MachineConstantPoolValue *MachineCPVal;
71 /// The offset of the constant from the start of the pool. The top bit is set
72 /// when Val is a MachineConstantPoolValue.
75 MachineConstantPoolEntry(Constant *V, unsigned O)
77 assert((int)Offset >= 0 && "Offset is too large");
80 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned O)
82 assert((int)Offset >= 0 && "Offset is too large");
84 Offset |= 1 << (sizeof(unsigned)*8-1);
87 bool isMachineConstantPoolEntry() const {
88 return (int)Offset < 0;
91 int getOffset() const {
92 return Offset & ~(1 << (sizeof(unsigned)*8-1));
95 const Type *getType() const;
98 /// The MachineConstantPool class keeps track of constants referenced by a
99 /// function which must be spilled to memory. This is used for constants which
100 /// are unable to be used directly as operands to instructions, which typically
101 /// include floating point and large integer constants.
103 /// Instructions reference the address of these constant pool constants through
104 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
105 /// code, these virtual address references are converted to refer to the
106 /// address of the function constant pool values.
107 /// @brief The machine constant pool.
108 class MachineConstantPool {
109 const TargetData *TD; ///< The machine's TargetData.
110 unsigned PoolAlignment; ///< The alignment for the pool.
111 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
113 /// @brief The only constructor.
114 MachineConstantPool(const TargetData *td) : TD(td), PoolAlignment(1) {}
115 ~MachineConstantPool();
117 /// getConstantPoolAlignment - Return the log2 of the alignment required by
118 /// the whole constant pool, of which the first element must be aligned.
119 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
121 /// getConstantPoolIndex - Create a new entry in the constant pool or return
122 /// an existing one. User must specify an alignment in bytes for the object.
123 unsigned getConstantPoolIndex(Constant *C, unsigned Alignment);
124 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment);
126 /// isEmpty - Return true if this constant pool contains no constants.
127 bool isEmpty() const { return Constants.empty(); }
129 const std::vector<MachineConstantPoolEntry> &getConstants() const {
133 /// print - Used by the MachineFunction printer to print information about
134 /// constant pool objects. Implemented in MachineFunction.cpp
136 void print(std::ostream &OS) const;
138 /// dump - Call print(std::cerr) to be called from the debugger.
143 } // End llvm namespace