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/Support/Streams.h"
31 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<<...
53 virtual void print(std::ostream &O) const = 0;
54 void print(std::ostream *O) const { if (O) print(*O); }
57 inline std::ostream &operator<<(std::ostream &OS,
58 const MachineConstantPoolValue &V) {
63 /// This class is a data container for one entry in a MachineConstantPool.
64 /// It contains a pointer to the value and an offset from the start of
65 /// the constant pool.
66 /// @brief An entry in a MachineConstantPool
67 class MachineConstantPoolEntry {
69 /// The constant itself.
72 MachineConstantPoolValue *MachineCPVal;
75 /// The offset of the constant from the start of the pool. The top bit is set
76 /// when Val is a MachineConstantPoolValue.
79 MachineConstantPoolEntry(Constant *V, unsigned O)
81 assert((int)Offset >= 0 && "Offset is too large");
84 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned O)
86 assert((int)Offset >= 0 && "Offset is too large");
88 Offset |= 1 << (sizeof(unsigned)*8-1);
91 bool isMachineConstantPoolEntry() const {
92 return (int)Offset < 0;
95 int getOffset() const {
96 return Offset & ~(1 << (sizeof(unsigned)*8-1));
99 const Type *getType() const;
102 /// The MachineConstantPool class keeps track of constants referenced by a
103 /// function which must be spilled to memory. This is used for constants which
104 /// are unable to be used directly as operands to instructions, which typically
105 /// include floating point and large integer constants.
107 /// Instructions reference the address of these constant pool constants through
108 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
109 /// code, these virtual address references are converted to refer to the
110 /// address of the function constant pool values.
111 /// @brief The machine constant pool.
112 class MachineConstantPool {
113 const TargetData *TD; ///< The machine's TargetData.
114 unsigned PoolAlignment; ///< The alignment for the pool.
115 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
117 /// @brief The only constructor.
118 explicit MachineConstantPool(const TargetData *td)
119 : TD(td), PoolAlignment(1) {}
120 ~MachineConstantPool();
122 /// getConstantPoolAlignment - Return the log2 of the alignment required by
123 /// the whole constant pool, of which the first element must be aligned.
124 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
126 /// getConstantPoolIndex - Create a new entry in the constant pool or return
127 /// an existing one. User must specify an alignment in bytes for the object.
128 unsigned getConstantPoolIndex(Constant *C, unsigned Alignment);
129 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,unsigned Alignment);
131 /// isEmpty - Return true if this constant pool contains no constants.
132 bool isEmpty() const { return Constants.empty(); }
134 const std::vector<MachineConstantPoolEntry> &getConstants() const {
138 /// print - Used by the MachineFunction printer to print information about
139 /// constant pool objects. Implemented in MachineFunction.cpp
141 void print(std::ostream &OS) const;
142 void print(std::ostream *OS) const { if (OS) print(*OS); }
144 /// dump - Call print(std::cerr) to be called from the debugger.
149 } // End llvm namespace