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
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/MC/SectionKind.h"
28 class FoldingSetNodeID;
32 class MachineConstantPool;
35 /// Abstract base class for all machine specific constantpool value subclasses.
37 class MachineConstantPoolValue {
38 virtual void anchor();
42 explicit MachineConstantPoolValue(Type *ty) : Ty(ty) {}
43 virtual ~MachineConstantPoolValue() {}
45 /// getType - get type of this MachineConstantPoolValue.
47 Type *getType() const { return Ty; }
49 virtual int getExistingMachineCPValue(MachineConstantPool *CP,
50 unsigned Alignment) = 0;
52 virtual void addSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;
54 /// print - Implement operator<<
55 virtual void print(raw_ostream &O) const = 0;
58 inline raw_ostream &operator<<(raw_ostream &OS,
59 const MachineConstantPoolValue &V) {
64 /// This class is a data container for one entry in a MachineConstantPool.
65 /// It contains a pointer to the value and an offset from the start of
66 /// the constant pool.
67 /// @brief An entry in a MachineConstantPool
68 class MachineConstantPoolEntry {
70 /// The constant itself.
72 const Constant *ConstVal;
73 MachineConstantPoolValue *MachineCPVal;
76 /// The required alignment for this entry. The top bit is set when Val is
77 /// a target specific MachineConstantPoolValue.
80 MachineConstantPoolEntry(const Constant *V, unsigned A)
84 MachineConstantPoolEntry(MachineConstantPoolValue *V, unsigned A)
87 Alignment |= 1U << (sizeof(unsigned) * CHAR_BIT - 1);
90 /// isMachineConstantPoolEntry - Return true if the MachineConstantPoolEntry
91 /// is indeed a target specific constantpool entry, not a wrapper over a
93 bool isMachineConstantPoolEntry() const {
94 return (int)Alignment < 0;
97 int getAlignment() const {
98 return Alignment & ~(1 << (sizeof(unsigned) * CHAR_BIT - 1));
101 Type *getType() const;
103 /// This method classifies the entry according to whether or not it may
104 /// generate a relocation entry. This must be conservative, so if it might
105 /// codegen to a relocatable entry, it should say so.
106 bool needsRelocation() const;
108 SectionKind getSectionKind(const DataLayout *DL) const;
111 /// The MachineConstantPool class keeps track of constants referenced by a
112 /// function which must be spilled to memory. This is used for constants which
113 /// are unable to be used directly as operands to instructions, which typically
114 /// include floating point and large integer constants.
116 /// Instructions reference the address of these constant pool constants through
117 /// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
118 /// code, these virtual address references are converted to refer to the
119 /// address of the function constant pool values.
120 /// @brief The machine constant pool.
121 class MachineConstantPool {
122 unsigned PoolAlignment; ///< The alignment for the pool.
123 std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
124 /// MachineConstantPoolValues that use an existing MachineConstantPoolEntry.
125 DenseSet<MachineConstantPoolValue*> MachineCPVsSharingEntries;
126 const DataLayout &DL;
128 const DataLayout &getDataLayout() const { return DL; }
131 /// @brief The only constructor.
132 explicit MachineConstantPool(const DataLayout &DL)
133 : PoolAlignment(1), DL(DL) {}
134 ~MachineConstantPool();
136 /// getConstantPoolAlignment - Return the alignment required by
137 /// the whole constant pool, of which the first element must be aligned.
138 unsigned getConstantPoolAlignment() const { return PoolAlignment; }
140 /// getConstantPoolIndex - Create a new entry in the constant pool or return
141 /// an existing one. User must specify the minimum required alignment for
143 unsigned getConstantPoolIndex(const Constant *C, unsigned Alignment);
144 unsigned getConstantPoolIndex(MachineConstantPoolValue *V,
147 /// isEmpty - Return true if this constant pool contains no constants.
148 bool isEmpty() const { return Constants.empty(); }
150 const std::vector<MachineConstantPoolEntry> &getConstants() const {
154 /// print - Used by the MachineFunction printer to print information about
155 /// constant pool objects. Implemented in MachineFunction.cpp
157 void print(raw_ostream &OS) const;
159 /// dump - Call print(cerr) to be called from the debugger.
163 } // End llvm namespace