1//===-- llvm/CodeGen/DwarfExpression.h - Dwarf Compile Unit ---*- C++ -*--===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains support for writing dwarf compile unit.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFEXPRESSION_H
15#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFEXPRESSION_H
16
17#include "llvm/IR/DebugInfo.h"
18#include "llvm/Support/DataTypes.h"
19
20namespace llvm {
21
22class AsmPrinter;
23class ByteStreamer;
24class TargetRegisterInfo;
25class DwarfUnit;
26class DIELoc;
27
28/// Base class containing the logic for constructing DWARF expressions
29/// independently of whether they are emitted into a DIE or into a .debug_loc
30/// entry.
31class DwarfExpression {
32protected:
33  // Various convenience accessors that extract things out of AsmPrinter.
34  const TargetRegisterInfo &TRI;
35  unsigned DwarfVersion;
36
37public:
38  DwarfExpression(const TargetRegisterInfo &TRI,
39                  unsigned DwarfVersion)
40    : TRI(TRI), DwarfVersion(DwarfVersion) {}
41  virtual ~DwarfExpression() {}
42
43  /// Output a dwarf operand and an optional assembler comment.
44  virtual void EmitOp(uint8_t Op, const char *Comment = nullptr) = 0;
45  /// Emit a raw signed value.
46  virtual void EmitSigned(int64_t Value) = 0;
47  /// Emit a raw unsigned value.
48  virtual void EmitUnsigned(uint64_t Value) = 0;
49  /// Return whether the given machine register is the frame register in the
50  /// current function.
51  virtual bool isFrameRegister(unsigned MachineReg) = 0;
52
53  /// Emit a dwarf register operation.
54  void AddReg(int DwarfReg, const char *Comment = nullptr);
55  /// Emit an (double-)indirect dwarf register operation.
56  void AddRegIndirect(int DwarfReg, int Offset, bool Deref = false);
57
58  /// Emit a dwarf register operation for describing
59  /// - a small value occupying only part of a register or
60  /// - a register representing only part of a value.
61  void AddOpPiece(unsigned SizeInBits, unsigned OffsetInBits = 0);
62  /// Emit a shift-right dwarf expression.
63  void AddShr(unsigned ShiftBy);
64
65  /// Emit an indirect dwarf register operation for the given machine register.
66  /// \return false if no DWARF register exists for MachineReg.
67  bool AddMachineRegIndirect(unsigned MachineReg, int Offset = 0);
68
69  /// \brief Emit a partial DWARF register operation.
70  /// \param MachineReg        the register
71  /// \param PieceSizeInBits   size and
72  /// \param PieceOffsetInBits offset of the piece in bits, if this is one
73  ///                          piece of an aggregate value.
74  ///
75  /// If size and offset is zero an operation for the entire
76  /// register is emitted: Some targets do not provide a DWARF
77  /// register number for every register.  If this is the case, this
78  /// function will attempt to emit a DWARF register by emitting a
79  /// piece of a super-register or by piecing together multiple
80  /// subregisters that alias the register.
81  ///
82  /// \return false if no DWARF register exists for MachineReg.
83  bool AddMachineRegPiece(unsigned MachineReg, unsigned PieceSizeInBits = 0,
84                          unsigned PieceOffsetInBits = 0);
85
86  /// Emit a signed constant.
87  void AddSignedConstant(int Value);
88  /// Emit an unsigned constant.
89  void AddUnsignedConstant(unsigned Value);
90
91  /// \brief Emit an entire expression on top of a machine register location.
92  ///
93  /// \param PieceOffsetInBits If this is one piece out of a fragmented
94  /// location, this is the offset of the piece inside the entire variable.
95  /// \return false if no DWARF register exists for MachineReg.
96  bool AddMachineRegExpression(const DIExpression *Expr, unsigned MachineReg,
97                               unsigned PieceOffsetInBits = 0);
98  /// Emit a the operations remaining the DIExpressionIterator I.
99  /// \param PieceOffsetInBits If this is one piece out of a fragmented
100  /// location, this is the offset of the piece inside the entire variable.
101  void AddExpression(DIExpression::expr_op_iterator I,
102                     DIExpression::expr_op_iterator E,
103                     unsigned PieceOffsetInBits = 0);
104};
105
106/// DwarfExpression implementation for .debug_loc entries.
107class DebugLocDwarfExpression : public DwarfExpression {
108  ByteStreamer &BS;
109
110public:
111  DebugLocDwarfExpression(const TargetRegisterInfo &TRI,
112                          unsigned DwarfVersion, ByteStreamer &BS)
113    : DwarfExpression(TRI, DwarfVersion), BS(BS) {}
114
115  void EmitOp(uint8_t Op, const char *Comment = nullptr) override;
116  void EmitSigned(int64_t Value) override;
117  void EmitUnsigned(uint64_t Value) override;
118  bool isFrameRegister(unsigned MachineReg) override;
119};
120
121/// DwarfExpression implementation for singular DW_AT_location.
122class DIEDwarfExpression : public DwarfExpression {
123const AsmPrinter ≈
124  DwarfUnit &DU;
125  DIELoc ¨
126
127public:
128  DIEDwarfExpression(const AsmPrinter &AP, DwarfUnit &DU, DIELoc &DIE);
129  void EmitOp(uint8_t Op, const char *Comment = nullptr) override;
130  void EmitSigned(int64_t Value) override;
131  void EmitUnsigned(uint64_t Value) override;
132  bool isFrameRegister(unsigned MachineReg) override;
133};
134}
135
136#endif
137