LLVM  8.0.0svn
MCDisassembler.h
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1 //===- llvm/MC/MCDisassembler.h - Disassembler interface --------*- 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 #ifndef LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H
11 #define LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H
12 
14 #include <cstdint>
15 #include <memory>
16 
17 namespace llvm {
18 
19 template <typename T> class ArrayRef;
20 class MCContext;
21 class MCInst;
22 class MCSubtargetInfo;
23 class raw_ostream;
24 
25 /// Superclass for all disassemblers. Consumes a memory region and provides an
26 /// array of assembly instructions.
28 public:
29  /// Ternary decode status. Most backends will just use Fail and
30  /// Success, however some have a concept of an instruction with
31  /// understandable semantics but which is architecturally
32  /// incorrect. An example of this is ARM UNPREDICTABLE instructions
33  /// which are disassemblable but cause undefined behaviour.
34  ///
35  /// Because it makes sense to disassemble these instructions, there
36  /// is a "soft fail" failure mode that indicates the MCInst& is
37  /// valid but architecturally incorrect.
38  ///
39  /// The enum numbers are deliberately chosen such that reduction
40  /// from Success->SoftFail ->Fail can be done with a simple
41  /// bitwise-AND:
42  ///
43  /// LEFT & TOP = | Success Unpredictable Fail
44  /// --------------+-----------------------------------
45  /// Success | Success Unpredictable Fail
46  /// Unpredictable | Unpredictable Unpredictable Fail
47  /// Fail | Fail Fail Fail
48  ///
49  /// An easy way of encoding this is as 0b11, 0b01, 0b00 for
50  /// Success, SoftFail, Fail respectively.
51  enum DecodeStatus {
52  Fail = 0,
53  SoftFail = 1,
54  Success = 3
55  };
56 
58  : Ctx(Ctx), STI(STI) {}
59 
60  virtual ~MCDisassembler();
61 
62  /// Returns the disassembly of a single instruction.
63  ///
64  /// \param Instr - An MCInst to populate with the contents of the
65  /// instruction.
66  /// \param Size - A value to populate with the size of the instruction, or
67  /// the number of bytes consumed while attempting to decode
68  /// an invalid instruction.
69  /// \param Address - The address, in the memory space of region, of the first
70  /// byte of the instruction.
71  /// \param Bytes - A reference to the actual bytes of the instruction.
72  /// \param VStream - The stream to print warnings and diagnostic messages on.
73  /// \param CStream - The stream to print comments and annotations on.
74  /// \return - MCDisassembler::Success if the instruction is valid,
75  /// MCDisassembler::SoftFail if the instruction was
76  /// disassemblable but invalid,
77  /// MCDisassembler::Fail if the instruction was invalid.
78  virtual DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
79  ArrayRef<uint8_t> Bytes, uint64_t Address,
80  raw_ostream &VStream,
81  raw_ostream &CStream) const = 0;
82 
83 private:
84  MCContext &Ctx;
85 
86 protected:
87  // Subtarget information, for instruction decoding predicates if required.
89  std::unique_ptr<MCSymbolizer> Symbolizer;
90 
91 public:
92  // Helpers around MCSymbolizer
94  int64_t Value,
95  uint64_t Address, bool IsBranch,
96  uint64_t Offset, uint64_t InstSize) const;
97 
98  void tryAddingPcLoadReferenceComment(int64_t Value, uint64_t Address) const;
99 
100  /// Set \p Symzer as the current symbolizer.
101  /// This takes ownership of \p Symzer, and deletes the previously set one.
102  void setSymbolizer(std::unique_ptr<MCSymbolizer> Symzer);
103 
104  MCContext& getContext() const { return Ctx; }
105 
106  const MCSubtargetInfo& getSubtargetInfo() const { return STI; }
107 
108  // Marked mutable because we cache it inside the disassembler, rather than
109  // having to pass it around as an argument through all the autogenerated code.
110  mutable raw_ostream *CommentStream = nullptr;
111 };
112 
113 } // end namespace llvm
114 
115 #endif // LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H
This class represents lattice values for constants.
Definition: AllocatorList.h:24
DecodeStatus
Ternary decode status.
Superclass for all disassemblers.
raw_ostream * CommentStream
bool tryAddingSymbolicOperand(MCInst &Inst, int64_t Value, uint64_t Address, bool IsBranch, uint64_t Offset, uint64_t InstSize) const
void setSymbolizer(std::unique_ptr< MCSymbolizer > Symzer)
Set Symzer as the current symbolizer.
std::unique_ptr< MCSymbolizer > Symbolizer
MCDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx)
Context object for machine code objects.
Definition: MCContext.h:63
const MCSubtargetInfo & STI
Instances of this class represent a single low-level machine instruction.
Definition: MCInst.h:161
void tryAddingPcLoadReferenceComment(int64_t Value, uint64_t Address) const
virtual ~MCDisassembler()
MCContext & getContext() const
Generic base class for all target subtargets.
uint32_t Size
Definition: Profile.cpp:47
LLVM Value Representation.
Definition: Value.h:73
const MCSubtargetInfo & getSubtargetInfo() const
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:46
virtual DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size, ArrayRef< uint8_t > Bytes, uint64_t Address, raw_ostream &VStream, raw_ostream &CStream) const =0
Returns the disassembly of a single instruction.