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#ifndef LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H 10#define LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H 11 12#include "llvm-c/Disassembler.h" 13#include "llvm/MC/MCDisassembler/MCSymbolizer.h" 14#include "llvm/Support/DataTypes.h" 15 16namespace llvm { 17 18template <typename T> class ArrayRef; 19class MCInst; 20class MCSubtargetInfo; 21class raw_ostream; 22class MCContext; 23 24/// Superclass for all disassemblers. Consumes a memory region and provides an 25/// array of assembly instructions. 26class MCDisassembler { 27public: 28 /// Ternary decode status. Most backends will just use Fail and 29 /// Success, however some have a concept of an instruction with 30 /// understandable semantics but which is architecturally 31 /// incorrect. An example of this is ARM UNPREDICTABLE instructions 32 /// which are disassemblable but cause undefined behaviour. 33 /// 34 /// Because it makes sense to disassemble these instructions, there 35 /// is a "soft fail" failure mode that indicates the MCInst& is 36 /// valid but architecturally incorrect. 37 /// 38 /// The enum numbers are deliberately chosen such that reduction 39 /// from Success->SoftFail ->Fail can be done with a simple 40 /// bitwise-AND: 41 /// 42 /// LEFT & TOP = | Success Unpredictable Fail 43 /// --------------+----------------------------------- 44 /// Success | Success Unpredictable Fail 45 /// Unpredictable | Unpredictable Unpredictable Fail 46 /// Fail | Fail Fail Fail 47 /// 48 /// An easy way of encoding this is as 0b11, 0b01, 0b00 for 49 /// Success, SoftFail, Fail respectively. 50 enum DecodeStatus { 51 Fail = 0, 52 SoftFail = 1, 53 Success = 3 54 }; 55 56 MCDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx) 57 : Ctx(Ctx), STI(STI), Symbolizer(), CommentStream(nullptr) {} 58 59 virtual ~MCDisassembler(); 60 61 /// Returns the disassembly of a single instruction. 62 /// 63 /// \param Instr - An MCInst to populate with the contents of the 64 /// instruction. 65 /// \param Size - A value to populate with the size of the instruction, or 66 /// the number of bytes consumed while attempting to decode 67 /// an invalid instruction. 68 /// \param Address - The address, in the memory space of region, of the first 69 /// byte of the instruction. 70 /// \param VStream - The stream to print warnings and diagnostic messages on. 71 /// \param CStream - The stream to print comments and annotations on. 72 /// \return - MCDisassembler::Success if the instruction is valid, 73 /// MCDisassembler::SoftFail if the instruction was 74 /// disassemblable but invalid, 75 /// MCDisassembler::Fail if the instruction was invalid. 76 virtual DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size, 77 ArrayRef<uint8_t> Bytes, uint64_t Address, 78 raw_ostream &VStream, 79 raw_ostream &CStream) const = 0; 80 81private: 82 MCContext &Ctx; 83 84protected: 85 // Subtarget information, for instruction decoding predicates if required. 86 const MCSubtargetInfo &STI; 87 std::unique_ptr<MCSymbolizer> Symbolizer; 88 89public: 90 // Helpers around MCSymbolizer 91 bool tryAddingSymbolicOperand(MCInst &Inst, 92 int64_t Value, 93 uint64_t Address, bool IsBranch, 94 uint64_t Offset, uint64_t InstSize) const; 95 96 void tryAddingPcLoadReferenceComment(int64_t Value, uint64_t Address) const; 97 98 /// Set \p Symzer as the current symbolizer. 99 /// This takes ownership of \p Symzer, and deletes the previously set one. 100 void setSymbolizer(std::unique_ptr<MCSymbolizer> Symzer); 101 102 MCContext& getContext() const { return Ctx; } 103 104 const MCSubtargetInfo& getSubtargetInfo() const { return STI; } 105 106 // Marked mutable because we cache it inside the disassembler, rather than 107 // having to pass it around as an argument through all the autogenerated code. 108 mutable raw_ostream *CommentStream; 109}; 110 111} // namespace llvm 112 113#endif 114