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//===- llvm/MC/MCDisassembler.h - Disassembler interface --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H
#define LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H
#include "llvm/MC/MCDisassembler/MCSymbolizer.h"
#include <cstdint>
#include <memory>
namespace llvm {
template <typename T> class ArrayRef;
class StringRef;
class MCContext;
class MCInst;
class MCSubtargetInfo;
class raw_ostream;
/// Superclass for all disassemblers. Consumes a memory region and provides an
/// array of assembly instructions.
class MCDisassembler {
public:
/// Ternary decode status. Most backends will just use Fail and
/// Success, however some have a concept of an instruction with
/// understandable semantics but which is architecturally
/// incorrect. An example of this is ARM UNPREDICTABLE instructions
/// which are disassemblable but cause undefined behaviour.
///
/// Because it makes sense to disassemble these instructions, there
/// is a "soft fail" failure mode that indicates the MCInst& is
/// valid but architecturally incorrect.
///
/// The enum numbers are deliberately chosen such that reduction
/// from Success->SoftFail ->Fail can be done with a simple
/// bitwise-AND:
///
/// LEFT & TOP = | Success Unpredictable Fail
/// --------------+-----------------------------------
/// Success | Success Unpredictable Fail
/// Unpredictable | Unpredictable Unpredictable Fail
/// Fail | Fail Fail Fail
///
/// An easy way of encoding this is as 0b11, 0b01, 0b00 for
/// Success, SoftFail, Fail respectively.
enum DecodeStatus {
Fail = 0,
SoftFail = 1,
Success = 3
};
MCDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx)
: Ctx(Ctx), STI(STI) {}
virtual ~MCDisassembler();
/// Returns the disassembly of a single instruction.
///
/// \param Instr - An MCInst to populate with the contents of the
/// instruction.
/// \param Size - A value to populate with the size of the instruction, or
/// the number of bytes consumed while attempting to decode
/// an invalid instruction.
/// \param Address - The address, in the memory space of region, of the first
/// byte of the instruction.
/// \param Bytes - A reference to the actual bytes of the instruction.
/// \param CStream - The stream to print comments and annotations on.
/// \return - MCDisassembler::Success if the instruction is valid,
/// MCDisassembler::SoftFail if the instruction was
/// disassemblable but invalid,
/// MCDisassembler::Fail if the instruction was invalid.
virtual DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
ArrayRef<uint8_t> Bytes, uint64_t Address,
raw_ostream &CStream) const = 0;
/// May parse any prelude that precedes instructions after the start of a
/// symbol. Needed for some targets, e.g. WebAssembly.
///
/// \param Name - The name of the symbol.
/// \param Size - The number of bytes consumed.
/// \param Address - The address, in the memory space of region, of the first
/// byte of the symbol.
/// \param Bytes - A reference to the actual bytes at the symbol location.
/// \param CStream - The stream to print comments and annotations on.
/// \return - MCDisassembler::Success if the bytes are valid,
/// MCDisassembler::Fail if the bytes were invalid.
virtual DecodeStatus onSymbolStart(StringRef Name, uint64_t &Size,
ArrayRef<uint8_t> Bytes, uint64_t Address,
raw_ostream &CStream) const;
private:
MCContext &Ctx;
protected:
// Subtarget information, for instruction decoding predicates if required.
const MCSubtargetInfo &STI;
std::unique_ptr<MCSymbolizer> Symbolizer;
public:
// Helpers around MCSymbolizer
bool tryAddingSymbolicOperand(MCInst &Inst,
int64_t Value,
uint64_t Address, bool IsBranch,
uint64_t Offset, uint64_t InstSize) const;
void tryAddingPcLoadReferenceComment(int64_t Value, uint64_t Address) const;
/// Set \p Symzer as the current symbolizer.
/// This takes ownership of \p Symzer, and deletes the previously set one.
void setSymbolizer(std::unique_ptr<MCSymbolizer> Symzer);
MCContext& getContext() const { return Ctx; }
const MCSubtargetInfo& getSubtargetInfo() const { return STI; }
// Marked mutable because we cache it inside the disassembler, rather than
// having to pass it around as an argument through all the autogenerated code.
mutable raw_ostream *CommentStream = nullptr;
};
} // end namespace llvm
#endif // LLVM_MC_MCDISASSEMBLER_MCDISASSEMBLER_H
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