//===- 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/ADT/StringRef.h"
#include "llvm/BinaryFormat/XCOFF.h"
#include "llvm/MC/MCDisassembler/MCSymbolizer.h"
#include <cstdint>
#include <memory>
#include <vector>
namespace llvm {
struct XCOFFSymbolInfoTy {
std::optional<XCOFF::StorageMappingClass> StorageMappingClass;
std::optional<uint32_t> Index;
bool IsLabel = false;
bool operator<(const XCOFFSymbolInfoTy &SymInfo) const;
};
struct SymbolInfoTy {
uint64_t Addr;
StringRef Name;
// XCOFF uses XCOFFSymInfo. Other targets use Type.
XCOFFSymbolInfoTy XCOFFSymInfo;
uint8_t Type;
private:
bool IsXCOFF;
bool HasType;
public:
SymbolInfoTy(uint64_t Addr, StringRef Name,
std::optional<XCOFF::StorageMappingClass> Smc,
std::optional<uint32_t> Idx, bool Label)
: Addr(Addr), Name(Name), XCOFFSymInfo{Smc, Idx, Label}, Type(0),
IsXCOFF(true), HasType(false) {}
SymbolInfoTy(uint64_t Addr, StringRef Name, uint8_t Type,
bool IsXCOFF = false)
: Addr(Addr), Name(Name), Type(Type), IsXCOFF(IsXCOFF), HasType(true) {}
bool isXCOFF() const { return IsXCOFF; }
private:
friend bool operator<(const SymbolInfoTy &P1, const SymbolInfoTy &P2) {
assert((P1.IsXCOFF == P2.IsXCOFF && P1.HasType == P2.HasType) &&
"The value of IsXCOFF and HasType in P1 and P2 should be the same "
"respectively.");
if (P1.IsXCOFF && P1.HasType)
return std::tie(P1.Addr, P1.Type, P1.Name) <
std::tie(P2.Addr, P2.Type, P2.Name);
if (P1.IsXCOFF)
return std::tie(P1.Addr, P1.XCOFFSymInfo, P1.Name) <
std::tie(P2.Addr, P2.XCOFFSymInfo, P2.Name);
return std::tie(P1.Addr, P1.Name, P1.Type) <
std::tie(P2.Addr, P2.Name, P2.Type);
}
};
using SectionSymbolsTy = std::vector<SymbolInfoTy>;
template <typename T> class ArrayRef;
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;
/// Used to perform separate target specific disassembly for a particular
/// symbol. May parse any prelude that precedes instructions after the
/// start of a symbol, or the entire symbol.
/// This is used for example by WebAssembly to decode preludes.
///
/// Base implementation returns std::nullopt. So all targets by default ignore
/// to treat symbols separately.
///
/// \param Symbol - 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 bytes are decoded
/// successfully. Size must hold the number of bytes that
/// were decoded.
/// - MCDisassembler::Fail if the bytes are invalid. Size
/// must hold the number of bytes that were decoded before
/// failing. The target must print nothing. This can be
/// done by buffering the output if needed.
/// - std::nullopt if the target doesn't want to handle the
/// symbol separately. Value of Size is ignored in this
/// case.
virtual std::optional<DecodeStatus>
onSymbolStart(SymbolInfoTy &Symbol, uint64_t &Size, ArrayRef<uint8_t> Bytes,
uint64_t Address, raw_ostream &CStream) const;
// TODO:
// Implement similar hooks that can be used at other points during
// disassembly. Something along the following lines:
// - onBeforeInstructionDecode()
// - onAfterInstructionDecode()
// - onSymbolEnd()
// It should help move much of the target specific code from llvm-objdump to
// respective target disassemblers.
/// Suggest a distance to skip in a buffer of data to find the next
/// place to look for the start of an instruction. For example, if
/// all instructions have a fixed alignment, this might advance to
/// the next multiple of that alignment.
///
/// If not overridden, the default is 1.
///
/// \param Address - The address, in the memory space of region, of the
/// starting point (typically the first byte of something
/// that did not decode as a valid instruction at all).
/// \param Bytes - A reference to the actual bytes at Address. May be
/// needed in order to determine the width of an
/// unrecognized instruction (e.g. in Thumb this is a simple
/// consistent criterion that doesn't require knowing the
/// specific instruction). The caller can pass as much data
/// as they have available, and the function is required to
/// make a reasonable default choice if not enough data is
/// available to make a better one.
/// \return - A number of bytes to skip. Must always be greater than
/// zero. May be greater than the size of Bytes.
virtual uint64_t suggestBytesToSkip(ArrayRef<uint8_t> Bytes,
uint64_t Address) 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 OpSize,
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