revng-revng/lib/Lift/InstructionTranslator.h

#pragma once

//
// This file is distributed under the MIT License. See LICENSE.md for details.
//

#include <cstdint>
#include <map>
#include <vector>

#include "llvm/ADT/SmallSet.h"
#include "llvm/Pass.h"

#include "revng/Lift/LibTcg.h"
#include "revng/Model/ProgramCounterHandler.h"
#include "revng/Support/IRBuilder.h"

#include "JumpTargetManager.h"

// Forward declarations
namespace llvm {
class BasicBlock;
class CallInst;
class Function;
class MDNode;
class Module;
} // namespace llvm

class JumpTargetManager;
class VariableManager;

/// Expands a PTC instruction to LLVM IR
class InstructionTranslator {
public:
  using LabeledBlocksMap = std::map<std::string, llvm::BasicBlock *>;

  /// \param Builder the revng::IRBuilder to be used to create the translated
  ///                code.
  /// \param Variables reference to the VariableManager.
  /// \param JumpTargets reference to the JumpTargetManager.
  /// \param Blocks reference to a `vector` of `BasicBlock`s used to keep track
  ///        on which `BasicBlock`s the InstructionTranslator worked on, for
  ///        further processing.
  InstructionTranslator(LibTcg &LibTcg,
                        revng::IRBuilder &Builder,
                        VariableManager &Variables,
                        JumpTargetManager &JumpTargets,
                        std::vector<llvm::BasicBlock *> Blocks,
                        bool EndiannessMismatch,
                        ProgramCounterHandler *PCH);

  // Emit a call to newpc
  llvm::CallInst *
  emitNewPCCall(revng::IRBuilder &Builder, MetaAddress PC, uint64_t Size) const;

  /// Result status of the translation of a PTC opcode
  enum TranslationResult {
    Abort, ///< An error occurred during translation, call abort and stop
    Stop, ///< Do not proceed with translation
    Success ///< The translation was successful
  };

  /// Handle a new instruction from the input code
  ///
  /// \param Instr the newly met PTCInstruction;
  /// \param Next the PTCInstruction immediately following \p Instr,
  ///             or `nullptr` if \p Instr is the last instruction
  ///             translated by libtinycode.
  /// \param EndPC PC of the instruction coming after the next
  ///              instruction after the last translated by
  ///              libtinycode.
  /// \param IsFirst true, if \p Instr is the first instruction
  ///                translated by libtinycode.
  ///
  /// \return a tuple with 4 entries: the
  ///         InstructionTranslator::TranslationResult, an `MDNode` containing
  ///         the disassembled instruction and the value of the PC and two
  ///         `MetaAddress` representing the current and next PC.
  // TODO: rename to newPC
  // TODO: the signature of this function is ugly
  std::tuple<TranslationResult, MetaAddress, MetaAddress>
  newInstruction(LibTcgInstruction *Instr,
                 LibTcgInstruction *Next,
                 MetaAddress StartPC,
                 MetaAddress EndPC,
                 bool IsFirst);

  /// Translate an ordinary instruction
  ///
  /// \param Instr the instruction to translate.
  /// \param PC the PC associated to \p Instr.
  /// \param SinceInstructionStart index of the TCG instruction since the last
  /// input instruction has started. \param NextPC the PC associated to
  /// instruction after \p Instr.
  ///
  /// \return see InstructionTranslator::TranslationResult.
  TranslationResult translate(LibTcgInstruction *Instr,
                              MetaAddress PC,
                              unsigned SinceInstructionStart,
                              MetaAddress NextPC);

  /// Translate a call to an helper
  ///
  /// \param Instr the PTCInstruction of the call to the helper.
  /// \param PC the PC associated to \p Instr.
  /// \param SinceInstructionStart index of the TCG instruction since the last
  /// input instruction has started.
  ///
  /// \return see InstructionTranslator::TranslationResult.
  TranslationResult translateCall(LibTcgInstruction *Instr,
                                  MetaAddress PC,
                                  unsigned SinceInstructionStart);

  /// Handle calls to `newPC` marker and emit coverage information
  void finalizeNewPCMarkers();

  /// Notifies InstructionTranslator about a new PTC translation
  void reset() { LabeledBasicBlocks.clear(); }

  /// Preprocess the translated instructions
  ///
  /// Check if the translated code contains a delay slot and return a blacklist
  /// of the LIBTCG_op_insn_start instructions that have to be
  /// ignored to merge the delay slot into the branch instruction.
  llvm::SmallSet<unsigned, 1> preprocess(const LibTcgTranslationBlock &TB);

  void registerDirectJumps();

private:
  std::optional<std::vector<llvm::Value *>>
  translateOpcode(LibTcgOpcode Opcode,
                  std::vector<LibTcgArgument> ConstArguments,
                  std::vector<llvm::Value *> InArguments);

  int64_t getEnvOffset(llvm::Instruction &I, int64_t Offset) const;

  void handleExitTB();

private:
  LibTcg &LibTcg;
  revng::IRBuilder &Builder;
  VariableManager &Variables;
  JumpTargetManager &JumpTargets;
  std::map<std::string, llvm::BasicBlock *> LabeledBasicBlocks;
  std::vector<llvm::BasicBlock *> Blocks;
  llvm::Module &TheModule;

  llvm::Function *TheFunction;

  bool EndiannessMismatch;

  llvm::Function *NewPCMarker;

  MetaAddress LastPC;

  ProgramCounterHandler *PCH = nullptr;
  llvm::SmallVector<llvm::BasicBlock *, 4> ExitBlocks;
};