Method loadInstrSeq

lib/loader/ast/instruction.cpp:126–229

Load instruction sequence. See "include/loader/loader.h".

// Load instruction sequence. See "include/loader/loader.h".
Expect<AST::InstrVec> Loader::loadInstrSeq(std::optional<uint64_t> SizeBound) {
  AST::InstrVec Instrs;
  std::vector<std::pair<OpCode, uint32_t>> BlockStack;
  uint32_t Cnt = 0;
  bool IsReachEnd = false;
  // Read opcode until the End code of the top block.
  do {
    // Read the opcode and check for errors.
    uint64_t Offset = FMgr.getOffset();
    EXPECTED_TRY(OpCode Code, loadOpCode().map_error([this](auto E) {
      return logLoadError(E, FMgr.getLastOffset(), ASTNodeAttr::Instruction);
    }));

    // Check with proposals.
    if (auto Res = Conf.isInstrNeedProposal(Code); unlikely(!!Res)) {
      return logNeedProposal(ErrCode::Value::IllegalOpCode, Res.value(), Offset,
                             ASTNodeAttr::Instruction);
    }

    auto logIllegalOpCode = [this, &Offset,
                             &SizeBound]() -> Unexpected<ErrCode> {
      if (SizeBound.has_value() && FMgr.getOffset() > SizeBound.value()) {
        return logLoadError(ErrCode::Value::ENDCodeExpected, Offset,
                            ASTNodeAttr::Instruction);
      } else {
        return logLoadError(ErrCode::Value::IllegalOpCode, Offset,
                            ASTNodeAttr::Instruction);
      }
    };

    // Process the instruction that contains a block.
    switch (Code) {
    case OpCode::Block:
    case OpCode::Loop:
    case OpCode::If:
    case OpCode::Try_table:
      BlockStack.emplace_back(Code, Cnt);
      break;
    case OpCode::Else: {
      if (BlockStack.size() == 0 || BlockStack.back().first != OpCode::If) {
        // An Else instruction appeared outside the If-block.
        return logIllegalOpCode();
      }
      uint32_t Pos = BlockStack.back().second;
      if (Instrs[Pos].getJumpElse() > 0) {
        // An Else instruction appeared before in this If-block.
        return logIllegalOpCode();
      }
      Instrs[Pos].setJumpElse(Cnt - Pos);
      break;
    }
    default:
      break;
    }

    // Create the instruction node and load contents.
    Instrs.emplace_back(Code, static_cast<uint32_t>(Offset));
    EXPECTED_TRY(loadInstruction(Instrs.back()));