void InterpreterMacroAssembler::get_cache_index_at_bcp(Register index,
                                                       int bcp_offset,
                                                       size_t index_size) {

  {- -------------------------------------------
  (1) (assert)
      ---------------------------------------- -}

      assert(bcp_offset > 0, "bcp is still pointing to start of bytecode");

  {- -------------------------------------------
  (1) コード生成:
      「バイトコード命令中に埋め込まれている index 情報を取得する」
      (なお, 引数で指定された大きさ(index_size) に応じて, 適切な大きさ分だけロードするコードを生成)
      ---------------------------------------- -}

      if (index_size == sizeof(u2)) {
        load_unsigned_short(index, Address(r13, bcp_offset));
      } else if (index_size == sizeof(u4)) {
        assert(EnableInvokeDynamic, "giant index used only for JSR 292");
        movl(index, Address(r13, bcp_offset));
        // Check if the secondary index definition is still ~x, otherwise
        // we have to change the following assembler code to calculate the
        // plain index.
        assert(constantPoolCacheOopDesc::decode_secondary_index(~123) == 123, "else change next line");
        notl(index);  // convert to plain index
      } else if (index_size == sizeof(u1)) {
        assert(EnableInvokeDynamic, "tiny index used only for JSR 292");
        load_unsigned_byte(index, Address(r13, bcp_offset));
      } else {
        ShouldNotReachHere();
      }
    }