code: public void genStat(JCTree tree, Env<GenContext> env, int crtFlags) {
          if (!genCrt) {
              genStat(tree, env);
              return;
          }
          int startpc = code.curCP();
          genStat(tree, env);
          if (tree.hasTag(Tag.BLOCK)) crtFlags |= CRT_BLOCK;
          code.crt.put(tree, crtFlags, startpc, code.curCP());
      }
docs: Derived visitor method: check whether CharacterRangeTable
  should be emitted, if so, put a new entry into CRTable
  and call method to generate bytecode.
  If not, just call method to generate bytecode.
  @see    #genStat(JCTree, Env)
  
  @param  tree     The tree to be visited.
  @param  env      The environment to use.
  @param  crtFlags The CharacterRangeTable flags
  indicating type of the entry.