gcc/testsuite/selftests/note_insn_basic_block.rtl

(function "example_of_note"
  (insn-chain
    (block 2
      (edge-from entry (flags "FALLTHRU"))
      (cnote 1 [bb 2] NOTE_INSN_BASIC_BLOCK)
      (edge-to exit (flags "FALLTHRU"))
    ) ;; block 2
  ) ;; insn-chain
) ;; function