gcc/ChangeLog:

2020-MM-DD  Kewen Lin  <linkw@gcc.gnu.org>

	* doc/md.texi (lenload@var{m}@var{n}): Document.
	(lenstore@var{m}@var{n}): Likewise.
	* internal-fn.c (len_load_direct): New macro.
	(len_store_direct): Likewise.
	(expand_len_load_optab_fn): Likewise.
	(expand_len_store_optab_fn): Likewise.
	(direct_len_load_optab_supported_p): Likewise.
	(direct_len_store_optab_supported_p): Likewise.
	(internal_load_fn_p): Handle IFN_LEN_LOAD.
	(internal_store_fn_p): Handle IFN_LEN_STORE.
	(internal_fn_stored_value_index): Handle IFN_LEN_STORE.
	* internal-fn.def (LEN_LOAD): New internal function.
	(LEN_STORE): Likewise.
	* optabs.def (lenload_optab, lenstore_optab): New optab.