re PR target/47440 (Use LCM for vzeroupper insertion)
PR target/47440
* config/i386/i386.c (check_avx256_stores): Remove.
(ix86_check_avx256_register): New.
(ix86_avx_u128_mode_needed): Use ix86_check_avx256_register.
Check the whole RTX for 256bit registers using for_each_rtx.
(ix86_check_avx_stores): New.
(ix86_avx_u128_mode_after): Change mode of CALL RTX to AVX_U128_CLEAN
if there are no 256bit registers used in the function return register.
(ix86_avx_u128_mode_entry): Use ix86_check_avx256_register.
(ix86_avx_u128_mode_exit): Ditto.