i386: Allow some V32HImode and V64QImode permutations even without AVX512BW [PR80355]

i386: Allow some V32HImode and V64QImode permutations even without AVX512BW [PR80355]

When working on the PR, I've noticed we generate terrible code for
V32HImode or V64QImode permutations for -mavx512f -mno-avx512bw.
Generally we can't do much with such permutations, but since PR68655
we can handle at least some, those expressible using V16SImode or V8DImode
permutations, but that wasn't reachable, because ix86_vectorize_vec_perm_const
didn't even try, it said without TARGET_AVX512BW it can't do anything, and
with it can do everything, no d.testing_p attempts.

This patch makes it try it for TARGET_AVX512F && !TARGET_AVX512BW.

The first hunk is to avoid ICE, expand_vec_perm_even_odd_1 asserts d->vmode
isn't V32HImode because expand_vec_perm_1 for AVX512BW handles already
all permutations, but when we let it through without !TARGET_AVX512BW,
expand_vec_perm_1 doesn't handle it.

If we want, that hunk can be dropped if we implement in
expand_vec_perm_even_odd_1 and its helper the even permutation as
vpmovdw + vpmovdw + vinserti64x4 and odd permutation as
vpsrld $16 + vpsrld $16 + vpmovdw + vpmovdw + vinserti64x4.

2021-08-10  Jakub Jelinek  <jakub@redhat.com>

	PR target/80355
	* config/i386/i386-expand.c (expand_vec_perm_even_odd): Return false
	for V32HImode if !TARGET_AVX512BW.
	(ix86_vectorize_vec_perm_const) <case E_V32HImode, case E_V64QImode>:
	If !TARGET_AVX512BW and TARGET_AVX512F and d.testing_p, don't fail
	early, but actually check the permutation.

	* gcc.target/i386/avx512f-pr80355-2.c: New test.