re PR target/91560 (Try harder for AVX non-AVX2 cross-lane permutations)

re PR target/91560 (Try harder for AVX non-AVX2 cross-lane permutations)

	PR target/91560
	* config/i386/i386-expand.c (expand_vec_perm_movs,
	expand_vec_perm_blend, expand_vec_perm_vpermil,
	expand_vec_perm_pshufb, expand_vec_perm_1,
	expand_vec_perm_pshuflw_pshufhw, expand_vec_perm_palignr,
	expand_vec_perm_interleave2, expand_vec_perm_vpermq_perm_1,
	expand_vec_perm_vperm2f128, expand_vec_perm_interleave3,
	expand_vec_perm_vperm2f128_vblend, expand_vec_perm_2vperm2f128_vshuf,
	expand_vec_perm_even_odd, expand_vec_perm_broadcast): Adjust function
	comments - replace ix86_expand_vec_perm_builtin_1 with
	ix86_expand_vec_perm_const_1.
	(expand_vec_perm2_vperm2f128_vblend): New function.
	(ix86_expand_vec_perm_const_1): New forward declaration.  Call
	expand_vec_perm2_vperm2f128_vblend as last resort.
	(canonicalize_perm): Formatting fix.

	* gcc.dg/torture/vshuf-8.inc: Add two further permutations.

From-SVN: r275027