re PR target/68655 (SSE2 cannot vec_perm of low and high part)

re PR target/68655 (SSE2 cannot vec_perm of low and high part)

	PR target/68655
	* config/i386/i386.c (canonicalize_vector_int_perm): New function.
	(expand_vec_perm_1): Use it and recurse if everything else
	failed.  Use nd.perm instead of perm2.
	(expand_vec_perm_even_odd_1): If testing_p, use gen_raw_REG
	instead of gen_lowpart for the target.
	(ix86_expand_vec_perm_const_1): Use canonicalize_vector_int_perm
	and recurse if everything else failed.

	* gcc.dg/torture/vshuf-4.inc (TESTS): Add one extra test.
	* gcc.dg/torture/vshuf-4.inc (TESTS): Add two extra tests.

From-SVN: r231247