https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94866
--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Hongtao.liu from comment #6)
> > So, the compiler still expects vec_concat/vec_select patterns to be present.
>
> v2df foo_v2df (v2df x)
> {
> return __builtin_shuffle (x, (v2df) { 0, 0 }, (v2di) { 0, 2 });
> }
>
> The testcase is not a typical vec_merge case, for vec_merge, the shuffle
> index should be {0, 3}. Here it happened to be a vec_merge because the
> second vector is all zero. And yes for this case, we still need to
> vec_concat:vec_select pattern.
I guess the original patch is the way to go then.
