[Bug target/78102] [5/6/7 regression] GCC refuses to generate PCMPEQQ instruction for SSE4.1

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78102

--- Comment #10 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #8)

> How would it expand?  Repeat all the vector condition/comparison lowering
> code from tree-vect-generic.c on RTL?  Compared to that I think it would be
> simpler to handle it in ix86_expand_int_vcond - if the only problematic mode
> is V2DImode, then that might be easier than just writing code that would
> handle arbitrary vectors.  That still means the vectorizer believes all the
> comparisons are supported and might result in really terrible code (rather
> than just giving up).

There are predicates in optabs-tree.c: expand_vec_cmp_expr_p and
expand_vec_cond_expr_p) that currently only check if the insn code is
available.

But, you are right. These predicates don't check if the comparison code can be
handled by the optab...