[Bug target/92658] x86 lacks vector extend / truncate

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92658

--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Uroš Bizjak from comment #3)
> Richi, should the following test also vectorize?

It doesn't vectorize because supportable_convert_operation returns false for:

(gdb) p debug_generic_expr (vectype_out)
vector(4) unsigned int
$1 = void
(gdb) p debug_generic_expr (vectype_in)
vector(4) unsigned char
$2 = void

and TYPE_MODE for "vector(4) unsigned char" returns E_SImode:

(gdb) p m1
$3 = E_V4SImode
(gdb) p m2
$4 = E_SImode

and:

  if (!VECTOR_MODE_P (m1) || !VECTOR_MODE_P (m2))
    return false;