This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: Difference between vec_shl_<vector_mode> and ashl<vector_mode>3
"Bingfeng Mei" <bmei@broadcom.com> writes:
> Thanks for prompt reply. Just out of curiosity. Isn't this naming
> convention for shift instructions inconsistent with other patterns?
> For example, we can define add<vector_mode>3 and GCC will
> automatically use it by vectorization or in plus expression of two
> vector types. Why does shift need special names?
It is inconsistent. I think it sort of accidentally fell out of using
different tree codes for vector shift operations and normal shift
operations. That difference exists so that the vectorizer can easily
use vector shift instructions when reducing to a result, although I
suspect that that difference could probably be eliminated as well.
Ian