On Wed, Mar 08, 2017 at 09:15:05AM +0100, Richard Biener wrote:
> Ok. Note that another option for the loopy case is to do
>
> for (;;)
> {
> vec >> by-one-elt;
> elt = BIT_FIELD_REF <vec, index-zero>;
> }
Indeed, that is a possibility, but I guess I'd need to construct
the result similarly if resv is non-NULL. Also, not sure about big endian
vectors and whether BIT_FIELD_REF with zero or size - elt_size is
more efficient there.
In any case, the PR was about s390 without vectors enabled, so this wouldn't
apply.
> when whole-vector shifts are available (they are constructed by
> VEC_PERM_EXPR if vec_perm_const_ok for that mask). If you end up
> doing variable-index array accesses you can as well spill the
> vector to memory and use memory accesses on that. Not sure how
> to arrange that from this part of the expander.
Shouldn't something else during the expansion force it into memory if it is
more efficient to expand it that way? Apparently it is forced into memory
on s390 and the ICE is that the backend doesn't like something on it.
Jakub
