"H.J. Lu" <hjl.to...@gmail.com> writes: > On 10/18/18, Richard Sandiford <richard.sandif...@arm.com> wrote: >> "H.J. Lu" <hjl.to...@gmail.com> writes: >>> On 10/17/18, Marc Glisse <marc.gli...@inria.fr> wrote: >>>> On Wed, 17 Oct 2018, H.J. Lu wrote: >>>> >>>>> We may simplify >>>>> >>>>> (subreg (vec_merge (vec_duplicate X) (vector) (const_int 1)) 0) >>>>> >>>>> to X when mode of X is the same as of mode of subreg. >>>> >>>> Hello, >>>> >>>> we already have code to simplify vec_select(vec_merge): >>>> >>>> /* If we select elements in a vec_merge that all come from the same >>>> operand, select from that operand directly. */ >>>> >>>> It would make sense to me to make the subreg transform as similar to it >>>> as >>>> possible, in particular you don't need to special case vec_duplicate, >>>> the >>>> transformation would see that everything comes from the first vector, >>>> produce (subreg (vec_duplicate X) 0), and let another transformation >>>> optimize that. >> >> Sorry, didn't see this before the OK. >> >>> What do you mean by another transformation? If simplify_subreg doesn't >>> return X for >>> >>> (subreg (vec_merge (vec_duplicate X) >>> (vector) >>> (const_int ((1 << N) | M))) >>> (N * sizeof (X))) >>> >>> >>> no further transformation will be done. >> >> I think the point was that we should transform: >> >> (subreg (vec_merge X >> (vector) >> (const_int ((1 << N) | M))) >> (N * sizeof (X))) >> >> into: >> >> simplify_gen_subreg (outermode, X, innermode, byte) >> >> which should further simplify when X is a vec_duplicate. > > But sizeof (X) is the size of scalar of vec_dup. How do we > check the mask of vec_merge?
Yeah, should be sizeof (outermode) (which was the same thing in the original pattern, but not here). Richard
