Hi Richard,
Sorry I forgot to commit this patch, which you had approved in:
https://gcc.gnu.org/pipermail/gcc-patches/2023-April/615308.html

Just for context for the following test:
svint32_t f_s32(int32x4_t x)
{
  return svdupq_s32 (x[0], x[1], x[2], x[3]);
}

-O3 -mcpu=generic+sve generates following code after interleave+zip1 patch:
f_s32:
        dup     s31, v0.s[1]
        mov     v30.8b, v0.8b
        ins     v31.s[1], v0.s[3]
        ins     v30.s[1], v0.s[2]
        zip1    v0.4s, v30.4s, v31.4s
        dup     z0.q, z0.q[0]
        ret

Code-gen with attached patch:
f_s32:
        dup     z0.q, z0.q[0]
        ret

Bootstrapped+tested on aarch64-linux-gnu.
OK to commit ?

Thanks,
Prathamesh