[Bug target/112105] [14 Regression] vector by lane operation costing broken since g:21416caf221fae4351319ef8ca8d41c0234bdfa7

[rsandifo at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112105

--- Comment #2 from Richard Sandiford <rsandifo at gcc dot gnu.org> ---
Seems to be due to aarch64_modes_tieable_p saying that
SF can't be tied to V2x2SF, so that a subreg of that
form is given a cost of 2 instructions.

Using:

  if (aarch64_vector_data_mode_p (mode1)
      || aarch64_vector_data_mode_p (mode2))
    return true;

makes the test work, but who knows what the knock-on
effects will be…