nir_lower_io_arrays_to_elements lowers arrays or matrices to elements,
which ends up to vectors for matrices, but a bunch of IO optimizations
only work for scalars.
Calling it before lower_io_to_scalar_early allows nir_link_opt_varyings
to remove duplicated inputs and replace constant inputs.
fossils-db (Navi10):
Totals from 294 (0.22% of 136546) affected shaders:
CodeSize: 861356 -> 860224 (-0.13%); split: -0.13%, +0.00%
Instrs: 161972 -> 161832 (-0.09%); split: -0.09%, +0.00%
Cycles: 1185680 -> 1185120 (-0.05%); split: -0.05%, +0.00%
SMEM: 31422 -> 31424 (+0.01%)
Copies: 9065 -> 9068 (+0.03%)
Only Talos and Dark Souls 3 are affected.
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7041>
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