intel/fs: switch from SIMD 1 to 8 instructions surface/sampler rematerialization

intel/fs: switch from SIMD 1 to 8 instructions surface/sampler rematerialization

SIMD1 instructions are problematic because they are considered partial
writes. This increases the liveness of the destination register
written by those instructions. To workaround this we use UNDEF
instructions to bound the liveness of the register. But this causing
other issues like in this case :

  undef(1) vgrf2
  mov(1)   vgrf2, u4.0
  add(1)   vgrf3, vgrf2.0, 64UD

In this case the copy propagation pass in unable to see that vgrf2 in
the add() instruction can be replaced with the uniform u4.0.

To fix this problem, we switch NoMask SIMD8 instructions that cover
the entire register. We can drop the UNDEF instructions and now copy
propagation can do its job.

Good results on 2 apps :

Cyberpunk 2077 :

  Totals from 7258 (68.80% of 10549) affected shaders:
  Instrs: 6332210 -> 6073833 (-4.08%); split: -4.11%, +0.03%
  Cycles: 130667501 -> 127351268 (-2.54%); split: -3.12%, +0.58%
  Subgroup size: 90320 -> 90400 (+0.09%)
  Spill count: 90 -> 68 (-24.44%)
  Fill count: 82 -> 64 (-21.95%)
  Scratch Memory Size: 8192 -> 6144 (-25.00%)
  Max live registers: 385464 -> 375152 (-2.68%)
  Max dispatch width: 64336 -> 64424 (+0.14%); split: +0.96%, -0.82%

  Gaining 60 SIMD16/SIMD32 shaders, loosing 33

Strange Brigade :

  Totals from 2137 (53.12% of 4023) affected shaders:
  Instrs: 1544031 -> 1457544 (-5.60%); split: -5.60%, +0.00%
  Cycles: 22292564 -> 21868978 (-1.90%); split: -2.43%, +0.53%
  Subgroup size: 25328 -> 25344 (+0.06%)
  Max live registers: 113716 -> 111214 (-2.20%)
  Max dispatch width: 17232 -> 18608 (+7.99%); split: +8.36%, -0.37%

  Gaining 138 SIMD16/SIMD32 shaders, loosing 4

On app slightly negatively affected :

Dota2 :

  Totals from 232 (14.73% of 1575) affected shaders:
  Instrs: 30029 -> 28194 (-6.11%)
  Cycles: 385155 -> 371422 (-3.57%); split: -3.59%, +0.02%
  Max live registers: 6792 -> 6780 (-0.18%)
  Max dispatch width: 2256 -> 2160 (-4.26%)

  Loosing 6 SIMD32 shaders

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24554>