ir3: use opt_shrink_vectors

This is useful to remove unused components from IO loads. This is not
only helpful for reducing the size of memory loads, but also for reducing
register pressure (as we need smaller vector registers).

Totals from 55567 (33.76% of 164575) affected shaders:
MaxWaves: 665780 -> 666690 (+0.14%); split: +0.15%, -0.01%
Instrs: 30850106 -> 30825516 (-0.08%); split: -0.33%, +0.25%
CodeSize: 62502952 -> 62336580 (-0.27%); split: -0.42%, +0.15%
NOPs: 5468972 -> 5463654 (-0.10%); split: -1.39%, +1.30%
MOVs: 1078607 -> 1060627 (-1.67%); split: -3.48%, +1.81%
Full: 807907 -> 805134 (-0.34%); split: -0.49%, +0.15%
(ss): 755846 -> 747963 (-1.04%); split: -2.51%, +1.46%
(sy): 367032 -> 363947 (-0.84%); split: -1.88%, +1.04%
(ss)-stall: 2907874 -> 2900183 (-0.26%); split: -1.97%, +1.71%
(sy)-stall: 10812082 -> 10599944 (-1.96%); split: -3.43%, +1.47%
STPs: 23062 -> 22980 (-0.36%)
LDPs: 35076 -> 32286 (-7.95%)
Preamble Instrs: 6668422 -> 6612037 (-0.85%); split: -1.35%, +0.51%
Early Preamble: 36055 -> 36169 (+0.32%); split: +0.32%, -0.01%
Cat0: 6015654 -> 6009409 (-0.10%); split: -1.29%, +1.18%
Cat1: 1631110 -> 1610537 (-1.26%); split: -2.54%, +1.28%
Cat2: 11783599 -> 11783634 (+0.00%); split: -0.02%, +0.02%
Cat3: 8198147 -> 8198526 (+0.00%); split: -0.00%, +0.01%
Cat5: 968517 -> 967899 (-0.06%); split: -0.06%, +0.00%
Cat6: 349200 -> 351795 (+0.74%); split: -0.01%, +0.75%
Cat7: 1009072 -> 1008909 (-0.02%); split: -0.58%, +0.56%

Signed-off-by: Job Noorman <jnoorman@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34600>

src/freedreno/ir3/ir3_nir.c

@@ -363,6 +363,9 @@ ir3_optimize_loop(struct ir3_compiler *compiler,
       progress |= OPT(s, nir_lower_bit_size, ir3_lower_bit_size, NULL);
       progress |= OPT(s, nir_opt_constant_folding);
 
+      /* Remove unused components from IO loads. */
+      progress |= OPT(s, nir_opt_shrink_vectors, true);
+
       const nir_opt_offsets_options offset_options = {
          /* How large an offset we can encode in the instr's immediate field.
           */