aco: fix combining add/sub to b2i if a new dest needs to be allocated

The uses vector needs to be expanded to avoid out of bounds access
and to make sure the number of uses is initialized to 0.

This fixes combining more v_and(a, v_subbrev_co_u32).

fossilds-db (Vega10):
Totals from 4574 (3.28% of 139517) affected shaders:
SGPRs: 291625 -> 292217 (+0.20%); split: -0.01%, +0.21%
VGPRs: 276368 -> 276188 (-0.07%); split: -0.07%, +0.01%
SpillSGPRs: 455 -> 533 (+17.14%)
SpillVGPRs: 76 -> 78 (+2.63%)
CodeSize: 23327500 -> 23304152 (-0.10%); split: -0.17%, +0.07%
MaxWaves: 22044 -> 22066 (+0.10%)
Instrs: 4583064 -> 4576301 (-0.15%); split: -0.15%, +0.01%
Cycles: 47925276 -> 47871968 (-0.11%); split: -0.13%, +0.01%
VMEM: 1599363 -> 1597473 (-0.12%); split: +0.08%, -0.19%
SMEM: 331461 -> 331126 (-0.10%); split: +0.08%, -0.18%
VClause: 80639 -> 80696 (+0.07%); split: -0.02%, +0.09%
SClause: 155992 -> 155993 (+0.00%); split: -0.02%, +0.02%
Copies: 333482 -> 333318 (-0.05%); split: -0.12%, +0.07%
Branches: 70967 -> 70968 (+0.00%)
PreSGPRs: 187078 -> 187711 (+0.34%); split: -0.01%, +0.35%
PreVGPRs: 244918 -> 244785 (-0.05%)

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7513>
(cherry picked from commit ec347ee9bc41f99dc8e398c652d873cc192bc99c)
3 files changed