fix(performance): Remove redundant slice access check from brillig

[vezenovm]

Description

Problem*

No issue, small optimization I found while exploring other Brillig gen optimizations.

Summary*

For every slice access, we code gen a slice access check against its dynamic index:

noir/compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs

Line 475 in 988adae

self.codegen_slice_access_check(index, length);

In Brillig gen we use !dfg.is_safe_index to determine whether to code gen an array index. This always returns false for slice types as we cannot check against their length. However, we already have generated a check the precedes the array access. We should generate this validation code for array types in Brillig gen.

Additional Context

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

Changes to Brillig bytecode sizes

Generated at commit: 6052552d0f89b9cbbc3d8ad8dc365dadac3284f2, compared to commit: 988adae231c1aca09fd4d08d5e7bf5e72deecf9d

🧾 Summary (10% most significant diffs)

Program	Brillig opcodes (+/-)	%
slice_dynamic_index_inliner_min	-450 ✅	-16.74%
slice_dynamic_index_inliner_max	-450 ✅	-18.00%
slice_dynamic_index_inliner_zero	-450 ✅	-18.00%
nested_array_in_slice_inliner_min	-195 ✅	-19.21%
nested_array_in_slice_inliner_zero	-195 ✅	-19.21%

---

Full diff report 👇

Program	Brillig opcodes (+/-)	%
hashmap_inliner_min	9,209 (-5)	-0.05%
hashmap_inliner_zero	7,529 (-5)	-0.07%
slice_coercion_inliner_min	478 (-8)	-1.65%
modulus_inliner_min	1,731 (-30)	-1.70%
modulus_inliner_max	1,716 (-30)	-1.72%
modulus_inliner_zero	1,716 (-30)	-1.72%
slice_loop_inliner_max	247 (-5)	-1.98%
derive_inliner_min	559 (-13)	-2.27%
hash_to_field_inliner_min	208 (-5)	-2.35%
hint_black_box_inliner_min	364 (-10)	-2.67%
hint_black_box_inliner_zero	354 (-10)	-2.75%
slice_loop_inliner_min	317 (-10)	-3.06%
slice_loop_inliner_zero	307 (-10)	-3.15%
derive_inliner_zero	316 (-13)	-3.95%
regression_4202_inliner_max	113 (-5)	-4.24%
regression_4202_inliner_min	113 (-5)	-4.24%
regression_4202_inliner_zero	113 (-5)	-4.24%
hint_black_box_inliner_max	314 (-15)	-4.56%
uhashmap_inliner_min	7,388 (-440)	-5.62%
uhashmap_inliner_zero	6,762 (-425)	-5.91%
array_to_slice_inliner_min	911 (-70)	-7.14%
slices_inliner_max	1,979 (-153)	-7.18%
slices_inliner_min	2,234 (-178)	-7.38%
slices_inliner_zero	1,907 (-163)	-7.87%
uhashmap_inliner_max	11,490 (-1,160)	-9.17%
array_to_slice_inliner_zero	674 (-70)	-9.41%
regression_capacity_tracker_inliner_max	216 (-23)	-9.62%
regression_capacity_tracker_inliner_min	216 (-23)	-9.62%
regression_capacity_tracker_inliner_zero	216 (-23)	-9.62%
array_to_slice_inliner_max	627 (-75)	-10.68%
nested_array_in_slice_inliner_max	850 (-155)	-15.42%
regression_7062_inliner_max	91 (-18)	-16.51%
regression_7062_inliner_min	91 (-18)	-16.51%
regression_7062_inliner_zero	91 (-18)	-16.51%
slice_dynamic_index_inliner_min	2,238 (-450)	-16.74%
slice_dynamic_index_inliner_max	2,050 (-450)	-18.00%
slice_dynamic_index_inliner_zero	2,050 (-450)	-18.00%
nested_array_in_slice_inliner_min	820 (-195)	-19.21%
nested_array_in_slice_inliner_zero	820 (-195)	-19.21%

[github-actions]

Changes to number of Brillig opcodes executed

Generated at commit: 6052552d0f89b9cbbc3d8ad8dc365dadac3284f2, compared to commit: 988adae231c1aca09fd4d08d5e7bf5e72deecf9d

🧾 Summary (10% most significant diffs)

Program	Brillig opcodes (+/-)	%
modulus_inliner_max	-2,544 ✅	-14.16%
modulus_inliner_zero	-2,544 ✅	-14.16%
regression_7062_inliner_max	-12 ✅	-15.19%
regression_7062_inliner_min	-12 ✅	-15.19%
regression_7062_inliner_zero	-12 ✅	-15.19%

---

Full diff report 👇

Program	Brillig opcodes (+/-)	%
hashmap_inliner_min	86,962 (-316)	-0.36%
hash_to_field_inliner_min	932 (-4)	-0.43%
hashmap_inliner_zero	72,465 (-316)	-0.43%
slice_coercion_inliner_min	465 (-4)	-0.85%
regression_capacity_tracker_inliner_max	901 (-12)	-1.31%
regression_capacity_tracker_inliner_min	901 (-12)	-1.31%
regression_capacity_tracker_inliner_zero	901 (-12)	-1.31%
slice_loop_inliner_max	869 (-32)	-3.55%
uhashmap_inliner_min	183,030 (-8,196)	-4.29%
slices_inliner_max	3,124 (-152)	-4.64%
uhashmap_inliner_zero	163,387 (-8,036)	-4.69%
slice_loop_inliner_min	1,211 (-64)	-5.02%
slice_loop_inliner_zero	1,197 (-64)	-5.08%
slices_inliner_min	3,947 (-212)	-5.10%
uhashmap_inliner_max	128,594 (-7,184)	-5.29%
slices_inliner_zero	3,379 (-192)	-5.38%
hint_black_box_inliner_min	942 (-60)	-5.99%
slice_dynamic_index_inliner_min	4,591 (-296)	-6.06%
hint_black_box_inliner_zero	928 (-60)	-6.07%
array_to_slice_inliner_max	1,537 (-100)	-6.11%
slice_dynamic_index_inliner_max	4,360 (-296)	-6.36%
slice_dynamic_index_inliner_zero	4,360 (-296)	-6.36%
array_to_slice_inliner_min	2,061 (-148)	-6.70%
nested_array_in_slice_inliner_max	1,265 (-92)	-6.78%
nested_array_in_slice_inliner_min	1,584 (-128)	-7.48%
nested_array_in_slice_inliner_zero	1,584 (-128)	-7.48%
array_to_slice_inliner_zero	1,796 (-148)	-7.61%
regression_4202_inliner_max	189 (-16)	-7.80%
regression_4202_inliner_min	189 (-16)	-7.80%
regression_4202_inliner_zero	189 (-16)	-7.80%
hint_black_box_inliner_max	615 (-60)	-8.89%
modulus_inliner_min	15,472 (-2,544)	-14.12%
modulus_inliner_max	15,422 (-2,544)	-14.16%
modulus_inliner_zero	15,422 (-2,544)	-14.16%
regression_7062_inliner_max	67 (-12)	-15.19%
regression_7062_inliner_min	67 (-12)	-15.19%
regression_7062_inliner_zero	67 (-12)	-15.19%

[TomAFrench]

Actually, looks like we could match on array_variable inside of validate_array_index and early return on vectors to encapsulate the check. ignore this