chore: Add Instruction::MakeArray to SSA

[jfecher]

Description

Problem*

Resolves #1733

Summary*

Adds a MakeArray instruction to explicitly create a new array. Now no other ValueIds can contain other ValueIds which simplifies a couple passes.

Additional Context

Still working on getting this working in brillig.

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.

[TomAFrench]

Seems like --show-ssa fixes the compilation failures on the few programs I tried.

[TomAFrench]

Disabling the normalization of valueids shows that we're deleting instructions in the DIE pass which shouldn't be removed. For example the load instruction when returning arr in quicksort is removed from array_sort.

This is happening because somehow the return value of this function (the loaded value) becomes a Value::Function rather than a Value::Instruction. We only mark return values as used if they're constants, instructions or block params so we end up removing the loaded instruction.

[TomAFrench]

I've merged in master so that this branch is up to date so will be handing this PR back now.

[github-actions]

Changes to Brillig bytecode sizes

Generated at commit: 42c75cca1668f0fda203ffe881a448a4b6615792, compared to commit: 7cc7197bf7b2e41c07e8d1979f7e9d45c676d11b

🧾 Summary (10% most significant diffs)

Program	Brillig opcodes (+/-)	%
slice_regex	+2,923 ❌	+119.84%
eddsa	+5,500 ❌	+49.20%
brillig_slices	+118 ❌	+25.60%
bigint	+482 ❌	+23.63%
side_effects_constrain_array	+24 ❌	+22.22%
slices	+434 ❌	+21.42%
databus_two_calldata_simple	+22 ❌	+20.75%

---

Full diff report 👇

Program	Brillig opcodes (+/-)	%
slice_regex	5,362 (+2,923)	+119.84%
eddsa	16,679 (+5,500)	+49.20%
brillig_slices	579 (+118)	+25.60%
bigint	2,522 (+482)	+23.63%
side_effects_constrain_array	132 (+24)	+22.22%
slices	2,460 (+434)	+21.42%
databus_two_calldata_simple	128 (+22)	+20.75%
databus	100 (+15)	+17.65%
databus_in_fn_with_empty_arr	49 (+7)	+16.67%
hashmap	30,358 (+3,986)	+15.11%
databus_composite_calldata	590 (+73)	+14.12%
sha256_var_padding_regression	5,729 (+700)	+13.92%
sha2_byte	3,563 (+414)	+13.15%
6	1,931 (+181)	+10.34%
brillig_keccak	1,890 (+177)	+10.33%
keccak256	1,890 (+177)	+10.33%
sha256	2,050 (+189)	+10.16%
sha256_var_size_regression	2,095 (+189)	+9.92%
databus_two_calldata	274 (+24)	+9.60%
debug_logs	5,462 (+470)	+9.42%
fold_complex_outputs	586 (+50)	+9.33%
nested_array_in_slice	1,310 (+110)	+9.17%
sha256_regression	7,498 (+595)	+8.62%
modulus	1,880 (+148)	+8.55%
merkle_insert	1,450 (+114)	+8.53%
conditional_regression_short_circuit	1,433 (+112)	+8.48%
uhashmap	25,497 (+1,982)	+8.43%
fold_2_to_17	561 (+38)	+7.27%
sha256_var_witness_const_regression	1,365 (+91)	+7.14%
array_to_slice	971 (+64)	+7.06%
7_function	601 (+34)	+6.00%
schnorr	1,586 (+86)	+5.73%
aes128_encrypt	539 (+28)	+5.48%
struct_inputs	293 (+15)	+5.40%
u128	3,273 (+166)	+5.34%
regression_5252	5,418 (+272)	+5.29%
array_dynamic_blackbox_input	1,206 (+56)	+4.87%
poseidonsponge_x5_254	4,508 (+189)	+4.38%
nested_array_dynamic	2,401 (+99)	+4.30%
regression_4449	829 (+28)	+3.50%
pedersen_check	570 (+18)	+3.26%
brillig_pedersen	570 (+18)	+3.26%
fold_numeric_generic_poseidon	720 (+22)	+3.15%
no_predicates_numeric_generic_poseidon	720 (+22)	+3.15%
poseidon_bn254_hash_width_3	5,672 (+173)	+3.15%
poseidon_bn254_hash	5,672 (+173)	+3.15%
strings	925 (+27)	+3.01%
brillig_cow_regression	2,392 (+56)	+2.40%
brillig_sha256	756 (+14)	+1.89%
array_dynamic_nested_blackbox_input	945 (+14)	+1.50%
ecdsa_secp256k1	969 (+14)	+1.47%
conditional_1	1,265 (+14)	+1.12%

[github-actions]

Changes to circuit sizes

Generated at commit: 42c75cca1668f0fda203ffe881a448a4b6615792, compared to commit: 7cc7197bf7b2e41c07e8d1979f7e9d45c676d11b

🧾 Summary (10% most significant diffs)

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
hashmap	-37,050 ✅	-39.68%	-59,930 ✅	-39.78%

---

Full diff report 👇

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
hashmap	56,333 (-37,050)	-39.68%	90,731 (-59,930)	-39.78%

[jfecher]

This is passing all tests now and showing a surprisingly large improvement in the hashmap test but also large regressions in brillig bytecode sizes.

[TomAFrench]

This is likely due to the fact that constant arrays are no long considered as "constants" by constant_allocation.rs. We're then not hoisting their usage up to avoid multiple initialisations.

[jfecher]

@TomAFrench hmm I tried updating is_constant_value there but doing so just leads to many panics on ValueIds not being available.

[michaeljklein]

LGTM

[jfecher]

Going to hold off on merging this for a bit due to the brillig size regressions

[vezenovm]

Going to hold off on merging this for a bit due to the brillig size regressions

Yeah would be good to avoid this regression.