chore: honk verifier opt + fix review by Maddiaa0 · Pull Request #20547 · AztecProtocol/aztec-packages

Maddiaa0 · 2026-02-16T14:08:49Z

Overview

This has been submitted for audit already, so I've attempted to make the changes / optimizations as small as possible. I came across these while reading through it again for the zk verifier.

Commits are squashed to please CI - however ive pushed them to a mirror so they still exist within the repository

removing a scalar mul which was being multiplied by 1
- 699c7e2
LAGRANGE_FIRST is always (1,2), constant_term_acc is always multiplied by (1,2) so add the scalars together
- 6f2c350
the remaining are batching all inversions into the same modexp
- 05217b8
- f1a5830

This pr will be squashed - see md/honk-golf-all-commits for commit by commit break down

Maddiaa0 · 2026-02-17T18:22:05Z

@copilot can you remove the commit of barretenberg/sol/src/honk/instance/other.sol

Copilot · 2026-02-17T18:22:14Z

@Maddiaa0 I've opened a new pull request, #20610, to work on those changes. Once the pull request is ready, I'll request review from you.

Maddiaa0 · 2026-02-18T10:12:35Z

    for (int i = 0; i < BARYCENTRIC_DOMAIN_SIZE; ++i) {
-        print_fr(bary_pointer, "BARYCENTRIC_LAGRANGE_DENOMINATOR_" + std::to_string(i) + "_LOC");
-        bary_pointer += 32;
+        print_fr(pointer, "BARYCENTRIC_LAGRANGE_DENOMINATOR_" + std::to_string(i) + "_LOC");


These were starting from "scratch space", but I've leaned towards not re-using allocations due to memory having a trivial gas overhead

Maddiaa0 · 2026-02-18T10:12:57Z

    // INVERSIONS
    print_header_centered("SHPLEMINI - RUNTIME MEMORY - INVERSIONS");

+    print_fr(pointer, "GEMINI_R_INV_LOC");


stored in memory now as the inversion is performed before usage

Maddiaa0 · 2026-02-18T10:13:12Z

    out << "// LOG_N challenge pow minus u\n";
    for (int i = 0; i < log_n; ++i) {
-        print_fr(pointer, "INVERTED_CHALLENEGE_POW_MINUS_U_" + std::to_string(i) + "_LOC");
+        print_fr(pointer, "INVERTED_CHALLENGE_POW_MINUS_U_" + std::to_string(i) + "_LOC");


Maddiaa0 · 2026-02-18T10:14:35Z


    out << "\n";
-    print_fr(pointer, "LATER_SCRATCH_SPACE");
+    for (int i = 0; i < 8 * log_n; ++i) {


Previously these were located in LATER_SCRATCH_SPACE, i thought it would be better to explicitly provide their memory locations in the layout at the top of the file.

Hidden allocations could be a source of footguns when refactoring

LHerskind

Using my 🥜 brain, but think there are a few unused bits than can be cut off. And then I am just curious about the first_lagrange really.

LHerskind · 2026-02-20T12:48:50Z

+                                mulmod(mload(PUBLIC_INPUTS_DELTA_NUMERATOR_CHALLENGE), pi_delta_inv, p)
+                            )
+                        }
+
                        // Normalise as last loop will have incremented the offset
                        bary_centric_inverses_off := sub(bary_centric_inverses_off, 0x20)
                        for {} gt(bary_centric_inverses_off, SUM_U_CHALLENGE_14) {


Don't this run for too long?

SUM_U_CHALLENGE_14 = 0x3cc0 and bary_centric_inversses_off = 0x4ce0, but the BARYCENTRIC_DENOMINATOR_INVERSES_0_0_LOC = 0x3de0 so it unds up looping more than planned and overwriting BARYCENTRIC_LAGRANGE_DENOMINATOR_7..0 (8 excess runs of the body). The accumulator and other values don't seem to be used afterwards, so it does not break currently, but just writing more than needed?

unbelievable catch, before this pr ( or maybe the last one ) barycentric_lagrange_denominator was in scratch space ( starting at 0x100 ). so this was correct, this pr updates such that the lagrange_denominators are stored in the slab with everything else. But does not update this pointer

fix is replacing SUM_U_CHALLENGE_14 with BARYCENTRIC_LAGRANGE_DENOMINATOR_7

see: https://github.com/AztecProtocol/aztec-packages/pull/20547/changes#r2821481981

LHerskind · 2026-02-20T12:52:31Z

@@ -4203,8 +4553,11 @@ contract BlakeOptHonkVerifier is IVerifier {
                )

                // Accumulator = accumulator + scalar[27] * vk[26]
+                // optimization - Lagrange first is always G - (1,2)


Are we absolutely sure that LAGRANGE_FIRST is always (1, 2)? Because then we should do that in both the optimized and base, to ensure that it is not different between the two variants and that will break together if it changes.

yeah it is - its enforced in the vk

LHerskind · 2026-02-20T12:55:44Z

                let neg_inverted_denominator := mload(NEG_INVERTED_DENOM_0_LOC)
                let shplonk_nu := mload(SHPLONK_NU_CHALLENGE)

                unshifted_scalar := addmod(pos_inverted_denominator, mulmod(shplonk_nu, neg_inverted_denominator, p), p)


If we are onlysetting it here, we mightn ot need the separate let unshifted_scaler := 0 and then almost instantly setting it?

ah this was getting around a stack too deep

LHerskind · 2026-02-20T13:08:21Z

+                    }
+                    /// {{ UNROLL_SECTION_END ACCUMULATE_INVERSES }}
+
+                    // Invert all elements (barycentric + PI delta + shplemini) as a single batch


Should we apply similar checks as in Fr.sol to avoid trying to invert a 0 value? If there is one 0 we would end up fully making all the accumulator 0. It should be caught by other parts of the verification, but 🤷

we could, but if we invert a zero everything will blow up after

LHerskind · 2026-02-20T13:14:40Z

I'm not sure you read this value, seems to start at BATCH_SCALAR_1_LOC onwards.

yep its now unused

LHerskind · 2026-02-20T13:16:23Z

+    uint256 internal constant BATCH_EVALUATION_ACCUMULATOR_INVERSION_13_LOC = 0x5f80;
+    uint256 internal constant BATCH_EVALUATION_ACCUMULATOR_INVERSION_14_LOC = 0x5fa0;
+
+    uint256 internal constant BATCHED_EVALUATION_LOC = 0x5fc0;


I don't think you actually use this one. It looks like you store it in memory, but then you use the stack item batched_evaluation right after and not the memory variant.

LHerskind

Very minor thing here.

LHerskind · 2026-03-18T14:42:23Z

I don't think we use this?

LHerskind · 2026-03-18T14:49:55Z

+
+                    // --- Phase 2: Shplemini forward pass ---
+                    // Compute shplemini denominators and accumulate into the running product.
+                    // Pre-inversion values stored in staging area (0x6800+), NOT in


The offset here looks stale now? Probably better to just refer to the constants by name or something?

Maddiaa0 · 2026-03-20T11:55:34Z

feat: use optimized verifier for rollup #21840
chore: honk verifier opt + fix review #20547 👈 (View in Graphite)
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## Overview This has been submitted for audit already, so I've attempted to make the changes / optimizations as small as possible. I came across these while reading through it again for the zk verifier. Commits are squashed to please CI - however ive pushed them to a mirror so they still exist within the repository - removing a scalar mul which was being multiplied by 1 - 699c7e2 - LAGRANGE_FIRST is always (1,2), constant_term_acc is always multiplied by (1,2) so add the scalars together - 6f2c350 - the remaining are batching all inversions into the same modexp - 05217b8 - f1a5830 This pr will be squashed - see [md/honk-golf-all-commits](https://github.com/AztecProtocol/aztec-packages/tree/md/honk-golf-all-commits) for commit by commit break down Co-authored-by: Alejo Amiras <alejo.amiras@gmail.com> Co-authored-by: Alex Gherghisan <alexghr@users.noreply.github.com> Co-authored-by: Ary Borenszweig <asterite@gmail.com> Co-authored-by: Charlie Lye <5764343+charlielye@users.noreply.github.com> Co-authored-by: David Banks <47112877+dbanks12@users.noreply.github.com> Co-authored-by: Esau <esau@aztecprotocol.com> Co-authored-by: Facundo <fcarreiro@users.noreply.github.com> Co-authored-by: IlyasRidhuan <ilyasridhuan@gmail.com> Co-authored-by: Jean M <132435771+jeanmon@users.noreply.github.com> Co-authored-by: Jonathan Hao <jonathan@aztec-labs.com> Co-authored-by: Jonathan Hao <jonathanpohsianghao@gmail.com> Co-authored-by: Josh Crites <jc@joshcrites.com> Co-authored-by: José Pedro Sousa <jose@aztecprotocol.com> Co-authored-by: José Pedro Sousa <outgoing@zpedro.dev> Co-authored-by: Khashayar Barooti <khashayar@aztecprotocol.com> Co-authored-by: LHerskind <16536249+LHerskind@users.noreply.github.com> Co-authored-by: Lasse Herskind <16536249+LHerskind@users.noreply.github.com> Co-authored-by: Lucas Xia <lucasxia01@gmail.com> Co-authored-by: MirandaWood <miranda@aztecprotocol.com> Co-authored-by: Mitch <mitchell@aztecprotocol.com> Co-authored-by: Mitchell Tracy <mitchellftracy@gmail.com> Co-authored-by: Nicolás Venturo <nicolas.venturo@gmail.com> Co-authored-by: PhilWindle <60546371+PhilWindle@users.noreply.github.com> Co-authored-by: PhilWindle <philip.windle@gmail.com> Co-authored-by: Raju Krishnamoorthy <krishnamoorthy@gmail.com> Co-authored-by: Rumata888 <isennovskiy@gmail.com> Co-authored-by: Santiago Palladino <santiago@aztec-labs.com> Co-authored-by: Sarkoxed <sarkoxed2013@yandex.ru> Co-authored-by: Savio <72797635+Savio-Sou@users.noreply.github.com> Co-authored-by: StoneMac65 <StoneMac65@gmail.com> Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com> Co-authored-by: benesjan <13470840+benesjan@users.noreply.github.com> Co-authored-by: benesjan <janbenes1234@gmail.com> Co-authored-by: critesjosh <18372439+critesjosh@users.noreply.github.com> Co-authored-by: danielntmd <danielntmd@nethermind.io> Co-authored-by: dbanks12 <david@aztec-labs.com> Co-authored-by: fcarreiro <facundo@aztecprotocol.com> Co-authored-by: federicobarbacovi <171914500+federicobarbacovi@users.noreply.github.com> Co-authored-by: guipublic <47281315+guipublic@users.noreply.github.com> Co-authored-by: iAmMichaelConnor <mike@aztecprotocol.com> Co-authored-by: jeanmon <jean@aztec-labs.com> Co-authored-by: jewelofchaos9 <jewelofchaos9@gmail.com> Co-authored-by: josh crites <jc@joshcrites.com> Co-authored-by: ledwards2225 <98505400+ledwards2225@users.noreply.github.com> Co-authored-by: ledwards2225 <l.edwards.d@gmail.com> Co-authored-by: lucasxia01 <lucasxia01@gmail.com> Co-authored-by: ludamad <163993+ludamad@users.noreply.github.com> Co-authored-by: ludamad <adam.domurad@gmail.com> Co-authored-by: ludamad <domuradical@gmail.com> Co-authored-by: mralj <nikola.mratinic@gmail.com> Co-authored-by: nventuro <2530770+nventuro@users.noreply.github.com> Co-authored-by: sergei iakovenko <105737703+iakovenkos@users.noreply.github.com> Co-authored-by: sirasistant <sirasistant@gmail.com> Co-authored-by: thunkar <gregojquiros@gmail.com>

AztecBot · 2026-03-20T12:58:14Z

✅ Run #1 — completed (8m)
Live status

Reviewed #20547 — 8 files, no correctness issues found. The unified batch inversion, ecMul-by-1 removal, and LAGRANGE_FIRST scalar merge are all mathematically sound. Full analysis: https://gist.github.com/AztecBot/4b8b28b393bfbb91e2e285873ea7f1c0

Gist

Backport #20547

Maddiaa0 force-pushed the md/honk-golf branch from f1a5830 to 965d231 Compare February 16, 2026 15:20

Copilot AI mentioned this pull request Feb 17, 2026

chore: lil bit of golfing on the ultra honk verifier #20610

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Maddiaa0 changed the base branch from next to md/fix-verifier February 18, 2026 10:01

Maddiaa0 marked this pull request as ready for review February 18, 2026 10:03

Maddiaa0 requested a review from LHerskind February 18, 2026 10:03

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AztecBot force-pushed the md/fix-verifier branch from 19451c7 to ed81ff5 Compare February 18, 2026 10:55

Base automatically changed from md/fix-verifier to next February 19, 2026 15:22

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Maddiaa0 changed the title ~~chore: lil bit of golfing on the ultra honk verifier~~ chore: honk verifier opt + fix review Mar 10, 2026

Maddiaa0 added the ci-no-squash label Mar 18, 2026

LHerskind reviewed Mar 18, 2026

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Maddiaa0 force-pushed the md/honk-golf branch from fd934f7 to d544b59 Compare March 20, 2026 11:55

Maddiaa0 requested review from IlyasRidhuan, charlielye, dbanks12, fcarreiro, jeanmon and sirasistant as code owners March 20, 2026 11:55

Maddiaa0 force-pushed the md/honk-golf branch from d544b59 to fd934f7 Compare March 20, 2026 11:55

Maddiaa0 removed request for IlyasRidhuan, charlielye, dbanks12 and sirasistant March 20, 2026 11:55

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LHerskind approved these changes Mar 20, 2026

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Maddiaa0 added ci-squash-and-merge ci-no-squash and removed ci-no-squash labels Mar 20, 2026

Maddiaa0 force-pushed the md/honk-golf branch from fd934f7 to 5827709 Compare March 20, 2026 12:18

Maddiaa0 mentioned this pull request Mar 20, 2026

feat: use optimized verifier for rollup #21840

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Maddiaa0 force-pushed the md/honk-golf branch from 5827709 to f207ea8 Compare March 20, 2026 12:31

AztecBot force-pushed the md/honk-golf branch from f207ea8 to 3363b62 Compare March 20, 2026 12:42

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Merged via the queue into next with commit 762f1ee Mar 20, 2026
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Maddiaa0 deleted the md/honk-golf branch March 20, 2026 13:52

saleel mentioned this pull request Mar 24, 2026

chore: backport honk verifier opt fixes to v4 #21967

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saleel added a commit that referenced this pull request Mar 25, 2026

chore: backport honk verifier opt fixes to v4 (#21967)

0711b81

Backport #20547

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