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fix(avm): precomp trace for get_p_limbs #19266

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Merged
IlyasRidhuan merged 1 commit into from
Jan 2, 2026
Merged

fix(avm): precomp trace for get_p_limbs #19266

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4 changes: 2 additions & 2 deletions barretenberg/cpp/src/barretenberg/vm2/constraining/avm_fixed_vk.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -451,9 +451,9 @@ class AvmFixedVKCommitments {
uint256_t(
"0x1f4f53d8c274f2019474fe304b7ec352663f08b2a128de79bdf7bc65e5db32b3")), // precomputed_sel_tag_parameters
Commitment(
uint256_t("0x2437c8d0dbe47dc612ccf4a5ad9cee871c4f57bc794166dcfb96b127fed46398"),
uint256_t("0x122c377cad49f6338188909ccb858cf8304b3b00383bd44be42861a3d4158090"),
uint256_t(
"0x1fc575fca116894d05b386b745949a6f438122e256d7dd889cc6bd0df5a4d20b")), // precomputed_sel_to_radix_p_limb_counts
"0x2af6b300db680f1713472c2c931cd10ec804eb227a659b7928dbc2bc01a33791")), // precomputed_sel_to_radix_p_limb_counts
Commitment(
uint256_t("0x1aad75d8502dcfee5df4a491c540577ad095025f94405a19bb3c314d9b88af45"),
uint256_t(
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46 changes: 46 additions & 0 deletions barretenberg/cpp/src/barretenberg/vm2/constraining/relations/gas.test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -415,5 +415,51 @@ TEST(GasConstrainingTest, DynGasFactorInvalidRadix)
execution::SR_DYN_GAS_ID_DECOMPOSITION);
}

TEST(GasConstrainingTest, DynGasFactorToRadixInvalidRadixLt2)
{
PrecomputedTraceBuilder precomputed_builder;

uint32_t radix = 1; // Invalid radix (must be >= 2)
uint32_t num_limbs = 20;
uint32_t num_p_limbs = static_cast<uint32_t>(get_p_limbs_per_radix_size(radix)); // Returns 0
TestTraceContainer trace({ {
{ C::execution_sel, 1 },
{ C::execution_register_1_, radix },
{ C::execution_register_2_, num_limbs },
{ C::execution_sel_should_check_gas, 1 },
// To Radix BE Dynamic Gas
{ C::execution_sel_gas_to_radix, 1 },
{ C::execution_dyn_gas_id, AVM_DYN_GAS_ID_TORADIX },
{ C::execution_two_five_six, 256 },
{ C::execution_sel_radix_gt_256, 0 },
{ C::execution_sel_lookup_num_p_limbs, 1 },
{ C::execution_num_p_limbs, num_p_limbs },
{ C::execution_sel_use_num_limbs, 1 }, // num_limbs (20) > num_p_limbs (0)
{ C::execution_dynamic_l2_gas_factor, num_limbs }, // max(20, 0) = 20
// GT Trace, used to check if radix > 256
{ C::gt_sel, 1 },
{ C::gt_input_a, radix },
{ C::gt_input_b, 256 },
{ C::gt_res, 0 },
},
{
// Gt Trace, compare num_limbs > num_p_limbs
{ C::gt_sel, 1 },
{ C::gt_input_a, num_limbs },
{ C::gt_input_b, num_p_limbs },
{ C::gt_res, 1 }, // 20 > 0
} });

precomputed_builder.process_misc(trace, 257);
precomputed_builder.process_to_radix_safe_limbs(trace);

// To Radix fails because radix < 2, but the lookup constraints must still satisfied for the gas relation to hold.
check_interaction<ExecutionTraceBuilder,
lookup_execution_check_radix_gt_256_settings,
lookup_execution_get_p_limbs_settings,
lookup_execution_get_max_limbs_settings>(trace);
check_relation<execution>(trace, execution::SR_DYN_L2_FACTOR_TO_RADIX_BE, execution::SR_DYN_GAS_ID_DECOMPOSITION);
}

} // namespace
} // namespace bb::avm2::constraining
4 changes: 2 additions & 2 deletions barretenberg/cpp/src/barretenberg/vm2/dsl/avm2_recursion_constraint.test.cpp
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Expand Up @@ -136,7 +136,7 @@ TEST_F(AvmRecursionConstraintTest, GateCountAndVKCheck)
using ProverInstance = ProverInstance_<UltraRollupFlavor>;

static constexpr FF EXPECTED_OUTER_VK_HASH =
FF("0x0c17c44b4c643765ef2ffc77cb6b77104910b0d4fc38de7ea0115301346e2b51");
FF("0x2b6a12d8695a0dc9a25d2a87df02dc42246be0eed271c41aab603d91901d71b7");

AcirConstraint constraint;
WitnessVector witness;
Expand Down Expand Up @@ -167,7 +167,7 @@ class AvmRecursionInnerCircuitTests : public ::testing::Test {
using FF = Builder::FF;

static constexpr FF EXPECTED_INNER_VK_HASH =
FF("0x0822fef4f7d002ccf7f18512598d0fc1a6b8b13143221330bcb1ce0990eba291");
FF("0x0efaaaece4a7b764beaa079f4e75156c56d2d14ea2e99f2421d0fc20c2acaa63");

static void SetUpTestSuite() { bb::srs::init_file_crs_factory(bb::srs::bb_crs_path()); }

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11 changes: 6 additions & 5 deletions barretenberg/cpp/src/barretenberg/vm2/tracegen/precomputed_trace.cpp
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Expand Up @@ -293,11 +293,12 @@ void PrecomputedTraceBuilder::process_to_radix_safe_limbs(TraceContainer& trace)

for (size_t i = 0; i < p_limbs_per_radix.size(); ++i) {
size_t decomposition_len = p_limbs_per_radix[i].size();
if (decomposition_len > 0) {
trace.set(C::precomputed_sel_to_radix_p_limb_counts, static_cast<uint32_t>(i), 1);
trace.set(C::precomputed_to_radix_safe_limbs, static_cast<uint32_t>(i), decomposition_len - 1);
trace.set(C::precomputed_to_radix_num_limbs_for_p, static_cast<uint32_t>(i), decomposition_len);
}
trace.set(C::precomputed_sel_to_radix_p_limb_counts, static_cast<uint32_t>(i), 1);
// Use 0 as fallback when decomposition_len == 0 (i.e. p_limbs_per_radix[0] and p_limbs_per_radix[1])
trace.set(C::precomputed_to_radix_safe_limbs,
static_cast<uint32_t>(i),
decomposition_len > 0 ? decomposition_len - 1 : 0);
trace.set(C::precomputed_to_radix_num_limbs_for_p, static_cast<uint32_t>(i), decomposition_len);
}
}

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