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Create is_first inside the lookup. (#1796)

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Since we can now create constant columns inside `constr` functions, we
don't need to pass `is_first` any more.
This commit is contained in:
chriseth
2024-09-13 10:31:02 +02:00
committed by GitHub
parent e668cdfc64
commit e2eadffa2a
4 changed files with 11 additions and 15 deletions
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17
std/protocols/lookup.asm
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@@ -53,14 +53,13 @@ let compute_next_z: Fp2<expr>, Fp2<expr>, Fp2<expr>, Constr, expr -> fe[] = quer
/// Adds constraints that enforce that rhs is the lookup for lhs
/// Arguments:
/// - is_first: A column that is 1 for the first row and 0 for the rest
/// - acc: A phase-2 witness column to be used as the accumulator. If 2 are provided, computations
/// are done on the F_{p^2} extension field.
/// - alpha: A challenge used to compress the LHS and RHS values
/// - beta: A challenge used to update the accumulator
/// - lookup_constraint: The lookup constraint
/// - multiplicities: The multiplicities which shows how many times each RHS value appears in the LHS
let lookup: expr, expr[], Fp2<expr>, Fp2<expr>, Constr, expr -> Constr[] = |is_first, acc, alpha, beta, lookup_constraint, multiplicities| {
let lookup: expr[], Fp2<expr>, Fp2<expr>, Constr, expr -> () = constr |acc, alpha, beta, lookup_constraint, multiplicities| {
let (lhs_selector, lhs, rhs_selector, rhs) = unpack_lookup_constraint(lookup_constraint);
@@ -93,12 +92,12 @@ let lookup: expr, expr[], Fp2<expr>, Fp2<expr>, Constr, expr -> Constr[] = |is_f
)
);
let (acc_1, acc_2) = unpack_ext(acc_ext);
let is_first: col = std::well_known::is_first;
[
// First and last acc needs to be 0
// (because of wrapping, the acc[0] and acc[N] are the same)
is_first * acc_1 = 0,
is_first * acc_2 = 0
] + constrain_eq_ext(update_expr, from_base(0))
let (acc_1, acc_2) = unpack_ext(acc_ext);
// First and last acc needs to be 0
// (because of wrapping, the acc[0] and acc[N] are the same)
is_first * acc_1 = 0;
is_first * acc_2 = 0;
constrain_eq_ext(update_expr, from_base(0));
};

3
test_data/std/lookup_via_challenges.asm
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@@ -31,7 +31,6 @@ machine Main with degree: 8 {
// TODO: Functions currently cannot add witness columns at later stages,
// so we have to manually create it here and pass it to permutation().
col witness stage(1) z;
let is_first: col = std::well_known::is_first;
lookup(is_first, [z], alpha, beta, lookup_constraint, m);
lookup([z], alpha, beta, lookup_constraint, m);
}

3
test_data/std/lookup_via_challenges_ext.asm
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@@ -39,8 +39,7 @@ machine Main with degree: 8 {
col witness stage(1) z2;
let z = Fp2::Fp2(z1, z2);
let is_first: col = std::well_known::is_first;
lookup(is_first, [z1, z2], alpha, beta, lookup_constraint, m);
lookup([z1, z2], alpha, beta, lookup_constraint, m);
// TODO: Helper columns, because we can't access the previous row in hints
col witness stage(1) z1_next;

3
test_data/std/lookup_via_challenges_ext_simple.asm
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@@ -33,8 +33,7 @@ machine Main with degree: 8 {
col witness stage(1) z2;
let z = Fp2::Fp2(z1, z2);
let is_first: col = std::well_known::is_first;
lookup(is_first, [z1, z2], alpha, beta, lookup_constraint, m);
lookup([z1, z2], alpha, beta, lookup_constraint, m);
// TODO: Helper columns, because we can't access the previous row in hints
col witness stage(1) z1_next;