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Optimise Boolean::enforce_equal. 

Use a single constraint instead of two.

Fixes #6.
This commit is contained in:
Jason Davies 2018-02-11 20:38:52 +00:00
parent 2c69abe268
commit 661f318eb7
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GPG Key ID: BAE3938318C90D61
1 changed files with 99 additions and 26 deletions
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125
src/circuit/boolean.rs
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@ -375,35 +375,44 @@ impl Boolean {
where E: Engine,
CS: ConstraintSystem<E>
{
let c = Self::xor(&mut cs, a, b)?;
match c {
Boolean::Constant(false) => {
Ok(())
match (a, b) {
(&Boolean::Constant(a), &Boolean::Constant(b)) => {
if a == b {
Ok(())
} else {
Err(SynthesisError::Unsatisfiable)
}
},
Boolean::Constant(true) => {
Err(SynthesisError::Unsatisfiable)
},
Boolean::Is(ref res) => {
(&Boolean::Constant(true), a) | (a, &Boolean::Constant(true)) => {
cs.enforce(
|| "enforce equals zero",
|| "enforce equal to one",
|lc| lc,
|lc| lc,
|lc| lc + res.get_variable()
|lc| lc + CS::one() - &a.lc(CS::one(), E::Fr::one())
);
Ok(())
},
Boolean::Not(ref res) => {
(&Boolean::Constant(false), a) | (a, &Boolean::Constant(false)) => {
cs.enforce(
|| "enforce equals one",
|| "enforce equal to zero",
|lc| lc,
|lc| lc,
|lc| lc + CS::one() - res.get_variable()
|_| a.lc(CS::one(), E::Fr::one())
);
Ok(())
},
(a, b) => {
cs.enforce(
|| "enforce equal",
|lc| lc,
|lc| lc,
|_| a.lc(CS::one(), E::Fr::one()) - &b.lc(CS::one(), E::Fr::one())
);
Ok(())
}
}
}
@ -636,24 +645,88 @@ mod test {
for b_bool in [false, true].iter().cloned() {
for a_neg in [false, true].iter().cloned() {
for b_neg in [false, true].iter().cloned() {
let mut cs = TestConstraintSystem::<Bls12>::new();
{
let mut cs = TestConstraintSystem::<Bls12>::new();
let mut a = Boolean::from(AllocatedBit::alloc(cs.namespace(|| "a"), Some(a_bool)).unwrap());
let mut b = Boolean::from(AllocatedBit::alloc(cs.namespace(|| "b"), Some(b_bool)).unwrap());
let mut a = Boolean::from(AllocatedBit::alloc(cs.namespace(|| "a"), Some(a_bool)).unwrap());
let mut b = Boolean::from(AllocatedBit::alloc(cs.namespace(|| "b"), Some(b_bool)).unwrap());
if a_neg {
a = a.not();
if a_neg {
a = a.not();
}
if b_neg {
b = b.not();
}
Boolean::enforce_equal(&mut cs, &a, &b).unwrap();
assert_eq!(
cs.is_satisfied(),
(a_bool ^ a_neg) == (b_bool ^ b_neg)
);
}
if b_neg {
b = b.not();
{
let mut cs = TestConstraintSystem::<Bls12>::new();
let mut a = Boolean::Constant(a_bool);
let mut b = Boolean::from(AllocatedBit::alloc(cs.namespace(|| "b"), Some(b_bool)).unwrap());
if a_neg {
a = a.not();
}
if b_neg {
b = b.not();
}
Boolean::enforce_equal(&mut cs, &a, &b).unwrap();
assert_eq!(
cs.is_satisfied(),
(a_bool ^ a_neg) == (b_bool ^ b_neg)
);
}
{
let mut cs = TestConstraintSystem::<Bls12>::new();
Boolean::enforce_equal(&mut cs, &a, &b).unwrap();
let mut a = Boolean::from(AllocatedBit::alloc(cs.namespace(|| "a"), Some(a_bool)).unwrap());
let mut b = Boolean::Constant(b_bool);
assert_eq!(
cs.is_satisfied(),
(a_bool ^ a_neg) == (b_bool ^ b_neg)
);
if a_neg {
a = a.not();
}
if b_neg {
b = b.not();
}
Boolean::enforce_equal(&mut cs, &a, &b).unwrap();
assert_eq!(
cs.is_satisfied(),
(a_bool ^ a_neg) == (b_bool ^ b_neg)
);
}
{
let mut cs = TestConstraintSystem::<Bls12>::new();
let mut a = Boolean::Constant(a_bool);
let mut b = Boolean::Constant(b_bool);
if a_neg {
a = a.not();
}
if b_neg {
b = b.not();
}
let result = Boolean::enforce_equal(&mut cs, &a, &b);
if (a_bool ^ a_neg) == (b_bool ^ b_neg) {
assert!(result.is_ok());
assert!(cs.is_satisfied());
} else {
assert!(result.is_err());
}
}
}
}
}