perf: save 4 scs in lookup2 api

Consensys · Mar 3, 2024 · a883c92 · a883c92
1 parent 7cc8816
commit a883c92
Showing 1 changed file with 4 additions and 7 deletions.
diff --git a/frontend/cs/scs/api.go b/frontend/cs/scs/api.go
@@ -457,14 +457,11 @@ func (builder *builder) Lookup2(b0, b1 frontend.Variable, i0, i1, i2, i3 fronten
 	//    (3) (in2 - in0) * s1 = RES - tmp2 - in0
 	// the variables tmp1 and tmp2 are new internal variables and the variables
 	// RES will be the returned result
-
-	// TODO check how it can be optimized for PLONK (currently it's a copy
-	// paste of the r1cs version)
-	tmp1 := builder.Add(i3, i0)
-	tmp1 = builder.Sub(tmp1, i2, i1)
+	tmp1 := builder.Sub(i3, i2)
+	tmp := builder.Sub(i0, i1)
+	tmp1 = builder.Add(tmp1, tmp)
 	tmp1 = builder.Mul(tmp1, b1)
-	tmp1 = builder.Add(tmp1, i1)
-	tmp1 = builder.Sub(tmp1, i0)  // (1) tmp1 = s1 * (in3 - in2 - in1 + in0) + in1 - in0
+	tmp1 = builder.Sub(tmp1, tmp) // (1) tmp1 = s1 * (in3 - in2 - in1 + in0) + in1 - in0
 	tmp2 := builder.Mul(tmp1, b0) // (2) tmp2 = tmp1 * s0
 	res := builder.Sub(i2, i0)
 	res = builder.Mul(res, b1)