feat: remove unnecessary state write

Author: TomAFrench

src/poseidon2.nr

@@ -71,22 +71,13 @@ impl Poseidon2 {
 
             // handle remaining elements after last full RATE-sized chunk
             let num_extra_fields = in_len % RATE;
-            let remainder_start = in_len - num_extra_fields;
-            state[0] += if num_extra_fields > 0 {
-                input[remainder_start]
-            } else {
-                0
-            };
-            state[1] += if num_extra_fields > 1 {
-                input[remainder_start + 1]
-            } else {
-                0
-            };
-            state[2] += if num_extra_fields > 2 {
-                input[remainder_start + 2]
-            } else {
-                0
-            };
+            if num_extra_fields != 0 {
+                let remainder_start = in_len - num_extra_fields;
+                state[0] += input[remainder_start];
+                if num_extra_fields > 1 {
+                    state[1] += input[remainder_start + 1]
+                }
+            }
         } else {
             let mut states: [[Field; 4]; N / RATE + 1] = [[0; 4]; N / RATE + 1];
             states[0] = state;