chore(contracts): contracts optimizations

contracts/contracts/Poll.sol

@@ -144,7 +144,9 @@ contract Poll is Params, Utilities, SnarkCommon, Ownable, EmptyBallotRoots, IPol
     }
 
     // init messageAq here by inserting placeholderLeaf
-    uint256[2] memory dat = [NOTHING_UP_MY_SLEEVE, 0];
+    uint256[2] memory dat;
+    dat[0] = NOTHING_UP_MY_SLEEVE;
+    dat[1] = 0;
 
     (Message memory _message, PubKey memory _padKey, uint256 placeholderLeaf) = padAndHashMessage(dat, 1);
     extContracts.messageAq.enqueue(placeholderLeaf);
@@ -165,7 +167,10 @@ contract Poll is Params, Utilities, SnarkCommon, Ownable, EmptyBallotRoots, IPol
     /// @notice topupCredit is a trusted token contract which reverts if the transfer fails
     extContracts.topupCredit.transferFrom(msg.sender, address(this), amount);
 
-    uint256[2] memory dat = [stateIndex, amount];
+    uint256[2] memory dat;
+    dat[0] = stateIndex;
+    dat[1] = amount;
+
     (Message memory _message, , uint256 messageLeaf) = padAndHashMessage(dat, 2);
 
     extContracts.messageAq.enqueue(messageLeaf);

contracts/contracts/Tally.sol

@@ -359,15 +359,16 @@ contract Tally is Ownable, SnarkCommon, CommonUtilities, Hasher, DomainObjs {
     );
 
     if (mode == Mode.QV) {
-      uint256[3] memory tally = [
-        hashLeftRight(computedRoot, _tallyResultSalt),
-        _spentVoiceCreditsHash,
-        _perVOSpentVoiceCreditsHash
-      ];
+      uint256[3] memory tally;
+      tally[0] = hashLeftRight(computedRoot, _tallyResultSalt);
+      tally[1] = _spentVoiceCreditsHash;
+      tally[2] = _perVOSpentVoiceCreditsHash;
 
       isValid = hash3(tally) == tallyCommitment;
     } else if (mode == Mode.NON_QV) {
-      uint256[2] memory tally = [hashLeftRight(computedRoot, _tallyResultSalt), _spentVoiceCreditsHash];
+      uint256[2] memory tally;
+      tally[0] = hashLeftRight(computedRoot, _tallyResultSalt);
+      tally[1] = _spentVoiceCreditsHash;
 
       isValid = hash2(tally) == tallyCommitment;
     }

contracts/contracts/VkRegistry.sol

@@ -152,8 +152,13 @@ contract VkRegistry is Ownable, DomainObjs, SnarkCommon, IVkRegistry {
     processVk.gamma2 = _processVk.gamma2;
     processVk.delta2 = _processVk.delta2;
 
-    for (uint8 i = 0; i < _processVk.ic.length; i++) {
+    uint256 processIcLength = _processVk.ic.length;
+    for (uint256 i = 0; i < processIcLength; ) {
       processVk.ic.push(_processVk.ic[i]);
+
+      unchecked {
+        i++;
+      }
     }
 
     processVkSet[_mode][processVkSig] = true;
@@ -164,8 +169,13 @@ contract VkRegistry is Ownable, DomainObjs, SnarkCommon, IVkRegistry {
     tallyVk.gamma2 = _tallyVk.gamma2;
     tallyVk.delta2 = _tallyVk.delta2;
 
-    for (uint8 i = 0; i < _tallyVk.ic.length; i++) {
+    uint256 tallyIcLength = _tallyVk.ic.length;
+    for (uint256 i = 0; i < tallyIcLength; ) {
       tallyVk.ic.push(_tallyVk.ic[i]);
+
+      unchecked {
+        i++;
+      }
     }
 
     tallyVkSet[_mode][tallyVkSig] = true;

contracts/contracts/crypto/Pairing.sol

@@ -113,20 +113,33 @@ library Pairing {
     G1Point memory d1,
     G2Point memory d2
   ) internal view returns (bool isValid) {
-    G1Point[4] memory p1 = [a1, b1, c1, d1];
-    G2Point[4] memory p2 = [a2, b2, c2, d2];
+    G1Point[4] memory p1;
+    p1[0] = a1;
+    p1[1] = b1;
+    p1[2] = c1;
+    p1[3] = d1;
+
+    G2Point[4] memory p2;
+    p2[0] = a2;
+    p2[1] = b2;
+    p2[2] = c2;
+    p2[3] = d2;
 
     uint256 inputSize = 24;
     uint256[] memory input = new uint256[](inputSize);
 
-    for (uint256 i = 0; i < 4; i++) {
-      uint256 j = i * 6;
+    for (uint8 i = 0; i < 4; ) {
+      uint8 j = i * 6;
       input[j + 0] = p1[i].x;
       input[j + 1] = p1[i].y;
       input[j + 2] = p2[i].x[0];
       input[j + 3] = p2[i].x[1];
       input[j + 4] = p2[i].y[0];
       input[j + 5] = p2[i].y[1];
+
+      unchecked {
+        i++;
+      }
     }
 
     uint256[1] memory out;