VTVL contest - gianganhnguyen's results

1. [G-1] ++i cost less gas compare i++ in for loops

File VTVLVesting.sol, line 353:

for (uint256 i = 0; i < length; i++) {
   ...
}

Becomes:

for (uint256 i = 0; i < length; ++i) {
    ...
}

2. [G-2] Using uncheck blocks to save gas - increments in for loop can be uncheck

File Vault.sol, line 443:

for (uint256 i = 0; i < length; i++) {
   ...
}

Becomes:

for (uint256 i = 0; i < length; i++) {
      ...
      unchecked { ++i; }
  }

3. [G-3] Initialize variable without assign equal 0 is cheaper than initialize with assign equal 0

File VTVLVesting.sol, line 27:

uint112 public numTokensReservedForVesting = 0;

Becomes:

uint112 public numTokensReservedForVesting;

File VTVLVesting.sol, line 148:

uint112 vestAmt = 0;

Becomes:

uint112 vestAmt;

File VTVLVesting.sol, line 353:

for (uint256 i = 0; i < length; i++) {

Becomes:

for (uint256 i; i < length; i++) {

4. [G-4] Using uncheck blocks to save gas

Solidity version 0.8+ comes with implicit overflow and underflow checks on unsigned integers. When an overflow or an underflow isn’t possible (as an example, when a comparison is made before the arithmetic operation), some gas can be saved by using an unchecked block

File VTVLVesting.sol, line 161:

vestAmt += _claim.cliffAmount;

Becomes:

unchecked {
  vestAmt += _claim.cliffAmount;
}

File VTVLVesting.sol, line 167-179:

uint40 currentVestingDurationSecs = _referenceTs - _claim.startTimestamp;
uint40 truncatedCurrentVestingDurationSecs = (currentVestingDurationSecs / _claim.releaseIntervalSecs) * _claim.releaseIntervalSecs;
uint40 finalVestingDurationSecs = _claim.endTimestamp - _claim.startTimestamp;
uint112 linearVestAmount = _claim.linearVestAmount * truncatedCurrentVestingDurationSecs / finalVestingDurationSecs;
vestAmt += linearVestAmount;

Becomes:

uint40 currentVestingDurationSecs;
uint40 truncatedCurrentVestingDurationSecs;
uint40 finalVestingDurationSecs;
uint112 linearVestAmount;
unchecked {
  currentVestingDurationSecs = _referenceTs - _claim.startTimestamp;
  truncatedCurrentVestingDurationSecs = (currentVestingDurationSecs / _claim.releaseIntervalSecs) * _claim.releaseIntervalSecs;
  finalVestingDurationSecs = _claim.endTimestamp - _claim.startTimestamp;
  linearVestAmount = _claim.linearVestAmount * truncatedCurrentVestingDurationSecs / finalVestingDurationSecs;
  vestAmt += linearVestAmount;
}

File VTVLVesting.sol, line 292:

uint112 allocatedAmount = _cliffAmount + _linearVestAmount;

Becomes:

uint112 allocatedAmount;
unchecked {
  allocatedAmount = _cliffAmount + _linearVestAmount;
}

File VTVLVesting.sol, line 301:

numTokensReservedForVesting += allocatedAmount;

Becomes:

unchecked {
  numTokensReservedForVesting += allocatedAmount;
}

File VTVLVesting.sol, line 377-384:

uint112 amountRemaining = allowance - usrClaim.amountWithdrawn;
usrClaim.amountWithdrawn += amountRemaining;
numTokensReservedForVesting -= amountRemaining;

Becomes:

uint112 amountRemaining;
unchecked {
   amountRemaining = allowance - usrClaim.amountWithdrawn;
   usrClaim.amountWithdrawn += amountRemaining;
   numTokensReservedForVesting -= amountRemaining;
}

File VTVLVesting.sol, line 429:

uint112 amountRemaining = finalVestAmt - _claim.amountWithdrawn;

Becomes:

uint112 amountRemaining;
unchecked {
  amountRemaining = finalVestAmt - _claim.amountWithdrawn;
}

File VTVLVesting.sol, line 433:

numTokensReservedForVesting -= amountRemaining;

Becomes:

unchecked {
  numTokensReservedForVesting -= amountRemaining;
}

5. [G-5] Cache read variables in memory to save gas

File VTVLVesting.sol, line 106:

Claim storage _claim = claims[_recipient];

Becomes:

Claim memory _claim = claims[_recipient];

Instances include:

File VTVLVesting.sol, line 124, 197, 207, 216.

6. [G-6] <x> += <y> cost more gas than <x> = <x> + <y>

File VTVLVesting.sol, line 161:

vestAmt += _claim.cliffAmount;

Becomes:

vestAmt = vestAmt + _claim.cliffAmount;

File VTVLVesting.sol, line 383:

numTokensReservedForVesting -= amountRemaining;

Becomes:

numTokensReservedForVesting = numTokensReservedForVesting - amountRemaining;

Instances include:

File VTVLVesting.sol, line 179, 301, 381, 433. File VariableSupplyERC20Token.sol, line 43.