VTVL contest - tgolding55's results

QA Report

Gas Optimizations

1. Custom Errors

Custom errors from Solidity 0.8.4 are cheaper than revert strings.

https://blog.soliditylang.org/2021/04/21/custom-errors/

Examples in contracts:

FullPremintERC20Token.sol

Line 11

require(supply_ > 0, "NO_ZERO_MINT");

---

VariableSupplyERC20Token

Line 27

require(initialSupply_ > 0 || maxSupply_ > 0, "INVALID_AMOUNT");

---

Line 37

require(account != address(0), "INVALID_ADDRESS");

---

Line 41

require(amount <= mintableSupply, "INVALID_AMOUNT");

---

AccessProtected.sol

Line 25

require(_admins[_msgSender()], "ADMIN_ACCESS_REQUIRED");

---

Line 40

require(admin != address(0), "INVALID_ADDRESS");

---

VTVLVesting.sol

Line 82

require(address(_tokenAddress) != address(0), "INVALID_ADDRESS");

---

Line 107

require(_claim.startTimestamp > 0, "NO_ACTIVE_CLAIM");

---

Line 111

require(_claim.isActive == true, "NO_ACTIVE_CLAIM");

---

Line 129

require(_claim.startTimestamp == 0, "CLAIM_ALREADY_EXISTS");

---

Line 255-257

require(_recipient != address(0), "INVALID_ADDRESS");
require(_linearVestAmount + _cliffAmount > 0, "INVALID_VESTED_AMOUNT");
require(_startTimestamp > 0, "INVALID_START_TIMESTAMP");

---

Line 262-264

require(_startTimestamp < _endTimestamp, "INVALID_END_TIMESTAMP"); // _endTimestamp must be after _startTimestamp
require(_releaseIntervalSecs > 0, "INVALID_RELEASE_INTERVAL");
require((_endTimestamp - _startTimestamp) % _releaseIntervalSecs == 0, "INVALID_INTERVAL_LENGTH");

---

Line 270-278

        require( 
            (
                _cliffReleaseTimestamp > 0 && 
                _cliffAmount > 0 && 
                _cliffReleaseTimestamp <= _startTimestamp
            ) || (
                _cliffReleaseTimestamp == 0 && 
                _cliffAmount == 0
        ), "INVALID_CLIFF");

---

Line 295

require(tokenAddress.balanceOf(address(this)) >= numTokensReservedForVesting + allocatedAmount, "INSUFFICIENT_BALANCE");

---

Line 344-351

require(_startTimestamps.length == length &&
_endTimestamps.length == length &&
_cliffReleaseTimestamps.length == length &&
_releaseIntervalsSecs.length == length &&
_linearVestAmounts.length == length &&
_cliffAmounts.length == length, 
"ARRAY_LENGTH_MISMATCH"
        );

---

Line 374

require(allowance > usrClaim.amountWithdrawn, "NOTHING_TO_WITHDRAW");

---

Line 402

require(amountRemaining >= _amountRequested, "INSUFFICIENT_BALANCE");

---

Line 426

require( _claim.amountWithdrawn < finalVestAmt, "NO_UNVESTED_AMOUNT");

---

Line 447

require(_otherTokenAddress != tokenAddress, "INVALID_TOKEN"); // tokenAddress address is already sure to be nonzero due to constructor

---

Line 449

require(bal > 0, "INSUFFICIENT_BALANCE");

---

2. != 0 is more efficient then > 0 for uints

!= 0 costs less gas compared to > 0 for unsigned integer.

Examples in contracts:

FullPremintERC20Token.sol

Line 11

require(supply_ > 0, "NO_ZERO_MINT");

---

VariableSupplyERC20Token

Line 27

require(initialSupply_ > 0 || maxSupply_ > 0, "INVALID_AMOUNT");

---

Line 31

if(initialSupply_ > 0) {

---

Line 40

if(mintableSupply > 0) {

---

VTVLVesting.sol

Line 107

require(_claim.startTimestamp > 0, "NO_ACTIVE_CLAIM");

---

Line 256-257

require(_linearVestAmount + _cliffAmount > 0, "INVALID_VESTED_AMOUNT"); // Actually only one of linearvested/cliff amount must be 0, not necessarily both
require(_startTimestamp > 0, "INVALID_START_TIMESTAMP");

---

Line 263

require(_releaseIntervalSecs > 0, "INVALID_RELEASE_INTERVAL");

---

Line 270-278

        require( 
            (
                _cliffReleaseTimestamp > 0 && 
                _cliffAmount > 0 && 
                _cliffReleaseTimestamp <= _startTimestamp
            ) || (
                _cliffReleaseTimestamp == 0 && 
                _cliffAmount == 0
        ), "INVALID_CLIFF");

---

Line 449

require(bal > 0, "INSUFFICIENT_BALANCE");

---

3. Unnecessary Default Value Initialization

When a variable is not initialized, it will have its default values. For example, 0 for uint, false for bool and address(0) for address.

uint a = 0;

to

uint a;

Examples in contracts:

VTVLVesting.sol

Line 27

uint112 public numTokensReservedForVesting = 0;

---

Line 148

uint112 vestAmt = 0;

---

Line 353

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

---

4. ++i is more efficient then i++

for(...; i++)

to

for(...; ++i)

Examples in contracts:

VTVLVesting.sol

Line 353

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

---

5. Splitting require statements

Instead of using the && operator in a single require statement to check multiple conditions,using multiple require statements with 1 condition per require statement will save gas.

require(a && b);

to

require(a);
require(b);

Examples in code: Line 344-351

require(_startTimestamps.length == length &&
_endTimestamps.length == length &&
_cliffReleaseTimestamps.length == length &&
 _releaseIntervalsSecs.length == length &&
 _linearVestAmounts.length == length &&
_cliffAmounts.length == length, 
"ARRAY_LENGTH_MISMATCH"
);

---

6. Increments can be unchecked

In Solidity 0.8+, there’s a default overflow check on unsigned integers. you can uncheck this in for-loops and save some gas.

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

to

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

Examples in code:

Line 353

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

---