Gas Optimizations

[code423n4]

Unnecessary usage of SafeMath

Details:

The functions from SafeMath used in AaveV3YieldSource.sol is not needed since the compiler has built in overflow checking for Solidity versions above 0.8. Consider removing SafeMath and replacing its operations for the corresponding native operations.

In particular the following changes must be applied:

• Remove L14 and L26

• Change L262 to

  uint256 _balanceDiff = _afterBalance - _beforeBalance;

• Change L361 to

  return _supply == 0 ? _tokens : (_tokens*_supply)/(aToken.balanceOf(address(this)));

• Change L373 to

  return _supply == 0 ? _shares : _shares*aToken.balanceOf(address(this))/_supply;

Gas saved:

• Before change:

  ·-------------------------------------------------------|---------------------------|-------------|-----------------------------·
  |                 Solc version: 0.8.10                  ·  Optimizer enabled: true  ·  Runs: 200  ·  Block limit: 30000000 gas  │
  ························································|···························|·············|······························
  |  Methods                                              ·              100 gwei/gas               ·       2794.03 usd/eth       │
  ·····························|··························|·············|·············|·············|···············|··············
  |  Contract                  ·  Method                  ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  claimRewards            ·      54735  ·      56896  ·      55816  ·            4  ·      15.60  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  decreaseERC20Allowance  ·      37465  ·      39638  ·      38910  ·            3  ·      10.87  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  increaseERC20Allowance  ·      59133  ·      61618  ·      61212  ·            7  ·      17.10  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  mint                    ·      51381  ·      68493  ·      61904  ·           13  ·      17.30  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110713  ·            1  ·      30.93  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·      13.41  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·      39.74  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·      16.59  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  ERC20Mintable             ·  approve                 ·      26692  ·      46592  ·      43275  ·            6  ·      12.09  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  ERC20Mintable             ·  mint                    ·      51408  ·      68820  ·      65715  ·           12  ·      18.36  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  ERC20Mintable             ·  transferFrom            ·          -  ·          -  ·      49823  ·            1  ·      13.92  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  Deployments                                          ·                                         ·  % of limit   ·             │
  ························································|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·     700.12  │
  ························································|·············|·············|·············|···············|··············
  |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·     322.46  │
  ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

• After change:

  ·-------------------------------------------------------|---------------------------|-------------|-----------------------------·
  |                 Solc version: 0.8.10                  ·  Optimizer enabled: true  ·  Runs: 200  ·  Block limit: 30000000 gas  │
  ························································|···························|·············|······························
  |  Methods                                              ·              100 gwei/gas               ·       2791.55 usd/eth       │
  ·····························|··························|·············|·············|·············|···············|··············
  |  Contract                  ·  Method                  ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  claimRewards            ·      54735  ·      56896  ·      55816  ·            4  ·      15.58  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  decreaseERC20Allowance  ·      37465  ·      39638  ·      38910  ·            3  ·      10.86  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  increaseERC20Allowance  ·      59133  ·      61618  ·      61212  ·            7  ·      17.09  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  mint                    ·      51381  ·      68493  ·      61904  ·           13  ·      17.28  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110584  ·            1  ·      30.87  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·      13.39  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110584  ·     153720  ·     142189  ·            6  ·      39.69  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·      16.58  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  ERC20Mintable             ·  approve                 ·      26692  ·      46592  ·      43275  ·            6  ·      12.08  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  ERC20Mintable             ·  mint                    ·      51408  ·      68820  ·      65715  ·           12  ·      18.34  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  ERC20Mintable             ·  transferFrom            ·          -  ·          -  ·      49823  ·            1  ·      13.91  │
  ·····························|··························|·············|·············|·············|···············|··············
  |  Deployments                                          ·                                         ·  % of limit   ·             │
  ························································|·············|·············|·············|···············|··············
  |  AaveV3YieldSourceHarness                             ·    2497329  ·    2497341  ·    2497339  ·        8.3 %  ·     697.14  │
  ························································|·············|·············|·············|···············|··············
  |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·     322.17  │
  ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

[PierrickGT]

Duplicate of https://github.com/code-423n4/2022-04-pooltogether-findings/issues/11

[PierrickGT]

Great report, should get extra points.