Gas Optimizations - Githubissues

1. State variables only set in the constructor should be declared `immutable`

Avoids a Gsset (20000 gas) in the constructor, and replaces each Gwarmacces (100 gas) with a PUSH32 (3 gas)

File: contracts/AaveV3YieldSource.sol   #1

127     IAToken public aToken;

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L127

File: contracts/AaveV3YieldSource.sol   #2

130     IRewardsController public rewardsController;

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L130

File: contracts/AaveV3YieldSource.sol   #3

133     IPoolAddressesProviderRegistry public poolAddressesProviderRegistry;

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L133

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..1d229ff 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -124,13 +124,13 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
   /* ============ Variables ============ */

   /// @notice Yield-bearing Aave aToken address.
-  IAToken public aToken;
+  IAToken public immutable aToken;

   /// @notice Aave RewardsController address.
-  IRewardsController public rewardsController;
+  IRewardsController public immutable rewardsController;

   /// @notice Aave poolAddressesProviderRegistry address.
-  IPoolAddressesProviderRegistry public poolAddressesProviderRegistry;
+  IPoolAddressesProviderRegistry public immutable poolAddressesProviderRegistry;

   /// @notice ERC20 token decimals.
   uint8 private immutable _decimals;

diff --git a/gas.orig b/gas.new
index d87edc2..a6cd51d 100644
--- a/gas.orig
+++ b/gas.new
@@ -5,21 +5,21 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Contract                  ·  Method                  ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  claimRewards            ·      54735  ·      56896  ·      55816  ·            4  ·          -  │
+|  AaveV3YieldSourceHarness  ·  claimRewards            ·      50521  ·      52682  ·      51602  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  decreaseERC20Allowance  ·      37465  ·      39638  ·      38910  ·            3  ·          -  │
+|  AaveV3YieldSourceHarness  ·  decreaseERC20Allowance  ·      35374  ·      37547  ·      36819  ·            3  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  increaseERC20Allowance  ·      59133  ·      61618  ·      61212  ·            7  ·          -  │
+|  AaveV3YieldSourceHarness  ·  increaseERC20Allowance  ·      57042  ·      59527  ·      59121  ·            7  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  mint                    ·      51381  ·      68493  ·      61904  ·           13  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110713  ·            1  ·          -  │
+|  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     106359  ·            1  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·          -  │
+|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     106314  ·     149466  ·     137930  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·          -  │
+|  AaveV3YieldSourceHarness  ·  transferERC20           ·      56227  ·      58376  ·      57302  ·            2  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  ERC20Mintable             ·  approve                 ·      26692  ·      46592  ·      43275  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2497750  ·    2497762  ·    2497760  ·        8.3 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

2. `internal` functions only called once can be inlined to save gas

Not inlining costs 20 to 40 gas because of two extra JUMP instructions and additional stack operations needed for function calls.

File: contracts/AaveV3YieldSource.sol   #1

369     function _sharesToToken(uint256 _shares) internal view returns (uint256) {

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L369

File: contracts/AaveV3YieldSource.sol   #2

388     function _poolProvider() internal view returns (IPoolAddressesProvider) {

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L388

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..d7ec7ec 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -201,7 +201,12 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @return The underlying balance of asset tokens.
    */
   function balanceOfToken(address _user) external override returns (uint256) {
-    return _sharesToToken(balanceOf(_user));
+    uint256 _shares = balanceOf(_user);
+    uint256 _supply = totalSupply();
+
+    // tokens = (shares * yieldSourceATokenTotalSupply) / totalShares
+    return _supply == 0 ? _shares : _shares.mul(aToken.balanceOf(address(this))).div(_supply);
+ 
   }

   /**
@@ -361,18 +366,6 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     return _supply == 0 ? _tokens : _tokens.mul(_supply).div(aToken.balanceOf(address(this)));
   }

-  /**
-   * @notice Calculates the number of asset tokens a user has in the yield source.
-   * @param _shares Amount of shares
-   * @return Number of asset tokens.
-   */
-  function _sharesToToken(uint256 _shares) internal view returns (uint256) {
-    uint256 _supply = totalSupply();
-
-    // tokens = (shares * yieldSourceATokenTotalSupply) / totalShares
-    return _supply == 0 ? _shares : _shares.mul(aToken.balanceOf(address(this))).div(_supply);
-  }
-
   /**
    * @notice Returns the underlying asset token address.
    * @return Underlying asset token address.
@@ -381,22 +374,13 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     return aToken.UNDERLYING_ASSET_ADDRESS();
   }

-  /**
-   * @notice Retrieves Aave PoolAddressesProvider address.
-   * @return A reference to PoolAddressesProvider interface.
-   */
-  function _poolProvider() internal view returns (IPoolAddressesProvider) {
-    return
-      IPoolAddressesProvider(
-        poolAddressesProviderRegistry.getAddressesProvidersList()[ADDRESSES_PROVIDER_ID]
-      );
-  }
-
   /**
    * @notice Retrieves Aave Pool address.
    * @return A reference to Pool interface.
    */
   function _pool() internal view returns (IPool) {
-    return IPool(_poolProvider().getPool());
+    return IPool(IPoolAddressesProvider(
+        poolAddressesProviderRegistry.getAddressesProvidersList()[ADDRESSES_PROVIDER_ID]
+      ).getPool());
   }
 }

diff --git a/gas.orig b/gas.new
index d87edc2..6948266 100644
--- a/gas.orig
+++ b/gas.new
@@ -13,11 +13,11 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  mint                    ·      51381  ·      68493  ·      61904  ·           13  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110713  ·            1  ·          -  │
+|  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110678  ·            1  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·          -  │
+|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110633  ·     153685  ·     142182  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2559043  ·    2559055  ·    2559053  ·        8.5 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

3. Using `> 0` costs more gas than `!= 0` when used on a `uint` in a `require()` statement

This change saves 6 gas per instance

File: contracts/AaveV3YieldSource.sol   #1

179       require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L179

File: contracts/AaveV3YieldSource.sol   #2

233       require(_shares > 0, "AaveV3YS/shares-gt-zero");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L233

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..e00ad47 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -176,7 +176,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {

     require(_owner != address(0), "AaveV3YS/owner-not-zero-address");

-    require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");
+    require(decimals_ != 0, "AaveV3YS/decimals-gt-zero");
     _decimals = decimals_;

     // Approve once for max amount
@@ -230,7 +230,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    */
   function supplyTokenTo(uint256 _depositAmount, address _to) external override nonReentrant {
     uint256 _shares = _tokenToShares(_depositAmount);
-    require(_shares > 0, "AaveV3YS/shares-gt-zero");
+    require(_shares != 0, "AaveV3YS/shares-gt-zero");

     address _underlyingAssetAddress = _tokenAddress();
     IERC20(_underlyingAssetAddress).safeTransferFrom(msg.sender, address(this), _depositAmount);

diff --git a/gas.orig b/gas.new
index d87edc2..9a90ad3 100644
--- a/gas.orig
+++ b/gas.new
@@ -17,7 +17,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·          -  │
+|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110662  ·     153714  ·     142211  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2505106  ·    2505118  ·    2505116  ·        8.4 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

4. Usage of `uints`/`ints` smaller than 32 bytes (256 bits) incurs overhead

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.

https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html Use a larger size then downcast where needed

File: contracts/AaveV3YieldSource.sol   #1

47       uint8 decimals,

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L47

File: contracts/AaveV3YieldSource.sol   #2

136     uint8 private immutable _decimals;

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L136

File: contracts/AaveV3YieldSource.sol   #3

145     uint16 private constant REFERRAL_CODE = uint16(188);

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L145

File: contracts/AaveV3YieldSource.sol   #4

165       uint8 decimals_,

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L165

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..0dfa477 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -44,7 +44,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     IPoolAddressesProviderRegistry poolAddressesProviderRegistry,
     string name,
     string symbol,
-    uint8 decimals,
+    uint256 decimals,
     address owner
   );

@@ -133,7 +133,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
   IPoolAddressesProviderRegistry public poolAddressesProviderRegistry;

   /// @notice ERC20 token decimals.
-  uint8 private immutable _decimals;
+  uint256 private immutable _decimals;

   /**
    * @dev Aave genesis market PoolAddressesProvider's ID.
@@ -142,7 +142,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
   uint256 private constant ADDRESSES_PROVIDER_ID = uint256(0);

   /// @dev PoolTogether's Aave Referral Code
-  uint16 private constant REFERRAL_CODE = uint16(188);
+  uint256 private constant REFERRAL_CODE = 188;

   /* ============ Constructor ============ */

@@ -162,7 +162,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     IPoolAddressesProviderRegistry _poolAddressesProviderRegistry,
     string memory _name,
     string memory _symbol,
-    uint8 decimals_,
+    uint256 decimals_,
     address _owner
   ) Ownable(_owner) ERC20(_name, _symbol) ReentrancyGuard() {
     require(address(_aToken) != address(0), "AaveV3YS/aToken-not-zero-address");
@@ -218,7 +218,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @return The number of decimals.
    */
   function decimals() public view virtual override returns (uint8) {
-    return _decimals;
+    return uint8(_decimals);
   }

   /**
@@ -234,7 +234,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {

     address _underlyingAssetAddress = _tokenAddress();
     IERC20(_underlyingAssetAddress).safeTransferFrom(msg.sender, address(this), _depositAmount);
-    _pool().supply(_underlyingAssetAddress, _depositAmount, address(this), REFERRAL_CODE);
+    _pool().supply(_underlyingAssetAddress, _depositAmount, address(this), uint16(REFERRAL_CODE));

     _mint(_to, _shares);

diff --git a/gas.orig b/gas.new
index d87edc2..367daee 100644
--- a/gas.orig
+++ b/gas.new
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2505659  ·    2505671  ·    2505669  ·        8.4 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

5. Don't use `SafeMath` once the solidity version is 0.8.0 or greater

Version 0.8.0 introduces internal overflow checks, so using SafeMath is redundant and adds overhead

File: contracts/AaveV3YieldSource.sol   #1

262   uint256 _balanceDiff = _afterBalance.sub(_beforeBalance);

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L262

File: contracts/AaveV3YieldSource.sol   #2

361   return _supply == 0 ? _tokens : _tokens.mul(_supply).div(aToken.balanceOf(address(this)));

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L361

File: contracts/AaveV3YieldSource.sol   #3

373   return _supply == 0 ? _shares : _shares.mul(aToken.balanceOf(address(this))).div(_supply);

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L373

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..6346344 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -11,7 +11,6 @@ import { IRewardsController } from "@aave/periphery-v3/contracts/rewards/interfa
 import { ERC20 } from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
-import { SafeMath } from "@openzeppelin/contracts/utils/math/SafeMath.sol";
 import { ReentrancyGuard } from "@openzeppelin/contracts/security/ReentrancyGuard.sol";

 import { Manageable, Ownable } from "@pooltogether/owner-manager-contracts/contracts/Manageable.sol";
@@ -23,7 +22,6 @@ import { IYieldSource } from "@pooltogether/yield-source-interface/contracts/IYi
  * @notice Yield Source for a PoolTogether prize pool that generates yield by depositing into Aave V3.
  */
 contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
-  using SafeMath for uint256;
   using SafeERC20 for IERC20;

   /* ============ Events ============ */
@@ -259,7 +257,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     _pool().withdraw(_underlyingAssetAddress, _redeemAmount, address(this));
     uint256 _afterBalance = _assetToken.balanceOf(address(this));

-    uint256 _balanceDiff = _afterBalance.sub(_beforeBalance);
+    uint256 _balanceDiff = _afterBalance - _beforeBalance;
     _assetToken.safeTransfer(msg.sender, _balanceDiff);

     emit RedeemedToken(msg.sender, _shares, _redeemAmount);
@@ -358,7 +356,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     uint256 _supply = totalSupply();

     // shares = (tokens * totalShares) / yieldSourceATokenTotalSupply
-    return _supply == 0 ? _tokens : _tokens.mul(_supply).div(aToken.balanceOf(address(this)));
+    return _supply == 0 ? _tokens : _tokens * _supply / aToken.balanceOf(address(this));
   }

   /**
@@ -370,7 +368,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     uint256 _supply = totalSupply();

     // tokens = (shares * yieldSourceATokenTotalSupply) / totalShares
-    return _supply == 0 ? _shares : _shares.mul(aToken.balanceOf(address(this))).div(_supply);
+    return _supply == 0 ? _shares : _shares * aToken.balanceOf(address(this)) / _supply;
   }

   /**

diff --git a/gas.orig b/gas.new
index d87edc2..1c91b72 100644
--- a/gas.orig
+++ b/gas.new
@@ -13,11 +13,11 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  mint                    ·      51381  ·      68493  ·      61904  ·           13  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110713  ·            1  ·          -  │
+|  AaveV3YieldSourceHarness  ·  redeemToken             ·          -  ·          -  ·     110584  ·            1  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·          -  │
+|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110584  ·     153720  ·     142189  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2497329  ·    2497341  ·    2497339  ·        8.3 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

6. `require()` or `revert()` statements that check input arguments should be at the top of the function

Checks that involve constants should come before checks that involve state variables

File: contracts/AaveV3YieldSource.sol   #1

177       require(_owner != address(0), "AaveV3YS/owner-not-zero-address");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L177

File: contracts/AaveV3YieldSource.sol   #2

179       require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L179

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..5d7d9fe 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -166,17 +166,16 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     address _owner
   ) Ownable(_owner) ERC20(_name, _symbol) ReentrancyGuard() {
     require(address(_aToken) != address(0), "AaveV3YS/aToken-not-zero-address");
+    require(_owner != address(0), "AaveV3YS/owner-not-zero-address");
+    require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");
+    require(address(_rewardsController) != address(0), "AaveV3YS/RC-not-zero-address");
+    require(address(_poolAddressesProviderRegistry) != address(0), "AaveV3YS/PR-not-zero-address");
     aToken = _aToken;

-    require(address(_rewardsController) != address(0), "AaveV3YS/RC-not-zero-address");
     rewardsController = _rewardsController;

-    require(address(_poolAddressesProviderRegistry) != address(0), "AaveV3YS/PR-not-zero-address");
     poolAddressesProviderRegistry = _poolAddressesProviderRegistry;

-    require(_owner != address(0), "AaveV3YS/owner-not-zero-address");
-
-    require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");
     _decimals = decimals_;

     // Approve once for max amount

diff --git a/gas.orig b/gas.new
index d87edc2..e76a03d 100644
--- a/gas.orig
+++ b/gas.new
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2505548  ·    2505560  ·    2505558  ·        8.4 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

7. Use custom errors rather than `revert()`/`require()` strings to save gas

File: contracts/AaveV3YieldSource.sol   #1

168       require(address(_aToken) != address(0), "AaveV3YS/aToken-not-zero-address");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L168

File: contracts/AaveV3YieldSource.sol   #2

171       require(address(_rewardsController) != address(0), "AaveV3YS/RC-not-zero-address");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L171

File: contracts/AaveV3YieldSource.sol   #3

174       require(address(_poolAddressesProviderRegistry) != address(0), "AaveV3YS/PR-not-zero-address");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L174

File: contracts/AaveV3YieldSource.sol   #4

177       require(_owner != address(0), "AaveV3YS/owner-not-zero-address");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L177

File: contracts/AaveV3YieldSource.sol   #5

179       require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L179

File: contracts/AaveV3YieldSource.sol   #6

233       require(_shares > 0, "AaveV3YS/shares-gt-zero");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L233

File: contracts/AaveV3YieldSource.sol   #7

276       require(_to != address(0), "AaveV3YS/payee-not-zero-address");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L276

File: contracts/AaveV3YieldSource.sol   #8

337       require(_token != address(aToken), "AaveV3YS/forbid-aToken-transfer");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L337

File: contracts/AaveV3YieldSource.sol   #9

349       require(_token != address(aToken), "AaveV3YS/forbid-aToken-allowance");

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L349

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..0a01635 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -26,6 +26,17 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
   using SafeMath for uint256;
   using SafeERC20 for IERC20;

+  error ATokenNotZeroAddress();
+  error RCNotZeroAddress();
+  error PRNotZeroAddress();
+  error OwnerNotZeroAddress();
+  error DecimalsGtZero();
+  error SharesGtZero();
+  error PayeeNotZeroAddress();
+  error ForbidATokenTransfer();
+  error ForbidATokenAllowance();
+
+
   /* ============ Events ============ */

   /**
@@ -165,18 +176,18 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     uint8 decimals_,
     address _owner
   ) Ownable(_owner) ERC20(_name, _symbol) ReentrancyGuard() {
-    require(address(_aToken) != address(0), "AaveV3YS/aToken-not-zero-address");
+    if (address(_aToken) == address(0)) revert ATokenNotZeroAddress();
     aToken = _aToken;

-    require(address(_rewardsController) != address(0), "AaveV3YS/RC-not-zero-address");
+    if (address(_rewardsController) == address(0)) revert RCNotZeroAddress();
     rewardsController = _rewardsController;

-    require(address(_poolAddressesProviderRegistry) != address(0), "AaveV3YS/PR-not-zero-address");
+    if (address(_poolAddressesProviderRegistry) == address(0)) revert PRNotZeroAddress();
     poolAddressesProviderRegistry = _poolAddressesProviderRegistry;

-    require(_owner != address(0), "AaveV3YS/owner-not-zero-address");
+    if (_owner == address(0)) revert OwnerNotZeroAddress();

-    require(decimals_ > 0, "AaveV3YS/decimals-gt-zero");
+    if (decimals_ == 0) revert DecimalsGtZero();
     _decimals = decimals_;

     // Approve once for max amount
@@ -230,7 +241,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    */
   function supplyTokenTo(uint256 _depositAmount, address _to) external override nonReentrant {
     uint256 _shares = _tokenToShares(_depositAmount);
-    require(_shares > 0, "AaveV3YS/shares-gt-zero");
+    if (_shares == 0) revert SharesGtZero();

     address _underlyingAssetAddress = _tokenAddress();
     IERC20(_underlyingAssetAddress).safeTransferFrom(msg.sender, address(this), _depositAmount);
@@ -273,7 +284,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @return True if operation was successful.
    */
   function claimRewards(address _to) external onlyManagerOrOwner returns (bool) {
-    require(_to != address(0), "AaveV3YS/payee-not-zero-address");
+    if (_to == address(0)) revert PayeeNotZeroAddress();

     address[] memory _assets = new address[](1);
     _assets[0] = address(aToken);
@@ -334,7 +345,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     address _to,
     uint256 _amount
   ) external onlyManagerOrOwner {
-    require(address(_token) != address(aToken), "AaveV3YS/forbid-aToken-transfer");
+    if (address(_token) == address(aToken)) revert ForbidATokenTransfer();
     _token.safeTransfer(_to, _amount);
     emit TransferredERC20(msg.sender, _to, _amount, _token);
   }
@@ -346,7 +357,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @param _token Address of the ERC20 token to check
    */
   function _requireNotAToken(address _token) internal view {
-    require(_token != address(aToken), "AaveV3YS/forbid-aToken-allowance");
+    if (_token == address(aToken)) revert ForbidATokenTransfer();
   }

   /**

diff --git a/gas.orig b/gas.new
index d87edc2..3aa8ff3 100644
--- a/gas.orig
+++ b/gas.new
@@ -17,7 +17,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  setManager              ·          -  ·          -  ·      47982  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·          -  │
+|  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110662  ·     153714  ·     142211  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2461083  ·    2461095  ·    2461093  ·        8.2 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

8. Functions guaranteed to revert when called by normal users can be marked `payable`

If a function modifier such as onlyOwner is used, the function will revert if a normal user tries to pay the function. Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided. The extra opcodes avoided are CALLVALUE(2),DUP1(3),ISZERO(3),PUSH2(3),JUMPI(10),PUSH1(3),DUP1(3),REVERT(0),JUMPDEST(1),POP(2), which costs an average of about 21 gas per call to the function, in addition to the extra deployment cost

File: contracts/AaveV3YieldSource.sol   #1

275     function claimRewards(address _to) external onlyManagerOrOwner returns (bool) {

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L275

File: contracts/AaveV3YieldSource.sol   #2

296     function decreaseERC20Allowance(
297       IERC20 _token,
298       address _spender,
299       uint256 _amount
300     ) external onlyManagerOrOwner {

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L296-L300

File: contracts/AaveV3YieldSource.sol   #3

315     function increaseERC20Allowance(
316       IERC20 _token,
317       address _spender,
318       uint256 _amount
319     ) external onlyManagerOrOwner {

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L315-L319

File: contracts/AaveV3YieldSource.sol   #4

332     function transferERC20(
333       IERC20 _token,
334       address _to,
335       uint256 _amount
336     ) external onlyManagerOrOwner {

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol#L332-L336

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..b16b82a 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -272,7 +272,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @param _to Address where the claimed rewards will be sent
    * @return True if operation was successful.
    */
-  function claimRewards(address _to) external onlyManagerOrOwner returns (bool) {
+  function claimRewards(address _to) payable external onlyManagerOrOwner returns (bool) {
     require(_to != address(0), "AaveV3YS/payee-not-zero-address");

     address[] memory _assets = new address[](1);
@@ -297,7 +297,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     IERC20 _token,
     address _spender,
     uint256 _amount
-  ) external onlyManagerOrOwner {
+  ) payable external onlyManagerOrOwner {
     _requireNotAToken(address(_token));
     _token.safeDecreaseAllowance(_spender, _amount);
     emit DecreasedERC20Allowance(msg.sender, _spender, _amount, _token);
@@ -316,7 +316,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     IERC20 _token,
     address _spender,
     uint256 _amount
-  ) external onlyManagerOrOwner {
+  ) payable external onlyManagerOrOwner {
     _requireNotAToken(address(_token));
     _token.safeIncreaseAllowance(_spender, _amount);
     emit IncreasedERC20Allowance(msg.sender, _spender, _amount, _token);
@@ -333,7 +333,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     IERC20 _token,
     address _to,
     uint256 _amount
-  ) external onlyManagerOrOwner {
+  ) payable external onlyManagerOrOwner {
     require(address(_token) != address(aToken), "AaveV3YS/forbid-aToken-transfer");
     _token.safeTransfer(_to, _amount);
     emit TransferredERC20(msg.sender, _to, _amount, _token);

diff --git a/gas.orig b/gas.new
index d87edc2..b10b8b3 100644
--- a/gas.orig
+++ b/gas.new
@@ -5,11 +5,11 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Contract                  ·  Method                  ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  claimRewards            ·      54735  ·      56896  ·      55816  ·            4  ·          -  │
+|  AaveV3YieldSourceHarness  ·  claimRewards            ·      54711  ·      56872  ·      55792  ·            4  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  decreaseERC20Allowance  ·      37465  ·      39638  ·      38910  ·            3  ·          -  │
+|  AaveV3YieldSourceHarness  ·  decreaseERC20Allowance  ·      37441  ·      39614  ·      38886  ·            3  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  increaseERC20Allowance  ·      59133  ·      61618  ·      61212  ·            7  ·          -  │
+|  AaveV3YieldSourceHarness  ·  increaseERC20Allowance  ·      59109  ·      61594  ·      61188  ·            7  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  mint                    ·      51381  ·      68493  ·      61904  ·           13  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -19,7 +19,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  AaveV3YieldSourceHarness  ·  supplyTokenTo           ·     110668  ·     153720  ·     142217  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness  ·  transferERC20           ·      58318  ·      60467  ·      59393  ·            2  ·          -  │
+|  AaveV3YieldSourceHarness  ·  transferERC20           ·      58294  ·      60443  ·      59369  ·            2  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
 |  ERC20Mintable             ·  approve                 ·      26692  ·      46592  ·      43275  ·            6  ·          -  │
 ·····························|··························|·············|·············|·············|···············|··············
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2586991  ·    2587003  ·    2587001  ·        8.6 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

9. Method IDs can be fiddled with to reduce gas costs

See this page for details

File: contracts/AaveV3YieldSource.sol (various lines)   #1

https://github.com/pooltogether/aave-v3-yield-source/blob/e63d1b0e396a5bce89f093630c282ca1c6627e44/contracts/AaveV3YieldSource.sol

diff --git a/AaveV3YieldSource.sol.orig b/AaveV3YieldSource.sol.new
index 3975311..dc04818 100644
--- a/AaveV3YieldSource.sol.orig
+++ b/AaveV3YieldSource.sol.new
@@ -180,7 +180,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     _decimals = decimals_;

     // Approve once for max amount
-    IERC20(_tokenAddress()).safeApprove(address(_pool()), type(uint256).max);
+    IERC20(_tokenAddress()).safeApprove(address(_pool_Jo$()), type(uint256).max);

     emit AaveV3YieldSourceInitialized(
       _aToken,
@@ -234,7 +234,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {

     address _underlyingAssetAddress = _tokenAddress();
     IERC20(_underlyingAssetAddress).safeTransferFrom(msg.sender, address(this), _depositAmount);
-    _pool().supply(_underlyingAssetAddress, _depositAmount, address(this), REFERRAL_CODE);
+    _pool_Jo$().supply(_underlyingAssetAddress, _depositAmount, address(this), REFERRAL_CODE);

     _mint(_to, _shares);

@@ -256,7 +256,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
     _burn(msg.sender, _shares);

     uint256 _beforeBalance = _assetToken.balanceOf(address(this));
-    _pool().withdraw(_underlyingAssetAddress, _redeemAmount, address(this));
+    _pool_Jo$().withdraw(_underlyingAssetAddress, _redeemAmount, address(this));
     uint256 _afterBalance = _assetToken.balanceOf(address(this));

     uint256 _balanceDiff = _afterBalance.sub(_beforeBalance);
@@ -385,7 +385,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @notice Retrieves Aave PoolAddressesProvider address.
    * @return A reference to PoolAddressesProvider interface.
    */
-  function _poolProvider() internal view returns (IPoolAddressesProvider) {
+  function _poolProvider_uaF() internal view returns (IPoolAddressesProvider) {
     return
       IPoolAddressesProvider(
         poolAddressesProviderRegistry.getAddressesProvidersList()[ADDRESSES_PROVIDER_ID]
@@ -396,7 +396,7 @@ contract AaveV3YieldSource is ERC20, IYieldSource, Manageable, ReentrancyGuard {
    * @notice Retrieves Aave Pool address.
    * @return A reference to Pool interface.
    */
-  function _pool() internal view returns (IPool) {
-    return IPool(_poolProvider().getPool());
+  function _pool_Jo$() internal view returns (IPool) {
+    return IPool(_poolProvider_uaF().getPool());
   }
 }

diff --git a/gas.orig b/gas.new
index d87edc2..72bf242 100644
--- a/gas.orig
+++ b/gas.new
@@ -29,7 +29,7 @@
 ·····························|··························|·············|·············|·············|···············|··············
 |  Deployments                                          ·                                         ·  % of limit   ·             │
 ························································|·············|·············|·············|···············|··············
-|  AaveV3YieldSourceHarness                             ·    2505760  ·    2505772  ·    2505770  ·        8.4 %  ·          -  │
+|  AaveV3YieldSourceHarness                             ·    2505748  ·    2505760  ·    2505758  ·        8.4 %  ·          -  │
 ························································|·············|·············|·············|···············|··············
 |  ERC20Mintable                                        ·          -  ·          -  ·    1154099  ·        3.8 %  ·          -  │
 ·-------------------------------------------------------|-------------|-------------|-------------|---------------|-------------·

code-423n4 / 2022-04-pooltogether-findings

Gas Optimizations #84

1. State variables only set in the constructor should be declared `immutable`

2. `internal` functions only called once can be inlined to save gas

3. Using `> 0` costs more gas than `!= 0` when used on a `uint` in a `require()` statement

4. Usage of `uints`/`ints` smaller than 32 bytes (256 bits) incurs overhead

5. Don't use `SafeMath` once the solidity version is 0.8.0 or greater

6. `require()` or `revert()` statements that check input arguments should be at the top of the function

7. Use custom errors rather than `revert()`/`require()` strings to save gas

8. Functions guaranteed to revert when called by normal users can be marked `payable`

9. Method IDs can be fiddled with to reduce gas costs

code-423n4 / 2022-04-pooltogether-findings

Gas Optimizations #84

1. State variables only set in the constructor should be declared immutable

2. internal functions only called once can be inlined to save gas

3. Using > 0 costs more gas than != 0 when used on a uint in a require() statement

4. Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead

5. Don't use SafeMath once the solidity version is 0.8.0 or greater

6. require() or revert() statements that check input arguments should be at the top of the function

7. Use custom errors rather than revert()/require() strings to save gas

8. Functions guaranteed to revert when called by normal users can be marked payable

9. Method IDs can be fiddled with to reduce gas costs

1. State variables only set in the constructor should be declared `immutable`

2. `internal` functions only called once can be inlined to save gas

3. Using `> 0` costs more gas than `!= 0` when used on a `uint` in a `require()` statement

4. Usage of `uints`/`ints` smaller than 32 bytes (256 bits) incurs overhead

5. Don't use `SafeMath` once the solidity version is 0.8.0 or greater

6. `require()` or `revert()` statements that check input arguments should be at the top of the function

7. Use custom errors rather than `revert()`/`require()` strings to save gas

8. Functions guaranteed to revert when called by normal users can be marked `payable`