Gas Optimizations

[code423n4]

Overview

Risk Rating	Number of issues
Gas Issues	13

Table of Contents:

• 1. Caching storage values in memory
• 2. Multiple accesses of a mapping/array should use a local variable cache
• 3. Use of the memory keyword when storage should be used
• 4. Unnecessary memory operations with an immutable variable
• 5. The result of a function call should be cached rather than re-calling the function
• 6. Unchecking arithmetics operations that can't underflow/overflow
• 7. <array>.length should not be looked up in every loop of a for-loop
• 8. ++i costs less gas compared to i++ or i += 1 (same for --i vs i-- or i -= 1)
• 9. Increments/decrements can be unchecked in for-loops
• 10. It costs more gas to initialize variables with their default value than letting the default value be applied
• 11. Upgrade pragma
• 12. Optimizations with assembly
  • 12.1. Use assembly for math (add, sub, mul, div)
  • 12.2. Use assembly to check for address(0)
  • 12.3. Use assembly to write storage values
• 13. Use Custom Errors instead of Revert Strings to save Gas

1. Caching storage values in memory

The code can be optimized by minimizing the number of SLOADs.

SLOADs are expensive (100 gas after the 1st one) compared to MLOADs/MSTOREs (3 gas each). Storage values read multiple times should instead be cached in memory the first time (costing 1 SLOAD) and then read from this cache to avoid multiple SLOADs.

• contracts/actions/MIMOEmptyVault.sol:

  76:     if (msg.sender != address(lendingPool)) { //@audit gas: SLOAD (lendingPool)
  77:       revert CustomErrors.CALLER_NOT_LENDING_POOL(msg.sender, address(lendingPool)); //@audit gas: SLOAD (lendingPool)
  98:     vaultCollateral.safeIncreaseAllowance(address(lendingPool), flashloanRepayAmount); //@audit gas: SLOAD (lendingPool)

• contracts/actions/MIMOLeverage.sol:

   81:     if (msg.sender != address(lendingPool)) { //@audit gas: SLOAD (lendingPool)
   82:       revert CustomErrors.CALLER_NOT_LENDING_POOL(msg.sender, address(lendingPool)); //@audit gas: SLOAD (lendingPool)
  100:     asset.safeIncreaseAllowance(address(lendingPool), flashloanRepayAmount); //@audit gas: SLOAD (lendingPool)

• contracts/actions/MIMORebalance.sol:

   79:     if (msg.sender != address(lendingPool)) { //@audit gas: SLOAD (lendingPool)
   80:       revert CustomErrors.CALLER_NOT_LENDING_POOL(msg.sender, address(lendingPool)); //@audit gas: SLOAD (lendingPool)
  101:     fromCollateral.safeIncreaseAllowance(address(lendingPool), flashloanRepayAmount); //@audit gas: SLOAD (lendingPool)

• contracts/actions/automated/MIMOAutoRebalance.sol:

  107:     if (msg.sender != address(lendingPool)) { //@audit gas: SLOAD (lendingPool)
  108:       revert CustomErrors.CALLER_NOT_LENDING_POOL(msg.sender, address(lendingPool)); //@audit gas: SLOAD (lendingPool)
  129:     fromCollateral.safeIncreaseAllowance(address(lendingPool), flashloanRepayAmount); //@audit gas: SLOAD (lendingPool)

• contracts/actions/managed/MIMOManagedRebalance.sol:

  108:     if (msg.sender != address(lendingPool)) { //@audit gas: SLOAD (lendingPool)
  109:       revert CustomErrors.CALLER_NOT_LENDING_POOL(msg.sender, address(lendingPool)); //@audit gas: SLOAD (lendingPool)
  130:     fromCollateral.safeIncreaseAllowance(address(lendingPool), flashloanRepayAmount); //@audit gas: SLOAD (lendingPool)

• contracts/proxy/MIMOProxy.sol:

  56:     if (owner != msg.sender) { //@audit gas: SLOAD (owner), this is important here as it impacts both the happy and sad paths
  62:         revert CustomErrors.EXECUTION_NOT_AUTHORIZED(owner, msg.sender, target, selector); //@audit gas: SLOAD (owner)
  72:     address owner_ = owner; //@audit gas: SLOAD (owner)
  82:     if (owner_ != owner) { //@audit gas: SLOAD (owner)
  83:       revert CustomErrors.OWNER_CHANGED(owner_, owner); //@audit gas: SLOAD (owner)

2. Multiple accesses of a mapping/array should use a local variable cache

Caching a mapping's value in a local storage or calldata variable when the value is accessed multiple times saves ~42 gas per access due to not having to perform the same offset calculation every time.

Affected code:

• MIMOEmptyVault.sol#executeOperation(): amounts[0]

File: MIMOEmptyVault.sol
63:   function executeOperation(
64:     address[] calldata assets,
65:     uint256[] calldata amounts,
...
81:     uint256 amount = amounts[0];
82:     vaultCollateral.safeTransfer(address(mimoProxy), amounts[0]);

• MIMOLeverage.sol#executeOperation(): amounts[0]

File: MIMOLeverage.sol
68:   function executeOperation(
69:     address[] calldata assets,
70:     uint256[] calldata amounts,
...
86:     asset.safeTransfer(address(mimoProxy), amounts[0]);
87:     uint256 flashloanRepayAmount = amounts[0] + premiums[0];

• MIMORebalance.sol#executeOperation(): amounts[0]

File: MIMORebalance.sol
63:   function executeOperation(
64:     address[] calldata assets,
65:     uint256[] calldata amounts,
...
84:     uint256 amount = amounts[0];
85:     fromCollateral.safeTransfer(address(mimoProxy), amounts[0]);

• MIMOAutoRebalance.sol#executeOperation(): amounts[0]

File: MIMOAutoRebalance.sol
090:   function executeOperation(
091:     address[] calldata assets,
092:     uint256[] calldata amounts,
...
112:     uint256 amount = amounts[0];
113:     fromCollateral.safeTransfer(address(mimoProxy), amounts[0]);
114:     uint256 flashloanRepayAmount = amounts[0] + premiums[0];

• MIMOManagedRebalance.sol#executeOperation(): amounts[0]

File: MIMOManagedRebalance.sol
091:   function executeOperation(
092:     address[] calldata assets,
093:     uint256[] calldata amounts,
...
113:     uint256 amount = amounts[0];
114:     fromCollateral.safeTransfer(address(mimoProxy), amounts[0]);
115:     uint256 flashloanRepayAmount = amounts[0] + premiums[0];

3. Use of the memory keyword when storage should be used

When copying a state struct in memory, there are as many SLOADs and MSTOREs as there are slots. When reading the whole struct multiple times is not needed, it's better to actually only read the relevant field(s). When only some of the fields are read several times, these particular values should be cached instead of the whole state struct.

Consider using a storage pointer instead of memory location here:

File: DexAddressProvider.sol
51:   function getDex(uint256 index) external view override returns (address, address) {
- 52:     Dex memory dex = _dexMapping[index];
+ 52:     Dex storage dex = _dexMapping[index];
53:     return (dex.proxy, dex.router);
54:   }

4. Unnecessary memory operations with an immutable variable

immutable variables aren't storage variable, their instances get replaced in the code with their value. This caching operation is unnecessary here:

File: MIMOVaultActions.sol
65:   function depositAndBorrow(
66:     IERC20 collateral,
67:     uint256 depositAmount,
68:     uint256 borrowAmount
69:   ) external override {
70:     IVaultsCore core_ = core; //@audit gas: unnecessary MSTORE as core is immutable
71:     collateral.safeTransferFrom(msg.sender, address(this), depositAmount);
72:     collateral.safeIncreaseAllowance(address(core_), depositAmount);//@audit gas: unnecessary MLOAD as core is immutable
73:     core_.depositAndBorrow(address(collateral), depositAmount, borrowAmount);//@audit gas: unnecessary MLOAD as core is immutable
74:   }

5. The result of a function call should be cached rather than re-calling the function

External calls are expensive. Consider using the already existing cached value for the following:

File: MIMOManagedRebalance.sol
50:   function rebalance(
...
61:     address vaultOwner = vaultsData.vaultOwner(rbData.vaultId);
...
- 65:     _takeFlashLoan(flData, abi.encode(vaultsData.vaultOwner(rbData.vaultId), managerFee, rbData, swapData));
+ 65:     _takeFlashLoan(flData, abi.encode(vaultOwner, managerFee, rbData, swapData));

6. Unchecking arithmetics operations that can't underflow/overflow

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: https://docs.soliditylang.org/en/v0.8.10/control-structures.html#checked-or-unchecked-arithmetic

Consider wrapping with an unchecked block here (around 25 gas saved per instance):

• File: MIMOAutoAction.sol

097:     if (swapResultValue >= rebalanceValue) {
098:       return true;
099:     }
100: 
101:     uint256 vaultVariation = (rebalanceValue - swapResultValue).wadDiv(rebalanceValue); //@audit should be unchecked due to L97

• File: MIMOManagedAction.sol

120:     if (swapResultValue >= rebalanceValue) {
121:       return true;
122:     }
123: 
124:     uint256 vaultVariation = (rebalanceValue - swapResultValue).wadDiv(rebalanceValue); //@audit should be unchecked due to L120

• File: MIMOLeverage.sol

132:     if (collateralBalanceAfter > flashloanRepayAmount) {
133:       token.safeIncreaseAllowance(address(core), collateralBalanceAfter - flashloanRepayAmount); //@audit should be unchecked due to L132

7. <array>.length should not be looked up in every loop of a for-loop

Note : This is describing an optimization that the sponsor already chose to ignore, to be thorough: https://github.com/code-423n4/2022-08-mimo/tree/main/docs/#for-loop-syntax

Reading array length at each iteration of the loop consumes more gas than necessary.

In the best case scenario (length read on a memory variable), caching the array length in the stack saves around 3 gas per iteration. In the worst case scenario (external calls at each iteration), the amount of gas wasted can be massive.

Here, consider storing the array's length in a variable before the for-loop, and use this new variable instead:

proxy/MIMOProxy.sol:132:    for (uint256 i = 0; i < targets.length; i++) {

8. ++i costs less gas compared to i++ or i += 1 (same for --i vs i-- or i -= 1)

Pre-increments and pre-decrements are cheaper.

For a uint256 i variable, the following is true with the Optimizer enabled at 10k:

Increment:

• i += 1 is the most expensive form
• i++ costs 6 gas less than i += 1
• ++i costs 5 gas less than i++ (11 gas less than i += 1)

Decrement:

• i -= 1 is the most expensive form
• i-- costs 11 gas less than i -= 1
• --i costs 5 gas less than i-- (16 gas less than i -= 1)

Note that post-increments (or post-decrements) return the old value before incrementing or decrementing, hence the name post-increment:

uint i = 1;  
uint j = 2;
require(j == i++, "This will be false as i is incremented after the comparison");

However, pre-increments (or pre-decrements) return the new value:

uint i = 1;  
uint j = 2;
require(j == ++i, "This will be true as i is incremented before the comparison");

In the pre-increment case, the compiler has to create a temporary variable (when used) for returning 1 instead of 2.

Affected code:

proxy/MIMOProxy.sol:132:    for (uint256 i = 0; i < targets.length; i++) {

Consider using pre-increments and pre-decrements where they are relevant (meaning: not where post-increments/decrements logic are relevant).

9. Increments/decrements can be unchecked in for-loops

Note : This is describing an optimization that the sponsor already chose to ignore, to be thorough: https://github.com/code-423n4/2022-08-mimo/tree/main/docs/#for-loop-syntax

In Solidity 0.8+, there's a default overflow check on unsigned integers. It's possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline.

ethereum/solidity#10695

Consider wrapping with an unchecked block here (around 25 gas saved per instance):

proxy/MIMOProxy.sol:132:    for (uint256 i = 0; i < targets.length; i++) {

The change would be:

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

The same can be applied with decrements (which should use break when i == 0).

The risk of overflow is non-existent for uint256 here.

10. It costs more gas to initialize variables with their default value than letting the default value be applied

If a variable is not set/initialized, it is assumed to have the default value (0 for uint, false for bool, address(0) for address...). Explicitly initializing it with its default value is an anti-pattern and wastes gas (around 3 gas per instance).

Affected code:

proxy/MIMOProxy.sol:132:    for (uint256 i = 0; i < targets.length; i++) {

Consider removing explicit initializations for default values.

11. Upgrade pragma

Using newer compiler versions and the optimizer give gas optimizations. Also, additional safety checks are available for free.

The advantages here are:

• Contract existence checks (>= 0.8.10): external calls skip contract existence checks if the external call has a return value

Consider upgrading here :

proxy/MIMOProxy.sol:2:pragma solidity >=0.8.4;
proxy/MIMOProxyFactory.sol:2:pragma solidity >=0.8.4;
proxy/MIMOProxyRegistry.sol:2:pragma solidity >=0.8.4;

12. Optimizations with assembly

The original warden who proved these type of findings is 0xKitsune. Clone the repo 0xKitsune/gas-lab, copy/paste the contract examples and run forge test --gas-report to replicate the gas reports with the optimizer turned on and set to 10000 runs.

12.1. Use assembly for math (add, sub, mul, div)

Use assembly for math instead of Solidity. You can check for overflow/underflow in assembly to ensure safety. If using Solidity versions < 0.8.0 and you are using Safemath, you can gain significant gas savings by using assembly to calculate values and checking for overflow/underflow.

POC Contract:

contract GasTest is DSTest {
    Contract0 c0;
    Contract1 c1;
    Contract2 c2;
    Contract3 c3;
    Contract4 c4;
    Contract5 c5;
    Contract6 c6;
    Contract7 c7;

    function setUp() public {
        c0 = new Contract0();
        c1 = new Contract1();
        c2 = new Contract2();
        c3 = new Contract3();
        c4 = new Contract4();
        c5 = new Contract5();
        c6 = new Contract6();
        c7 = new Contract7();
    }

    function testGas() public {
        c0.addTest(34598345, 100);
        c1.addAssemblyTest(34598345, 100);
        c2.subTest(34598345, 100);
        c3.subAssemblyTest(34598345, 100);
        c4.mulTest(34598345, 100);
        c5.mulAssemblyTest(34598345, 100);
        c6.divTest(34598345, 100);
        c7.divAssemblyTest(34598345, 100);
    }
}

contract Contract0 {
    //addition in Solidity
    function addTest(uint256 a, uint256 b) public pure {
        uint256 c = a + b;
    }
}

contract Contract1 {
    //addition in assembly
    function addAssemblyTest(uint256 a, uint256 b) public pure {
        assembly {
            let c := add(a, b)

            if lt(c, a) {
                mstore(0x00, "overflow")
                revert(0x00, 0x20)
            }
        }
    }
}

contract Contract2 {
    //subtraction in Solidity
    function subTest(uint256 a, uint256 b) public pure {
        uint256 c = a - b;
    }
}

contract Contract3 {
    //subtraction in assembly
    function subAssemblyTest(uint256 a, uint256 b) public pure {
        assembly {
            let c := sub(a, b)

            if gt(c, a) {
                mstore(0x00, "underflow")
                revert(0x00, 0x20)
            }
        }
    }
}

contract Contract4 {
    //multiplication in Solidity
    function mulTest(uint256 a, uint256 b) public pure {
        uint256 c = a * b;
    }
}

contract Contract5 {
    //multiplication in assembly
    function mulAssemblyTest(uint256 a, uint256 b) public pure {
        assembly {
            let c := mul(a, b)

            if lt(c, a) {
                mstore(0x00, "overflow")
                revert(0x00, 0x20)
            }
        }
    }
}

contract Contract6 {
    //division in Solidity
    function divTest(uint256 a, uint256 b) public pure {
        uint256 c = a * b;
    }
}

contract Contract7 {
    //division in assembly
    function divAssemblyTest(uint256 a, uint256 b) public pure {
        assembly {
            let c := div(a, b)

            if gt(c, a) {
                mstore(0x00, "underflow")
                revert(0x00, 0x20)
            }
        }
    }
}

POC Gas Report:

╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract0 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 40493              ┆ 233             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ addTest            ┆ 303             ┆ 303 ┆ 303    ┆ 303 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract1 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 37087              ┆ 216             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ addAssemblyTest    ┆ 263             ┆ 263 ┆ 263    ┆ 263 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract2 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 40293              ┆ 232             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ subTest            ┆ 300             ┆ 300 ┆ 300    ┆ 300 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract3 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 37287              ┆ 217             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ subAssemblyTest    ┆ 263             ┆ 263 ┆ 263    ┆ 263 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract4 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 41893              ┆ 240             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ mulTest            ┆ 325             ┆ 325 ┆ 325    ┆ 325 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract5 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 37087              ┆ 216             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ mulAssemblyTest    ┆ 265             ┆ 265 ┆ 265    ┆ 265 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract6 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 41893              ┆ 240             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ divTest            ┆ 325             ┆ 325 ┆ 325    ┆ 325 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract7 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 37287              ┆ 217             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ divAssemblyTest    ┆ 265             ┆ 265 ┆ 265    ┆ 265 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯

Affected code:

actions/automated/MIMOAutoAction.sol:41:    uint256 maxVarFee = (autoParams.targetRatio.wadDiv(toVaultMcr + autoParams.mcrBuffer) + WadRayMath.WAD).wadDiv(
actions/automated/MIMOAutoAction.sol:101:    uint256 vaultVariation = (rebalanceValue - swapResultValue).wadDiv(rebalanceValue);
actions/automated/MIMOAutoRebalance.sol:16:        targetRatio * (vaultDebt + fixedFee) - collateralValue
actions/automated/MIMOAutoRebalance.sol:18:          targetRatio / mcrB - 1 - targetRatio * variableFee 
actions/automated/MIMOAutoRebalance.sol:114:    uint256 flashloanRepayAmount = amounts[0] + premiums[0];
actions/automated/MIMOAutoRebalance.sol:180:    uint256 targetRatio = autoVault.targetRatio + 1e15; // add 0.1% to account for rounding
actions/automated/MIMOAutoRebalance.sol:184:    uint256 rebalanceValue = (targetRatio.wadMul(vaultState.vaultDebt + autoVault.fixedFee) -
actions/automated/MIMOAutoRebalance.sol:186:        (targetRatio.wadDiv(toVaultMcr + autoVault.mcrBuffer) - targetRatio.wadMul(autoVault.varFee) - WadRayMath.WAD)
actions/automated/MIMOAutoRebalance.sol:189:    autoFee = autoVault.fixedFee + rebalanceValue.wadMul(autoVault.varFee);
actions/automated/MIMOAutoRebalance.sol:191:    mintAmount = rebalanceValue.wadDiv(toVaultMcr + autoVault.mcrBuffer) - autoFee;
actions/automated/MIMOAutoRebalance.sol:275:    uint256 swapResultValue = priceFeed.convertFrom(autoVault.toCollateral, vaultBBalanceAfter - vaultBBalanceBefore);
actions/managed/MIMOManagedAction.sol:124:    uint256 vaultVariation = (rebalanceValue - swapResultValue).wadDiv(rebalanceValue);
actions/managed/MIMOManagedRebalance.sol:60:    uint256 managerFee = managedVault.fixedFee + flData.amount.wadMul(managedVault.varFee);
actions/managed/MIMOManagedRebalance.sol:115:    uint256 flashloanRepayAmount = amounts[0] + premiums[0];
actions/managed/MIMOManagedRebalance.sol:193:    uint256 swapResultValue = priceFeed.convertFrom(toCollateral, vaultBBalanceAfter - vaultBBalanceBefore);
actions/managed/MIMOManagedRebalance.sol:206:    uint256 minVaultBRatio = a.config().collateralMinCollateralRatio(toCollateral) + managedVault.mcrBuffer;
actions/MIMOEmptyVault.sol:83:    uint256 flashloanRepayAmount = amount + premiums[0];
actions/MIMOLeverage.sol:87:    uint256 flashloanRepayAmount = amounts[0] + premiums[0];
actions/MIMOLeverage.sol:133:      token.safeIncreaseAllowance(address(core), collateralBalanceAfter - flashloanRepayAmount);
actions/MIMOLeverage.sol:134:      core.deposit(address(token), collateralBalanceAfter - flashloanRepayAmount);
actions/MIMORebalance.sol:86:    uint256 flashloanRepayAmount = amount + premiums[0];
actions/MIMORebalance.sol:127:    core.depositAndBorrow(address(rbData.toCollateral), depositAmount, rbData.mintAmount + fee);
proxy/MIMOProxy.sol:75:    uint256 stipend = gasleft() - minGasReserve;

12.2. Use assembly to check for address(0)

contract GasTest is DSTest {
    Contract0 c0;
    Contract1 c1;

    function setUp() public {
        c0 = new Contract0();
        c1 = new Contract1();
    }

    function testGas() public view {
        c0.ownerNotZero(address(this));
        c1.assemblyOwnerNotZero(address(this));
    }
}

contract Contract0 {
    function ownerNotZero(address _addr) public pure {
        require(_addr != address(0), "zero address)");
    }
}

contract Contract1 {
    function assemblyOwnerNotZero(address _addr) public pure {
        assembly {
            if iszero(_addr) {
                mstore(0x00, "zero address")
                revert(0x00, 0x20)
            }
        }
    }
}

POC Gas Report:

╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract0 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 61311              ┆ 338             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ ownerNotZero       ┆ 258             ┆ 258 ┆ 258    ┆ 258 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭──────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract1 contract   ┆                 ┆     ┆        ┆     ┆         │
╞══════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost      ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 44893                ┆ 255             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name        ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ assemblyOwnerNotZero ┆ 252             ┆ 252 ┆ 252    ┆ 252 ┆ 1       │
╰──────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯

Affected code:

actions/automated/MIMOAutoAction.sol:19:    if (address(_a) == address(0) || address(_proxyRegistry) == address(0)) {
actions/automated/MIMOAutoRebalance.sol:41:    if (_mimoRebalance == address(0)) {
actions/managed/MIMOManagedAction.sol:20:    if (address(_a) == address(0) || address(_proxyRegistry) == address(0)) {
actions/managed/MIMOManagedRebalance.sol:34:    if (_mimoRebalance == address(0)) {
actions/MIMOEmptyVault.sol:31:    if (address(_proxyRegistry) == address(0)) {
actions/MIMOFlashloan.sol:22:    if (address(_lendingPool) == address(0)) {
actions/MIMOLeverage.sol:31:    if (address(_proxyRegistry) == address(0)) {
actions/MIMORebalance.sol:31:    if (address(_proxyRegistry) == address(0)) {
actions/MIMOSwap.sol:27:    if (address(_a) == address(0) || address(_dexAP) == address(0)) {
actions/MIMOSwap.sol:47:    require(proxy != address(0), Errors.INVALID_AGGREGATOR);
actions/MIMOSwap.sol:48:    require(router != address(0), Errors.INVALID_AGGREGATOR);
actions/MIMOVaultActions.sol:33:    if (address(_core) == address(0) || address(_vaultsData) == address(0) || address(_stablex) == address(0)) {
proxy/MIMOProxyRegistry.sol:49:    if (address(currentProxy) != address(0) && currentProxy.owner() == owner) {

12.3. Use assembly to write storage values

contract GasTest is DSTest {
    Contract0 c0;
    Contract1 c1;

    function setUp() public {
        c0 = new Contract0();
        c1 = new Contract1();
    }

    function testGas() public {
        c0.updateOwner(0x158B28A1b1CB1BE12C6bD8f5a646a0e3B2024734);
        c1.assemblyUpdateOwner(0x158B28A1b1CB1BE12C6bD8f5a646a0e3B2024734);
    }
}

contract Contract0 {
    address owner = 0xb4c79daB8f259C7Aee6E5b2Aa729821864227e84;

    function updateOwner(address newOwner) public {
        owner = newOwner;
    }
}

contract Contract1 {
    address owner = 0xb4c79daB8f259C7Aee6E5b2Aa729821864227e84;

    function assemblyUpdateOwner(address newOwner) public {
        assembly {
            sstore(owner.slot, newOwner)
        }
    }
}

POC Gas Report:

╭────────────────────┬─────────────────┬──────┬────────┬──────┬─────────╮
│ Contract0 contract ┆                 ┆      ┆        ┆      ┆         │
╞════════════════════╪═════════════════╪══════╪════════╪══════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆      ┆        ┆      ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 60623              ┆ 261             ┆      ┆        ┆      ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg  ┆ median ┆ max  ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ updateOwner        ┆ 5302            ┆ 5302 ┆ 5302   ┆ 5302 ┆ 1       │
╰────────────────────┴─────────────────┴──────┴────────┴──────┴─────────╯
╭────────────────────┬─────────────────┬──────┬────────┬──────┬─────────╮
│ Contract1 contract ┆                 ┆      ┆        ┆      ┆         │
╞════════════════════╪═════════════════╪══════╪════════╪══════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆      ┆        ┆      ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 54823              ┆ 232             ┆      ┆        ┆      ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg  ┆ median ┆ max  ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ assemblyUpdateOwner┆ 5236            ┆ 5236 ┆ 5236   ┆ 5236 ┆ 1       │
╰────────────────────┴─────────────────┴──────┴────────┴──────┴─────────╯

Affected code:

actions/automated/MIMOAutoAction.sol:32:  function setAutomation(uint256 vaultId, AutomatedVault calldata autoParams) external override {
actions/managed/MIMOManagedAction.sol:33:  function setManagement(uint256 vaultId, ManagedVault calldata mgtParams) external override {
actions/managed/MIMOManagedAction.sol:55:  function setManager(address manager, bool isManager) external override {
proxy/MIMOProxy.sol:104:  function setPermission(

13. Use Custom Errors instead of Revert Strings to save Gas

Custom errors are available from solidity version 0.8.4. Custom errors save ~50 gas each time they're hit by avoiding having to allocate and store the revert string. Not defining the strings also save deployment gas

Additionally, custom errors can be used inside and outside of contracts (including interfaces and libraries).

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

Starting from Solidity v0.8.4, there is a convenient and gas-efficient way to explain to users why an operation failed through the use of custom errors. Until now, you could already use strings to give more information about failures (e.g., revert("Insufficient funds.");), but they are rather expensive, especially when it comes to deploy cost, and it is difficult to use dynamic information in them.

POC Contract:

contract GasTest is DSTest {
    Contract0 c0;
    Contract1 c1;

    function setUp() public {
        c0 = new Contract0();
        c1 = new Contract1();
    }

    function testFailGas() public {
        c0.stringErrorMessage();
        c1.customErrorMessage();
    }
}

contract Contract0 {
    function stringErrorMessage() public {
        bool check = false;
        require(check, "error message");
    }
}

contract Contract1 {
    error CustomError();

    function customErrorMessage() public {
        bool check = false;
        if (!check) {
            revert CustomError();
        }
    }
}

POC Gas Report:

╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract0 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 34087              ┆ 200             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ stringErrorMessage ┆ 218             ┆ 218 ┆ 218    ┆ 218 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯
╭────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ Contract1 contract ┆                 ┆     ┆        ┆     ┆         │
╞════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost    ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ 26881              ┆ 164             ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ Function Name      ┆ min             ┆ avg ┆ median ┆ max ┆ # calls │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ customErrorMessage ┆ 161             ┆ 161 ┆ 161    ┆ 161 ┆ 1       │
╰────────────────────┴─────────────────┴─────┴────────┴─────┴─────────╯

Consider replacing all revert strings with custom errors in the solution.

actions/MIMOEmptyVault.sol:96:    require(flashloanRepayAmount <= vaultCollateral.balanceOf(address(this)), Errors.CANNOT_REPAY_FLASHLOAN);
actions/MIMOLeverage.sol:130:    require(collateralBalanceAfter >= flashloanRepayAmount, Errors.CANNOT_REPAY_FLASHLOAN);
actions/MIMORebalance.sol:129:    require(
actions/MIMOSwap.sol:47:    require(proxy != address(0), Errors.INVALID_AGGREGATOR);
actions/MIMOSwap.sol:48:    require(router != address(0), Errors.INVALID_AGGREGATOR);

[m19]

We found this gas report really outstanding