G-01 Using calldata instead of memory for read-only arguments in external functions saves gas (1 instance)
G-02 += costs more gas than = + for state variables (12 instances)
G-03 internal functions only called once can be inlined to save gas (2 instances)
G-04 Using bools for storage incurs overhead (11 instances)
G-05 Using > 0 costs more gas than != 0 when used on a uint in a require() statement (1 instance0
G-06 ++i costs less gas than i++, especially when it’s used in for-loops (2 instances)
G-07 Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead (88 instances)
G-08 Using private rather than public for constants, saves gas (9 instances)
G-09 Empty blocks should be removed or emit something (2 instances)
G-10 calldata instead of memory for read-only function parameter (5 instances)
Total: 133 instances in 10 issues
G-01 Using calldata instead of memory for read-only arguments in external functions saves gas
When a function with a memory array is called externally, the abi.decode() step has to use a for-loop to copy each index of the calldata to the memory index. Each iteration of this for-loop costs at least 60 gas (i.e. 60 * .length). Using calldata directly, obliviates the need for such a loop in the contract code and runtime execution. Structs have the same overhead as an array of length one
G-07 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
G-08 Using private rather than public for constants, saves gas
If needed, the value can be read from the verified contract source code. Savings are due to the compiler not having to create non-payable getter functions for deployment calldata, and not adding another entry to the method ID table
G-09 Empty blocks should be removed or emit something
The code should be refactored such that they no longer exist, or the block should do something useful, such as emitting an event or reverting. If the contract is meant to be extended, the contract should be abstract and the function signatures be added without any default implementation. If the block is an empty if-statement block to avoid doing subsequent checks in the else-if/else conditions, the else-if/else conditions should be nested under the negation of the if-statement, because they involve different classes of checks, which may lead to the introduction of errors when the code is later modified (if(x){}else if(y){...}else{...} => if(!x){if(y){...}else{...}})
G-10 calldata instead of memory for read-only function parameter
If a reference type function parameter is read-only, it is cheaper in gas to use calldata instead of memory. Calldata is a non-modifiable, non-persistent area where function arguments are stored, and behaves mostly like memory. Try to use calldata as a data location because it will avoid copies and also makes sure that the data cannot be modified.
Summary
G-01 Using calldata instead of memory for read-only arguments in external functions saves gas (1 instance) G-02 += costs more gas than = + for state variables (12 instances)
G-03 internal functions only called once can be inlined to save gas (2 instances)
G-04 Using bools for storage incurs overhead (11 instances)
G-05 Using > 0 costs more gas than != 0 when used on a uint in a require() statement (1 instance0
G-06 ++i costs less gas than i++, especially when it’s used in for-loops (2 instances)
G-07 Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead (88 instances)
G-08 Using private rather than public for constants, saves gas (9 instances)
G-09 Empty blocks should be removed or emit something (2 instances)
G-10 calldata instead of memory for read-only function parameter (5 instances)
Total: 133 instances in 10 issues
G-01 Using calldata instead of memory for read-only arguments in external functions saves gas
When a function with a memory array is called externally, the abi.decode() step has to use a for-loop to copy each index of the calldata to the memory index. Each iteration of this for-loop costs at least 60 gas (i.e. 60 *.length). Using calldata directly, obliviates the need for such a loop in the contract code and runtime execution. Structs have the same overhead as an array of length one
1 instance in 1 file: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L162
G-02 += costs more gas than = + for state variables
12 instances in 5 files:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/TRSRY.sol#L96 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/TRSRY.sol#L97 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/TRSRY.sol#L131
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L136 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L222
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/VOTES.sol#L58
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/BondCallback.sol#L143 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/BondCallback.sol#L144
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Heart.sol#L103
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L198 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L252 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L254
G-03 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.
2 instances in 2 files:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L391-395
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/TRSRY.sol#L137-L141
G-04 Using bools for storage incurs overhead
Booleans are more expensive than uint256 or any type that takes up a full word because each write operation emits an extra SLOAD to first read the slot's contents, replace the bits taken up by the boolean, and then write back. This is the compiler's defense against contract upgrades and pointer aliasing, and it cannot be disabled. https://github.com/OpenZeppelin/openzeppelin-contracts/blob/58f635312aa21f947cae5f8578638a85aa2519f5/contracts/security/ReentrancyGuard.sol#L23-L27 Use uint256(1) and uint256(2) for true/false
11 instances in 5 files:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L113 https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L181 https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L194 https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L197
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L62
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L63 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L66
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/BondCallback.sol#L24
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Heart.sol#L33
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L105 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L117
G-05 Using > 0 costs more gas than != 0 when used on a uint in a require() statement
This change saves 6 gas per instance
1 instance in 1 file:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L247
G-06 ++i costs less gas than i++, especially when it’s used in for-loops (--i/i-- too)
Saves 6 gas PER LOOP
2 instances in 1 file:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/utils/KernelUtils.sol#L49 https://github.com/code-423n4/2022-08-olympus/blob/main/src/utils/KernelUtils.sol#L64
G-07 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
88 instances in 10 files:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L100
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/TRSRY.sol#L51
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/MINTR.sol#L25
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/RANGE.sol#L45 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/RANGE.sol#L115 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/RANGE.sol#L148 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/RANGE.sol#L200
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L27 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L28 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L44 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L47 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L50 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L53 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L56 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L59 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L75 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L76 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L84 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L87 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L97 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L113 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L127 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L185 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L240 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L266 https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L289
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/VOTES.sol#L27
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/INSTR.sol#L28
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L51 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L52 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L53 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L54 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L83 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L86 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L89 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L97 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L108 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L116 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L127 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L128 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L129 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L210 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L216 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L375 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L376 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L377 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L403 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L404 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L418 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L455 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L456 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L528 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L529 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L530 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L535 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L536 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L548 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L560 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L561 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L562 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L665 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L705 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L707 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L708 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L717 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L719 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L720
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/PriceConfig.sol#L45 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/PriceConfig.sol#L58 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/PriceConfig.sol#L69
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L13 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L14 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L15 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L16 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L17 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L18 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L19 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L20 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L31 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L32 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L33 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L85 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L93 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L94 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L95 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L101 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L110 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L111 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L112
G-08 Using private rather than public for constants, saves gas
If needed, the value can be read from the verified contract source code. Savings are due to the compiler not having to create non-payable getter functions for deployment calldata, and not adding another entry to the method ID table
9 instances in 4 files:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/RANGE.sol#L65
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L59
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L89
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L121 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L124 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L127 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L130 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L133 https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L137
G-09 Empty blocks should be removed or emit something
The code should be refactored such that they no longer exist, or the block should do something useful, such as emitting an event or reverting. If the contract is meant to be extended, the contract should be abstract and the function signatures be added without any default implementation. If the block is an empty if-statement block to avoid doing subsequent checks in the else-if/else conditions, the else-if/else conditions should be nested under the negation of the if-statement, because they involve different classes of checks, which may lead to the introduction of errors when the code is later modified (if(x){}else if(y){...}else{...} => if(!x){if(y){...}else{...}})
2 instances in 1 file:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L139 https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L143
G-10 calldata instead of memory for read-only function parameter
If a reference type function parameter is read-only, it is cheaper in gas to use calldata instead of memory. Calldata is a non-modifiable, non-persistent area where function arguments are stored, and behaves mostly like memory. Try to use calldata as a data location because it will avoid copies and also makes sure that the data cannot be modified.
5 instances in 3 files:
https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L139 https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L143 https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L393
https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L205
https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/TreasuryCustodian.sol#L53