AsArrays Code Style Findings

AAS-01C: Ineffectual Usage of Safe Arithmetics

Type	Severity	Location
Language Specific		AsArrays.sol:L149

Description:

The linked mathematical operation is guaranteed to be performed safely by surrounding conditionals evaluated in either require checks or if-else constructs.

Example:

Copy
146require(begin < end && end <= self.length);
147
148// Calculate the number of elements in the slice
149uint256 sliceLength = end - begin;

Recommendation:

Given that safe arithmetics are toggled on by default in pragma versions of 0.8.X, we advise the linked statement to be wrapped in an unchecked code block thereby optimizing its execution cost.

Alleviation (59b75fbee1d8f3dee807c928f18be41c58b904e1):

The referenced statement is no longer present in the codebase in any shape or form rendering this exhibit inapplicable.

AAS-02C: Inefficient Iteration of Search Loops

Type	Severity	Location
Gas Optimization		AsArrays.sol:L47, L68

Description:

The referenced loops will iterate from 0 to identify the maximum and minimum respectively, however, their value entries are already initialized with the first entry of the array.

Example:

Copy
36/**
37 * @notice Returns the max value in an array.
38 * @param self Storage array containing uint256 type variables
39 * @return value The highest value in the array
40 */
41function max(uint256[] storage self) public view returns (uint256 value) {
42    assembly {
43        mstore(0x60, self.slot)
44        value := sload(keccak256(0x60, 0x20))
45
46        for {
47            let i := 0
48        } lt(i, sload(self.slot)) {
49            i := add(i, 1)
50        } {
51            switch gt(sload(add(keccak256(0x60, 0x20), i)), value)
52            case 1 {
53                value := sload(add(keccak256(0x60, 0x20), i))
54            }
55        }
56    }
57}
58
59/// @notice Returns the minimum value in an array.
60/// @param self Storage array containing uint256 type variables
61/// @return value The highest value in the array
62function min(uint256[] storage self) public view returns (uint256 value) {
63    assembly {
64        mstore(0x60, self.slot)
65        value := sload(keccak256(0x60, 0x20))
66
67        for {
68            let i := 0
69        } lt(i, sload(self.slot)) {
70            i := add(i, 1)
71        } {
72            switch gt(sload(add(keccak256(0x60, 0x20), i)), value)
73            case 0 {
74                value := sload(add(keccak256(0x60, 0x20), i))
75            }
76        }
77    }
78}

Recommendation:

We advise the loops to begin at 1, optimizing each function's gas cost by one iteration.

Alleviation (cf5194da53ebf026da6c8efa74daada96719cc71):

Both loops will now begin iteration at the 1 index, optimizing their gas cost by one iteration.

AAS-03C: Inefficient Iterator Type

Type	Severity	Location
Gas Optimization		AsArrays.sol:L169, L173, L177

Description:

The referenced for loops utilize a uint64 variable as an iterator which is inefficient.

Example:

Copy
169arr = new uint8[](n); for (uint64 i = 0; i < n; i++) arr[i] = a;

Recommendation:

As the EVM is built to operate on 32-byte (256-bit) data types, we advise the iterator types to be bumped to uint256, optimizing their gas cost.

Alleviation (59b75fbee1d8f3dee807c928f18be41c58b904e1):

All referenced iterators have been updated to the uint256 data type, optimizing the codebase as advised.

AAS-04C: Inexistent Error Messages

Type	Severity	Location
Code Style		AsArrays.sol:L131, L146

Description:

The linked require checks have no error messages explicitly defined.

Example:

Copy
131require(begin < end && end <= self.length);

Recommendation:

We advise each to be set so to increase the legibility of the codebase and aid in validating the require checks' conditions.

Alleviation (59b75fbee1d8f3dee807c928f18be41c58b904e1):

In-line documentation was introduced to clarify what the error is. Given that the contracts of the Astrolab DAO codebase tread closely to the bytecode size limit, we consider this approach as an adequate alleviation.

AAS-05C: Loop Iterator Optimizations

Type	Severity	Location
Gas Optimization		AsArrays.sol:L114, L155, L169, L173, L177

Description:

The linked for loops increment / decrement their iterator "safely" due to Solidity's built - in safe arithmetics (post-0.8.X).

Example:

Copy
114for (uint i = 0; i < dt.length; i++) {

Recommendation:

We advise the increment / decrement operations to be performed in an unchecked code block as the last statement within each for loop to optimize their execution cost.

Alleviation (59b75fbee1d8f3dee807c928f18be41c58b904e1):

The referenced loop iterator increment statements have been relocated at the end of each respective for loop's body and have been unwrapped in an unchecked code block, optimizing their gas cost.