Gas Optimizations

[code423n4]

Summary

Id	Title
1	Redundant zero initialization
2	Short require strings save gas
3	Use != 0 instead of > 0

1. Redundant zero initialization

Solidity does not recognize null as a value, so uint variables are initialized to zero. Setting a uint variable to zero is redundant and can waste gas.

There are several places where an int is initialized to zero, which looks like:

withholdRatio = 0;

Affected Codes

• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L63
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L64
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L94
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L129
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/OperatorRegistry.sol#L63
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/OperatorRegistry.sol#L84
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/OperatorRegistry.sol#L114
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/ERC20/ERC20PermitPermissionedMint.sol#L84

2. Short require strings save gas

Strings in solidity are handled in 32 byte chunks. A require string longer than 32 bytes uses more gas. Shortening these strings will save gas.

One cases of this gas optimization was found
35 chars
https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L167

3. Use != 0 instead of > 0

Using > 0 uses slightly more gas than using != 0. Use != 0 when comparing uint variables to zero, which cannot hold values below zero

Affected Codes

• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L79
• https://github.com/code-423n4/2022-09-frax/blob/55ea6b1ef3857a277e2f47d42029bc0f3d6f9173/src/frxETHMinter.sol#L126