Gas Optimizations in Solidity

Gas Costly Patterns

• Comparison with Unilateral Outcome in a Loop
• Constant Outcome of a Loop
• Dead Code
• Expensive Operations in a Loop
• Loop Fusion
• Opaque Predicate
• Repeated Computations in a Loop
• Storage Variable as Loop Length
• Unnecessary Libraries

Gas Saving Patterns

• Proper Data Types
• Explicit Function Visibility
• Short Circuiting
• Constants and Immutables
• Struct Bit Packing

Gas Golfing

• Short Revert Strings
• Unchecked Arithmetic
• Optimal Comparison Operator
• Payable Functions
• Function Ordering
• Using Mulmod Over Mul & Div
• Optimal Increment and Decrement Operators

Sources/References

• https://medium.com/coinmonks/optimizing-your-solidity-contracts-gas-usage-9d65334db6c7
• https://ethereum.stackexchange.com/questions/28813/how-to-write-an-optimized-gas-cost-smart-contract
• https://arxiv.org/pdf/1703.03994.pdf
• https://ethereum.stackexchange.com/questions/3067/why-does-uint8-cost-more-gas-than-uint256
• https://www.youtube.com/watch?v=qwBkeJ84d2g&feature=youtu.be&t=68
• https://ethereum.stackexchange.com/questions/11556/use-string-type-or-bytes32
• https://gist.github.com/hrkrshnn/ee8fabd532058307229d65dcd5836ddc
• https://github.com/ZeroEkkusu/re-golf-course