Advanced Solidity: Understanding and Optimizing Gas Costs

Analyze storage gas costs in Ethereum, including zero to non-zero (20,000 gas plus 2,100 cold storage access fee), non-zero to zero refunds, and the impact of cold storage access fee.

Explain why the 5000 gas cost appears when changing storage from non-zero to non-zero, detailing cold storage load and gas reset, and noting first access adds the cold storage load.

Explore how storage uses 32-byte slots in solidity, causing small integers to incur full-slot gas costs. See examples with 128-to-128 mappings, uint16 arrays, and uint8 values costing around 43,000 gas.

Discover how assigning an unchanged storage value still consumes gas, analyze cold storage vs store costs, and learn a caching-then-conditional update pattern to save gas in Solidity contracts.

Explain how Solidity stores dynamic arrays and the gas costs of array operations, including transaction initiation, storing length, and writing elements, with tricks like cold storage and op-code stepping.

Examine how gas refunds relate to storage changes in ethereum. Reference the yellow paper and IP 3529 adjustments, including the removal of self-destruct refunds and the cap at one fifth of costs.

Examine how refunds influence gas costs when setting variables to zero, including array deletions, and learn to count down rather than up to maximize refunds.

Compare ERC20 transfers and gas costs across zero-to-nonzero, nonzero-to-zero, and nonzero-to-nonzero scenarios to surface storage-operations costs and refunds. Understand how events increase gas usage in benchmarks.

Explore how Solidity stores structs and strings in storage slots, revealing gas costs, packing behavior, and cold versus warm storage effects.

Discover how variable packing stores two values in a single 32-byte slot, uses offsets and masking to read A and B, and when packing saves gas in Solidity.

Explore memory cost explosion in Ethereum and the quadratic gas costs of large memory allocations, including 256 bit numbers.

Solidity memory is never cleared, so allocating memory in a transaction raises gas costs and can hit the quadratic portion of the formula; avoid loop allocations.

Learn how function names affect gas costs through selectors and dispatch. Each extra function adds about 22 gas from push, checks, and jumps, so place gas-sensitive selectors near the top.

Compare less than and less than or equal to in Solidity to understand how opcodes impact gas costs and why choosing cheaper equivalents improves efficiency.

Explore bit shifting in Solidity: left and right shifts represent multiply and divide by two, compare gas costs of shifting versus multiplication, and review overflow risks and benchmark results.

Compare reverting early versus after storage writes to minimize gas costs, showing that reverts undo all state changes and charge gas only up to the revert point.

Explore short circuiting in Solidity, where or and and operators skip evaluation to save gas. Compare memory reads costing 2100 gas with timestamp checks costing two gas, and decide presale ordering.

Analyze how precomputing constant expressions in Solidity bytecode can lead to hard-coded results, using pushes and a function selector, while noting where optimization may fail and affect gas costs.