# EIP-1884: Repricing for Trie-Size-Dependent Opcodes

## What is an EIP?

**Definition**: EIPs (Ethereum Improvement Proposals) are formal proposals for changes to the Ethereum platform, covering protocol specifications, APIs, and contract standards.

**Purpose**: EIPs standardize suggestions and improvements, ensuring community consensus and transparency.

### Types of EIPs
- **Standards Track**: Changes to Ethereum’s core (e.g protocol updates).
- **Informational**: Optional guidelines or information.
- **Meta**: Off-chain processes (e.g. governance).

**Key Point**: EIPs evolve Ethereum through community driven proposals.

## EIP Creation Process

### Stages
1. **Idea**: Discussed in forums like Ethereum Magicians.
2. **Draft**: Submitted to the EIP repository with proper format.
3. **Review**: Community peer review.
4. **Last Call**: Final 14-day review period.
5. **Final**: Accepted and implemented (may require a hard fork).

### Other Statuses
- **Stagnant**: Inactive for 6+ months.
- **Withdrawn**: Author pulls the proposal.
- **Living**: Continuously updated e.g EIP-1.

**Key Point**: A rigorous process ensures technical and community alignment.

## EIP-1884 Overview

**Title**: Repricing for Trie-Size-Dependent Opcodes
**Proposed**: March 28, 2019
**Category**: Standards Track (Core)
**Status**: Final (Istanbul hard fork, December 2019)
**Authors**: Martin Holst Swende, Peter Szilagyi

**Summary**: Reprices opcodes (SLOAD, BALANCE, EXTCODEHASH) to match resource use and introduces the SELFBALANCE opcode.

**Key Point**: Addresses gas pricing issues due to Ethereum’s growing state size.

## Why EIP-1884 Was Proposed

**Problem**: Growth in Ethereum’s state size made opcodes like SLOAD and BALANCE resource intensive, leading to:
- **Attacks**: Underpriced opcodes enabled block-filling exploits.
- **Gas Limit Issues**: Inconsistent block processing times.
- **Need**: Fair gas costs to prevent abuse and stabilize the network.

**Context**: Extends EIP-150 (2016), which repriced SLOAD (50 to 200 gas) and BALANCE (20 to 400 gas).

**Key Point**: Aligns costs with current network demands.

## EIP-1884 Technical Details

### Opcode Repricing
- **SLOAD**: Increased from 200 to 800 gas (reflects higher trie lookup costs).
- **BALANCE (EXTBALANCE)**: Increased from 400 to 700 gas (aligned with EXTCODESIZE/EXTCODEHASH).
- **EXTCODEHASH**: Increased from 400 to 700 gas (consistent with BALANCE).

### New Opcode
- **SELFBALANCE**: Added at 0x47, costing 5 gas (GasFastStep) for efficient balance queries.

**Implementation**: Deployed via the Istanbul hard fork; validated with state tests.

**Key Point**: Repricing reflects resource use; SELFBALANCE improves efficiency.

## How EIP-1884 Works

- **Cost Balancing**: Higher gas costs for SLOAD, BALANCE, and EXTCODEHASH deter abuse and stabilize gas limits.
- **SELFBALANCE Efficiency**: Low-cost (5 gas) alternative for contracts to check their own balance.
- **Compatibility**: Minimal impact; some contracts may require gas optimization.
- **Outcome**: Reduces attack risks, ensures fair pricing, and improves performance.

**Key Point**: Enhances Ethereum’s scalability and security.

## Impact and Context

- **Related EIPs**: Builds on EIP-150 (repricing) and EIP-1052 (EXTCODEHASH), addressing state growth.
- **Implementation**: Deployed in the Istanbul hard fork (December 2019).
- **Consensus**: Validated via Ethereum Magicians, GitHub, and IstanbulTests.
- **Broader Impact**: Improves efficiency, scalability, and sets a precedent for future repricing.

**Key Point**: Critical for Ethereum’s performance and security.

## Conclusion

**EIP-1884** strengthens Ethereum by addressing inefficiencies in gas pricing caused by state growth. By repricing key opcodes and introducing **SELFBALANCE**, it enhances network security, stabilizes gas usage, and improves contract efficiency. Implemented in the Istanbul hard fork, it remains a pivotal step in Ethereum’s evolution toward scalability and resilience.