EIP 3322: Efficient Gas Storage

EIPS/eip-3322.md

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+---
+eip: 3322
+title: Account gas storage opcodes
+author: William Morriss (@wjmelements)
+discussions-to: https://ethereum-magicians.org/t/eip-3322-efficient-gas-storage/5470
+status: Draft
+type: Standards Track
+category: Core
+created: 2020-03-04
+---
+
+## Simple Summary
+Allows contract accounts to store gas that can be transferred to the refund counter.
+
+## Abstract
+Contracts can persist gas for later transfer to the refund counter.
+Three opcodes are introduced to read, add to, and use this gas counter.
+
+## Motivation
+The refund mechanism is currently being used by gas tokens to arbitrage gas price.
+This brings gas supply elasticity and price stability by moving gas from blocks with less demand to blocks with more demand.
+Unfortunately this rewards unnecessary state growth.
+By introducing a superior gas storage mechanism, the gas market will require less storage and computation.
+
+## Specification
+Contract accounts gain an unsigned gas refund counter, initially zero.
+
+Three new opcodes are introduced to manage this state.
+
+* `SELFGAS` (`0x48`): Pushes the current account's gas refund counter onto the stack.
+Shares gas pricing with `SELFBALANCE`.
+* `USEGAS` (`0x49`): Pops `amount` from the stack.
+The minimum of `amount` and the current account's gas refund counter is transferred to the execution context's refund counter.
+Costs `5000` gas.
+* `STOREGAS` (`0x4a`): Pops `amount` from the stack.
+Costs `5000 + amount` gas.
+Increases the current account's gas refund counter by `amount`.
+
+## Rationale
+By reusing the execution context's refund counter we can reuse its 50% DoS protection, which limits its block elasticity contribution to 2x.
+
+The gas costs are based on similar opcodes `SELFBALANCE` and `SSTORE`.
+
+Most accounts will store no gas, so the per-account storage overhead should be minimal or even zero in the normal case.
+
+The opcode numbers chosen are in the same `0x4X` range as `SELFBALANCE` and `GASLIMIT`.
+
+## Backwards Compatibility
+Because the gas is added to the refund counter, no compatibility issues are anticipated.
+
+## Test Cases
+| Code             | Used Gas | Refund | Original | Final |
+|------------------|----------|--------|----------|-------|
+| 0x60004900       |     5003 |      0 |        0 |     0 |
+| 0x60034900       |     5003 |      2 |        2 |     0 |
+| 0x60034900       |     5003 |      3 |        3 |     0 |
+| 0x60034900       |     5003 |      3 |        4 |     1 |
+| 0x60034960034900 |    10006 |      4 |        4 |     0 |
+| 0x60034960034900 |    10006 |      6 |        6 |     0 |
+| 0x484900         |     5010 | 100000 |   100000 |     0 |
+| 0x61ffff4a00     |    70538 |      0 |        0 | 65535 |
+
+
+## Security Considerations
+DoS is already limited by the 50% refund limit.
+
+## Copyright
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).