Reduced gas cost for static calls made to precompiles (#2046)

* Reduced gas cost for static calls made to precompiles

* Rename to EIP-2046

* Add discussion URL

* Add 2046 to Istanbul

* Fix header
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Alex Beregszaszi 2019-05-23 22:13:26 +01:00 committed by Nick Johnson
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- [EIP-1884](https://eips.ethereum.org/EIPS/eip-1884): Repricing for trie-size-dependent opcodes
- [EIP-1930](https://eips.ethereum.org/EIPS/eip-1930): CALLs with strict gas semantic. Revert if not enough gas available.
- [EIP-2028](https://eips.ethereum.org/EIPS/eip-2028): Calldata gas cost reduction
- [EIP-2046](https://eips.ethereum.org/EIPS/eip-2046): Reduced gas cost for static calls made to precompiles
## Timeline

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EIPS/eip-2046.md Normal file
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---
eip: 2046
title: Reduced gas cost for static calls made to precompiles
author: Alex Beregszaszi (@axic)
discussions-to: https://ethereum-magicians.org/t/eip-2046-reduced-gas-cost-for-static-calls-made-to-precompiles/3291
status: Draft
type: Standards Track
category: Core
created: 2019-05-17
requires: 214, 1352
---
## Simple Summary
This change reduces the gas cost of using precompiled contracts.
## Abstract
Reduce the base gas cost of calling precompiles using `STATICCALL` from 700 to 40. This should allow more efficient use of precompiles as well as precompiles with a total cost below 700.
## Motivation
The Spurious Dragon hard fork increased the cost of calls significantly to account for loading contract code from the state without making an exception for precompiles, whose "code" is always loaded.
This made use of certain precompiles impractical.
FIXME: extend this with recent reasoning about ECC repricings.
## Specification
After block `HF` the `STATICCALL` (`0xfa`) instruction charges different basic gas cost (G<sub>call</sub> in [Yellow Paper]'s notation) depending on the destination address provided:
- for precompiles (address range as per [EIP-1352]) the cost is `40`
- for every other address the cost remains unchanged (`700`)
## Rationale
Only the `STATICCALL` instruction was changed to reduce the impact of the change. This should not be a limiting factor, given precompiles (currently) do not have a state and cannot change the state.
However, contracts created and deployed before Byzantium likely will not use `STATICCALL` and as a result this change will not reduce their costs.
Contrary to EIP-1109 gas reduction to `0` is not proposed. The cost `40` is kept as a cost representing the context switching needed.
## Backwards Compatibility
This EIP should be backwards compatible. The only effect is that the cost is reduced. Since the cost is not reduced to zero, it should not be possible for a malicious proxy contract, when deployed before
the `HF`, to do any state changing operation.
## Test Cases
TBA
## Implementation
TBA
## References
This has been previously suggested as part of [EIP-1109](https://github.com/ethereum/EIPs/pull/1109) and [EIP-1231](https://github.com/ethereum/EIPs/pull/1231).
However EIP-1109 was later changed to a very different approach. The author [has suggested to change EIP-1109](https://ethereum-magicians.org/t/eip-1109-remove-call-costs-for-precompiled-contracts/447/7).
## Acknowledgements
Jordi Baylina (@jbaylina) and Matthew Di Ferrante (@mattdf) who have proposed this before.
## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
[Yellow Paper]: https://github.com/ethereum/yellowpaper
[EIP-1352]: https://eips.ethereum.org/EIPS/eip-1352