forked from DecentralizedClimateFoundation/DCIPs
106 lines
2.8 KiB
Markdown
106 lines
2.8 KiB
Markdown
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---
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eip: 3521
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title: Reduce access list cost
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author: Matt Garnett (@lightclient)
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discussions-to: https://ethereum-magicians.org/t/eip-3521-reduce-access-list-cost/6072
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status: Stagnant
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type: Standards Track
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category: Core
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created: 2021-04-15
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requires: 2028, 2930
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---
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## Simple Summary
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Reduce the cost of declaring `tx.to` storage keys in access lists.
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## Motivation
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Currently, a transaction must read at least 25 distinct storage slots in `tx.to`
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before it's more expensive to forego an access list.
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```
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ACCESS_LIST_ADDRESS_COST + (ACCESS_LIST_STORAGE_KEY_COST + WARM_STORAGE_READ_COST) * x = COLD_SLOAD_COST * x
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x = 24
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```
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EIP-2930 requires the address under which the storage keys reside be declared
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explicitly, since it must be added to the EIP-2929 `accessed_addresses` list.
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However, `tx.to` is a special case that is added by default, so paying
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`ACCESS_LIST_ADDRESS_COST` for `tx.to` is essentially paying twice for the same
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address. Avoiding overpayment here will reduce the differential to just 5 unique
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reads before using an access list is cheaper -- making them a more attractive
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option.
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## Specification
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Treat the first occurrence of `tx.to` in an access list as `calldata` for gas
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accounting purposes. Do not charge `ACCESS_LIST_ADDRESS_COST` for it. Storage
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keys underneath the address are unaffected.
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If `tx.to == nil`, `tx.to` is defined be the derived contract address created by
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the transaction.
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## Rationale
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### Why charge at all?
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EIP-2930 is specifically written to make access lists simple to reason about and
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validate. It may be possible to modify the structure of the access list to avoid
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including `tx.to` explicitly, but this would renege on the spirit of EIP-2930.
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### Why charge as `calldata`?
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The cost of `calldata` was thoroughly analyzed in EIP-2028 to determine
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a fair value that is not susceptible to denial-of-service attacks. We consider
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this the lower bound on how much transaction data should cost. Since there is
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no computation burden imposed for adding `tx.to` to the `accessed_addresses`
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map (it's added by default by [EIP-2929](./eip-2929.md)), there is no reason to charge more than
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the absolute minimum for the data.
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## Test Cases
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```
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{
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"0xffffffffffffffffffffffffffffffffffffffff": []
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}
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cost = 320
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{
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"0x00ffffffffffffffffffffffffffffffffffffff": []
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}
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cost = 308
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{
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"0xffffffffffffffffffffffffffffffffffffffff": []
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"0xffffffffffffffffffffffffffffffffffffffff": []
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}
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cost = 2720
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{
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"0xffffffffffffffffffffffffffffffffffffffff": [
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"0x00"
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]
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"0xffffffffffffffffffffffffffffffffffffffff": []
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}
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cost = 4620
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{
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"0xffffffffffffffffffffffffffffffffffffffff": [
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"0x00"
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]
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"0xffffffffffffffffffffffffffffffffffffffff": [
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"0x00"
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]
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}
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cost = 6520
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```
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## Backwards Compatibility
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No issues.
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## Security Considerations
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None.
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## Copyright
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Copyright and related rights waived via [CC0](../LICENSE.md).
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