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Update EIP-7907: clarify code warming #9877

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7907: clarify code warming
lightclient Jun 9, 2025
ea8102a
7907: increase base cost of EXTCODESIZE to 5000
lightclient Jun 9, 2025
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12 changes: 8 additions & 4 deletions EIPS/eip-7907.md
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Expand Up @@ -28,17 +28,21 @@ Improving developer experience is the primary motivation for increasing the cont
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119](https://www.rfc-editor.org/rfc/rfc2119) and [RFC 8174](https://www.rfc-editor.org/rfc/rfc8174).

1. Update the [EIP-170](./eip-170.md) contract code size limit of 24KB (`0x6000` bytes) to 256KB (`0x40000` bytes).
2. Change the gas schedule for opcodes which load code. Specifically, the opcodes `CALL`, `STATICCALL`, `DELEGATECALL`, `CALLCODE` and `EXTCODECOPY` are modified so that `largeContractCost = ceil32(excess_contract_size) * GAS_INIT_CODE_WORD_COST // 32` gas is added to the access cost if the code is cold, where `excess_contract_size = max(0, contract_size - 0x6000)`, and `GAS_INIT_CODE_WORD_COST = 2`. (Cf. initcode metering: [EELS](https://github.com/ethereum/execution-specs/blob/1a587803e3e698407d204888b02342393f8b4fe5/src/ethereum/cancun/vm/gas.py#L269)). This introduces a new warm state for contract code - warm if the code has been loaded, cold if not.
2. Change the gas schedule for opcodes which load code. Specifically, the opcodes `CALL`, `STATICCALL`, `DELEGATECALL`, `CALLCODE` and `EXTCODECOPY` are modified so that `largeContractCost = ceil32(excess_contract_size) * GAS_INIT_CODE_WORD_COST // 32` gas is added to the access cost if the code is cold, where `excess_contract_size = max(0, contract_size - 0x6000)`, and `GAS_INIT_CODE_WORD_COST = 2`. (Cf. initcode metering: [EELS](https://github.com/ethereum/execution-specs/blob/1a587803e3e698407d204888b02342393f8b4fe5/src/ethereum/cancun/vm/gas.py#L269)). This introduces a [new warm state](#code-warming) for contract code - warm if the code has been loaded, cold if not.
3. Update the [EIP-3860](./eip-3860.md) contract initcode size limit of 48KB (`0xc000` bytes) to 512KB (`0x80000` bytes).
4. Increase the base cost of `EXTCODESIZE` to `5000`
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so EXTCODESIZE will always cost at least 5000?


### Code warming

The concept of warm and cold accounts which was previously defined in [EIP-2929](./eip-2929.md) is extended in this EIP to include the concept of warm and cold code. This allows for four possible states an account can be in during execution, with respect to gas pricing: cold-cold, cold-warm, warm-cold, and warm-warm. See the table below with examples.
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Is it possible to have warm-cold variant? Should the account code be defined by its hash or by its account address?

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Right, warm-cold isn't possible if we define code by account, but if it is by hash it will be.

I think either option is acceptable.

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It feels more aligned if we use the account address. Not sure if we have notion of bytecode hash anywhere


| Contract | Gas changes (only opcodes that load code) | How? |
| ----------------------- | ------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------- |
| Cold account and code | Add `largeContractCost` to `COLD_ACCOUNT_ACCESS_COST=2600` | Contract not in access list nor accessed prior in the txn |
| Warm account, cold code | Add `largeContractCost` to `WARM_STORAGE_READ_COST=100` | Already accessed balance, storage, or included in access list ([EIP-2930](./eip-2930.md)) |
| Warm account and code | No change to existing gas schedule. `WARM_STORAGE_READ_COST=100` | Contract created with `CREATE`/`CREATE2`, or `CALL`, `STATICCALL`, `DELEGATECALL`, `CALLCODE` or `EXTCODECOPY` made on the contract, previously in the txn (opcodes that load contract code) |

`COLD_ACCOUNT_ACCESS_COST` and `WARM_STORAGE_READ_COST` are defined in [EIP-2929](./eip-2929.md#parameters).

3. Update the [EIP-3860](./eip-3860.md) contract initcode size limit of 48KB (`0xc000` bytes) to 512KB (`0x80000` bytes).
*Note: `COLD_ACCOUNT_ACCESS_COST` and `WARM_STORAGE_READ_COST` are defined in [EIP-2929](./eip-2929.md#parameters).*

## Rationale

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