EIP-5027: Remove the limit on contract code size
Change the limit on contract size from 24576 to infinity
Abstract
Remove the limit on the contract code size, i.e., only limit the contract code size by block gas limit, with minimal changes to existing code and proper gas metering adjustment to avoid possible attacks.
Motivation
The motivation is to remove the limit on the code size so that users can deploy a large-code contract without worrying about splitting the contract into several sub-contracts.
With the dramatic growth of dApplications, the functionalities of smart contracts are becoming more and more complicated, and thus, the sizes of newly developed contracts are steadily increasing. As a result, we are facing more and more issues with the 24576-bytes contract size limit. Although several techniques such as splitting a large contract into several sub-contracts can alleviate the issue, these techniques inevitably increase the burden of developing/deploying/maintaining smart contracts.
The proposal implements a solution to remove the existing 24576-bytes limit of the code size. Further, the proposal aims to minimize the changes in the client implementation (e.g., Geth) with
- proper gas metering to avoid abusing the node resources for contract-related opcodes, i.e,
CODESIZE (0x38)/CODECOPY (0x39)/EXTCODESIZE (0x3B)/EXTCODECOPY (0x3C)/EXTCODEHASH (0x3F)/DELEGATECALL (0xF4)/CALL (0xF1)/CALLCODE (0xF2)/STATICCALL (0xFA)/CREATE (0xF0)/CREATE2 (0xF5)
; and - no change to the existing structure of the Ethereum state.
Specification
Parameters
Constant | Value |
---|---|
FORK_BLKNUM | TBD |
CODE_SIZE_UNIT | 24576 |
COLD_ACCOUNT_CODE_ACCESS_COST_PER_UNIT | 2600 |
CREATE_DATA_GAS | 200 |
If block.number >= FORK_BLKNUM
, the contract creation initialization can return data with any length, but the contract-related opcodes will take extra gas as defined below:
-
For
CODESIZE/CODECOPY/EXTCODESIZE/EXTCODEHASH
, the gas is unchanged. -
For CREATE/CREATE2, if the newly created contract size >
CODE_SIZE_UNIT
, the opcodes will take extra write gas as
(CODE_SIZE - CODE_SIZE_UNIT) * CREATE_DATA_GAS
.
- For
EXTCODECOPY/CALL/CALLCODE/DELEGATECALL/STATICCALL
, if the contract code size >CODE_SIZE_UNIT
, then the opcodes will take extra gas as
if the contract is not in accessed_code_in_addresses
or 0
if the contract is in accessed_code_in_addresses
, where //
is the integer divide operator, and accessed_code_in_addresses: Set[Address]
is a transaction-context-wide set similar to access_addresses
and accessed_storage_keys
.
When a transaction execution begins, accessed_code_in_addresses
will include tx.sender
, tx.to
, and all precompiles.
When CREATE/CREATE2/EXTCODECOPY/CALL/CALLCODE/DELEGATECALL/STATICCALL
is called, immediately add the address to accessed_code_in_addresses
.
Rationale
Gas Metering
The goal is to measure the CPU/IO cost of the contract read/write operations reusing existing gas metering so that the resources will not be abused.
-
For code-size-related opcodes (
CODESIZE
/EXTCODESIZE
), we would expect the client to implement a mapping from the hash of code to the size, so reading the code size of a large contract should still be O(1). -
For
CODECOPY
, the data is already loaded in memory (as part ofCALL/CALLCODE/DELEGATECALL/STATICCALL
), so we do not charge extra gas. -
For
EXTCODEHASH
, the value is already in the account, so we do not charge extra gas. -
For
EXTCODECOPY/CALL/CALLCODE/DELEGATECALL/STATICCALL
, since it will read extra data from the database, we will additionally chargeCOLD_ACCOUNT_CODE_ACCESS_COST_PER_UNIT
per extraCODE_SIZE_UNIT
. -
For
CREATE/CREATE2
, since it will create extra data to the database, we will additionally chargeCREATE_DATA_GAS
per extra bytes.
Backwards Compatibility
All existing contracts will not be impacted by the proposal.
Only contracts deployed before EIP-170 could possibly be longer than the current max code size, and the reference implementation was able to successfully import all blocks before that fork.
Reference Implementation
The reference implementation on Geth is available at 0001-unlimit-code-size.patch.
Security Considerations
TBD
Copyright
Copyright and related rights waived via CC0.