upgrade EVM to support solidity v0.8.23

[gzliudan]

EVM upgrade plan

Authors: Dan Liu, XDC Protocol Team

Note: this post is an updated and more detailed version of a previous EVM upgrade post.

1. Context

The XDC network currently only supports solidity v0.8.6 in ful and v0.8.19 partially. Here is the current support status:

solidity	compatibility	unsupported EIP(opcode)
v0.8.6	Full
v0.8.7	Partial	EIP-3198(BASEFEE)
v0.8.8	Partial
v0.8.9	Partial
v0.8.10	Partial
v0.8.11	Partial
v0.8.12	Partial
v0.8.13	Partial
v0.8.14	Partial
v0.8.15	Partial
v0.8.16	Partial
v0.8.17	Partial
v0.8.18	Partial	EIP-4399(RANDOM, PREVRANDAO)
v0.8.19	Partial
v0.8.20	No	EIP-3855(PUSH0)
v0.8.21	No
v0.8.22	No
v0.8.23	No
v0.8.24	No	EIP-1153(TLOAD/TSTORE), EIP-4844(BLOBHASH), EIP-5656(MCOPY), EIP-6780, EIP-7516(BLOBBASEFEE)

To meet on-chain development needs and embrace latest ZK and rollup techniques, the XDC network should fully support Solidity V0.8.23. To achieve this, we need to upgrade XDC's EVM, which mainly involves adding new opcodes. This post specifies the EVM upgrade plan.

V0.8.24 is a huge yet very recent upgrade. For the timebeing and for system reliability, we will not consider it for now.

2. Methodology

2.1 opcodes

To support solidity v0.8.23, the following opcodes must be added to EVM:

• BASEFEE: exposes the block's base fee
• RANDOM, PREVRANDAO: return arbitrary values in the full 256-bit range
• PUSH0: smaller code size and gas savings

2.2 Special note about EIP-1559

The opcode BASEFEE was implement in EIP-3198, which is part of the gigantic EIP-1559 upgrade. However, EIP-1559 is mainly about adaptive fees, which is not of high priority for XDC. Therefore, we will only impellent EIP-3198 without implementing the entire EIP-1559. But we can implement the JSONRPC API for EIP-1559 based on fixed gas price.

3. Detailed Operations

3.1 Preparation

Upgrade package vm by pick some new commits from Ethereum codebase after 2018. Our vm package is updated by the PR new EVM Upgrade on 2019-01-04. Our code is a bit outdated now. We reviewed all new commits about vm package, and plan to apply the following PR from Ethereum into XDC chain. This will not only improve the performance of our network, but will also make further EIP upgrade on XDC much easier.

• PR #20787: use uint256 in EVM implementation
• PR #21336: use pointers to operations vs. copy by value
• PR #21605: params: make 2200 in line with spec
• PR #22774: replace repeated string with variable in tests
• PR #22766: clean up contract creation error handling
• PR #22797: fix interpreter comments
• PR #22825: avoid duplicate log in json logger
• PR #23092: e: remove unused methods ReturnGas
• PR #23450: fix typo in comment
• PR #23499: rework jumpdest analysis benchmarks
• PR #23928: don't use iota for opcode definitions
• PR #23967: use proper JumpTable type
• PR #23956: remove unused unofficial opcodes
• PR #23974: simplify op lookup in contract
• PR #23952: Simplify error handling in interpreter loop
• PR #23976: rename SHA3 instruction to KECCAK256
• PR #23977: don't copy JumpTable when no EIP mods are needed
• PR #23970: Move interpreter.ReadOnly check into the opcode implementations
• PR #24022: rename opSuicide to opSelfdestruct
• PR #24040: remove stack.pushN
• PR #24031: fill gaps in jump table with opUndefined
• PR #24026: move interpreter interruption check to jump instructions
• PR #24066: remove no-recursion option from confi
• PR #24085: remove unused code (IsStaticJump)
• PR #24120: reverse bit order in bytes of code bitmap
• PR #24017: make INVALID a defined opcode
• PR #24851: clean up some dead functions
• PR #24850: separate opcode group for 0x20 range
• PR #24847: optimize Memory.Set32
• PR #25131: better handle error on eip activation check
• PR #28453: performance tweak of OpCode.String()

3.2 EIP-3198

We can pick codes from Ethereum in the implementation of EIP-1559:

• PR #22837: all: implement eip-1559
• PR #22896: EIP-1559: miner changes
• PR #22898: EIP-1559 tx pool support
• PR #22970: core: add new eip-1559 tx constraints
• PR #22964: 1559 rpc
• PR #22995: core, eth, miner: enforce configured mining reward post 1559 too
• PR #22930: miner/stress: add stress test for eip 1559
• PR #23010: all: rename internal 1559 gas fields, add support for graphql
• PR #22966: cmd/clef, signer: support 1559 type transactions in clef
• PR #23027: core, internal: support various eth_call invocations post 1559
• PR #23028: eth/ethconfig: bump the RPC gas cap to 50M, since 1559 exceeds 25
• PR #23038: accounts/abi/bind: fix bounded contracts and sim backend for 1559
• PR #23050: core, graphql, internal: expose effectiveGasPrice in receipts
• PR #23054: tests: fix eip1559 tx on non-eip1559 network
• PR #23102: accounts/abi/bind: fix gas price suggestion with pre EIP-1559 clients
• PR #23159: ethstats: fix full node interface post 1559
• PR #23244: core: fix pre-check for account balance under EIP-1559
• PR #23345: internal/ethapi/api: return maxFeePerGas for gasPrice for EIP-1559 txs
• PR #23309: internal/ethapi/api, accounts/abi/bind: Cap highest gas limit by account balance for 1559 fee parameters
• PR #23840: accounts/abi/bind/backends: make suggestGP compatible with non-1559 chains
• PR #25994: params: make eip1559 params non-global
• PR #27828: consensus/misc: move eip1559 into a package
• PR #28462: ethclient: fix forwarding 1559 gas fields

3.3 EIP-4399

We can pick codes from Ethereum in the implementation of EIP-4399:

• PR #24141: core/evm: Random opcode
• PR #25691: core/vm: rename RANDOM to PREVRANDAO

3.4 EIP-3855

We can pick codes from Ethereum in the implementation of EIP-3855:

• PR #24039: core/vm: implement EIP-3855: PUSH0 instruction
• PR #28520: eth/tracers/js: fix isPush for push0

4. Develop schedule

We will work from the latest commit of the dev-upgrade branch. Each PR will also be merged into the dev-upgrade branch.

In terms of role, Dan Liu and Gerui Wang will develop the code. Galaxy Deng will provide test smart contracts. The protocol team will also provide infra support.

id	task	develop	local test	owner	helper
3.1	preparation	1-2 week	1-2 week	Dan
3.2	EIP-3198	1-2 weeks	1-2 weeks	Dan	Galaxy
3.3	EIP-4399	1-2 weeks	1-2 weeks	Gerui	Galaxy
3.4	EIP-3855	1-2 weeks	1-2 weeks	Gerui	Galaxy

The expected total development time will be 6-8 weeks.

5. Test Strategy

5.1 Local test

• Each PR should be shipped with comprehensive unit tests and should pass all test cases
• Local network will be deployed for each PR
• Test cases will include all combinations: network with or without PR, smart contacts with lower or higher solidity version
• Use curl, remix, MetaMask for integration test

5.2 Online test

After the development:

• a switch block number will be set for XDC devnet, Apothem testnet, and XDC mainnet, separately
• one-month of devnet test: documentation on the upgrade and API change
• two-month of apothem test: coordinate with the foundation to invite the community to try out and provide feedback
• one-month of security audit(optional)
• ready for mainnet launch

6. Future Work

• upgrade the EVM for subnet
• implement EIP-1559

[gzliudan]

Done!