t8n: CHAINID opcode ignores --state.chainid (hardcoded to 1)

[chfast]

Summary

evmone-t8n returns CHAINID = 1 even when run with a different --state.chainid.

The same tx/env/alloc produces different post-state vs geth evm t8n when the contract executes CHAINID.

Reproducer (Cancun, chain id = 2)

alloc.json

{
  "0x095e7baea6a6c7c4c2dfeb977efac326af552d87": {
    "code": "0x4660005500",
    "nonce": "0x0",
    "balance": "0x0",
    "storage": {}
  },
  "0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
    "code": "0x",
    "nonce": "0x0",
    "balance": "0xde0b6b3a7640000",
    "storage": {}
  }
}

env.json

{
  "currentCoinbase": "0x8888f1f195afa192cfee860698584c030f4c9db1",
  "currentNumber": "0x01",
  "currentTimestamp": "0x54c99069",
  "currentGasLimit": "0x2fefd8",
  "currentRandom": "0x0000000000000000000000000000000000000000000000000000000000000001",
  "parentBeaconBlockRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "currentBaseFee": "0x1",
  "currentExcessBlobGas": "0x0",
  "withdrawals": []
}

txs.json

[
  {
    "chainId": "0x2",
    "gas": "0x186a0",
    "gasPrice": "0x1",
    "hash": "0x0c22569888cd0d60438efe2aa73f0432747521c0b00ae6d23438460a3472b6fd",
    "input": "0x",
    "nonce": "0x0",
    "r": "0x4b2e52f9747df7f24e93ee6f19a920dcf6bab9696cabf27c5e662f5cbf2baf4d",
    "s": "0x6d2be974c69cbcf0965c2e69bc02300702575bcd6ee3c21abe2a84aad25a4eac",
    "sender": "0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b",
    "to": "0x095e7baea6a6c7c4c2dfeb977efac326af552d87",
    "v": "0x27",
    "value": "0x0"
  }
]

Commands

# evmone
evmone-t8n \
  --state.fork Cancun --state.chainid 2 \
  --input.alloc alloc.json --input.env env.json --input.txs txs.json \
  --output.basedir out-evmone --output.result result.json --output.alloc alloc.json

# geth
evm t8n \
  --state.fork Cancun --state.chainid 2 \
  --input.alloc alloc.json --input.env env.json --input.txs txs.json \
  --output.basedir out-geth --output.result result.json --output.alloc alloc.json

Observed divergence

• txRoot and receiptsRoot match.
• stateRoot differs:
  • evmone: 0x37bdda8f0c6377867644e4dca47b1a57e529c3b0f16cdef6d15e6674fff411ee
  • geth: 0xa15bdc8810f73f3f6831d201a3b01a7fe3fc31f56593fb94c30bb2272a4ff1de
• Contract storage slot 0x0 after execution:
  • evmone: ...0001
  • geth: ...0002

Control: with --state.chainid 1 and a chain-1 tx, both clients agree and store ...0001.

Suspected root cause

In evmone test host tx context:

• test/state/host.cpp sets chain id to a hardcoded 0x01_bytes32 in get_tx_context().

So CHAINID opcode does not reflect configured chain id.

For reference, geth CHAINID uses chain configuration:

• core/vm/eips.go: opChainID pushes evm.chainConfig.ChainID.