execution, rlp: switch total difficulty and chainID to uint256.Int

[yperbasis]

Summary

Migrate total difficulty and chain ID from *big.Int to *uint256.Int (or uint256.Int) across the codebase, and drop the rlp package's reflect-based big.Int support that's no longer needed.

Total difficulty

• On-wire / on-disk: NewBlockPacket.TD and rawdb.ReadTd / ReadTdByHash / WriteTd use uint256.Int. Wire and DB bytes are unchanged — uint256.Int encodes to the same canonical big-endian RLP as big.Int.
• chain.Config.TerminalTotalDifficulty *uint256.Int. Existing chainspec JSON parses without changes (uint256's UnmarshalJSON accepts both unquoted decimal numbers and quoted strings); the DB-stored config round-trips through Erigon. Re-marshaling emits a quoted decimal string instead of an unquoted JSON number; Erigon reads either.
• In-memory APIs migrated: rules.ChainHeaderReader.GetTd, ethash.ShouldReorg, headerdownload.HeaderInserter (incl. FeedHeaderFunc / FeedHeaderPoW / GetLocalTd), execmodule.ExecutionModule.GetTD, polygon ExecutionClient.GetTd, p2p.Publisher.PublishNewBlock + publishTask.td, sentry_multi_client.BroadcastNewBlock, bodydownload.BlockPropagator, ethstats.assembleBlockStats, rawdb.Transitioned, chainspec.IsChainPoS / currentTDProvider, the engineapi newPayload TD var, tracing.BlockEvent.TD, eth.NodeInfo.Difficulty, and the testFork comparator in execution/tests/blockchain_test.go.
• Every TD summation (FeedHeaderPoW, InsertBlocks, rawdbreset snapshot fill, checkPrefetchedBlock, import_cmd.go side-chain accumulator) uses AddOverflow and surfaces overflow as an error (or a logged skip on the propagator's best-effort path) — uint256.Int.Add silently wraps, unlike big.Int.Add.

Transaction chainID

• chain.Config.ChainID *uint256.Int and chain.Rules.ChainID *uint256.Int. Same JSON-shape concession as TerminalTotalDifficulty — existing chainspec JSON parses unchanged.
• Transaction.SigningHash(chainID *uint256.Int) interface + 7 implementations; the 5 *SigHash structs' ChainID fields are *uint256.Int. LatestSignerForChainID and NewKeyedTransactorWithChainID take *uint256.Int directly.
• evmtypes.BlockContext.Rules builds chain.Rules in uint256 directly (drops math/big).
• cmd/evm/t8ntool ChainIDFlag switched from cli.Int64Flag to cli.Uint64Flag to match the type now consumed downstream.
• Rationale for the uint256 ceiling: EIP-7702 caps authorization chain_id < 2**256; the stagnant EIP-2294 even proposes a ~2^63 chainID bound. uint256 strictly contains every chainID the protocol can use. Largest in-tree chainID is sepolia at 11,155,111.

RLP big.Int support removed

With every production TD and chainID off *big.Int, no type in this repo encodes/decodes *big.Int via the rlp package anymore. Removed:

• exported rlp.EncodeBigInt, rlp.BigIntLen, rlp.ErrNegativeBigInt
• reflect-based writeBigIntPtr, writeBigIntNoPtr, decodeBigInt, decodeBigIntNoPtr, the bigInt reflect type var, and the dispatch entries in makeWriter / makeDecoder
• Stream.BigInt, Stream.decodeBigInt, encBuffer.writeBigInt, EncoderBuffer.WriteBigInt
• the cmd/rlpgen bigIntHandle / bigIntPtrHandle code paths and the big.Int / *big.Int fields in the rlpgen testing fixture (regenerated)

The legacy ethereum/tests rlptest.json/bigint vector encodes 2^256 — above the uint256 ceiling — so TestRLP SkipLoads it with a comment citing EIP-7702 / EIP-2294. The other mediumint* vectors fit in uint256 and round-trip through translateJSON via uint256.FromBig.

JSON-RPC carve-outs (intentionally kept *hexutil.Big)

Hex-encoded JSON-RPC wire types remain *hexutil.Big (which is *big.Int under the hood) since the JSON-RPC convention is hex-encoded big numbers. Conversion to *uint256.Int happens internally at the boundary:

• rpc/ethapi/api.go CallArgs.ChainID (and the 43 other *hexutil.Big fields in the same struct family)
• eth_simulation args.ChainID
• NewRPCBorTransaction chainId field on the JSON response

Introducing a hexutil.U256 shim to migrate these would be a separate refactor.

Downstream impact

• Erigon-internal: none beyond this PR.
• Downstream tracers implementing tracing.Hooks.OnBlockStart(event tracing.BlockEvent) against Erigon's tracing package see a compile error on event.TD if they treat it as *big.Int; one-line fix is event.TD.ToBig() at the read site.
• Downstream importers of github.com/erigontech/erigon/execution/rlp that call the removed rlp.EncodeBigInt / rlp.BigIntLen / Stream.BigInt helpers will break; switch to the uint256 equivalents or do the conversion at the boundary.
• admin_nodeInfo JSON output for the difficulty field shifts from an unquoted decimal number to a quoted decimal string (same shape as terminalTotalDifficulty). Most consumers treating it as a big number string already accept both.

Test plan

• make lint — 0 issues
• make erigon integration — clean build
• go test -short ./... — passes locally
• Manually verified chain.Config JSON round-trip: existing unquoted-decimal genesis input parses; new quoted-string output re-parses
• CI

Diff size

124 files, +432 / −765 — more code removed than added.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR migrates total difficulty (TD) and transaction chain ID usage from *big.Int to *uint256.Int / uint256.Int across execution, P2P, and Polygon components, and removes the execution RLP package’s reflect-based big.Int encoding/decoding support that becomes unnecessary after the migration.

Changes:

• Switch TD plumbing (DB accessors, wire types, sync/execution APIs) to uint256 with explicit overflow handling via AddOverflow.
• Switch transaction signing APIs and RLP signing payload fields from *big.Int chain IDs to *uint256.Int.
• Remove big.Int support from execution/rlp and regenerate/update rlpgen fixtures and related tests.

Reviewed changes

Copilot reviewed 74 out of 75 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
txnprovider/txpool/pool_txn_parser_test.go	Update tx signing-hash test to pass *uint256.Int chain ID.
rpc/jsonrpc/graphql_api.go	Convert TD uint256 to big.Int for hexutil.Big JSON output.
polygon/sync/sync.go	Ensure TD is present before publishing; pass TD by value.
polygon/sync/p2p_service.go	Update Polygon sync P2P service interface to TD uint256.Int.
polygon/sync/p2p_service_mock.go	Update gomock for new TD uint256.Int signature.
polygon/sync/execution_client.go	Update execution client TD return type to *uint256.Int.
polygon/p2p/service.go	Update PublishNewBlock to accept TD uint256.Int.
polygon/bor/bor_test.go	Update bor tests for NewBlockPacket.TD as uint256.Int.
p2p/sentry/status_data_provider.go	Use TD *uint256.Int directly from rawdb and default missing TD to 0.
p2p/sentry/status_data_provider_test.go	Update test TD writes to uint256.Int.
p2p/sentry/sentry_multi_client/broadcast.go	Update broadcast new-block TD parameter to uint256.Int.
p2p/sentry/sentry_grpc_server_test.go	Use *uint256.Int TD directly for status data conversion.
p2p/protocols/eth/protocol.go	Change NewBlockPacket.TD to uint256.Int; update RLP encode/decode.
p2p/protocols/eth/handler.go	Convert TD *uint256.Int to *big.Int at geth-compat boundary for NodeInfo.
node/ethstats/ethstats.go	Accept TD as *uint256.Int and stringify for ethstats payload.
node/eth/backend.go	Convert stored TD *uint256.Int to *big.Int for existing callers.
execution/vm/runtime/runtime_test.go	Update fake chain reader TD signature to *uint256.Int.
execution/types/transaction.go	Change Transaction.SigningHash to accept *uint256.Int.
execution/types/transaction_test.go	Update signing-hash tests to uint256 chain ID.
execution/types/transaction_signing.go	Pass signer chain ID as *uint256.Int into SigningHash.
execution/types/set_code_tx.go	Switch set-code tx signing payload ChainID type to *uint256.Int.
execution/types/legacy_tx.go	Switch legacy tx signing payload ChainID type to *uint256.Int.
execution/types/dynamic_fee_tx.go	Switch 1559 tx signing payload ChainID type to *uint256.Int.
execution/types/block_test.go	Rename/update panic-prevention test to target EncodeUint256.
execution/types/blob_tx.go	Switch blob tx signing payload ChainID type to *uint256.Int.
execution/types/blob_tx_wrapper.go	Update wrapper SigningHash signature to *uint256.Int.
execution/types/access_list_tx.go	Switch 2930 tx signing payload ChainID type to *uint256.Int.
execution/types/aa_transaction.go	Update AA SigningHash signature and convert big chainID at call sites.
execution/tests/testutil/rlp_test_util.go	Update RLP JSON test translation/decoding to use uint256.
execution/tests/rlp_test.go	Skip legacy bigint vector that exceeds uint256 ceiling.
execution/tests/blockgen/chain_makers.go	Update fake chain reader TD signature to *uint256.Int.
execution/tests/blockchain_test.go	Convert TD reads to uint256, compare accordingly, and bridge to big.Int where needed.
execution/state/genesiswrite/genesis_write.go	Write genesis TD using uint256.Int value.
execution/stagedsync/rawdbreset/reset_stages.go	Accumulate TD as uint256.Int with overflow checks when filling DB from snapshots.
execution/stagedsync/headerdownload/header_data_struct.go	Update HeaderInserter local TD to *uint256.Int.
execution/stagedsync/headerdownload/header_algos.go	Update feed/insert TD plumbing to uint256 + overflow errors and CmpBig at TTD boundary.
execution/stagedsync/headerdownload/header_algo_test.go	Update header download tests for uint256 TD and comparisons.
execution/stagedsync/exec3.go	Convert *uint256.Int TD to *big.Int for tracing hook compatibility.
execution/stagedsync/chain_reader.go	Change ChainReader.GetTd return type to *uint256.Int.
execution/stagedsync/bodydownload/body_algos.go	Compute propagated TD as uint256.Int with overflow handling.
execution/stagedsync/bodydownload/block_propagator.go	Change block propagator TD parameter to uint256.Int.
execution/rlp/encode.go	Remove reflect-based big.Int encoding and exported helpers; keep uint256 encoding.
execution/rlp/encode_test.go	Remove big.Int encoding tests; add/keep uint256 tests and benchmark.
execution/rlp/encbuffer.go	Remove big.Int buffer-writing helpers; keep uint256 support.
execution/rlp/decode.go	Remove reflect-based big.Int decoding and Stream big-int APIs; keep uint256.
execution/rlp/decode_test.go	Remove big.Int decoding tests/fixtures; keep uint256 coverage.
execution/protocol/rules/rules.go	Update ChainHeaderReader.GetTd to return *uint256.Int.
execution/protocol/rules/merge/merge.go	Compare TD vs TTD via uint256.Int.CmpBig.
execution/protocol/rules/merge/merge_test.go	Update merge rule tests for uint256 TD reader signature.
execution/protocol/rules/ethash/forkchoice.go	Update forkchoice ShouldReorg to compare *uint256.Int TD values.
execution/protocol/rules/ethash/forkchoice_test.go	Update forkchoice tests to use uint256 TDs.
execution/protocol/block_exec.go	Convert *uint256.Int TD to *big.Int for tracer boundary.
execution/p2p/publisher.go	Publish NewBlock with TD as uint256.Int value.
execution/p2p/publisher_test.go	Update publisher tests for NewBlockPacket.TD as uint256.Int.
execution/p2p/message_sender_test.go	Update message sender tests for NewBlockPacket.TD as uint256.Int.
execution/execmodule/interface.go	Change ExecutionModule.GetTD return type to *uint256.Int.
execution/execmodule/inserters.go	Compute and store TD in overlay as uint256 with overflow checks.
execution/execmodule/getters.go	Update GetTD signature to return *uint256.Int.
execution/execmodule/execmoduletester/exec_module_tester.go	Update block propagator test hook signature for uint256.Int TD.
execution/execmodule/exec_module.go	Update internal getTD helper to return *uint256.Int.
execution/execmodule/chainreader/chain_reader.go	Update engine chain reader GetTd to return *uint256.Int.
execution/exec/chain_reader.go	Update execution chain reader GetTd to return *uint256.Int.
execution/engineapi/testing_api_test.go	Update stub GetTD signature to return *uint256.Int.
execution/engineapi/engine_server.go	Use CmpBig for TD vs TTD comparisons with *uint256.Int.
execution/engineapi/engine_server_getpayload_test.go	Update stub GetTD signature to return *uint256.Int.
execution/abi/bind/auth.go	Convert *big.Int chainID to *uint256.Int at signing boundary.
db/rawdb/accessors_chain.go	Store/read TD as uint256 (encoding unchanged); compare to TTD via CmpBig.
db/rawdb/accessors_chain_test.go	Update TD storage tests to use uint256.
db/consensuschain/consensus_chain_reader.go	Update consensus chain reader GetTd to return *uint256.Int.
cmd/utils/app/import_cmd.go	Sum side-chain TD with uint256 + overflow checks and persist via new rawdb API.
cmd/rlpgen/testing/testing_struct.go	Remove big.Int fields from rlpgen test fixture.
cmd/rlpgen/testing/gen_testingstruct_rlp.go	Regenerate fixture RLP code without big.Int paths.
cmd/rlpgen/testing/encdec_test.go	Remove big.Int random generation/comparisons from rlpgen tests.
cmd/rlpgen/matcher.go	Remove big.Int / *big.Int handler mapping from rlpgen.
cmd/rlpgen/handlers.go	Remove big.Int handlers from rlpgen generator.

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• cmd/rlpgen/testing/gen_testingstruct_rlp.go: Language not supported

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Copilot reviewed 121 out of 122 changed files in this pull request and generated 1 comment.

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Comments suppressed due to low confidence (1)

execution/abi/bind/auth.go:47

• After changing NewKeyedTransactorWithChainID to accept *uint256.Int, there are still call sites passing *big.Int (e.g., execution/abi/bind/bind_test.go uses big.NewInt(1337)), which will cause compile failures in tests. Update remaining callers/imports to use uint256.NewInt / uint256.MustFromBig at the boundary.

// NewKeyedTransactorWithChainID is a utility method to easily create a transaction signer
// from a single private key.
func NewKeyedTransactorWithChainID(key *ecdsa.PrivateKey, chainID *uint256.Int) (*TransactOpts, error) {
	keyAddr := crypto.PubkeyToAddress(key.PublicKey)
	if chainID == nil {
		return nil, ErrNoChainID
	}
	signer := types.LatestSignerForChainID(chainID)
	return &TransactOpts{

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Copilot reviewed 122 out of 123 changed files in this pull request and generated 1 comment.

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• cmd/rlpgen/testing/gen_testingstruct_rlp.go: Language not supported

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Copilot reviewed 123 out of 124 changed files in this pull request and generated no new comments.

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