refactor(revm): drop custom SLOAD/SSTORE overrides in favour of native instructions

[panos-xyz]

Summary

Deletes sload_morph / sstore_morph from crates/revm/src/evm.rs and restores the native EthInstructions for SLOAD (0x54) and SSTORE (0x55). -171 / +14, one file.

Closes #187 — but not with the mechanism that issue proposed. See my analysis there: the handler-level transaction_id sync described in the issue is a no-op on revm 41 (the ids already match; the trigger is the is_cold flag), and implementing it as written reintroduced the divergence at exactly +2800 gas. The real precondition was a revm bump, which #188 delivers.

Third in a stack — merge order matters, and getting it wrong is a chain split:

#188  chore: upgrade reth dependencies to v2.5.2      (brings revm 42)
 └─ #191  fix: close reth 2.5.2 upgrade gaps
     └─ this PR

Why the overrides existed

Token fee deduction leaves the caller's fee-token slot in a specific state, which is the same state morph-geth has:

field	value	morph-geth equivalent
original_value	DB-committed (pre-deduction)	GetCommittedState()
present_value	fee-deducted	GetState()
is_cold	true	not in accessList

In go-ethereum the EIP-2200 committed value and the EIP-2929 access list are deliberately independent. revm <= 41 conflated them in EvmStorageSlot::mark_warm_with_transaction_id:

let is_cold = self.is_cold_transaction_id(transaction_id);  // tx_id differs || self.is_cold
if is_cold {
    self.original_value = self.present_value;   // one condition drove both gas and re-baseline
}

Charging the 2100 cold cost required setting is_cold, and setting is_cold forced the re-baseline. EIP-2200 then saw a clean slot and charged SSTORE_RESET (2900) instead of the dirty-slot 100 — 2800 gas per write against morph-geth. The overrides existed purely to undo that.

Why they are no longer needed

bluealloy/revm#3746 (released in revm-state 42.0.0, still present in 43.0.0) keys the re-baseline on the transaction boundary instead of on the cold flag, while leaving the returned is_cold — and therefore the cold gas charge — untouched. The committed value now survives an explicit mark_cold(), so native SLOAD/SSTORE produce geth-equivalent gas on their own.

Verification

Controlled comparison against the golden e2e test, one variable between the rows:

tree	morph_tx_v0_token_fee_transfer_to_fee_token_contract_gas_regression
revm 41 + overrides	48_128 — previous state
revm 41 − overrides	50_928 — +2800, the divergence the overrides hid
revm 42 − overrides	48_128 — this PR

The middle row matters as much as the last: it proves that test is a real tripwire and not a permanently green assertion. It is therefore left untouched as the gate for this change.

Full local run on the pushed commit:

cargo nextest run --workspace                     644 passed, 0 failed
cargo nextest run -p morph-node -E 'binary(it)'   101 passed, 0 failed
cargo clippy --all --all-targets -- -D warnings   clean
cargo fmt --all -- --check                        clean

Note CI's Build / Clippy / Run Tests / E2E Tests workflows are gated on pull_request: branches: [main], so they will not run while this PR targets a non-main base. The gates above were run locally on cd881df; they need a real CI run once the stack is retargeted.

Drifts this retires

The copies had already accumulated three divergences from upstream — the concrete evidence that hand-maintaining SSTORE was the wrong trade:

1. EIP-8037 never mirrored. Upstream sstore_default_gas_accounting charges state_gas! and calls refill_reservoir; sstore_morph had neither. Dormant only because every Morph hardfork maps below SpecId::AMSTERDAM (asserted by test_morph_hardforks_do_not_enable_amsterdam_state_gas).
2. Stale cold-load threshold. revm 42 moved the SSTORE skip check from cold_storage_additional_cost() (2000) to cold_storage_cost() (2100); sstore_morph still used the old one. Unreachable — the Istanbul reentrancy sentry already requires remaining > call_stipend (2300) before that branch.
3. Over-broad repair. The original_value restore ran for every cold slot, including slots of an account created within the same transaction, where revm reports ZERO while the DB may hold residual storage. Practically unreachable (SELFDESTRUCT is disabled in Morph), but wrong by construction.

Kept

blockhash_morph (0x40) and the disabled SELFDESTRUCT / BLOBHASH / BLOBBASEFEE opcodes — genuine Morph semantics, unrelated to revm's version. A comment at the registration site now records why 0x54/0x55 are deliberately not overridden, so the workaround does not get reintroduced.

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