SELFDESTRUCT

SELFDESTRUCT opcode on MegaETH — EIP-6780 semantics, same-transaction destruction, beneficiary account metering, and spec history from MiniRex to Rex5.

This page specifies the availability and semantics of the SELFDESTRUCT opcode in MegaETH. It defines the current behavior and records the earlier MiniRex restriction.

Motivation

Ethereum deprecated the legacy SELFDESTRUCT behavior because it breaks assumptions about contract permanence and state growth, and it interacts poorly with modern state-management and witness-generation requirements. MegaETH inherits the same motivation.

The protocol therefore needs to specify whether SELFDESTRUCT is disabled entirely or, when enabled, which restricted semantics apply.

Specification

Stable Behavior

SELFDESTRUCT MUST follow EIP-6780 semantics.

If the executing contract was created in the same transaction, SELFDESTRUCT MUST:

• transfer the remaining balance to the target address, and
• remove the contract's code and storage.

If the executing contract was not created in the same transaction, SELFDESTRUCT MUST:

• transfer the remaining balance to the target address, and
• preserve the contract's code and storage.

SELFDESTRUCT targeting the beneficiary MUST trigger beneficiary gas detention.

Beneficiary Account Creation

When SELFDESTRUCT transfers a non-zero balance to a target address that does not yet exist in state, the value transfer creates a new account. A node MUST meter this account creation identically to account creation by any other means:

• charge the account-creation storage gas (ACCOUNT_CREATION_STORAGE_GAS_BASE × (multiplier − 1), where multiplier is the target's SALT bucket multiplier), and
• record the creation against the data size (+SELFDESTRUCT_BENEFICIARY_DATA_BYTES), KV updates (+1), and state growth (+1) resource lanes.

A SELFDESTRUCT whose transferred balance is zero MUST NOT incur any of these charges, because a zero-value transfer does not create the target account. A SELFDESTRUCT whose target already exists in state MUST NOT incur these charges.

State Growth Refund

When a contract that was created in the same transaction executes SELFDESTRUCT (EIP-6780 semantics), the node MUST apply a state growth refund:

• -1 for the account itself (reversing the +1 from CREATE/CREATE2).
• -1 for each storage slot whose original value was zero and current value is non-zero (reversing each +1 from SSTORE).

This refund MUST only be applied on the first effective destruction. If the same account is the target of SELFDESTRUCT more than once in the same transaction, subsequent destructions MUST NOT produce additional refunds.

This refund MUST NOT be applied when SELFDESTRUCT targets a pre-existing account (one not created in the current transaction), because pre-existing accounts do not have their code and storage removed under EIP-6780.

The refund is frame-aware: if the call frame that performed the SELFDESTRUCT reverts, the refund MUST be discarded together with the destruction effect.

Constants

Constant	Value	Description
ACCOUNT_CREATION_STORAGE_GAS_BASE	25,000	Base storage gas charged when a value transfer creates a previously empty account
SELFDESTRUCT_BENEFICIARY_DATA_BYTES	40	Data-size bytes recorded for the beneficiary account write on beneficiary creation

Rationale

Why disable SELFDESTRUCT before Rex2? MegaETH initially disabled SELFDESTRUCT to avoid inheriting destructive account-lifecycle behavior before the protocol defined the intended stable semantics.

Why adopt EIP-6780 in stable behavior? EIP-6780 is the post-Cancun Ethereum behavior and provides a widely understood baseline. Adopting it restores compatibility while avoiding legacy full-destruction behavior for long-lived contracts.

Why meter beneficiary account creation? A value-carrying SELFDESTRUCT to a non-existent target creates an account exactly as a value-transferring CALL to an empty address does. Charging the same account-creation storage gas and recording the same resource-lane usage closes a path by which state could be grown at compute-gas cost only, without going through the metered account-creation surcharge.

Security Considerations

If SELFDESTRUCT targeting the beneficiary does not trigger gas detention, contracts can use it to access beneficiary balance without being detained, creating an unmitigated conflict hotspot for parallel execution.

If SELFDESTRUCT does not charge new-account costs when it creates its target, an attacker can create accounts and grow state through SELFDESTRUCT at compute-gas cost only, bypassing the account-creation storage gas and resource-lane accounting that every other account-creation path pays.

Spec History

• MiniRex, Rex, and Rex1 disable SELFDESTRUCT; executing it halts with InvalidFEOpcode.
• Rex2 re-enables SELFDESTRUCT with EIP-6780 semantics.
• Rex4 — added beneficiary-triggered volatile-access behavior for SELFDESTRUCT, and state growth refund for same-transaction-created accounts destroyed by SELFDESTRUCT.
• Rex5 — charged account-creation storage gas and recorded data-size, KV-update, and state-growth usage when a value-carrying SELFDESTRUCT creates a previously non-existent beneficiary account.