REVERT instruction

The five-minute read

One action, walked through

1. Open EIP 140 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: The REVERT instruction provides a way to stop execution and revert state changes, without consuming all provided gas and with the ability to return a reason.
3. Name the object that changes: REVERT, EVM, BYZANTIUM_FORK_BLKNUM.
4. Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

The argument, unpacked

What has to be true

• You are implementing EIP 140 at the status the text itself states: Final.
• The object that has to change is REVERT, EVM, BYZANTIUM_FORK_BLKNUM. A neighbouring document with a similar name is not this one.
• Constants in the text can be superseded by a later fork. Cite the EIP number and the fork you mean.

What happened after the paper

The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

What to check before you use the idea

• What does REVERT instruction charge, reject, or redefine on the first touch versus a later one?
• Does a reverted subcall roll the change back?
• Can you point at the object in a client: REVERT, EVM, BYZANTIUM_FORK_BLKNUM?

Terms

EIP 140

The public text titled REVERT instruction.

Final

The document's own label for how finished the text is. It is not a market fact.

The problem the paper names

An underpriced or ambiguous EVM rule is not a feature. It is a block that takes longer than the gas limit claimed, or a client that disagrees about the result.

What the design proposes

• The REVERT instruction provides a way to stop execution and revert state changes, without consuming all provided gas and with the ability to return a reason.
• The REVERT instruction will stop execution, roll back all state changes done so far and provide a pointer to a memory section, which can be interpreted as an error code or message.
• While doing so, it will not consume all the remaining gas.

How the mechanism is specified

• Taken from the specification, the next constraint is: The REVERT instruction will stop execution, roll back all state changes done so far and provide a pointer to a memory section, which can be interpreted as an error code or message.
• Locate REVERT, EVM, BYZANTIUM_FORK_BLKNUM in EIP 140 and apply it to one transaction or call.
• Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

• A gas or opcode change is not a throughput benchmark. It is a relative price and a validity rule.
• Constants in the text can be superseded by a later fork. Cite the EIP number and the fork you mean.
• The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it.

Why a venture studio still reads it

Use EIP 140 when a pitch says 'REVERT instruction' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.