Smart Contract Types

In addition to the common types used throughout go-ethereum, the following types are important for smart contracts.

operation

The operation struct defines an EVM opcode:

type operation struct {
    // execute is the operation function
    execute executionFunc
    // gasCost is the gas function and returns the gas required for execution
    gasCost gasFunc
    // validateStack validates the stack (size) for the operation
    validateStack stackValidationFunc
    // memorySize returns the memory size required for the operation
    memorySize memorySizeFunc

    halts   bool // indicates whether the operation should halt further execution
    jumps   bool // indicates whether the program counter should not increment
    writes  bool // determines whether this a state modifying operation
    valid   bool // indication whether the retrieved operation is valid and known
    reverts bool // determines whether the operation reverts state (implicitly halts)
    returns bool // determines whether the operations sets the return data content
}

Notice the jumps property, a Boolean, which if set indicates that the program counter should not increment after executing any form of jump opcode.

The destinations type maps the hash of a smart contract to a bit vector for each the smart contract’s entry points. If a bit is set, that indicates the EMV’s program counter should increment after executing the entry point. analysis.go defines the destinations type like this:

// destinations stores one map per contract (keyed by hash of code).
// The maps contain an entry for each location of a JUMPDEST instruction.
type destinations map[common.Hash]bitvec

InstructionSet

The EVM instruction set for each version of the EVM are defined in jump_table.go.