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EVM opcodes vs ewasm methods

These tables compares EVM opcodes with ewasm methods and wasm instructions. The EVM defines 134 opcodes (as of the Byzantium hard fork). Of these 134 opcodes, some represent generic machine instructions (ADD, MUL, ISZERO, XOR, etc.) and the rest are Ethereum-specific operations (SLOAD, SSTORE, GASPRICE, BLOCKHASH, etc.).

When EVM bytecode is transpiled to ewasm bytecode, the Ethereum-specific opcodes translate to corresponding ewasm interface methods (Ethereum Environment Interface (EEI) methods). These interface methods are provided as host functions to the wasm VM. All other EVM opcodes are not Ethereum-specific and do not access data from the Ethereum environment, so they reduce to pure wasm instructions.

To reference EVM opcodes, try the yellow paper, the readable yellow paper, or the pyethereum implementation.

To reference ewasm interface methods, see the EEI spec.

EVM opcodes (Byzantium) with corresponding ewasm methods (Ethereum Environment Interface (EEI) Revision 4)

EVM opcode ewasm interface method
0x00: STOP finish(0, 0)
0x30: ADDRESS getAddress
0x31: BALANCE getBalance
0x32: ORIGIN getTxOrigin
0x33: CALLER getCaller
0x34: CALLVALUE getCallValue
0x35: CALLDATALOAD callDataCopy(resultOffset, dataOffset, 32)
0x36: CALLDATASIZE getCallDataSize
0x37: CALLDATACOPY callDataCopy(resultOffset, dataOffset, size)
0x38: CODESIZE getCodeSize
0x39: CODECOPY codeCopy
0x3a: GASPRICE getTxGasPrice
0x3b: EXTCODESIZE getExternalCodeSize
0x3c: EXTCODECOPY externalCodeCopy
0x3d: RETURNDATASIZE getReturnDataSize
0x3e: RETURNDATACOPY returnDataCopy
0x40: BLOCKHASH getBlockHash
0x41: COINBASE getBlockCoinbase
0x42: TIMESTAMP getBlockTimestamp
0x43: NUMBER getBlockNumber
0x44: DIFFICULTY getBlockDifficulty
0x45: GASLIMIT getBlockGasLimit
0x54: SLOAD storageLoad
0x55: SSTORE storageStore
0x58: PC -
0x5a: GAS getGasLeft
0xa0: LOG0 log(0,..)
...
0xa4: LOG4 log(4,..)
0xf0: CREATE create
0xf1: CALL call
0xf2: CALLCODE callCode
0xf3: RETURN finish
0xf4: DELEGATECALL callDelegate
0xfa: STATICCALL callStatic
0xfd: REVERT revert
0xff: SELFDESTRUCT selfDestruct

†. In EVM, the Program Counter (PC) opcode returns the currently executing bytecode position. When EVM is transpiled to ewasm with evm2wasm, this bytecode position is calculated by the transpiler and inserted as a wasm constant. For ewasm code that is not transpiled from EVM, there is no interface method corresponding to the PC opcode.

EVM opcodes vs WebAssembly instructions

Whereas EVM is an untyped VM with a 256-bit word size, WebAssembly is a typed VM with 32-bit and 64-bit word sizes. The two wasm base types are integers and floats, which when combined with the two word sizes, create four types: i32, i64, f32, f64.

Ethereum WebAssembly, or ewasm, is a subset of wasm. Only the integer types (i32 and i64) are supported, floating point types and floating point instructions are not supported. In total, 60 wasm instructions are supported in ewasm:

  • 10 control flow instructions
  • 11 basic instructions
  • 19 integer arithmetic instructions
  • 10 integer comparison instructions
  • 3 integer conversion instructions
  • 7 memory instructions (load, store, extend)

ewasm excludes the wasm floating point instructions:

  • 14 floating point arithmetic instructions
  • 6 floating point comparison instructions
  • 7 floating point conversion instructions

To reference wasm instructions, see the wasm spec or reference manual.

EVM opcodes that reduce to wasm instructions

EVM opcode (256-bit) wasm instruction i32/i64 (32-bit or 64-bit)
0x01: ADD i32.add
0x02: MUL i32.mul
0x03: SUB i32.sub
0x04: DIV i32.div_u
0x05: SDIV i32.div_s
0x06: MOD i32.rem_u
0x07: SMOD i32.rem_s
0x08: ADDMOD -
0x09: MULMOD -
0x0a: EXP -
0x0b: SIGNEXTEND -
0x10: LT i32.lt_u
0x11: GT i32.gt_u
0x12: SLT i32.lt_s
0x13: SGT i32.gt_s
0x14: EQ i32.eq
0x15: ISZERO i32.eqz
0x16: AND i32.and
0x17: OR i32.or
0x18: XOR i32.xor
0x19: NOT i32.sub (i32.const 0xffffffff)
0x1a: BYTE i32.load8
0x20: SHA3 -
0x50: POP drop
0x51: MLOAD i32.load
0x52: MSTORE i32.store
0x53: MSTORE8 i32.store
0x56: JUMP br
0x57: JUMPI br_if, br_table
0x59: MSIZE current_memory
0x5b: JUMPDEST block, loop
0xfe: INVALID unreachable
0x60: PUSH1 i32.const
...
0x7f: PUSH32 i32.const
0x80: DUP1 get_global, get_local
...
0x8f: DUP16 get_global, get_local
0x90: SWAP1 get_global, get_local
...
0x9f: SWAP16 get_global, get_local

‡. Some EVM opcodes, such as ADDMOD (modular addition), EXP (exponentiation), or SHA3 (Keccak-256 hash), do not have simple reductions to single wasm instructions (or to only a few wasm instructions). The functionality of these opcodes is replicated by a relatively large wasm module (for instance, SHA3 reduces to about 900 lines of wast code).