Openevm

[!NOTE]
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[!WARNING] See v2 Site

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

†. <small id="f1">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.</small>

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

‡. <small id="f2">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).</small>