evmdis's Introduction

evmdis

evmdis is an EVM disassembler. It performs static analysis on the bytecode to provide a higher level of abstraction for the bytecode than raw EVM operations.

Features include:

Separates bytecode into basic blocks.
Jump target analysis, assigning labels to jump targets and replacing addresses with label names.
Composes individual operations into compound expressions where possible.

Example

The following contract, compiled with solc --optimize:

contract Test {
    function double(uint a) returns (uint) {
        return multiply(a, 2);
    }

    function triple(uint a) returns (uint) {
        return multiply(a, 3);
    }

    function multiply(uint a, uint b) internal returns (uint) {
        return a * b;
    }
}

Produces the following disassembly:

0x4     MSTORE(0x40, 0x60)
0xD     PUSH(CALLDATALOAD(0x0) / 0x2 ** 0xE0)
0x13    DUP1
0x17    JUMPI(:label0, POP() == 0xEEE97206)

0x18    DUP1
0x21    JUMPI(:label2, 0xF40A049D == POP())

0x23    STOP()

:label0
0x25    PUSH(:label3)
0x29    PUSH(CALLDATALOAD(0x4))
0x2A    PUSH(0x0)
0x2C    PUSH(:label4)
0x2E    DUP3
0x2F    PUSH(0x2)

:label1
0x32    PUSH(POP() * POP())
0x33    SWAP1
0x34    JUMP(POP())

:label2
0x36    PUSH(:label3)
0x3A    PUSH(CALLDATALOAD(0x4))
0x3B    PUSH(0x0)
0x3D    PUSH(:label4)
0x3F    DUP3
0x40    PUSH(0x3)
0x44    JUMP(:label1)

:label3
0x46    PUSH(0x60)
0x48    SWAP1
0x49    DUP2
0x4A    MSTORE(POP(), POP())
0x4E    RETURN(POP(), 0x20)

:label4
0x50    SWAP3
0x51    SWAP2
0x52    POP()
0x53    POP()
0x54    JUMP(POP())

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