Solia saysEVM Object Format restructures bytecode into a versioned container with explicit code, data, and type sections — enabling static jumps, banning dynamic JUMP, and modernizing the runtime.
Legacy EVM bytecode is one monolithic blob with implicit code/data mixing and dynamic JUMP destinations checked at runtime. EOF (EVM Object Format) wraps bytecode in a versioned container with explicit sections: a header (magic 0xEF00 + section table), a type section, code sections per function, and a data section. Static relative jumps replace dynamic JUMP, so JUMPDEST analysis vanishes from the runtime.
The payoff is a cleaner runtime, faster validation, and the ability to evolve the bytecode format without breaking old contracts. EOF ships alongside related EIPs (3540, 3670, 4200, …) and forms the basis for future opcodes. The demo contrasts the two formats.
Power-ups you unlock
Versioned container: magic 0xEF00 + section table
Explicit sections: type, code (per function), data
Static relative jumps replace dynamic JUMP
Eliminates runtime JUMPDEST analysis
Foundation for future bytecode evolution
The Reentrancy Reaper attacks — common mistakes
Assuming EOF is already mandatory (it is on the roadmap)
Treating EOF as a runtime change (it is mostly a format change)
Forgetting the legacy format still runs alongside EOF
Confusing EOF with account abstraction (different EIPs)
Boss battleLay out the legacy bytecode model vs the EOF container model and identify three improvements.
Example code
<!doctype html><html><head><meta charset="utf-8"></head>
<body style="background:#06040d;color:#e6e0ff;font-family:monospace;padding:20px"><pre id="o"></pre>
<script>
const legacy = {
header: 'none',
layout: 'monolithic blob: opcodes + data interleaved',
jumps: 'dynamic JUMP / JUMPI, JUMPDEST analysis at runtime',
validation: 'minimal at deploy; risk at runtime'
};
const eof = {
header: '0xEF00 (magic) + version + section table',
layout: 'sections: [type] [code₀ code₁ …] [data]',
jumps: 'static relative jumps (RJUMP, RJUMPI), no JUMPDEST analysis',
validation: 'strict at deploy: malformed code is rejected'
};
const improvements = [
'1. faster runtime (no JUMPDEST analysis)',
'2. structured functions for future opcodes',
'3. clean separation of code and data',
'4. versioned format → can evolve without breaking old contracts'
];
document.getElementById('o').textContent = [
'LEGACY EVM bytecode:',
...Object.entries(legacy).map(([k,v]) => ' ' + k.padEnd(11) + v),
'',
'EOF container:',
...Object.entries(eof).map(([k,v]) => ' ' + k.padEnd(11) + v),
'',
'improvements:',
...improvements
].join('\n');
</script></body></html>