The Fragility of Bytecode-Level Compatibility Guarantees

EVM precompiles like ecRecover or modExp are hardcoded gas costs and addresses that diverge instantly on new L2s. This creates silent consensus failures where identical bytecode behaves differently.

• Forks like Arbitrum and Polygon must meticulously re-implement and re-price each precompile.
• A single missed precompile can brick DeFi protocols with $100M+ TVL relying on that logic.
• Creates permanent fragmentation; a "universal" contract is now chain-specific.

Bytecode execution cost is not intrinsic; it depends on a chain's gas oracle and L1 data pricing model. A contract optimized for ~50 gwei on Ethereum can become economically non-viable on an L2 with a different fee market.

• OP Stack chains use a Gas Price Oracle contract; Arbitrum uses a centralized sequencer for L1 price updates.
• zkEVMs like zkSync Era introduce unique opcode gas costs, breaking performance assumptions.
• Results in 10-100x cost variance for the same logical operation across chains.

Bytecode assumes uniform state access patterns, but L2s and alt-VMs like Fuel or Monoova implement state storage and proofs differently. A contract relying on specific SLOAD or SSTORE gas refund behavior will fail or be exploited.

• zkRollups require state diffs for proofs, making constant SSTORE ops prohibitively expensive.
• Parallel EVMs like Monad or Sei change cache hierarchies, making some access patterns 10x slower.
• Forces developers to write chain-aware logic, defeating the purpose of a virtual machine.

Optimism's migration to Bedrock required a coordinated network pause and a new genesis block, breaking the core EVM-equivalence promise of seamless state migration. The upgrade introduced a new precompiled contract for L1 block attributes, a bytecode-level change that was incompatible with the previous chain.\n- Forced Re-Deployment: All contracts referencing the old L1 attributes had to be manually redeployed.\n- Protocol Risk: Highlighted that even "EVM-equivalent" chains can't guarantee forward compatibility for their own upgrades.

A subtle difference in CREATE2 salt handling between Polygon zkEVM and the EVM created a critical vulnerability. The zkEVM's prover used a different hashing mechanism, allowing an attacker to precompute and front-run contract addresses that were impossible on Mainnet.\n- Security Breach: Exploited to steal funds from a launchpad before user deposits.\n- Testing Gap: Revealed that standard EVM test suites (like Foundry's) missed this bytecode-level nuance, creating a false sense of security.

Arbitrum Nitro forked Geth, introducing custom precompiles for L1→L2 communication. While mostly compatible, this created a subtle divergence in gas metering and state access patterns for those precompiles. Contracts relying on precise gas estimates or accessing block.basefee within these contexts behaved unpredictably.\n- Silent Bugs: Applications worked in tests but failed under mainnet load due to gas miscalculations.\n- Vendor Lock-in: DApps became implicitly dependent on Arbitrum's specific Geth fork, not the canonical EVM specification.

zkSync Era's architecture treats ETH as an ERC20 token in its state tree, not as the native currency of the EVM. This breaks core assumptions for protocols that use low-level calls like address.transfer() or check address.balance. The msg.value opcode works, but any contract logic inspecting the native ETH balance or using certain Solidity patterns fails.\n- Deployment Friction: Major protocols like Aave and Uniswap required significant, non-trivial refactoring for deployment.\n- Abstraction Leak: Developers must consciously work around the VM's internal abstraction, defeating the purpose of EVM compatibility.

Ethereum's EIPs and hard forks are not just consensus changes; they alter the underlying execution semantics. A contract compiled for London may behave unpredictably on a chain that hasn't forked. This breaks the core assumption that bytecode is a universal constant.

• Risk: Silent failures in critical logic like SELFDESTRUCT or gas calculations.
• Action: Treat the EVM version as a first-class dependency, not a guarantee.

Move compatibility guarantees from the bytecode layer to the contract ABI and semantic layer. Use canonical interfaces like ERC-20/721 and enforce them via EIP-165 interface detection. This decouples your protocol from VM-specific quirks.

• Benefit: Interoperability survives VM upgrades and divergent L2 implementations.
• Tooling: Leverage Foundry's forge inspect and Sourcify for verification, not just bytecode hashes.

An audit on mainnet bytecode provides zero guarantees for its behavior on other chains like Arbitrum, Optimism, or Polygon zkEVM. Their VMs have subtle differences in precompiles, gas costs, and block structure.

• Action: Mandate chain-specific audits for any deployment beyond Ethereum L1.
• Metric: Audit scope must include chain-specific integration tests and gas profiling.

For critical cross-chain operations, bypass bytecode trust entirely. Use intent-based systems like UniswapX, CowSwap, or Across Protocol, which abstract settlement. The user expresses a desired outcome; a solver network competes to fulfill it, often via atomic arbitrage.

• Benefit: Removes dependency on the correctness of remote contract bytecode.
• Trade-off: Introduces solver trust and MEV considerations.

Canonical bridges (e.g., Arbitrum Bridge, Optimism Portal) lock $10B+ TVL in bytecode that must remain compatible forever. A single VM divergence can freeze funds. This creates a systemic fragility point for the entire ecosystem.

• Action: For new designs, prefer light-client bridges or zero-knowledge proofs of state which verify consensus, not just execution.
• Example: zkBridge models using Succinct, Herodotus, or Lagrange.

Your CI/CD pipeline is incomplete if it only tests on a single EVM. Use differential fuzzing against multiple VM targets: geth, erigon, reth, besu, and relevant L2 execution clients. Foundry and Hardhat can be orchestrated to run the same tests across different environments.

• Output: A compatibility matrix identifying VM-specific failures.
• Goal: Catch semantic drift before it hits production.