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Introduction to ewasm
This document discusses eWASM, which is the Ethereum Virtual Machine implemented using WebAssembly (WASM). Some key points: - eWASM mirrors the EVM stack-based design in WASM but uses locals instead of a deep stack and has a more RISC instruction set. - High-level EVM instructions are removed and replaced by importing standard interface functions defined in the Ethereum Environment Interface (EEI). - A system contract called Sentinel is used to insert metering statements and reject invalid eWASM bytecode before deployment. - eWASM has potential performance benefits over EVM but some challenges remain around storage model, metering approaches,
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Introduction to ewasm
- 1. EWASM VM -次世代的 Ethereum Virtual Machine @hydai 2019/08/17
- 2. hydai Blog: hyd.ai Mail: hydai@hyd.ai GitHub:@hydai Work: @SecondState Focus on Compiler and Virtual Machine technology.
- 3. – Eth1x/Istanbul meetupBerlin Save Ethereum, Scale Ethereum.
- 4. EVM recap • Stack-basedvirtual machine (or interpreter…) • 256 bit stack items • Too many high level instructions • Storage(SSTORE, SLOAD) • SHA3(keccak-256) • Call, Create Contract… • Too far away from actual machine architecture • Less language support (Vyper, Solidity)
- 5. How about wasm? •Also, a stack-based machine but… • has locals ( ~= register or memory) • only access top 3 items from stack v.s EVM’s 16 • Support 32/64 bit operations • No high level instructions • RISC Instruction Set, can map to a common CPU ISA • Large community power • Supported in all major browser • Lots of implementations • Lots of language support (C++, Rust, …)
- 6. wasm engine • Tool •binaryen (a toolkit contains an interpreter in C++) • wabt (a toolkit contains an interpreter in C++) • wavm (LLVM-based JIT) • wagon (interpreter in Golang) • parity-wasm (interpreter in Rust) • Browser (hyper interpreter/JIT) • Chrome (V8) • Edge (chakra) • Firefox (spidermonkey)
- 7. What is ewasm? •ewasm ⊂ wasm • NOT support floating point number • LIMITED imports and exports (wasm section) • Will inject bytecode metering and has runtime metering
- 8. Where did thehigh level instructions go?
- 9. Ethereum Environment Interface •EEI defines a set of ewasm imported functions • With standard interface, clients can implement easier • Because EEI is not native instructions in bytecode • Quick prototyping and doing specific upgrades ewasm module EEI blockchain
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- 12. System Contract • Compiledinto wasm bytecode • Deployed on chain (like normal contract) • Or be part of client (like precompiles) • Examples: • Byzantium precompiles • sha256, ripemd160, ecrecover, modexp, … • Use upper-bound metering • Sentinel (verification and metering)
- 13. Sentinel Contract? • Beforecontract deployment • Reject non-ewasm bytecode (e.g. floating point) • Insert metering statements • basic-block-based metering (call useGas in the beginning of block) ewasm bytecode Sentinel deployed on chain
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- 15. Client with EVM-C support EVM-C Heru WasmEngine in C++ EEI Runtime ewasm bytecode Sentinel
- 16. EVM-C • Connect clientand VM implementation • Ethereum Virtual Machine includes EVM1 and eWASM • With EVM-C, VM can be linked statically or loaded as plugin (.dll, .so) • C means C language API
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- 19. Is ewasm apanacea for ethereum?
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- 21. Issue 1 -Storage Model • eWASM = EVM 1.0 mirrored in wasm • Storage model is not compatible with rent • Here comes eWASM 1.X!!! • New storage model designed for rent!!!
- 22. Issue 2 -Performance Is eWASM always better than EVM1?
- 26. What happens?!!!!! • Generalwasm engine supports 32/64 bit operations • 128/256 bit operations will be simulated by 32/64 bit operations • EVM has the precompiles……
- 27. Issue 3 -Metering • Basic block metering • Super block metering • Upper bound metering
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- 32. Reference • ewasm forsharding • https://drive.google.com/file/d/19t4qCqEK2RPt0p1XYx- a2FdZSAlCq7H0/view • ewasm updates • https://drive.google.com/file/d/ 1CRc0qBQTebNKw7NRZXzxbHovrigW0bqf/view • ewasm design • https://github.com/ewasm/design • EEI • https://github.com/ewasm/design/blob/master/eth_interface.md • wasm-intro • https://rsms.me/wasm-intro