The state of Swift for WebAssembly in 2022

by Yuta Saito

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The state of Swift for WebAssembly in 2022 iOSDC 2022 @kateinoigakukun 1

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About Me • @kateinoigakukun • Working at GoodNotes • SwiftWasm ͷϝϯςφ • ৽ถ Swift / CRuby / LLVM ίϛολ • Love Swift ! 2

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About this talk 1. Ϟνϕʔγϣϯ 2. SwiftWasm ͷϢʔεέʔε & σϞ 3. աڈ2೥ͷਐḿ 4. Future Work 3

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Ϟνϕʔγϣϯ 4

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Swiftͷ޷͖ͳͱ͜Ζ • ίϯύΠϧ͕௨Ε͹େମಈ͘ • ਖ਼͍͠ίʔυΛ؆୯ʹॻͨ͘ΊͷIDEࢧԉ • ॊೈͳܕγεςϜ • ஋ܕࢦ޲ • ConcurrencyͰਅՁΛൃش 5

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SwiftͰ΍Γ͍ͨ͜ͱ Run Swift anywhere • Webϒϥ΢βͰಈ͘Swift • AndroidͰಈ͘Swift • Ϋϥ΢υϓϥοτϑΥʔϜͰಈ͘Swift • SwiftͰॻ͚ΔϢʔβϓϥάΠϯ (e.g. VSCode Extension) 6

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WebAssembly is a game changer A binary instruction format for a stack-based machine Designed to be • Portable • Size- and Load-time efﬁcient • Secure by Sandbox 7

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WebAssemblyͷ࣮ߦϑϩʔ 8

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SwiftWasm Project https://swiftwasm.org SwiftͷWebAssemblyରԠΛਐΊΔϓϩδΣΫτ • ίϯύΠϥΛ௚ͯ͠ύονΛૹͬͨΓɺ • WebAssembly޲͚ͷπʔϧνΣΠϯΛ഑෍ͨ͠Γɺ • JavaScriptKitͳͲͷपลϥΠϒϥϦͷ։ൃ 9

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Demo: Run Swift on browser 10

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ϓϩμΫγϣϯͰͷSwiftWasmͷϢʔεέʔε • GoodNotes1 • Note-taking app • Web Viewer for sharing • Luminal2 • Python notebook on browser 2 https://getluminal.com/ 1 https://www.goodnotes.com/ 13

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GoodNotesͷϨϯμϥ͕Web Ͱಈ͍ͯΔ༷ࢠ 14

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WebAssembly is not only for Web 15

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WebAssembly is not only for Web • αϯυϘοΫεʹΑΔ҆શੑɺϙʔλϒϧͳΞʔΩςΫνϟɺ ଟݴޠαϙʔτ͸ଞͷ෼໺Ͱ΋خ͍͠ • ServerlessϓϥοτϑΥʔϜ • ϓϥάΠϯγεςϜ • and more… 16

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WASI (WebAssembly System Interface) WebҎ֎Ͱ΋WasmΛಈ͔ͨ͢Ίͷඪ४γεςϜίʔϧن໿ 17

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https://hacks.mozilla.org/2019/03/standardizing-wasi-a-webassembly-system-interface/ 18

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https://hacks.mozilla.org/2019/03/standardizing-wasi-a-webassembly-system-interface/ 19

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WASI compatible things Platforms • Node.js / Deno / Wasmtime • Fastly Compute@Edge • Cloudﬂare Workers • VSCode Extensions • Fluent Bit • Etc… Languages • C / C++ • Rust • Swift • Ruby • Etc… 20

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Wasm͸ಈ͔͢؀ڥ΋ίϯύΠϥ΋خ͍͠ • ಈ͔͢ଆ: WebAssemblyϥϯλΠϜ͑͋͞Ε͹ɺ༷ʑͳݴޠΛ αϙʔτ͢Δ͜ͱ͕Ͱ͖Δ • ίϯύΠϥଆ: WebAssemblyʹίϯύΠϧͰ͖Ε͹ɺ༷ʑͳ؀ ڥͰಈ͔ͤΔ 21

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Demo: Swift CLI on WebAssembly 22

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Web Ҏ֎ͷSwiftWasmͷϢʔεέʔε • Fastly Compute@Edge3 • Serverless platform based on WebAssembly • Enarx4 • WebAssembly + Conﬁdential Computing on TEE (Trusted Execution Environment) 4 https://enarx.dev/docs/webassembly/swift 3 https://www.fastly.com/jp/blog/introducing-serverless-swift-building-on-compute-edge-with-andrew-barba 24

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Demo: Swift at Compute@Edge 25

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For more info https://swift.cloud/blog/deploy-server-side-swift-to-fastly 27

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ٕज़తͳਐḿ (2020~2022) • Relative PointerαϙʔτΛWasmʹ௥Ճ • 70Ҏ্ͷύονΛΞοϓετϦʔϜʹϚʔδ • Swift ConcurrencyʹରԠ • Tokamak Fiber Renderer • μWASI 28

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Relative Pointer SwiftͰ࢖ΘΕ͍ͯΔϙΠϯλදݱͷςΫχοΫ • 64bit؀ڥͰ΋32bitʹऩ·Δ • → όΠφϦαΠζخ͍͠ • Ґஔಠཱ • → ʢେࡶ೺ʹݴ͏ͱʣ ΞϓϦىಈ͕଎ͯ͘خ͠ 29

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Relative Pointer • Wasmͷ࢓༷Ͱ͸දݱͰ͖ͳ͔ͬͨ template uintptr_t applyRelativeOffset(BasePtrTy *basePtr, Offset offset) { #ifdef __wasm__ // WebAssembly: hack: disable relative pointers return (uintptr_t)(intptr_t)offset; #endif auto base = reinterpret_cast(basePtr); auto extendOffset = (uintptr_t)(intptr_t)offset; return base + extendOffset; } 30

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Relative Pointer ϋοΫ͸ਏ͍ • ίϯύΠϥͱϥϯλΠϜ྆ํʹେྔͷมߋ͕ඞཁ • ΞοϓετϦʔϜͰ৽͘͠Relative Pointerͷ࢖༻͕૿͑Δͨͼ ʹέΞ͕ඞཁ 31

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WasmʹRelative PointerαϙʔτΛ௥Ճ • WasmଆʹRelative Pointer ʹඞཁͳػೳΛఏҊ&࣮૷ 32

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WebAssemblyͷͨΊʹSwiftΛ௚͢ 33

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WebAssemblyͷͨΊʹSwiftΛ௚͢ SwiftͷͨΊʹWebAssemblyΛ௚͢ 34

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ϋοΫ͕ফͤͯϋοϐʔ 35

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Upstreaming patches • 44 patches for apple/swift • 16 patches for apple/swift-corelibs-foundation • 14 patches for apple/swift-package-manager • 4 patches for LLVM They are made by only 2 people! 36

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Swift Concurrency on Wasm JavaScriptKit provides a global executor implementation based on JS event-loop import JavaScriptEventLoop import JavaScriptKit JavaScriptEventLoop.installGlobalExecutor() func printZen() async throws { let fetch = JSObject.global.fetch.function! let response = try await JSPromise(fetch("https://api.github.com/zen").object!)!.value let text = try await JSPromise(response.text().object!)!.value print(text) } 37

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Tokamak Fiber Renderer • React 16Ҏ߱ͱಉ౳ͷΞϧΰϦζϜ • ਂ͘ωετͨ͠ViewͰ΋ελοΫΦʔόʔϑϩʔ͕ى͖ͳ͍ • ͜Ε·ͰͷStack Reconciler͸30 viewsͷωετͰ ελοΫΦʔόʔϑϩʔ͍ͯͨ͠ • Fiber ReconcilerͰ͸700·ͰOK https://github.com/TokamakUI/Tokamak/pull/471 38

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μWASI (swiftwasm/uwasi) • ܰྔWASI࣮૷ for ϒϥ΢β & Node.js • ैདྷͷ3rd-partyͷ࣮૷͸େ͖͗ͨ͢… (65.6 KB) • େ൒ͷػೳ͸࢖ͬͯͳ͔ͬͨ • SwiftWasmͰ৽͍͠ϞϊΛఏڙ: • Minimal: 3 KB • All features enabled: 6 KB https://github.com/swiftwasm/uwasi 39

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Help wanted! • ·ͩ·ͩ΍Δ͜ͱ୔ࢁ • ଟछଟ༷ͳ೉қ౓/ϨΠϠ • ॿ͚͍ͯͩ͘͞ λεΫͷྖҬ 40

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Future Work • KeyPathݺͼग़͠ن໿ΛSIL্ʹ੍ఆ • LLVM LTOʹΑΔίʔυ࡟ݮΛnon-AppleϓϥοτϑΥʔϜʹҠ ২ • LLVMʹllvm.linker.usedΛ௥Ճͯ͠ɺϦϯΫ࣌GCΛ༗ޮԽ • Web APIϕʔεͷFoundationNetworkingޓ׵࣮૷ • ܕ෇͖ͷJS <-> SwiftϒϦοδίʔυੜ੒ث 41

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GoodNotes is hiring! https://www.goodnotes.com/careers • Senior Software Engineer, Cross Platform (Swift, Wasm) • Senior Software Engineer, iOS • etc... 42

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Thank you :) 43