vendor-submodules

What is under vendor/

• vendor/wasm/ - WebAssembly/spec
• vendor/wasi/ - WebAssembly/WASI
• vendor/component-model/ - WebAssembly/component-model (CM spec)
  • Canonical built-ins: vendor/component-model/design/mvp/CanonicalABI.md
  • Concurrency (async, streams, futures): vendor/component-model/design/mvp/Concurrency.md
  • Explainer: vendor/component-model/design/mvp/Explainer.md
• vendor/wasmtime/ - a Wasm runtime with WASI P3 support
• vendor/wasm-tools/ - the Wasm toolchain the Wado compiler builds on

git submodule update --init --recommend-shallow fetches them.

Syncing

mise run sync-vendor

vendor/wasmtime goes to the exact version in Cargo.lock, which WASI P3 compatibility requires. The other submodules go to their remote HEAD.

Building against a patched wasmtime

To test a change to wasmtime itself, edit vendor/wasmtime in place and add to the workspace Cargo.toml:

[patch.crates-io]
wasmtime = { path = "vendor/wasmtime/crates/wasmtime" }
wasmtime-wasi = { path = "vendor/wasmtime/crates/wasi" }
wasmtime-wasi-http = { path = "vendor/wasmtime/crates/wasi-http" }
wasmtime-wasi-tls = { path = "vendor/wasmtime/crates/wasi-tls" }

Those four names redirect 31 crates. The cranelift-*, pulley-*, wasmtime-internal-* and wiggle* crates follow through the dependency graph. sync-vendor already holds the submodule at the Cargo.lock version, so the sources match what the workspace expects and nothing needs porting.

Keep the stanza on a throwaway branch. CI checks out without submodules (submodules: false, also actions/checkout's default), so on main every job dies while parsing the manifest. Landing it means turning submodule checkout on across every workflow.

reference/ holds patches written this way, each with its measurement:

• current_thread_split.patch — splits the cold deferred-frame replay out of StoreOpaque::current_thread so the fast path inlines. Removes ~1 point of CPU; throughput flat.
• trace_fiber_roots.patch — tracks fiber-owning reps instead of scanning the whole component ResourceTable per GC. Not measurable.