From fe4fc9d2509843f787dfc65f89111adc1987e059 Mon Sep 17 00:00:00 2001
From: Ben Reeves <benwolverine2019@gmail.com>
Date: Sat, 7 Sep 2024 19:02:53 -0500
Subject: [PATCH] feat: New `data-threads` attribute for rust assets.

This enables the `threads`, `bulk-memory`, and `mutable-globals`
options in `wasm-opt`, which if absent can result in `wasm-opt`
failing to optimize wasm modules compiled with threading features.

Fixes #866.
---
 examples/wasm_threads/index.html |  1 +
 guide/src/assets/index.md        |  1 +
 site/content/assets.md           |  1 +
 src/pipelines/rust/mod.rs        | 10 ++++++++++
 4 files changed, 13 insertions(+)

diff --git a/examples/wasm_threads/index.html b/examples/wasm_threads/index.html
index 4e0f3890..4a2d2f8e 100644
--- a/examples/wasm_threads/index.html
+++ b/examples/wasm_threads/index.html
@@ -14,6 +14,7 @@
             rel="rust"
             href="Cargo.toml"
             data-wasm-opt="z"
+            data-threads
             data-bindgen-target="web"
         />
         <link data-trunk rel="copy-file" href="assets/_headers" />
diff --git a/guide/src/assets/index.md b/guide/src/assets/index.md
index dd8f6be4..85318652 100644
--- a/guide/src/assets/index.md
+++ b/guide/src/assets/index.md
@@ -31,6 +31,7 @@ This will typically look like: `<link data-trunk rel="{type}" href="{path}" ..ot
 - `data-weak-refs`: (optional) instruct `wasm-bindgen` to enable [weak references](https://rustwasm.github.io/docs/wasm-bindgen/reference/weak-references.html).
 - `data-typescript`: (optional) instruct `wasm-bindgen` to output Typescript bindings. Defaults to false.
 - `data-bindgen-target`: (optional) specifies the value of the `wasm-bindgen` [flag `--target`](https://rustwasm.github.io/wasm-bindgen/reference/deployment.html) (see link for possible values). Defaults to `no-modules`. The main use-case is to switch to `web` with `data-type="worker"` which reduces backwards [compatibility](https://caniuse.com/mdn-api_worker_worker_ecmascript_modules) but with some [advantages](https://rustwasm.github.io/wasm-bindgen/examples/without-a-bundler.html?highlight=no-modules#using-the-older---target-no-modules).
+- `data-threads`: (optional) instruct `wasm-opt` to enable `threads`, `bulk-memory`, and `mutable-globals`. See the [`wasm-bindgen` Parallel Raytracing example](https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html) or [this rustwasm blog post](https://rustwasm.github.io/2018/10/24/multithreading-rust-and-wasm.html) for more information.
 - `data-loader-shim`: (optional) instruct `trunk` to create a loader shim for web workers. Defaults to false.
 - `data-cross-origin`: (optional) the `crossorigin` setting when loading the code & script resources. Defaults to plain `anonymous`.
 - `data-integrity`: (optional) the `integrity` digest type for code & script resources. Defaults to plain `sha384`.
diff --git a/site/content/assets.md b/site/content/assets.md
index 20a7b28a..5e8cbd29 100644
--- a/site/content/assets.md
+++ b/site/content/assets.md
@@ -35,6 +35,7 @@ This will typically look like: `<link data-trunk rel="{type}" href="{path}" ..ot
   - `data-weak-refs`: (optional) instruct `wasm-bindgen` to enable [weak references](https://rustwasm.github.io/docs/wasm-bindgen/reference/weak-references.html).
   - `data-typescript`: (optional) instruct `wasm-bindgen` to output Typescript bindings. Defaults to false.
   - `data-bindgen-target`: (optional) specifies the value of the `wasm-bindgen` [flag `--target`](https://rustwasm.github.io/wasm-bindgen/reference/deployment.html) (see link for possible values). Defaults to `no-modules`. The main use-case is to switch to `web` with `data-type="worker"` which reduces backwards [compatibility](https://caniuse.com/mdn-api_worker_worker_ecmascript_modules) but with some [advantages](https://rustwasm.github.io/wasm-bindgen/examples/without-a-bundler.html?highlight=no-modules#using-the-older---target-no-modules).
+  - `data-threads`: (optional) instruct `wasm-opt` to enable `threads`, `bulk-memory`, and `mutable-globals`. See the [`wasm-bindgen` Parallel Raytracing example](https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html) or [this rustwasm blog post](https://rustwasm.github.io/2018/10/24/multithreading-rust-and-wasm.html) for more information.
   - `data-loader-shim`: (optional) instruct `trunk` to create a loader shim for web workers. Defaults to false.
   - `data-cross-origin`: (optional) the `crossorigin` setting when loading the code & script resources. Defaults to plain `anonymous`.
   - `data-integrity`: (optional) the `integrity` digest type for code & script resources. Defaults to plain `sha384`.
diff --git a/src/pipelines/rust/mod.rs b/src/pipelines/rust/mod.rs
index f011fed5..576ed77b 100644
--- a/src/pipelines/rust/mod.rs
+++ b/src/pipelines/rust/mod.rs
@@ -73,6 +73,8 @@ pub struct RustApp {
     reference_types: bool,
     /// An option to instruct wasm-bindgen to enable weak references.
     weak_refs: bool,
+    /// An option to instruct wasm-opt to allow atomics, bulk-memory, and mutable-globals.
+    threads: bool,
     /// An optional optimization setting that enables wasm-opt. Can be nothing, `0` (default), `1`,
     /// `2`, `3`, `4`, `s or `z`. Using `0` disables wasm-opt completely.
     wasm_opt: WasmOptLevel,
@@ -156,6 +158,7 @@ impl RustApp {
             .unwrap_or(RustAppType::Main);
         let reference_types = attrs.contains_key("data-reference-types");
         let weak_refs = attrs.contains_key("data-weak-refs");
+        let threads = attrs.contains_key("data-threads");
         let wasm_opt = attrs
             .get("data-wasm-opt")
             .map(|val| val.parse())
@@ -256,6 +259,7 @@ impl RustApp {
             no_demangle,
             reference_types,
             weak_refs,
+            threads,
             wasm_opt,
             wasm_bindgen_target,
             app_type,
@@ -304,6 +308,7 @@ impl RustApp {
             no_demangle: false,
             reference_types: false,
             weak_refs: false,
+            threads: false,
             wasm_opt: WasmOptLevel::Off,
             app_type: RustAppType::Main,
             wasm_bindgen_target: WasmBindgenTarget::Web,
@@ -878,6 +883,11 @@ impl RustApp {
         if self.reference_types {
             args.push("--enable-reference-types");
         }
+        if self.threads {
+            args.push("--enable-threads");
+            args.push("--enable-bulk-memory");
+            args.push("--enable-mutable-globals");
+        }
 
         // Invoke wasm-opt.
         tracing::debug!("calling wasm-opt");