Series of build changes for web release to minimize generated wasm (#9870)

Co-authored-by: jprochazk <[email protected]>
Co-authored-by: Jan Procházka <[email protected]>

Author: timsaucer

Cargo.toml

@@ -394,6 +394,13 @@ opt-level = 2
 # debug = true # good for profilers
 panic = "abort" # This leads to better optimizations and smaller binaries (and is the default in Wasm anyways).
 
+[profile.web-release]
+panic = 'abort'      # Removes panic handling code
+inherits = "release"
+lto = true
+opt-level = 'z'      # Optimize for size
+codegen-units = 1
+
 
 ## Bench
 

crates/build/re_dev_tools/src/build_web_viewer/lib.rs

@@ -32,14 +32,14 @@ fn target_directory() -> Utf8PathBuf {
 
 #[derive(Clone, Copy, PartialEq, Eq)]
 pub enum Profile {
-    Release,
+    WebRelease,
     Debug,
 }
 
 impl Profile {
     pub fn as_str(&self) -> &'static str {
         match self {
-            Self::Release => "release",
+            Self::WebRelease => "web-release",
             Self::Debug => "debug",
         }
     }
@@ -126,8 +126,8 @@ pub fn build(
         if !features.is_empty() {
             cmd.arg(format!("--features={features}"));
         }
-        if profile == Profile::Release {
-            cmd.arg("--release");
+        if profile == Profile::WebRelease {
+            cmd.arg("--profile=web-release");
         }
 
         // This is required for unstable WebGPU apis to work
@@ -200,7 +200,7 @@ pub fn build(
         );
     }
 
-    if profile == Profile::Release {
+    if profile == Profile::WebRelease {
         eprintln!("Optimizing wasm with wasm-opt…");
         let start_time = Instant::now();
 
@@ -213,9 +213,12 @@ pub fn build(
             "--output",
             wasm_path.as_str(),
             "--enable-reference-types",
+            "--vacuum",
         ];
         if debug_symbols {
             args.push("-g");
+        } else {
+            args.push("--strip-debug");
         }
         cmd.args(args);
         eprintln!("{root_dir}> {cmd:?}");

crates/build/re_dev_tools/src/build_web_viewer/mod.rs

@@ -50,7 +50,7 @@ fn default_features() -> String {
 
 pub fn main(args: Args) -> anyhow::Result<()> {
     let profile = if args.release && !args.debug {
-        Profile::Release
+        Profile::WebRelease
     } else if !args.release && args.debug {
         Profile::Debug
     } else {

pixi.toml

@@ -198,7 +198,7 @@ rerun-web-release = { cmd = "cargo run --package rerun-cli --no-default-features
 #
 # This installs the `wasm32-unknown-unknown` rust target if it's not already installed.
 # (this looks heavy but takes typically below 0.1s!)
-rerun-build-web-release = "rustup target add wasm32-unknown-unknown && cargo run --quiet -p re_dev_tools -- build-web-viewer --no-default-features --features analytics,map_view --release -g"
+rerun-build-web-release = "rustup target add wasm32-unknown-unknown && cargo run --quiet -p re_dev_tools -- build-web-viewer --no-default-features --features analytics,map_view --release"
 
 rs-check = { cmd = "rustup target add wasm32-unknown-unknown && python scripts/ci/rust_checks.py", depends-on = [
   "rerun-build-web", # The checks require the web viewer wasm to be around.

rerun_js/web-viewer/build-wasm.mjs

@@ -57,6 +57,12 @@ function re_viewer_js() {
   const end = `wasm_bindgen = Object.assign(__wbg_init, { initSync }, __exports);
 
 })();`;
+  if (code.indexOf(start) === -1) {
+    throw new Error("failed to run js build script: failed to patch re_viewer.js, could not find replace start marker");
+  }
+  if (code.indexOf(end) === -1) {
+    throw new Error("failed to run js build script: failed to patch re_viewer.js, could not find replace end marker");
+  }
   code = code.replace(start, "").replace(end, "");
 
   code = `
@@ -66,10 +72,11 @@ ${code}
 function deinit() {
   __wbg_init.__wbindgen_wasm_module = null;
   wasm = null;
+  cachedUint8ArrayMemory0 = null;
   cachedFloat32ArrayMemory0 = null;
   cachedInt32ArrayMemory0 = null;
   cachedUint32ArrayMemory0 = null;
-  cachedUint8ArrayMemory0 = null;
+  cachedDataViewMemory0 = null;
 }
 
 return Object.assign(__wbg_init, { initSync, deinit }, __exports);
@@ -80,19 +87,32 @@ return Object.assign(__wbg_init, { initSync, deinit }, __exports);
   // Otherwise we end up with an exceptioon during closure destruction which prevents the references from all being
   // cleaned up properly.
   // TODO(jprochazk): Can we force these to run before we null `wasm` instead?
-  const closure_dtors = `const CLOSURE_DTORS = (typeof FinalizationRegistry === 'undefined')
-        ? { register: () => {}, unregister: () => {} }
-        : new FinalizationRegistry(state => {
-        wasm.__wbindgen_export_4.get(state.dtor)(state.a, state.b)
-    });`;
+  const closure_dtors_start_marker = "const CLOSURE_DTORS";
+  const closure_dtors_end_marker = "});";
+
+  const closure_dtors_start = code.indexOf(closure_dtors_start_marker);
+  if (closure_dtors_start === -1) {
+    throw new Error("failed to run js build script: failed to patch re_viewer.js, could not find CLOSURE_DTORS start");
+  }
+  const closure_dtors_end = code.indexOf(closure_dtors_end_marker, closure_dtors_start);
+  if (closure_dtors_end === -1) {
+    throw new Error("failed to run js build script: failed to patch re_viewer.js, could not find CLOSURE_DTORS end");
+  }
+
+  let m = code.substring(closure_dtors_start, closure_dtors_end).match(/__wbindgen_export_\d+/);
+  if (!m) {
+    throw new Error("failed to run js build script: failed to patch re_viewer.js, could not find __wbindgen_export within CLOSURE_DTORS");
+  }
+
+  let wbindgen_export = m[0];
 
   const closure_dtors_patch = `const CLOSURE_DTORS = (typeof FinalizationRegistry === 'undefined')
         ? { register: () => {}, unregister: () => {} }
         : new FinalizationRegistry(state => {
-        wasm?.__wbindgen_export_4.get(state.dtor)(state.a, state.b)
+        wasm?.${wbindgen_export}.get(state.dtor)(state.a, state.b)
     });`;
 
-  code = code.replace(closure_dtors, closure_dtors_patch);
+  code = code.substring(0, closure_dtors_start) + closure_dtors_patch + code.slice(closure_dtors_end + closure_dtors_end_marker.length);
 
   fs.writeFileSync(path.join(__dirname, "re_viewer.js"), code);
 }