Optimize binary with wasm-opt in release mode

Cargo.toml

@@ -14,6 +14,11 @@ default-run = "bevy"
 name = "bevy"
 path = "src/bin/main.rs"
 
+[features]
+# To optimize the Wasm binaries
+# Increases compile times (of the CLI) quite a bit
+wasm-opt = ["dep:wasm-opt"]
+
 [dependencies]
 # CLI argument parsing
 clap = { version = "4.5.16", features = ["derive"] }
@@ -42,3 +47,6 @@ actix-web = "4.9.0"
 
 # Opening the app in the browser
 webbrowser = "1.0.2"
+
+# Optimizing Wasm binaries
+wasm-opt = { version = "0.116.1", optional = true }

src/build/args.rs

@@ -19,6 +19,12 @@ impl BuildArgs {
         matches!(self.subcommand, Some(BuildSubcommands::Web))
     }
 
+    /// Whether to build with optimizations.
+    #[cfg(feature = "wasm-opt")]
+    pub(crate) fn is_release(&self) -> bool {
+        self.cargo_args.compilation_args.is_release
+    }
+
     /// The profile used to compile the app.
     pub(crate) fn profile(&self) -> &str {
         self.cargo_args.compilation_args.profile()

src/build/mod.rs

@@ -28,6 +28,11 @@ pub fn build(args: &BuildArgs) -> anyhow::Result<()> {
             args.profile(),
         )?;
         wasm_bindgen::bundle(&bin_target)?;
+
+        #[cfg(feature = "wasm-opt")]
+        if args.is_release() {
+            crate::web::wasm_opt::optimize_bin(&bin_target)?;
+        }
     } else {
         cargo::build::command().args(cargo_args).ensure_status()?;
     }

src/lib.rs

@@ -5,3 +5,4 @@ pub mod external_cli;
 pub mod lint;
 pub mod run;
 pub mod template;
+pub(crate) mod web;

src/run/args.rs

@@ -19,6 +19,12 @@ impl RunArgs {
         matches!(self.subcommand, Some(RunSubcommands::Web(_)))
     }
 
+    /// Whether to build with optimizations.
+    #[cfg(feature = "wasm-opt")]
+    pub(crate) fn is_release(&self) -> bool {
+        self.cargo_args.compilation_args.is_release
+    }
+
     /// The profile used to compile the app.
     pub(crate) fn profile(&self) -> &str {
         self.cargo_args.compilation_args.profile()

src/run/mod.rs

@@ -38,6 +38,11 @@ pub fn run(args: &RunArgs) -> anyhow::Result<()> {
         )?;
         wasm_bindgen::bundle(&bin_target)?;
 
+        #[cfg(feature = "wasm-opt")]
+        if args.is_release() {
+            crate::web::wasm_opt::optimize_bin(&bin_target)?;
+        }
+
         let port = web_args.port;
         let url = format!("http://localhost:{port}");
 

src/web/mod.rs

@@ -0,0 +1,2 @@
+#[cfg(feature = "wasm-opt")]
+pub(crate) mod wasm_opt;

src/web/wasm_opt.rs

@@ -0,0 +1,38 @@
+use std::{fs, path::Path, time::Instant};
+
+use anyhow::Context as _;
+
+use crate::run::BinTarget;
+
+/// Optimize the binary with wasm-opt.
+pub(crate) fn optimize_bin(bin_target: &BinTarget) -> anyhow::Result<()> {
+    let wasm_path = bin_target
+        .artifact_directory
+        .clone()
+        .join(format!("{}_bg.wasm", bin_target.bin_name));
+
+    optimize_path(&wasm_path)
+}
+
+/// Optimize the Wasm binary at the given path with wasm-opt.
+fn optimize_path(path: &Path) -> anyhow::Result<()> {
+    println!("Optimizing with wasm-opt...");
+
+    let start = Instant::now();
+    let size_before = fs::metadata(path)?.len();
+
+    wasm_opt::OptimizationOptions::new_optimize_for_size()
+        .run(path, path)
+        .context("failed to optimize with wasm-opt")?;
+
+    let size_after = fs::metadata(path)?.len();
+    let size_reduction = 1. - (size_after as f32) / (size_before as f32);
+    let duration = Instant::now() - start;
+
+    println!(
+        "    Finished in {duration:.2?}. Size reduced by {:.0}%.",
+        size_reduction * 100.
+    );
+
+    Ok(())
+}