add cycles and size optimization defaults as options

docs/dfx-json-schema.json

@@ -418,7 +418,7 @@
         },
         "optimize": {
           "title": "Optimize Canister WASM",
-          "description": "Whether run `ic-wasm shrink --optimize <level>` after building the Canister. Disabled by default.",
+          "description": "Whether run `ic-wasm shrink --optimize <level>` after building the Canister. Level can be set to \"cycles\" to optimize for cycle usage, \"size\" to optimize for binary size, or any of \"O4, O3, O2, O1, O0, Oz, Os\". Disabled by default.",
           "type": [
             "string",
             "null"

src/dfx/src/lib/builders/custom.rs

@@ -151,10 +151,7 @@ impl CanisterBuilder for CustomBuilder {
         // Custom canister may have WASM gzipped
         if is_wasm_format(&wasm)? {
             if let Some(level) = optimize {
-                info!(
-                    self.logger,
-                    "Optimize and shrink WASM module at level {}", level
-                );
+                info!(self.logger, "Optimize and shrink WASM module.");
                 super::optimize_wasm(&wasm, level)?;
             } else if shrink {
                 info!(self.logger, "Shrink WASM module size.");

src/dfx/src/lib/builders/mod.rs

@@ -497,8 +497,14 @@ fn optimize_wasm(wasm_path: impl AsRef<Path>, level: &str) -> DfxResult {
     let wasm = std::fs::read(wasm_path).context("Could not read the WASM module.")?;
     let mut module =
         ic_wasm::utils::parse_wasm(&wasm, true).context("Could not parse the WASM module.")?;
-    ic_wasm::shrink::shrink_with_wasm_opt(&mut module, level)
-        .context("Could not optimize the WASM module.")?;
+    match level {
+        // O3 empirically gives best cycle savings
+        "cycles" => ic_wasm::shrink::shrink_with_wasm_opt(&mut module, "O3"),
+        "size" => ic_wasm::shrink::shrink_with_wasm_opt(&mut module, "Oz"),
+        _ => ic_wasm::shrink::shrink_with_wasm_opt(&mut module, level),
+    }
+    .context("Could not optimize the WASM module.")?;
+
     module
         .emit_wasm_file(wasm_path)
         .with_context(|| format!("Could not write optimized WASM to {:?}.", wasm_path))?;

src/dfx/src/lib/builders/motoko.rs

@@ -169,10 +169,7 @@ impl CanisterBuilder for MotokoBuilder {
         let optimize = canister_info.get_optimize();
         let shrink = canister_info.get_shrink().unwrap_or(true);
         if let Some(level) = optimize {
-            info!(
-                self.logger,
-                "Optimize and shrink WASM module at level {}", level
-            );
+            info!(self.logger, "Optimize and shrink WASM module.");
             super::optimize_wasm(motoko_info.get_output_wasm_path(), level)?;
         } else if shrink {
             info!(self.logger, "Shrink WASM module size.");

src/dfx/src/lib/builders/rust.rs

@@ -100,10 +100,7 @@ impl CanisterBuilder for RustBuilder {
         let optimize = canister_info.get_optimize();
         let shrink = canister_info.get_shrink().unwrap_or(true);
         if let Some(level) = optimize {
-            info!(
-                self.logger,
-                "Optimize and shrink WASM module at level {}", level
-            );
+            info!(self.logger, "Optimize and shrink WASM module.");
             super::optimize_wasm(rust_info.get_output_wasm_path(), level)?;
         } else if shrink {
             info!(self.logger, "Shrink WASM module size.");