Add option to use LTO in release builds

Shrinks rslib.so from about 40MB to about 26MB, at the cost of considerably
higher build time in a release build.

.buildkite/linux/release-entrypoint

@@ -4,7 +4,7 @@ set -e
 
 export PATH="$PATH:/state/rust/cargo/bin"
 export BUILD_ROOT=/state/build
-export RELEASE=1
+export RELEASE=2
 ln -sf out/node_modules .
 
 if [ $(uname -m) = "aarch64" ]; then

Cargo.toml

@@ -152,3 +152,7 @@ debug = 0
 debug = 0
 [profile.dev.package.rsbridge]
 debug = 0
+
+[profile.release-lto]
+inherits = "release"
+lto = true

build/configure/src/bundle.rs

@@ -8,6 +8,7 @@ use ninja_gen::archives::empty_manifest;
 use ninja_gen::archives::with_exe;
 use ninja_gen::archives::OnlineArchive;
 use ninja_gen::archives::Platform;
+use ninja_gen::build::BuildProfile;
 use ninja_gen::cargo::CargoBuild;
 use ninja_gen::cargo::RustOutput;
 use ninja_gen::git::SyncSubmodule;
@@ -269,7 +270,7 @@ fn build_pyoxidizer(build: &mut Build) -> Result<()> {
                 "--manifest-path={} --target-dir={} -p pyoxidizer",
                 "qt/bundle/PyOxidizer/Cargo.toml", "$builddir/bundle/rust"
             ),
-            release_override: Some(true),
+            release_override: Some(BuildProfile::Release),
         },
     )?;
     Ok(())
@@ -320,7 +321,8 @@ impl BuildAction for BuildBundle {
                     overriden_rust_target_triple()
                         .unwrap_or_else(|| Platform::current().as_rust_triple()),
                 ),
-                true,
+                // our pyoxidizer bin uses lto on the release profile
+                BuildProfile::Release,
             )],
         );
     }

build/configure/src/rust.rs

@@ -3,6 +3,7 @@
 
 use anyhow::Result;
 use ninja_gen::action::BuildAction;
+use ninja_gen::build::BuildProfile;
 use ninja_gen::build::FilesHandle;
 use ninja_gen::cargo::CargoBuild;
 use ninja_gen::cargo::CargoClippy;
@@ -202,7 +203,7 @@ pub fn check_minilints(build: &mut Build) -> Result<()> {
                     outputs: &[RustOutput::Binary("minilints")],
                     target: None,
                     extra_args: "-p minilints",
-                    release_override: Some(false),
+                    release_override: Some(BuildProfile::Debug),
                 },
             )
         }

build/ninja_gen/src/build.rs

@@ -19,7 +19,7 @@ use crate::input::BuildInput;
 pub struct Build {
     pub variables: HashMap<&'static str, String>,
     pub buildroot: Utf8PathBuf,
-    pub release: bool,
+    pub build_profile: BuildProfile,
     pub pools: Vec<(&'static str, usize)>,
     pub trailing_text: String,
     pub host_platform: Platform,
@@ -40,7 +40,7 @@ impl Build {
 
         let mut build = Build {
             buildroot,
-            release: std::env::var("RELEASE").is_ok(),
+            build_profile: BuildProfile::from_env(),
             host_platform: Platform::current(),
             variables: Default::default(),
             pools: Default::default(),
@@ -102,7 +102,7 @@ impl Build {
         };
 
         let mut statement =
-            BuildStatement::from_build_action(group, action, &self.groups, self.release);
+            BuildStatement::from_build_action(group, action, &self.groups, self.build_profile);
 
         if first_invocation {
             let command = statement.prepare_command(command)?;
@@ -218,7 +218,7 @@ struct BuildStatement<'a> {
     env_vars: Vec<String>,
     working_dir: Option<String>,
     create_dirs: Vec<String>,
-    release: bool,
+    build_profile: BuildProfile,
     bypass_runner: bool,
 }
 
@@ -227,7 +227,7 @@ impl BuildStatement<'_> {
         group: &str,
         mut action: impl BuildAction,
         existing_outputs: &'a HashMap<String, Vec<String>>,
-        release: bool,
+        build_profile: BuildProfile,
     ) -> BuildStatement<'a> {
         let mut stmt = BuildStatement {
             existing_outputs,
@@ -244,7 +244,7 @@ impl BuildStatement<'_> {
             env_vars: Default::default(),
             working_dir: None,
             create_dirs: Default::default(),
-            release,
+            build_profile,
             bypass_runner: action.bypass_runner(),
         };
         action.files(&mut stmt);
@@ -328,6 +328,23 @@ fn expand_inputs(
     vec
 }
 
+#[derive(Debug, Eq, PartialEq, Clone, Copy)]
+pub enum BuildProfile {
+    Debug,
+    Release,
+    ReleaseWithLto,
+}
+
+impl BuildProfile {
+    fn from_env() -> Self {
+        match std::env::var("RELEASE").unwrap_or_default().as_str() {
+            "1" => Self::Release,
+            "2" => Self::ReleaseWithLto,
+            _ => Self::Debug,
+        }
+    }
+}
+
 pub trait FilesHandle {
     /// Add inputs to the build statement. Can be called multiple times with
     /// different variables. This is a shortcut for calling .expand_inputs()
@@ -391,7 +408,7 @@ pub trait FilesHandle {
     /// at the folder.
     fn create_dir_all(&mut self, key: &str, path: impl Into<String>);
 
-    fn release_build(&self) -> bool;
+    fn build_profile(&self) -> BuildProfile;
 }
 
 impl FilesHandle for BuildStatement<'_> {
@@ -474,8 +491,8 @@ impl FilesHandle for BuildStatement<'_> {
         expand_inputs(inputs, self.existing_outputs)
     }
 
-    fn release_build(&self) -> bool {
-        self.release
+    fn build_profile(&self) -> BuildProfile {
+        self.build_profile
     }
 
     fn add_output_stamp(&mut self, path: impl Into<String>) {

build/ninja_gen/src/cargo.rs

@@ -7,6 +7,7 @@ use camino::Utf8PathBuf;
 
 use crate::action::BuildAction;
 use crate::archives::with_exe;
+use crate::build::BuildProfile;
 use crate::build::FilesHandle;
 use crate::input::BuildInput;
 use crate::inputs;
@@ -31,7 +32,12 @@ impl RustOutput<'_> {
         }
     }
 
-    pub fn path(&self, rust_base: &Utf8Path, target: Option<&str>, release: bool) -> String {
+    pub fn path(
+        &self,
+        rust_base: &Utf8Path,
+        target: Option<&str>,
+        build_profile: BuildProfile,
+    ) -> String {
         let filename = match *self {
             RustOutput::Binary(package) => {
                 if cfg!(windows) {
@@ -56,20 +62,26 @@ impl RustOutput<'_> {
         if let Some(target) = target {
             path = path.join(target);
         }
-        path = path
-            .join(if release { "release" } else { "debug" })
-            .join(filename);
+        path = path.join(profile_output_dir(build_profile)).join(filename);
         path.to_string()
     }
 }
 
+fn profile_output_dir(profile: BuildProfile) -> &'static str {
+    match profile {
+        BuildProfile::Debug => "debug",
+        BuildProfile::Release => "release",
+        BuildProfile::ReleaseWithLto => "release-lto",
+    }
+}
+
 #[derive(Debug, Default)]
 pub struct CargoBuild<'a> {
     pub inputs: BuildInput,
     pub outputs: &'a [RustOutput<'a>],
     pub target: Option<&'static str>,
     pub extra_args: &'a str,
-    pub release_override: Option<bool>,
+    pub release_override: Option<BuildProfile>,
 }
 
 impl BuildAction for CargoBuild<'_> {
@@ -80,8 +92,8 @@ impl BuildAction for CargoBuild<'_> {
     fn files(&mut self, build: &mut impl FilesHandle) {
         let release_build = self
             .release_override
-            .unwrap_or_else(|| build.release_build());
-        let release_arg = if release_build { "--release" } else { "" };
+            .unwrap_or_else(|| build.build_profile());
+        let release_arg = profile_arg_for_cargo(release_build).unwrap_or_default();
         let target_arg = if let Some(target) = self.target {
             format!("--target {target}")
         } else {
@@ -114,6 +126,14 @@ impl BuildAction for CargoBuild<'_> {
     }
 }
 
+fn profile_arg_for_cargo(profile: BuildProfile) -> Option<&'static str> {
+    match profile {
+        BuildProfile::Debug => None,
+        BuildProfile::Release => Some("--release"),
+        BuildProfile::ReleaseWithLto => Some("--profile release-lto"),
+    }
+}
+
 fn setup_flags(build: &mut Build) -> Result<()> {
     build.once_only("cargo_flags_and_pool", |build| {
         build.variable("cargo_flags", "--locked");

build/ninja_gen/src/configure.rs

@@ -4,6 +4,7 @@
 use anyhow::Result;
 
 use crate::action::BuildAction;
+use crate::build::BuildProfile;
 use crate::build::FilesHandle;
 use crate::cargo::CargoBuild;
 use crate::cargo::RustOutput;
@@ -33,7 +34,7 @@ impl BuildAction for ConfigureBuild {
                 outputs: &[RustOutput::Binary("configure")],
                 target: None,
                 extra_args: "-p configure",
-                release_override: Some(false),
+                release_override: Some(BuildProfile::Debug),
             },
         )?;
         Ok(())

docs/development.md

@@ -105,7 +105,8 @@ To run Anki in optimized mode, use:
 ./tools/runopt
 ```
 
-Or set RELEASE=1.
+Or set RELEASE=1 or RELEASE=2. The latter will further optimize the output, but make
+the build much slower.
 
 ## Building redistributable wheels
 

qt/bundle/Cargo.toml

@@ -55,3 +55,6 @@ build-mode-pyoxidizer-exe = []
 # to the directory containing build artifacts produced by `pyoxidizer`. If not
 # set, OUT_DIR will be used.
 build-mode-prebuilt-artifacts = []
+
+[profile.release]
+lto = true