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rustbuild: Compile rustc with ThinLTO

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This commit enables ThinLTO for the compiler as well as multiple codegen units.
This is intended to get the benefits of parallel codegen while also avoiding
any major loss of perf. Finally this commit is also intended as further testing
for #45320 and shaking out bugs.
This commit is contained in:
Alex Crichton 2017-10-19 20:02:46 -07:00
parent 95272a07f1
commit 1af1c2de36
3 changed files with 18 additions and 6 deletions
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3
src/bootstrap/bin/rustc.rs
View File

@ -175,6 +175,9 @@ fn main() {
if let Ok(s) = env::var("RUSTC_CODEGEN_UNITS") {
cmd.arg("-C").arg(format!("codegen-units={}", s));
}
if stage != "0" && env::var("RUSTC_THINLTO").is_ok() {
cmd.arg("-Ccodegen-units=16").arg("-Zthinlto");
}
// Emit save-analysis info.
if env::var("RUSTC_SAVE_ANALYSIS") == Ok("api".to_string()) {

14
src/bootstrap/builder.rs
View File

@ -471,8 +471,6 @@ impl<'a> Builder<'a> {
.env("RUSTC", self.out.join("bootstrap/debug/rustc"))
.env("RUSTC_REAL", self.rustc(compiler))
.env("RUSTC_STAGE", stage.to_string())
.env("RUSTC_CODEGEN_UNITS",
self.config.rust_codegen_units.to_string())
.env("RUSTC_DEBUG_ASSERTIONS",
self.config.rust_debug_assertions.to_string())
.env("RUSTC_SYSROOT", self.sysroot(compiler))
@ -486,6 +484,10 @@ impl<'a> Builder<'a> {
})
.env("TEST_MIRI", self.config.test_miri.to_string());
if let Some(n) = self.config.rust_codegen_units {
cargo.env("RUSTC_CODEGEN_UNITS", n.to_string());
}
if let Some(host_linker) = self.build.linker(compiler.host) {
cargo.env("RUSTC_HOST_LINKER", host_linker);
}
@ -618,6 +620,14 @@ impl<'a> Builder<'a> {
// FIXME: cargo bench does not accept `--release`
if self.config.rust_optimize && cmd != "bench" {
cargo.arg("--release");
if mode != Mode::Libstd &&
self.config.rust_codegen_units.is_none() &&
self.build.is_rust_llvm(compiler.host)
{
cargo.env("RUSTC_THINLTO", "1");
}
}
if self.config.locked_deps {
cargo.arg("--locked");

7
src/bootstrap/config.rs
View File

@ -81,7 +81,7 @@ pub struct Config {
// rust codegen options
pub rust_optimize: bool,
pub rust_codegen_units: u32,
pub rust_codegen_units: Option<u32>,
pub rust_debug_assertions: bool,
pub rust_debuginfo: bool,
pub rust_debuginfo_lines: bool,
@ -307,7 +307,6 @@ impl Config {
config.submodules = true;
config.docs = true;
config.rust_rpath = true;
config.rust_codegen_units = 1;
config.channel = "dev".to_string();
config.codegen_tests = true;
config.ignore_git = false;
@ -470,8 +469,8 @@ impl Config {
config.musl_root = rust.musl_root.clone().map(PathBuf::from);
match rust.codegen_units {
Some(0) => config.rust_codegen_units = num_cpus::get() as u32,
Some(n) => config.rust_codegen_units = n,
Some(0) => config.rust_codegen_units = Some(num_cpus::get() as u32),
Some(n) => config.rust_codegen_units = Some(n),
None => {}
}
}