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prevent constant rebuilds of rustc-main (and thus everything else)

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Pietro Albini 2023-08-08 10:19:21 +02:00
parent 6742e2b185
commit da00356e55
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GPG key ID: CD76B35F7734769E
2 changed files with 36 additions and 21 deletions
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37
src/bootstrap/compile.rs
View file

@ -31,6 +31,7 @@ use crate::util::get_clang_cl_resource_dir;
use crate::util::{exe, is_debug_info, is_dylib, output, symlink_dir, t, up_to_date};
use crate::LLVM_TOOLS;
use crate::{CLang, Compiler, DependencyType, GitRepo, Mode};
use filetime::FileTime;
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Std {
@ -904,19 +905,12 @@ impl Step for Rustc {
// our LLVM wrapper. Unless we're explicitly requesting `librustc_driver` to be built with
// debuginfo (via the debuginfo level of the executables using it): strip this debuginfo
// away after the fact.
// FIXME: to make things simpler for now, limit this to the host and target where we know
// `strip -g` is both available and will fix the issue, i.e. on a x64 linux host that is not
// cross-compiling. Expand this to other appropriate targets in the future.
if builder.config.rust_debuginfo_level_rustc == DebuginfoLevel::None
&& builder.config.rust_debuginfo_level_tools == DebuginfoLevel::None
&& target == "x86_64-unknown-linux-gnu"
&& target == builder.config.build
{
let target_root_dir = stamp.parent().unwrap();
let rustc_driver = target_root_dir.join("librustc_driver.so");
if rustc_driver.exists() {
output(Command::new("strip").arg("--strip-debug").arg(rustc_driver));
}
strip_debug(builder, target, &rustc_driver);
}
builder.ensure(RustcLink::from_rustc(
@ -1974,3 +1968,30 @@ pub enum CargoMessage<'a> {
success: bool,
},
}
pub fn strip_debug(builder: &Builder<'_>, target: TargetSelection, path: &Path) {
// FIXME: to make things simpler for now, limit this to the host and target where we know
// `strip -g` is both available and will fix the issue, i.e. on a x64 linux host that is not
// cross-compiling. Expand this to other appropriate targets in the future.
if target != "x86_64-unknown-linux-gnu" || target != builder.config.build || !path.exists() {
return;
}
let previous_mtime = FileTime::from_last_modification_time(&path.metadata().unwrap());
// Note: `output` will propagate any errors here.
output(Command::new("strip").arg("--strip-debug").arg(path));
// After running `strip`, we have to set the file modification time to what it was before,
// otherwise we risk Cargo invalidating its fingerprint and rebuilding the world next time
// bootstrap is invoked.
//
// An example of this is if we run this on librustc_driver.so. In the first invocation:
// - Cargo will build librustc_driver.so (mtime of 1)
// - Cargo will build rustc-main (mtime of 2)
// - Bootstrap will strip librustc_driver.so (changing the mtime to 3).
//
// In the second invocation of bootstrap, Cargo will see that the mtime of librustc_driver.so
// is greater than the mtime of rustc-main, and will rebuild rustc-main. That will then cause
// everything else (standard library, future stages...) to be rebuilt.
t!(filetime::set_file_mtime(path, previous_mtime));
}

20
src/bootstrap/llvm.rs
View file

@ -512,27 +512,21 @@ impl Step for Llvm {
// When building LLVM as a shared library on linux, it can contain unexpected debuginfo:
// some can come from the C++ standard library. Unless we're explicitly requesting LLVM to
// be built with debuginfo, strip it away after the fact, to make dist artifacts smaller.
// FIXME: to make things simpler for now, limit this to the host and target where we know
// `strip -g` is both available and will fix the issue, i.e. on a x64 linux host that is not
// cross-compiling. Expand this to other appropriate targets in the future.
if builder.llvm_link_shared()
&& builder.config.llvm_optimize
&& !builder.config.llvm_release_debuginfo
&& target == "x86_64-unknown-linux-gnu"
&& target == builder.config.build
{
// Find the name of the LLVM shared library that we just built.
let lib_name = find_llvm_lib_name("so");
// If the shared library exists in LLVM's `/build/lib/` or `/lib/` folders, strip its
// debuginfo. Note: `output` will propagate any errors here.
let strip_if_possible = |path: PathBuf| {
if path.exists() {
output(Command::new("strip").arg("--strip-debug").arg(path));
}
};
strip_if_possible(out_dir.join("lib").join(&lib_name));
strip_if_possible(out_dir.join("build").join("lib").join(&lib_name));
// debuginfo.
crate::compile::strip_debug(builder, target, &out_dir.join("lib").join(&lib_name));
crate::compile::strip_debug(
builder,
target,
&out_dir.join("build").join("lib").join(&lib_name),
);
}
t!(stamp.write());