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Auto merge of #113923 - DianQK:restore-no-builtins-lto, r=pnkfelix

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Restore `#![no_builtins]` crates participation in LTO.

After #113716, we can make `#![no_builtins]` crates participate in LTO again.

`#![no_builtins]` with LTO does not result in undefined references to the error. I believe this type of issue won't happen again.

Fixes #72140.  Fixes #112245. Fixes #110606.  Fixes #105734. Fixes #96486. Fixes #108853. Fixes #108893. Fixes #78744. Fixes #91158. Fixes https://github.com/rust-lang/cargo/issues/10118. Fixes https://github.com/rust-lang/compiler-builtins/issues/347.

 The `nightly-2023-07-20` version does not always reproduce problems due to changes in compiler-builtins, core, and user code. That's why this issue recurs and disappears.
Some issues were not tested due to the difficulty of reproducing them.

r? pnkfelix

cc `@bjorn3` `@japaric` `@alexcrichton` `@Amanieu`
This commit is contained in:
bors 2023-12-01 21:45:18 +00:00
commit 8c2b577217
16 changed files with 134 additions and 90 deletions
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46
compiler/rustc_codegen_ssa/src/back/link.rs
View file

@ -270,8 +270,14 @@ pub fn each_linked_rlib(
for &cnum in crates {
match fmts.get(cnum.as_usize() - 1) {
Some(&Linkage::NotLinked | &Linkage::Dynamic | &Linkage::IncludedFromDylib) => continue,
Some(_) => {}
Some(&Linkage::NotLinked | &Linkage::Dynamic) => continue,
Some(&Linkage::IncludedFromDylib) => {
// We always link crate `compiler_builtins` statically. When enabling LTO, we include it as well.
if info.compiler_builtins != Some(cnum) {
continue;
}
}
Some(&Linkage::Static) => {}
None => return Err(errors::LinkRlibError::MissingFormat),
}
let crate_name = info.crate_name[&cnum];
@ -520,8 +526,7 @@ fn link_staticlib<'a>(
&codegen_results.crate_info,
Some(CrateType::Staticlib),
&mut |cnum, path| {
let lto = are_upstream_rust_objects_already_included(sess)
&& !ignored_for_lto(sess, &codegen_results.crate_info, cnum);
let lto = are_upstream_rust_objects_already_included(sess);
let native_libs = codegen_results.crate_info.native_libraries[&cnum].iter();
let relevant = native_libs.clone().filter(|lib| relevant_lib(sess, lib));
@ -1256,24 +1261,6 @@ fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) {
}
}
/// Returns a boolean indicating whether the specified crate should be ignored
/// during LTO.
///
/// Crates ignored during LTO are not lumped together in the "massive object
/// file" that we create and are linked in their normal rlib states. See
/// comments below for what crates do not participate in LTO.
///
/// It's unusual for a crate to not participate in LTO. Typically only
/// compiler-specific and unstable crates have a reason to not participate in
/// LTO.
pub fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool {
// If our target enables builtin function lowering in LLVM then the
// crates providing these functions don't participate in LTO (e.g.
// no_builtins or compiler builtins crates).
!sess.target.no_builtins
&& (info.compiler_builtins == Some(cnum) || info.is_no_builtins.contains(&cnum))
}
/// This functions tries to determine the appropriate linker (and corresponding LinkerFlavor) to use
pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
fn infer_from(
@ -2739,10 +2726,6 @@ fn rehome_sysroot_lib_dir<'a>(sess: &'a Session, lib_dir: &Path) -> PathBuf {
// symbols). We must continue to include the rest of the rlib, however, as
// it may contain static native libraries which must be linked in.
//
// (*) Crates marked with `#![no_builtins]` don't participate in LTO and
// their bytecode wasn't included. The object files in those libraries must
// still be passed to the linker.
//
// Note, however, that if we're not doing LTO we can just pass the rlib
// blindly to the linker (fast) because it's fine if it's not actually
// included as we're at the end of the dependency chain.
@ -2768,9 +2751,7 @@ fn add_static_crate<'a>(
cmd.link_rlib(&rlib_path);
};
if !are_upstream_rust_objects_already_included(sess)
|| ignored_for_lto(sess, &codegen_results.crate_info, cnum)
{
if !are_upstream_rust_objects_already_included(sess) {
link_upstream(cratepath);
return;
}
@ -2784,8 +2765,6 @@ fn add_static_crate<'a>(
let canonical_name = name.replace('-', "_");
let upstream_rust_objects_already_included =
are_upstream_rust_objects_already_included(sess);
let is_builtins =
sess.target.no_builtins || !codegen_results.crate_info.is_no_builtins.contains(&cnum);
let mut archive = archive_builder_builder.new_archive_builder(sess);
if let Err(error) = archive.add_archive(
@ -2802,9 +2781,8 @@ fn add_static_crate<'a>(
// If we're performing LTO and this is a rust-generated object
// file, then we don't need the object file as it's part of the
// LTO module. Note that `#![no_builtins]` is excluded from LTO,
// though, so we let that object file slide.
if upstream_rust_objects_already_included && is_rust_object && is_builtins {
// LTO module.
if upstream_rust_objects_already_included && is_rust_object {
return true;
}