Auto merge of #131634 - davidlattimore:lld-protected, r=Kobzol

Use protected visibility when building rustc with LLD

https://github.com/rust-lang/compiler-team/issues/782

I wasn't sure about having two commits in a PR, but I figured, at least initially it might make sense to discuss these commits together. Happy to squash, or move the second commit to a separate PR.

I contemplated trying to enable protected visibility for more cases when LLD will be used other than just `-Zlinker-features=+lld`, but that would be more a complex change that probably still wouldn't cover all cases when LLD is used, so went with the simplest option of just checking if the linker-feature is enabled.

r? lqd
This commit is contained in:
bors 2024-11-01 05:25:27 +00:00
commit 9fa9ef385c

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@ -1056,6 +1056,14 @@ pub fn rustc_cargo(
cargo.rustflag("-l").rustflag("Enzyme-19");
}
// Building with protected visibility reduces the number of dynamic relocations needed, giving
// us a faster startup time. However GNU ld < 2.40 will error if we try to link a shared object
// with direct references to protected symbols, so for now we only use protected symbols if
// linking with LLD is enabled.
if builder.build.config.lld_mode.is_used() {
cargo.rustflag("-Zdefault-visibility=protected");
}
// We currently don't support cross-crate LTO in stage0. This also isn't hugely necessary
// and may just be a time sink.
if compiler.stage != 0 {