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Auto merge of #118568 - DianQK:no-builtins-symbols, r=pnkfelix

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Avoid adding builtin functions to `symbols.o`

We found performance regressions in #113923. The problem seems to be that `--gc-sections` does not remove these symbols. I tested that lld removes these symbols, but ld and gold do not.

I found that `used` adds symbols to `symbols.o` at 3e202ead60/compiler/rustc_codegen_ssa/src/back/linker.rs (L1786-L1791).
The PR removes builtin functions.

Note that under LTO, ld still preserves these symbols. (lld will still remove them.)

The first commit also fixes #118559. But I think the second commit also makes sense.
This commit is contained in:
bors 2023-12-07 20:31:55 +00:00
commit 503e129328
6 changed files with 30 additions and 4 deletions
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2
compiler/rustc_codegen_llvm/src/back/lto.rs
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@ -60,7 +60,7 @@ fn prepare_lto(
};
let symbol_filter = &|&(ref name, info): &(String, SymbolExportInfo)| {
if info.level.is_below_threshold(export_threshold) || info.used {
if info.level.is_below_threshold(export_threshold) || info.used || info.used_compiler {
Some(CString::new(name.as_str()).unwrap())
} else {
None