mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Rollup merge of #92024 - pcwalton:per-codegen-unit-names, r=davidtwco

Browse Source 
rustc_codegen_llvm: Give each codegen unit a unique DWARF name on all platforms, not just Apple ones.

To avoid breaking split DWARF, we need to ensure that each codegen unit has a
unique `DW_AT_name`. This is because there's a remote chance that different
codegen units for the same module will have entirely identical DWARF entries
for the purpose of the DWO ID, which would violate Appendix F ("Split Dwarf
Object Files") of the DWARF 5 specification. LLVM uses the algorithm specified
in section 7.32 "Type Signature Computation" to compute the DWO ID, which does
not include any fields that would distinguish compilation units. So we must
embed the codegen unit name into the `DW_AT_name`.

Closes #88521.
This commit is contained in:
Matthias Krüger 2021-12-18 14:49:41 +01:00 committed by GitHub
commit 53a95ea289
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 19 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
View File

@ -1040,14 +1040,25 @@ pub fn compile_unit_metadata<'ll, 'tcx>(
None => PathBuf::from(&*tcx.crate_name(LOCAL_CRATE).as_str()),
};
// The OSX linker has an idiosyncrasy where it will ignore some debuginfo
// if multiple object files with the same `DW_AT_name` are linked together.
// As a workaround we generate unique names for each object file. Those do
// not correspond to an actual source file but that is harmless.
if tcx.sess.target.is_like_osx {
name_in_debuginfo.push("@");
name_in_debuginfo.push(codegen_unit_name);
}
// To avoid breaking split DWARF, we need to ensure that each codegen unit
// has a unique `DW_AT_name`. This is because there's a remote chance that
// different codegen units for the same module will have entirely
// identical DWARF entries for the purpose of the DWO ID, which would
// violate Appendix F ("Split Dwarf Object Files") of the DWARF 5
// specification. LLVM uses the algorithm specified in section 7.32 "Type
// Signature Computation" to compute the DWO ID, which does not include
// any fields that would distinguish compilation units. So we must embed
// the codegen unit name into the `DW_AT_name`. (Issue #88521.)
//
// Additionally, the OSX linker has an idiosyncrasy where it will ignore
// some debuginfo if multiple object files with the same `DW_AT_name` are
// linked together.
//
// As a workaround for these two issues, we generate unique names for each
// object file. Those do not correspond to an actual source file but that
// is harmless.
name_in_debuginfo.push("@");
name_in_debuginfo.push(codegen_unit_name);
debug!("compile_unit_metadata: {:?}", name_in_debuginfo);
let rustc_producer =