cg_llvm: Reuse LLVM-C Comdat support

Migrate `llvm::set_comdat` and `llvm::SetUniqueComdat` to LLVM-C FFI.

Note, now we can call `llvm::set_comdat` only when the target actually
supports adding comdat. As this has no convenient LLVM-C API, we
implement this as `TargetOptions::supports_comdat`.

Co-authored-by: Stuart Cook <Zalathar@users.noreply.github.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
index 4192dc39de0..4f93e6ab1e5 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
@@ -13,6 +13,7 @@ use rustc_middle::mir::coverage::CoverageKind;
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::layout::HasTyCtxt;
 use rustc_target::abi::{Align, Size};
+use rustc_target::spec::HasTargetSpec;
 use tracing::{debug, instrument};
 
 use crate::builder::Builder;
@@ -336,7 +337,9 @@ pub(crate) fn save_func_record_to_mod<'ll, 'tcx>(
     llvm::set_section(llglobal, covfun_section_name);
     // LLVM's coverage mapping format specifies 8-byte alignment for items in this section.
     llvm::set_alignment(llglobal, Align::EIGHT);
-    llvm::set_comdat(cx.llmod, llglobal, func_record_var_name.to_str().unwrap());
+    if cx.target_spec().supports_comdat() {
+        llvm::set_comdat(cx.llmod, llglobal, &func_record_var_name);
+    }
     cx.add_used_global(llglobal);
 }