Use weak_odr linkage when reusing definitions across codegen units

When reuing a definition across codegen units, we obviously cannot use
internal linkage, but using external linkage means that we can end up
with multiple conflicting definitions of a single symbol across
multiple crates. Since the definitions should all be equal
semantically, we can use weak_odr linkage to resolve the situation.

Fixes #32518

1 files changed, 13 insertions, 0 deletions

diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index 6ff90a8f53a..697b2d3f539 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -1189,3 +1189,16 @@ extern "C" void LLVMRustPositionBuilderAtStart(LLVMBuilderRef B, LLVMBasicBlockR
     auto point = unwrap(BB)->getFirstInsertionPt();
     unwrap(B)->SetInsertPoint(unwrap(BB), point);
 }
+
+extern "C" void LLVMRustSetComdat(LLVMModuleRef M, LLVMValueRef V, const char *Name) {
+    Triple TargetTriple(unwrap(M)->getTargetTriple());
+    GlobalObject *GV = unwrap<GlobalObject>(V);
+    if (!TargetTriple.isOSBinFormatMachO()) {
+        GV->setComdat(unwrap(M)->getOrInsertComdat(Name));
+    }
+}
+
+extern "C" void LLVMRustUnsetComdat(LLVMValueRef V) {
+    GlobalObject *GV = unwrap<GlobalObject>(V);
+    GV->setComdat(nullptr);
+}