[clang] [CIR] Fix typeinfo linkage and comdat (PR #192721)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Andy Kaylor (andykaylor)

<details>
<summary>Changes</summary>

We weren't properly setting the linkage on typeinfo objects, leading to multiple definition linking error when typeinfo for a class was referenced in multiple source files. We had the correct linkage available in the buildTypeInfo function, but we weren't doing anything with it. This also prevented us from hitting the diagnostic saying that we should have set the comdat attribute for the typeinfo. This change fixes both of those problems.

---
Full diff: https://github.com/llvm/llvm-project/pull/192721.diff


4 Files Affected:

- (modified) clang/include/clang/CIR/MissingFeatures.h (-1) 
- (modified) clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp (+4-5) 
- (modified) clang/test/CIR/CodeGen/rtti-member-pointer.cpp (+4-4) 
- (modified) clang/test/CIR/CodeGen/rtti-qualfn.cpp (+2-2) 


``````````diff
diff --git a/clang/include/clang/CIR/MissingFeatures.h b/clang/include/clang/CIR/MissingFeatures.h
index 9fd9397e85e63..92d052de4e8db 100644
--- a/clang/include/clang/CIR/MissingFeatures.h
+++ b/clang/include/clang/CIR/MissingFeatures.h
@@ -39,7 +39,6 @@ struct MissingFeatures {
   static bool opGlobalAnnotations() { return false; }
   static bool opGlobalCtorPriority() { return false; }
   static bool setDSOLocal() { return false; }
-  static bool setComdat() { return false; }
 
   static bool supportIFuncAttr() { return false; }
   static bool supportVisibility() { return false; }
diff --git a/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp b/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
index 75658b23790bf..a1f2aabfe18bb 100644
--- a/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
@@ -1610,6 +1610,8 @@ mlir::Attribute CIRGenItaniumRTTIBuilder::buildTypeInfo(
   cir::GlobalOp gv =
       CIRGenModule::createGlobalOp(cgm, loc, name, init.getType(),
                                    /*isConstant=*/true);
+  gv.setLinkageAttr(
+      cir::GlobalLinkageKindAttr::get(&cgm.getMLIRContext(), linkage));
 
   // Export the typeinfo in the same circumstances as the vtable is
   // exported.
@@ -1629,11 +1631,8 @@ mlir::Attribute CIRGenItaniumRTTIBuilder::buildTypeInfo(
     oldGV->erase();
   }
 
-  if (cgm.supportsCOMDAT() && cir::isWeakForLinker(gv.getLinkage())) {
-    assert(!cir::MissingFeatures::setComdat());
-    cgm.errorNYI("buildTypeInfo: supportsCOMDAT & isWeakForLinker");
-    return {};
-  }
+  if (cgm.supportsCOMDAT() && cir::isWeakForLinker(linkage))
+    gv.setComdat(true);
 
   CharUnits align = cgm.getASTContext().toCharUnitsFromBits(
       cgm.getTarget().getPointerAlign(LangAS::Default));
diff --git a/clang/test/CIR/CodeGen/rtti-member-pointer.cpp b/clang/test/CIR/CodeGen/rtti-member-pointer.cpp
index f6c296e5c4dd4..b223857a9630c 100644
--- a/clang/test/CIR/CodeGen/rtti-member-pointer.cpp
+++ b/clang/test/CIR/CodeGen/rtti-member-pointer.cpp
@@ -25,8 +25,8 @@ void throw_data_member_ptr() {
 
 // LLVM-DAG: @_ZTSM1Ai = linkonce_odr global [5 x i8] c"M1Ai\00", comdat
 // LLVM-DAG: @_ZTS1A = linkonce_odr global [3 x i8] c"1A\00", comdat
-// LLVM-DAG: @_ZTI1A = constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 16), ptr @_ZTS1A }
-// LLVM-DAG: @_ZTIM1Ai = constant { ptr, ptr, i32, ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv129__pointer_to_member_type_infoE, i64 16), ptr @_ZTSM1Ai, i32 0, ptr @_ZTIi, ptr @_ZTI1A }
+// LLVM-DAG: @_ZTI1A = linkonce_odr constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 16), ptr @_ZTS1A }, comdat
+// LLVM-DAG: @_ZTIM1Ai = linkonce_odr constant { ptr, ptr, i32, ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv129__pointer_to_member_type_infoE, i64 16), ptr @_ZTSM1Ai, i32 0, ptr @_ZTIi, ptr @_ZTI1A }, comdat
 // LLVM-DAG: call void @__cxa_throw(ptr %{{.*}}, ptr @_ZTIM1Ai, ptr null)
 
 // OGCG-DAG: @_ZTSM1Ai = linkonce_odr constant [5 x i8] c"M1Ai\00", comdat
@@ -47,8 +47,8 @@ void throw_member_fn_ptr() {
 
 // LLVM-DAG: @_ZTSM1AFvvE = linkonce_odr global [8 x i8] c"M1AFvvE\00", comdat
 // LLVM-DAG: @_ZTSFvvE = linkonce_odr global [5 x i8] c"FvvE\00", comdat
-// LLVM-DAG: @_ZTIFvvE = constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv120__function_type_infoE, i64 16), ptr @_ZTSFvvE }
-// LLVM-DAG: @_ZTIM1AFvvE = constant { ptr, ptr, i32, ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv129__pointer_to_member_type_infoE, i64 16), ptr @_ZTSM1AFvvE, i32 0, ptr @_ZTIFvvE, ptr @_ZTI1A }
+// LLVM-DAG: @_ZTIFvvE = linkonce_odr constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv120__function_type_infoE, i64 16), ptr @_ZTSFvvE }, comdat
+// LLVM-DAG: @_ZTIM1AFvvE = linkonce_odr constant { ptr, ptr, i32, ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv129__pointer_to_member_type_infoE, i64 16), ptr @_ZTSM1AFvvE, i32 0, ptr @_ZTIFvvE, ptr @_ZTI1A }, comdat
 // LLVM-DAG: call void @__cxa_throw(ptr %{{.*}}, ptr @_ZTIM1AFvvE, ptr null)
 
 // OGCG-DAG: @_ZTSM1AFvvE = linkonce_odr constant [8 x i8] c"M1AFvvE\00", comdat
diff --git a/clang/test/CIR/CodeGen/rtti-qualfn.cpp b/clang/test/CIR/CodeGen/rtti-qualfn.cpp
index ed9a06014480b..d57e7fce7915f 100644
--- a/clang/test/CIR/CodeGen/rtti-qualfn.cpp
+++ b/clang/test/CIR/CodeGen/rtti-qualfn.cpp
@@ -24,9 +24,9 @@ void f() noexcept {
 // CIR: cir.throw %{{.*}} : !cir.ptr<!cir.ptr<!cir.func<()>>>, @_ZTIPDoFvvE
 
 // LLVM-DAG: @_ZTSFvvE = linkonce_odr global [5 x i8] c"FvvE\00", comdat
-// LLVM-DAG: @_ZTIFvvE = constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv120__function_type_infoE, i64 16), ptr @_ZTSFvvE }
+// LLVM-DAG: @_ZTIFvvE = linkonce_odr constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv120__function_type_infoE, i64 16), ptr @_ZTSFvvE }, comdat
 // LLVM-DAG: @_ZTSPDoFvvE = linkonce_odr global [8 x i8] c"PDoFvvE\00", comdat
-// LLVM-DAG: @_ZTIPDoFvvE = constant { ptr, ptr, i32, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv119__pointer_type_infoE, i64 16), ptr @_ZTSPDoFvvE, i32 64, ptr @_ZTIFvvE }
+// LLVM-DAG: @_ZTIPDoFvvE = linkonce_odr constant { ptr, ptr, i32, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv119__pointer_type_infoE, i64 16), ptr @_ZTSPDoFvvE, i32 64, ptr @_ZTIFvvE }, comdat
 // LLVM: call void @__cxa_throw(ptr %{{.*}}, ptr @_ZTIPDoFvvE, ptr null)
 
 // OGCG-DAG: @_ZTSFvvE = linkonce_odr constant [5 x i8] c"FvvE\00", comdat

``````````

</details>


https://github.com/llvm/llvm-project/pull/192721