Merge pull request #21533 from compnerd/excessive-force

IRGen: COMDAT the force load thunks

Author: compnerd

lib/IRGen/IRGenModule.cpp

@@ -960,19 +960,25 @@ void IRGenModule::addLinkLibrary(const LinkLibrary &linkLib) {
     encodeForceLoadSymbolName(buf, linkLib.getName());
     auto ForceImportThunk =
         Module.getOrInsertFunction(buf, llvm::FunctionType::get(VoidTy, false));
-    if (useDllStorage())
-      cast<llvm::GlobalValue>(ForceImportThunk)
-          ->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
+    ApplyIRLinkage({llvm::GlobalValue::ExternalLinkage,
+                    llvm::GlobalValue::DefaultVisibility,
+                    useDllStorage()
+                        ? llvm::GlobalValue::DLLImportStorageClass
+                        : llvm::GlobalValue::DefaultStorageClass})
+        .to(cast<llvm::GlobalValue>(ForceImportThunk));
 
     buf += "_$";
     appendEncodedName(buf, IRGen.Opts.ModuleName);
 
     if (!Module.getGlobalVariable(buf.str())) {
       auto ref = new llvm::GlobalVariable(Module, ForceImportThunk->getType(),
                                           /*isConstant=*/true,
-                                          llvm::GlobalValue::WeakAnyLinkage,
+                                          llvm::GlobalValue::WeakODRLinkage,
                                           ForceImportThunk, buf.str());
-      ref->setVisibility(llvm::GlobalValue::HiddenVisibility);
+      ApplyIRLinkage({llvm::GlobalValue::WeakODRLinkage,
+                      llvm::GlobalValue::HiddenVisibility,
+                      llvm::GlobalValue::DefaultStorageClass})
+          .to(ref);
       auto casted = llvm::ConstantExpr::getBitCast(ref, Int8PtrTy);
       LLVMUsed.push_back(casted);
     }
@@ -1083,9 +1089,12 @@ void IRGenModule::emitAutolinkInfo() {
         llvm::Function::Create(llvm::FunctionType::get(VoidTy, false),
                                llvm::GlobalValue::ExternalLinkage, buf,
                                &Module);
-    if (useDllStorage())
-      ForceImportThunk
-          ->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
+    ApplyIRLinkage({llvm::GlobalValue::ExternalLinkage,
+                    llvm::GlobalValue::DefaultVisibility,
+                    useDllStorage()
+                        ? llvm::GlobalValue::DLLExportStorageClass
+                        : llvm::GlobalValue::DefaultStorageClass})
+        .to(ForceImportThunk);
 
     auto BB = llvm::BasicBlock::Create(getLLVMContext(), "", ForceImportThunk);
     llvm::IRBuilder<> IRB(BB);

test/Serialization/autolinking.swift

@@ -45,7 +45,7 @@ import someModule
 // FORCE-LOAD-HEX:   ret void
 // FORCE-LOAD-HEX: }
 
-// FORCE-LOAD-CLIENT: @"_swift_FORCE_LOAD_$_module_$_autolinking" = weak hidden constant void ()* @"_swift_FORCE_LOAD_$_module"
+// FORCE-LOAD-CLIENT: @"_swift_FORCE_LOAD_$_module_$_autolinking" = weak_odr hidden constant void ()* @"_swift_FORCE_LOAD_$_module"
 // FORCE-LOAD-CLIENT: @llvm.used = appending global [{{[0-9]+}} x i8*] [
 // FORCE-LOAD-CLIENT: i8* bitcast (void ()** @"_swift_FORCE_LOAD_$_module_$_autolinking" to i8*)
 // FORCE-LOAD-CLIENT: ], section "llvm.metadata"