From baba78daf2b3a3ee9bfa21f1f8ff3584aa982ac8 Mon Sep 17 00:00:00 2001
From: Andrew Ng <andrew.ng@sony.com>
Date: Mon, 10 Jun 2024 19:39:28 +0100
Subject: [clang] Fix loss of `dllexport` for exported template specialization
 (#94664)

When dropping DLL attributes, ensure that the most recent declaration is
being checked.
---
 clang/lib/CodeGen/CodeGenModule.cpp | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

(limited to 'clang/lib/CodeGen/CodeGenModule.cpp')

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 75b1449..dd4a665 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4512,6 +4512,19 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {
   return Resolver;
 }
 
+bool CodeGenModule::shouldDropDLLAttribute(const Decl *D,
+                                           const llvm::GlobalValue *GV) const {
+  auto SC = GV->getDLLStorageClass();
+  if (SC == llvm::GlobalValue::DefaultStorageClass)
+    return false;
+  const Decl *MRD = D->getMostRecentDecl();
+  return (((SC == llvm::GlobalValue::DLLImportStorageClass &&
+            !MRD->hasAttr<DLLImportAttr>()) ||
+           (SC == llvm::GlobalValue::DLLExportStorageClass &&
+            !MRD->hasAttr<DLLExportAttr>())) &&
+          !shouldMapVisibilityToDLLExport(cast<NamedDecl>(MRD)));
+}
+
 /// GetOrCreateLLVMFunction - If the specified mangled name is not in the
 /// module, create and return an llvm Function with the specified type. If there
 /// is something in the module with the specified name, return it potentially
@@ -4564,8 +4577,7 @@ llvm::Constant *CodeGenModule::GetOrCreateLLVMFunction(
     }
 
     // Handle dropped DLL attributes.
-    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>() &&
-        !shouldMapVisibilityToDLLExport(cast_or_null<NamedDecl>(D))) {
+    if (D && shouldDropDLLAttribute(D, Entry)) {
       Entry->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
       setDSOLocal(Entry);
     }
@@ -4859,8 +4871,7 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName, llvm::Type *Ty,
     }
 
     // Handle dropped DLL attributes.
-    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>() &&
-        !shouldMapVisibilityToDLLExport(D))
+    if (D && shouldDropDLLAttribute(D, Entry))
       Entry->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
 
     if (LangOpts.OpenMP && !LangOpts.OpenMPSimd && D)
-- 
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