This fixes the case where the wrong symbol is emitted leading to linking errors when you reference a class before defining it (GNU runtime).
Patch by David Chisnall.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74772 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjCGNU.cpp b/lib/CodeGen/CGObjCGNU.cpp
index 1e2218f..6554da9 100644
--- a/lib/CodeGen/CGObjCGNU.cpp
+++ b/lib/CodeGen/CGObjCGNU.cpp
@@ -180,7 +180,7 @@
std::string symbolName = "__objc_class_name_" + className;
llvm::GlobalVariable *ClassSymbol = TheModule.getGlobalVariable(symbolName);
if (!ClassSymbol) {
- ClassSymbol = new llvm::GlobalVariable(LongTy, false,
+ ClassSymbol = new llvm::GlobalVariable(LongTy, false,
llvm::GlobalValue::ExternalLinkage, 0, symbolName, &TheModule);
}
new llvm::GlobalVariable(ClassSymbol->getType(), true,
@@ -859,9 +859,14 @@
std::string ClassName = ClassDecl->getNameAsString();
// Emit the symbol that is used to generate linker errors if this class is
// referenced in other modules but not declared.
- new llvm::GlobalVariable(LongTy, false, llvm::GlobalValue::ExternalLinkage,
- llvm::ConstantInt::get(LongTy, 0), "__objc_class_name_" + ClassName,
- &TheModule);
+ std::string classSymbolName = "__objc_class_name_" + ClassName;
+ if (llvm::GlobalVariable *symbol =
+ TheModule.getGlobalVariable(classSymbolName)) {
+ symbol->setInitializer(llvm::ConstantInt::get(LongTy, 0));
+ } else {
+ new llvm::GlobalVariable(LongTy, false, llvm::GlobalValue::ExternalLinkage,
+ llvm::ConstantInt::get(LongTy, 0), classSymbolName, &TheModule);
+ }
// Get the size of instances.
int instanceSize = Context.getASTObjCImplementationLayout(OID).getSize() / 8;