From 92d8a29ca0d506cea28718644527c4711ee3e694 Mon Sep 17 00:00:00 2001 From: Erik Pilkington Date: Fri, 12 Oct 2018 17:22:10 +0000 Subject: [CodeGen] Handle extern references to OBJC_CLASS_$_* Some ObjC users declare a extern variable named OBJC_CLASS_$_Foo, then use it's address as a Class. I.e., one could define isInstanceOfF: BOOL isInstanceOfF(id c) { extern void OBJC_CLASS_$_F; return [c class] == (Class)&OBJC_CLASS_$_F; } This leads to asserts in clang CodeGen if there is an @implementation of F in the same TU as an instance of this pattern, because CodeGen assumes that a variable named OBJC_CLASS_$_* has the right type. This commit fixes the problem by RAUWing the old (incorrectly typed) global with a new global, then removing the old global. rdar://45077269 Differential revision: https://reviews.llvm.org/D53154 llvm-svn: 344373 --- clang/lib/CodeGen/CGObjCMac.cpp | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) (limited to 'clang/lib/CodeGen/CGObjCMac.cpp') diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp index 2b6d895f93c..fffa62d7d23 100644 --- a/clang/lib/CodeGen/CGObjCMac.cpp +++ b/clang/lib/CodeGen/CGObjCMac.cpp @@ -7188,15 +7188,21 @@ CGObjCNonFragileABIMac::GetClassGlobal(StringRef Name, Weak ? llvm::GlobalValue::ExternalWeakLinkage : llvm::GlobalValue::ExternalLinkage; - - llvm::GlobalVariable *GV = CGM.getModule().getGlobalVariable(Name); - if (!GV) { - GV = new llvm::GlobalVariable(CGM.getModule(), ObjCTypes.ClassnfABITy, - false, L, nullptr, Name); + if (!GV || GV->getType() != ObjCTypes.ClassnfABITy->getPointerTo()) { + auto *NewGV = new llvm::GlobalVariable(ObjCTypes.ClassnfABITy, false, L, + nullptr, Name); if (DLLImport) - GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); + NewGV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); + + if (GV) { + GV->replaceAllUsesWith( + llvm::ConstantExpr::getBitCast(NewGV, GV->getType())); + GV->eraseFromParent(); + } + GV = NewGV; + CGM.getModule().getGlobalList().push_back(GV); } assert(GV->getLinkage() == L); -- cgit v1.2.3