Handle ConstantAggregateZero when upgrading global_ctors.

llvm-svn: 209075

llvm/lib/IR/AutoUpgrade.cpp

@@ -191,10 +191,12 @@ static bool UpgradeGlobalStructors(GlobalVariable *GV) {
       StructType::get(GV->getContext(), Tys, /*isPacked=*/false);
 
   // Build new constants with a null third field filled in.
-  ConstantArray *OldInit = dyn_cast<ConstantArray>(GV->getInitializer());
-  if (!OldInit)
+  Constant *OldInitC = GV->getInitializer();
+  ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
+  if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
     return false;
   std::vector<Constant *> Initializers;
+  if (OldInit) {
     for (Use &U : OldInit->operands()) {
       ConstantStruct *Init = cast<ConstantStruct>(&U);
       Constant *NewInit =
@@ -202,6 +204,7 @@ static bool UpgradeGlobalStructors(GlobalVariable *GV) {
                             Constant::getNullValue(VoidPtrTy), nullptr);
       Initializers.push_back(NewInit);
     }
+  }
   assert(Initializers.size() == ATy->getNumElements());
 
   // Replace the old GV with a new one.

llvm/test/Bitcode/upgrade-global-ctors.ll

@@ -0,0 +1,3 @@
+; RUN:  llvm-dis < %s.bc| FileCheck %s
+
+; CHECK: @llvm.global_ctors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer