3 files changed, 37 insertions, 22 deletions

diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
index 9d36b723b96..1a253916d7c 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
@@ -155,8 +155,8 @@ bool ObjCARCAPElim::runOnModule(Module &M) {
   for (User::op_iterator OI = Init->op_begin(), OE = Init->op_end();
        OI != OE; ++OI) {
     Value *Op = *OI;
-    // llvm.global_ctors is an array of pairs where the second members
-    // are constructor functions.
+    // llvm.global_ctors is an array of three-field structs where the second
+    // members are constructor functions.
     Function *F = dyn_cast<Function>(cast<ConstantStruct>(Op)->getOperand(1));
     // If the user used a constructor function with the wrong signature and
     // it got bitcasted or whatever, look the other way.
diff --git a/llvm/lib/Transforms/Utils/CtorUtils.cpp b/llvm/lib/Transforms/Utils/CtorUtils.cpp
index 7cf793f6266..a3594248de0 100644
--- a/llvm/lib/Transforms/Utils/CtorUtils.cpp
+++ b/llvm/lib/Transforms/Utils/CtorUtils.cpp
@@ -29,26 +29,28 @@ namespace {
 void installGlobalCtors(GlobalVariable *GCL,
                         const std::vector<Function *> &Ctors) {
   // If we made a change, reassemble the initializer list.
-  Constant *CSVals[2];
-  CSVals[0] = ConstantInt::get(Type::getInt32Ty(GCL->getContext()), 65535);
-  CSVals[1] = nullptr;
+  Constant *CSVals[3];
 
   StructType *StructTy =
       cast<StructType>(GCL->getType()->getElementType()->getArrayElementType());
 
   // Create the new init list.
   std::vector<Constant *> CAList;
-  for (unsigned i = 0, e = Ctors.size(); i != e; ++i) {
-    if (Ctors[i]) {
-      CSVals[1] = Ctors[i];
+  for (Function *F : Ctors) {
+    Type *Int32Ty = Type::getInt32Ty(GCL->getContext());
+    if (F) {
+      CSVals[0] = ConstantInt::get(Int32Ty, 65535);
+      CSVals[1] = F;
     } else {
-      Type *FTy = FunctionType::get(Type::getVoidTy(GCL->getContext()), false);
-      PointerType *PFTy = PointerType::getUnqual(FTy);
-      CSVals[1] = Constant::getNullValue(PFTy);
-      CSVals[0] =
-          ConstantInt::get(Type::getInt32Ty(GCL->getContext()), 0x7fffffff);
+      CSVals[0] = ConstantInt::get(Int32Ty, 0x7fffffff);
+      CSVals[1] = Constant::getNullValue(StructTy->getElementType(1));
     }
-    CAList.push_back(ConstantStruct::get(StructTy, CSVals));
+    // FIXME: Only allow the 3-field form in LLVM 4.0.
+    size_t NumElts = StructTy->getNumElements();
+    if (NumElts > 2)
+      CSVals[2] = Constant::getNullValue(StructTy->getElementType(2));
+    CAList.push_back(
+        ConstantStruct::get(StructTy, makeArrayRef(CSVals, NumElts)));
   }
 
   // Create the array initializer.
diff --git a/llvm/lib/Transforms/Utils/ModuleUtils.cpp b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
index ff6e6f9c60d..d9dbbca1c36 100644
--- a/llvm/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
@@ -24,16 +24,16 @@ static void appendToGlobalArray(const char *Array,
                                 Module &M, Function *F, int Priority) {
   IRBuilder<> IRB(M.getContext());
   FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
-  StructType *Ty = StructType::get(
-      IRB.getInt32Ty(), PointerType::getUnqual(FnTy), NULL);
-
-  Constant *RuntimeCtorInit = ConstantStruct::get(
-      Ty, IRB.getInt32(Priority), F, NULL);
 
   // Get the current set of static global constructors and add the new ctor
   // to the list.
   SmallVector<Constant *, 16> CurrentCtors;
-  if (GlobalVariable * GVCtor = M.getNamedGlobal(Array)) {
+  StructType *EltTy;
+  if (GlobalVariable *GVCtor = M.getNamedGlobal(Array)) {
+    // If there is a global_ctors array, use the existing struct type, which can
+    // have 2 or 3 fields.
+    ArrayType *ATy = cast<ArrayType>(GVCtor->getType()->getElementType());
+    EltTy = cast<StructType>(ATy->getElementType());
     if (Constant *Init = GVCtor->getInitializer()) {
       unsigned n = Init->getNumOperands();
       CurrentCtors.reserve(n + 1);
@@ -41,13 +41,26 @@ static void appendToGlobalArray(const char *Array,
         CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
     }
     GVCtor->eraseFromParent();
+  } else {
+    // Use a simple two-field struct if there isn't one already.
+    EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
+                            nullptr);
   }
 
+  // Build a 2 or 3 field global_ctor entry.  We don't take a comdat key.
+  Constant *CSVals[3];
+  CSVals[0] = IRB.getInt32(Priority);
+  CSVals[1] = F;
+  // FIXME: Drop support for the two element form in LLVM 4.0.
+  if (EltTy->getNumElements() >= 3)
+    CSVals[2] = llvm::Constant::getNullValue(IRB.getInt8PtrTy());
+  Constant *RuntimeCtorInit =
+      ConstantStruct::get(EltTy, makeArrayRef(CSVals, EltTy->getNumElements()));
+
   CurrentCtors.push_back(RuntimeCtorInit);
 
   // Create a new initializer.
-  ArrayType *AT = ArrayType::get(RuntimeCtorInit->getType(),
-                                 CurrentCtors.size());
+  ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
   Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
 
   // Create the new global variable and replace all uses of