Add comdat key field to llvm.global_ctors and llvm.global_dtors
This allows us to put dynamic initializers for weak data into the same
comdat group as the data being initialized. This is necessary for MSVC
ABI compatibility. Once we have comdats for guard variables, we can use
the combination to help GlobalOpt fire more often for weak data with
guarded initialization on other platforms.
Reviewers: nlewycky
Differential Revision: http://reviews.llvm.org/D3499
llvm-svn: 209015
diff --git a/llvm/lib/Transforms/Utils/ModuleUtils.cpp b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
index ff6e6f9..d9dbbca 100644
--- a/llvm/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
@@ -24,16 +24,16 @@
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 @@
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