PR18097: Support initializing an _Atomic(T) from an object of C++ class type T
or a class derived from T. We already supported this when initializing
_Atomic(T) from T for most (and maybe all) other reasonable values of T.
llvm-svn: 214390
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index b2f08c3..b508dcb 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1045,6 +1045,25 @@
llvm::Constant *CodeGenModule::EmitConstantValue(const APValue &Value,
QualType DestType,
CodeGenFunction *CGF) {
+ // For an _Atomic-qualified constant, we may need to add tail padding.
+ if (auto *AT = DestType->getAs<AtomicType>()) {
+ QualType InnerType = AT->getValueType();
+ auto *Inner = EmitConstantValue(Value, InnerType, CGF);
+
+ uint64_t InnerSize = Context.getTypeSize(InnerType);
+ uint64_t OuterSize = Context.getTypeSize(DestType);
+ if (InnerSize == OuterSize)
+ return Inner;
+
+ assert(InnerSize < OuterSize && "emitted over-large constant for atomic");
+ llvm::Constant *Elts[] = {
+ Inner,
+ llvm::ConstantAggregateZero::get(
+ llvm::ArrayType::get(Int8Ty, (OuterSize - InnerSize) / 8))
+ };
+ return llvm::ConstantStruct::getAnon(Elts);
+ }
+
switch (Value.getKind()) {
case APValue::Uninitialized:
llvm_unreachable("Constant expressions should be initialized.");