NFC: make AtomicOrdering an enum class

Summary:
In the context of http://wg21.link/lwg2445 C++ uses the concept of
'stronger' ordering but doesn't define it properly. This should be fixed
in C++17 barring a small question that's still open.

The code currently plays fast and loose with the AtomicOrdering
enum. Using an enum class is one step towards tightening things. I later
also want to tighten related enums, such as clang's
AtomicOrderingKind (which should be shared with LLVM as a 'C++ ABI'
enum).

This change touches a few lines of code which can be improved later, I'd
like to keep it as NFC for now as it's already quite complex. I have
related changes for clang.

As a follow-up I'll add:
  bool operator<(AtomicOrdering, AtomicOrdering) = delete;
  bool operator>(AtomicOrdering, AtomicOrdering) = delete;
  bool operator<=(AtomicOrdering, AtomicOrdering) = delete;
  bool operator>=(AtomicOrdering, AtomicOrdering) = delete;
This is separate so that clang and LLVM changes don't need to be in sync.

Reviewers: jyknight, reames

Subscribers: jyknight, llvm-commits

Differential Revision: http://reviews.llvm.org/D18775

llvm-svn: 265602

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/unittests/Analysis/AliasAnalysisTest.cpp b/llvm/unittests/Analysis/AliasAnalysisTest.cpp
index 2d0eaca..3ef635c 100644
--- a/llvm/unittests/Analysis/AliasAnalysisTest.cpp
+++ b/llvm/unittests/Analysis/AliasAnalysisTest.cpp
@@ -179,12 +179,12 @@ TEST_F(AliasAnalysisTest, getModRefInfo) {
   auto *Load1 = new LoadInst(Addr, "load", BB);
   auto *Add1 = BinaryOperator::CreateAdd(Value, Value, "add", BB);
   auto *VAArg1 = new VAArgInst(Addr, PtrType, "vaarg", BB);
-  auto *CmpXChg1 = new AtomicCmpXchgInst(Addr, ConstantInt::get(IntType, 0),
-                                         ConstantInt::get(IntType, 1),
-                                         Monotonic, Monotonic, CrossThread, BB);
+  auto *CmpXChg1 = new AtomicCmpXchgInst(
+      Addr, ConstantInt::get(IntType, 0), ConstantInt::get(IntType, 1),
+      AtomicOrdering::Monotonic, AtomicOrdering::Monotonic, CrossThread, BB);
   auto *AtomicRMW =
       new AtomicRMWInst(AtomicRMWInst::Xchg, Addr, ConstantInt::get(IntType, 1),
-                        Monotonic, CrossThread, BB);
+                        AtomicOrdering::Monotonic, CrossThread, BB);
 
   ReturnInst::Create(C, nullptr, BB);