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, 3 insertions, 3 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 70d00c2682a..0aedb419201 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -8323,9 +8323,9 @@ static Instruction* callIntrinsic(IRBuilder<> &Builder, Intrinsic::ID Id) {
 Instruction* PPCTargetLowering::emitLeadingFence(IRBuilder<> &Builder,
                                          AtomicOrdering Ord, bool IsStore,
                                          bool IsLoad) const {
-  if (Ord == SequentiallyConsistent)
+  if (Ord == AtomicOrdering::SequentiallyConsistent)
     return callIntrinsic(Builder, Intrinsic::ppc_sync);
-  if (isAtLeastRelease(Ord))
+  if (isReleaseOrStronger(Ord))
     return callIntrinsic(Builder, Intrinsic::ppc_lwsync);
   return nullptr;
 }
@@ -8333,7 +8333,7 @@ Instruction* PPCTargetLowering::emitLeadingFence(IRBuilder<> &Builder,
 Instruction* PPCTargetLowering::emitTrailingFence(IRBuilder<> &Builder,
                                           AtomicOrdering Ord, bool IsStore,
                                           bool IsLoad) const {
-  if (IsLoad && isAtLeastAcquire(Ord))
+  if (IsLoad && isAcquireOrStronger(Ord))
     return callIntrinsic(Builder, Intrinsic::ppc_lwsync);
   // FIXME: this is too conservative, a dependent branch + isync is enough.
   // See http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html and