Subzero: Support non sequentially consistent memory orderings for atomic ops.

src/IceIntrinsics.h

Index: src/IceIntrinsics.h
diff --git a/src/IceIntrinsics.h b/src/IceIntrinsics.h
index fb066b982b66a92ac0f5b34f50c44851f81d5786..9fd42c92e0d66636c96ee42bfd37f6617a35778b 100644
--- a/src/IceIntrinsics.h
+++ b/src/IceIntrinsics.h
@@ -91,7 +91,11 @@ public:
     MemoryOrderNum // Invalid, keep last.
   };
 
-  static bool VerifyMemoryOrder(uint64_t Order);
+  // Verify memory ordering rules for atomic intrinsics.  For
+  // AtomicCmpxchg, Order is the "success" ordering and OrderOther is
+  // the "failure" ordering.  Returns true if valid, false if invalid.
+  static bool isMemoryOrderValid(IntrinsicID ID, uint64_t Order,
+                                 uint64_t OrderOther = MemoryOrderInvalid);
 
   enum SideEffects { SideEffects_F = 0, SideEffects_T = 1 };