Revert "NFC: unify clang / LLVM atomic ordering"

This reverts commit 537951f2f16d6a8542571c7722fcbae07d4e62c2.

Causes an assert in:
  test/Transforms/AtomicExpand/SPARC/libcalls.ll
  (Ordering2 != AtomicOrdering::NotAtomic && "expect atomic MO")

Bot:
  http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-incremental_check/21724/testReport/junit/LLVM/Transforms_AtomicExpand_SPARC/libcalls_ll/

I'm not getting this assert on my local debug build, but I'll revert
just to be sure.

llvm-svn: 266576

1 files changed, 38 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index 74cbea94542..e0c7fd6f883 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -937,6 +937,39 @@ bool llvm::expandAtomicRMWToCmpXchg(AtomicRMWInst *AI,
   return true;
 }
 
+// This converts from LLVM's internal AtomicOrdering enum to the
+// memory_order_* value required by the __atomic_* libcalls.
+static int libcallAtomicModel(AtomicOrdering AO) {
+  enum {
+    AO_ABI_memory_order_relaxed = 0,
+    AO_ABI_memory_order_consume = 1,
+    AO_ABI_memory_order_acquire = 2,
+    AO_ABI_memory_order_release = 3,
+    AO_ABI_memory_order_acq_rel = 4,
+    AO_ABI_memory_order_seq_cst = 5
+  };
+
+  switch (AO) {
+  case AtomicOrdering::NotAtomic:
+    llvm_unreachable("Expected atomic memory order.");
+  case AtomicOrdering::Unordered:
+  case AtomicOrdering::Monotonic:
+    return AO_ABI_memory_order_relaxed;
+  // Not implemented yet in llvm:
+  // case AtomicOrdering::Consume:
+  //  return AO_ABI_memory_order_consume;
+  case AtomicOrdering::Acquire:
+    return AO_ABI_memory_order_acquire;
+  case AtomicOrdering::Release:
+    return AO_ABI_memory_order_release;
+  case AtomicOrdering::AcquireRelease:
+    return AO_ABI_memory_order_acq_rel;
+  case AtomicOrdering::SequentiallyConsistent:
+    return AO_ABI_memory_order_seq_cst;
+  }
+  llvm_unreachable("Unknown atomic memory order.");
+}
+
 // In order to use one of the sized library calls such as
 // __atomic_fetch_add_4, the alignment must be sufficient, the size
 // must be one of the potentially-specialized sizes, and the value
@@ -1118,14 +1151,12 @@ bool AtomicExpand::expandAtomicOpToLibcall(
   // TODO: the "order" argument type is "int", not int32. So
   // getInt32Ty may be wrong if the arch uses e.g. 16-bit ints.
   ConstantInt *SizeVal64 = ConstantInt::get(Type::getInt64Ty(Ctx), Size);
-  assert(Ordering != AtomicOrdering::NotAtomic && "expect atomic MO");
   Constant *OrderingVal =
-      ConstantInt::get(Type::getInt32Ty(Ctx), (int)toCABI(Ordering));
-  assert(Ordering2 != AtomicOrdering::NotAtomic && "expect atomic MO");
-  Constant *Ordering2Val =
-      CASExpected
-          ? ConstantInt::get(Type::getInt32Ty(Ctx), (int)toCABI(Ordering2))
-          : nullptr;
+      ConstantInt::get(Type::getInt32Ty(Ctx), libcallAtomicModel(Ordering));
+  Constant *Ordering2Val = CASExpected
+                               ? ConstantInt::get(Type::getInt32Ty(Ctx),
+                                                  libcallAtomicModel(Ordering2))
+                               : nullptr;
   bool HasResult = I->getType() != Type::getVoidTy(Ctx);
 
   RTLIB::Libcall RTLibType;