1 files changed, 14 insertions, 2 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index d10f4ec2f92..67a15406d49 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -343,8 +343,9 @@ X86TargetLowering::X86TargetLowering(X86TargetMachine &TM)
   if (Subtarget->hasSSE1())
     setOperationAction(ISD::PREFETCH      , MVT::Other, Legal);
 
-  if (!Subtarget->hasSSE2())
-    setOperationAction(ISD::MEMBARRIER    , MVT::Other, Expand);
+  // We may not have a libcall for MEMBARRIER so we should lower this.
+  setOperationAction(ISD::MEMBARRIER    , MVT::Other, Custom);
+  
   // On X86 and X86-64, atomic operations are lowered to locked instructions.
   // Locked instructions, in turn, have implicit fence semantics (all memory
   // operations are flushed before issuing the locked instruction, and they
@@ -7508,6 +7509,16 @@ SDValue X86TargetLowering::LowerXALUO(SDValue Op, SelectionDAG &DAG) const {
   return Sum;
 }
 
+SDValue X86TargetLowering::LowerMEMBARRIER(SDValue Op, SelectionDAG &DAG) const{
+  DebugLoc dl = Op.getDebugLoc();
+  
+  if (!Subtarget->hasSSE2())
+    return DAG.getNode(X86ISD::MEMBARRIER, dl, MVT::Other, Op.getOperand(0),
+                       DAG.getConstant(0, MVT::i32));
+                       
+  return DAG.getNode(X86ISD::MEMBARRIER, dl, MVT::Other, Op.getOperand(0));
+}
+
 SDValue X86TargetLowering::LowerCMP_SWAP(SDValue Op, SelectionDAG &DAG) const {
   EVT T = Op.getValueType();
   DebugLoc dl = Op.getDebugLoc();
@@ -7597,6 +7608,7 @@ SDValue X86TargetLowering::LowerLOAD_SUB(SDValue Op, SelectionDAG &DAG) const {
 SDValue X86TargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   switch (Op.getOpcode()) {
   default: llvm_unreachable("Should not custom lower this!");
+  case ISD::MEMBARRIER:         return LowerMEMBARRIER(Op,DAG);
   case ISD::ATOMIC_CMP_SWAP:    return LowerCMP_SWAP(Op,DAG);
   case ISD::ATOMIC_LOAD_SUB:    return LowerLOAD_SUB(Op,DAG);
   case ISD::BUILD_VECTOR:       return LowerBUILD_VECTOR(Op, DAG);