R600: Add support for local memory atomic add

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190080 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/R600/SILowerControlFlow.cpp b/lib/Target/R600/SILowerControlFlow.cpp
index 09cf25b..a6c43bb 100644
--- a/lib/Target/R600/SILowerControlFlow.cpp
+++ b/lib/Target/R600/SILowerControlFlow.cpp
@@ -488,6 +488,7 @@
           NeedWQM = true;
           // Fall through
         case AMDGPU::DS_WRITE_B32:
+        case AMDGPU::DS_ADD_U32_RTN:
           NeedM0 = true;
           break;