From bcbc0710620ef764376c47f445b6de6170d6e5db Mon Sep 17 00:00:00 2001
From: Sergei Bastrakov <sergey.bastrakov@gmail.com>
Date: Wed, 19 Feb 2020 10:32:14 +0100
Subject: [PATCH] Activate the thread-element switching for the Omp4 backend
 with CUPLA_KERNEL_OPTI

This is now consistent with the Omp2Blocks backend, fixes #156
---
 include/cupla/traits/IsThreadSeqAcc.hpp | 16 ++++++++++++++++
 include/cupla/types.hpp                 | 15 +++++++++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/include/cupla/traits/IsThreadSeqAcc.hpp b/include/cupla/traits/IsThreadSeqAcc.hpp
index 3d6b89480..405d87fdd 100644
--- a/include/cupla/traits/IsThreadSeqAcc.hpp
+++ b/include/cupla/traits/IsThreadSeqAcc.hpp
@@ -91,6 +91,22 @@ namespace traits
     };
 #endif
 
+#ifdef ALPAKA_ACC_CPU_BT_OMP4_ENABLED
+    template<
+        typename T_KernelDim,
+        typename T_IndexType
+    >
+    struct IsThreadSeqAcc<
+        ::alpaka::acc::AccCpuOmp4<
+            T_KernelDim,
+            T_IndexType
+        >
+    >
+    {
+        static constexpr bool value = true;
+    };
+#endif
+
 } // namespace traits
 } // namespace CUPLA_ACCELERATOR_NAMESPACE
 } // namespace cupla
diff --git a/include/cupla/types.hpp b/include/cupla/types.hpp
index 5d2db88f6..838c17f5b 100644
--- a/include/cupla/types.hpp
+++ b/include/cupla/types.hpp
@@ -130,10 +130,17 @@ inline namespace CUPLA_ACCELERATOR_NAMESPACE
 #endif
 
 #ifdef ALPAKA_ACC_CPU_BT_OMP4_ENABLED
-    using Acc = ::alpaka::acc::AccCpuOmp4<
-        KernelDim,
-        IdxType
-    >;
+    #if (CUPLA_NUM_SELECTED_DEVICES == 1)
+        using Acc = ::alpaka::acc::AccCpuOmp4<
+            KernelDim,
+            IdxType
+        >;
+    #else
+        using AccThreadSeq = ::alpaka::acc::AccCpuOmp4<
+            KernelDim,
+            IdxType
+        >;
+    #endif
 #endif
 
 #endif