Merge pull request #8740 from luotao1/warning

fix warning: statement is unreachable

Author: luotao1

paddle/fluid/framework/dim.h

@@ -157,15 +157,15 @@ HOSTDEVICE int64_t& indexer<0>(Dim<0>& dim, int idx) {
   throw std::invalid_argument("Invalid index");
 #else
   PADDLE_ASSERT(false);
-#endif
-#if (defined __CUDA_ARCH__) && (CUDA_VERSION < 8000)
+#if CUDA_VERSION < 8000
   // On CUDA versions previous to 8.0, only __shared__ variables
   // could be declared as static in the device code.
   int64_t head = 0;
 #else
   static int64_t head = 0;
 #endif
   return head;
+#endif
 }
 
 template <int D>
@@ -189,15 +189,15 @@ HOSTDEVICE int64_t indexer<0>(const Dim<0>& dim, int idx) {
   throw std::invalid_argument("Invalid index");
 #else
   PADDLE_ASSERT(false);
-#endif
-#if (defined __CUDA_ARCH__) && (CUDA_VERSION < 8000)
+#if CUDA_VERSION < 8000
   // On CUDA versions previous to 8.0, only __shared__ variables
   // could be declared as static in the device code.
   int64_t head = 0;
 #else
   static int64_t head = 0;
 #endif
   return head;
+#endif
 }
 
 }  // namespace