Fix oneapi-default workflow (#801)

* Set `SYCL_FLAGS` when oneapi-default is used
* Use `NOT` instead of `NOT DEFINED`
   The former returns FALSE if the variable is defined but empty (which is the case when using `cmake-presets`).

Author: thilinarmtb

CMakePresets.json

@@ -104,7 +104,9 @@
         "CXX": "icpx",
         "FC": "ifx",
         "CXXFLAGS": "-Wno-uninitialized",
-        "OCCA_ENABLE_DPCPP": "ON"
+        "OCCA_ENABLE_DPCPP": "ON",
+        "OCCA_DPCPP_COMPILER": "icpx",
+        "OCCA_DPCPP_COMPILER_FLAGS": "-fsycl"
       }
     }
   ],

cmake/FindDPCPP.cmake

@@ -39,9 +39,9 @@ find_library(
     lib
 )
 
-if(NOT DEFINED SYCL_FLAGS)
-  if(DEFINED ENV{SYCL_FLAGS})
-    set(SYCL_FLAGS $ENV{SYCL_FLAGS})
+if(NOT OCCA_DPCPP_COMPILER_FLAGS)
+  if(DEFINED ENV{OCCA_DPCPP_COMPILER_FLAGS})
+    set(SYCL_FLAGS $ENV{OCCA_DPCPP_COMPILER_FLAGS})
   else()
     set(SYCL_FLAGS -fsycl)
   endif()

examples/CMakeLists.txt

@@ -51,7 +51,7 @@ macro(compile_example target file mode)
   install(TARGETS ${target} DESTINATION ${install_dir})
   install(FILES ${OKLS} DESTINATION ${install_dir})
 
-  if (NOT DEFINED OCCA_ENABLE_TESTS)
+  if (NOT OCCA_ENABLE_TESTS)
     return()
   endif()
   if (${mode})

examples/cpp/CMakeLists.txt

@@ -20,6 +20,6 @@ add_subdirectory(19_stream_tags)
 add_subdirectory(20_native_dpcpp_kernel)
 add_subdirectory(30_device_function)
 
-if (NOT DEFINED OCCA_CLANG_BASED_TRANSPILER)
+if (NOT OCCA_CLANG_BASED_TRANSPILER)
   add_subdirectory(31_oklt_v3_moving_avg)
 endif()