[dev] configure optimize options explicitly for different build types (#6161)

CMakeLists.txt

@@ -108,10 +108,24 @@ dgl_feature_option(
     "dev"
 )
 
-# Set debug compile option for gdb, only happens when -DCMAKE_BUILD_TYPE=DEBUG
-if (NOT MSVC)
-  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DDEBUG -O0 -g3 -ggdb")
-endif(NOT MSVC)
+# Set optimization options for different build types.
+if (${BUILD_TYPE} STREQUAL "dev")
+  if (MSVC)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /Od")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Od")
+  else()
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -g3 -ggdb")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O0 -g3 -ggdb")
+  endif()
+else()
+  if (MSVC)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /O2")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /O2")
+  else()
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O2")
+  endif()
+endif()
 
 if(USE_CUDA)
   message(STATUS "Build with CUDA support")
@@ -157,8 +171,8 @@ if(MSVC)
   endif()
 else(MSVC)
   include(CheckCXXCompilerFlag)
-  set(CMAKE_C_FLAGS "-O2 -Wall -fPIC ${CMAKE_C_FLAGS}")
-  set(CMAKE_CXX_FLAGS "-O2 -Wall -fPIC ${CMAKE_CXX_FLAGS}")
+  set(CMAKE_C_FLAGS "-Wall -fPIC ${CMAKE_C_FLAGS}")
+  set(CMAKE_CXX_FLAGS "-Wall -fPIC ${CMAKE_CXX_FLAGS}")
   if(NOT APPLE)
     set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--warn-common ${CMAKE_SHARED_LINKER_FLAGS}")
   endif(NOT APPLE)