In my case, I just had to delete the two lines in darktablerc file
cldevice_v4_intelrhdgraphics520=0 250 0 16 16 128 0 1 0.000000 cldevice_v4_intelrhdgraphics520_id0=400
then using darktable_cltest.exe, two new lines were written on that file
cldevice_v4_intelrhdgraphics520=0 250 0 16 16 128 0 0 0.118311 cldevice_v4_intelrhdgraphics520_building=-cl-fast-relaxed-math
any way thanks a lot for your quick answers