from Imagemagick sources..
but you can try latest (dcraw 9.28) commit from this repo..
in theory it might make cingg's raw decoding a bit faster on opencl-capable gpu...
only performace claim I found was
"With an OpenCL version of dcraw.c converting an 6034x4012 NEF file to JPEG takes 4.7 seconds instead of 13.8 seconds on my machine.