IL isn't binary code (simply by definition, IL == intermediate language). It isn't a big difference to have your source in C99 OpenCL or IL as most time consuming part is "IL to device ISA" compilation.
And at ISA level there are small differences (of course if you aren't using any R8xx specific instructions otherwise it'll be big differences) between R7xx & R8xx. There are even differences between 710 & 770 binary code or -- in general -- between any targets enumerated by CALtarget in cal.h.