Thanks for the raw. I'm not familiar with the Canon G15, but this raw shows the most bizzare Adobe profiles I've ever seen. As I guessed in my original reply, the problem with clippiing on this image is all in the profiles.
True, there is no clipping in the raw, as others have shown with a raw analyzer. Far from it, in fact. But load this raw in LR or ACR and significant clipping shows up under the default settings, which use the "Adobe Standard" profile. But shift to any other profile and the clipping goes away.
The other profiles also give major shifts in color. That's common with the Adobe profiles for most camera models, but the shifts in color AND tone curves for this G15 image are greater than anything I've ever seen. Makes me a bit suspicious about the Adobe profiles for that camera.
In fact, if you shift this image to any other Adobe profile (faithful, camera standard, neutral), you can then increase exposure by 1 to 2 full stops before any clipping occurs.
I converted the cr2 sample to DNG and loaded it in the DNG profile editor to look at the tone curves. The base tone curve for the Adobe Standard profile is huge compared to the others. So it's that tone curve that is driving all the values beyond clipping. Looks like the G15 really, really needs custom profiles.