On Fri, Jun 29, 2018 at 12:04:22PM +0100, Dave Martin wrote:

Can sparse be hacked to identify pointer subtractions where the pointers
are cannot be statically proved to point into the same allocation?

sparse only see the (deatils of) the function it analyses and all
visible declarations, nothing more.

It would be more a job for smatch which do global analysis.
But to identify such subtractions yu must already have a (good)
pointer alias analysis which I don't think smatch do (but I can
be wrong, Dan & smatch's ml added in CC).

-- Luc Van Oostenryck