> > > > Except that it doesn't seem to work for even the simplest of test > > cases. For instance, it reports dont_know for two uses of the > > same SSA_NAME. > > > > This doesn't fill me with confidence ... > > We have code on autovec to do more advanced data dependence testing. > > However, in general, data dependence testing on pointers is a losing > proposition, because it involves a lot of aliasing work to determine > whether you could have put one piece of memory in the way of the other, > instead of just simple array dependence, where you know the aggregates > are disjoint.
I.E. you have to start proving a lot of stuff about the base, and verify the base doesn't change, etc. This is why most compilers implement array form recovery, even in cases where you are iterating through a pointer (recovering an indexing form), so that you can do regular data dependence stuff on it. This was my goal with the MEM_REF stuff.
