http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48702
--- Comment #18 from davidxl <xinliangli at gmail dot com> 2011-05-17 20:40:41 UTC --- (In reply to comment #17) > > This is not really heuristic -- it prevents compiler from generating code in > > ivopt that violates the aliasing assumption. > > no, it does not. Does, but may not fully do. > For example, you only consider the case whent the base of the > memory > reference is addr_expr, and when the step is negative. However, ivopts may > generate > "pointers" outside of the memory objects in other cases as well; Those would be bugs too -- do you have such examples? David > and if those > get used in > mem_refs (where the computations are currently interpreted according to the > pointer > arithmetics rules, for the purpose of alias analysis), this leads to > misscompilations.
