SCEV: Make the final add of an inbounds GEP nuw if we know that the index is positive.
We can't do this for the general case as saying a GEP with a negative index doesn't have unsigned wrap isn't valid for negative indices. %gep = getelementptr inbounds i32* %p, i64 -1 But an inbounds GEP cannot run past the end of address space. So we check for the very common case of a positive index and make GEPs derived from that NUW. Together with Andy's recent non-unit stride work this lets us analyze loops like void foo3(int *a, int *b) { for (; a < b; a++) {} } PR12375, PR12376. Differential Revision: http://llvm-reviews.chandlerc.com/D2033 llvm-svn: 193514
Loading
Please register or sign in to comment