https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78684
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to amker from comment #6) > Ok, in this case I need to check idx_step is negative if it's signed type; > or idx_step has sign bit if it's unsigned type (negative step in effect). > tree_int_cst_sgn always returning 1 for (sizetype)-1 looks not working here? tree_int_cst_compare (idx_step, size_zero_node) < 0 would be also always false for unsigned types. Perhaps you can use wi::neg_p (idx_step) then, that will return true whenever idx_step in corresponding signed type (with the same precision as idx_step's type) is negative. But, is it right to consider those as negative steps? I mean, say for (unsigned long long c = 0; c < 0x8000000000000005ULL; c += 0x8000000000000001ULL) is actually positive step, not negative one.
