https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114074
--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:a0b1798042d033fd2cc2c806afbb77875dd2909b commit r14-9193-ga0b1798042d033fd2cc2c806afbb77875dd2909b Author: Richard Biener <rguent...@suse.de> Date: Mon Feb 26 13:33:21 2024 +0100 tree-optimization/114074 - CHREC multiplication and undefined overflow When folding a multiply CHRECs are handled like {a, +, b} * c is {a*c, +, b*c} but that isn't generally correct when overflow invokes undefined behavior. The following uses unsigned arithmetic unless either a is zero or a and b have the same sign. I've used simple early outs for INTEGER_CSTs and otherwise use a range-query since we lack a tree_expr_nonpositive_p and get_range_pos_neg isn't a good fit. PR tree-optimization/114074 * tree-chrec.h (chrec_convert_rhs): Default at_stmt arg to NULL. * tree-chrec.cc (chrec_fold_multiply): Canonicalize inputs. Handle poly vs. non-poly multiplication correctly with respect to undefined behavior on overflow. * gcc.dg/torture/pr114074.c: New testcase. * gcc.dg/pr68317.c: Adjust expected location of diagnostic. * gcc.dg/vect/vect-early-break_119-pr114068.c: Do not expect loop to be vectorized.
