https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105984
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:74e6a40335765077e235269f19d2d9905d0d9e44 commit r13-1133-g74e6a40335765077e235269f19d2d9905d0d9e44 Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Jun 16 14:36:04 2022 +0200 match.pd: Fix up __builtin_mul_overflow_p signed type optimization [PR105984] Earlier in the simplification pattern, we require that @0 has compatible type to the type of IMAGPART_EXPR, but for @1 which is a non-zero constant all we require is that it the constant fits into that type. Later the code checks if the constant is negative, because when min / max values are divided by negative divisor, lo will be higher than hi. In the following testcase, @1 has unsigned char type, while @0 has int type, so @1 which is 254 is wi::neg_p and we were swapping lo and hi, even when @1 cast to int isn't negative. We could use tree_int_cst_sgn (@1) < 0 as the check instead and it would work both for narrower types of @1 and even same or wider ones, but I've noticed we probably don't want to call fold_convert (TREE_TYPE (@0), @1) twice and when we save that result in a temporary, we can just use wi::neg_p on that temporary. 2022-06-16 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/105984 * match.pd (__builtin_mul_overflow_p (x, cst, (stype) 0) -> x > stype_max / cst || x < stype_min / cst): fold_convert @1 to TREE_TYPE (@0) just once and test for negative divisor also on that folded constant instead of on @1. * gcc.c-torture/execute/pr105984.c: New test.
