https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118915
--- Comment #13 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-13 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:9005efee26bf4a63a86953aeb6c0b93d7ceb2f0a commit r13-9591-g9005efee26bf4a63a86953aeb6c0b93d7ceb2f0a Author: Jakub Jelinek <ja...@redhat.com> Date: Mon Feb 24 12:19:16 2025 +0100 reassoc: Fix up optimize_range_tests_to_bit_test [PR118915] The following testcase is miscompiled due to a bug in optimize_range_tests_to_bit_test. It is trying to optimize check for a in [-34,-34] or [-26,-26] or [-6,-6] or [-4,inf] ranges. Another reassoc optimization folds the the test for the first two ranges into (a + 34U) & ~8U in [0U,0U] range, and extract_bit_test_mask actually has code to virtually undo it and treat that again as test for a being -34 or -26. The problem is that optimize_range_tests_to_bit_test remembers in the type variable TREE_TYPE (ranges[i].exp); from the first range. If extract_bit_test_mask doesn't do that virtual undoing of the BIT_AND_EXPR handling, that is just fine, the returned exp is ranges[i].exp. But if the first range is BIT_AND_EXPR, the type could be different, the BIT_AND_EXPR form has the optional cast to corresponding unsigned type in order to avoid introducing UB. Now, type was used to fill in the max value if ranges[j].high was missing in subsequently tested range, and so in this particular testcase the [-4,inf] range which was signed int and so [-4,INT_MAX] was treated as [-4,UINT_MAX] instead. And we were subtracting values of 2 different types and trying to make sense out of that. The following patch fixes this by using the type of the low bound (which is always non-NULL) for the max value of the high bound instead. 2025-02-24 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/118915 * tree-ssa-reassoc.cc (optimize_range_tests_to_bit_test): For highj == NULL_TREE use TYPE_MAX_VALUE (TREE_TYPE (lowj)) rather than TYPE_MAX_VALUE (type). * gcc.c-torture/execute/pr118915.c: New test. (cherry picked from commit 5806279610783805286ebcd0af3b455602a3a8f9)
