https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105533
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Testcase for the first compile time UB (-O3): long long a, b, c; void foo (long long e) { long long d = a & 9223372036854775808ULL; c = b; if (d && e) c = c | d; } Testcase for the second compile time UB (-O2): int a[64]; int p; void foo (void) { int stack_elt = 1; while (p) { stack_elt -= 11; a[stack_elt] != 0; } }