https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81323
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Another testcase from a different PR: __attribute__((noinline)) static int foo (int a, int b) { return a == b; } int bar (int a, int b) { return foo (a, b) != 0; } __attribute__((noinline)) static int baz (int a) { if (a > 10 || a < -10) return 0; return a; } int qux (int a) { return baz (a) == 42; } where if we determine that foo always returns [0, 1] and baz [-10, 10], then we can optimize that return ret != 0; into return ret; and ret == 42 into 0.