https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69013
davidxl at google dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |davidxl at google dot com --- Comment #5 from davidxl at google dot com --- The assertion is indeed too strict. See static unsigned compute_uninit_opnds_pos (gphi *phi) { size_t i, n; unsigned uninit_opnds = 0; n = gimple_phi_num_args (phi); /* Bail out for phi with too many args. */ if (n > 32) return 0; ... } it is possible that empty bitset is returned -- so the fix looks ok.