> Happens with UBSAN compiler for: > > $ gcc gcc/testsuite/gcc.c-torture/execute/pr71494.c -O1 -flto > ... > /home/marxin/Programming/gcc/gcc/ipa-modref-tree.h:550:33: runtime error: load > of value 255, which is not a valid value for type 'bool' > #0 0x18acc38 in modref_tree<tree_node*>::merge(modref_tree<tree_node*>*, > vec<modref_parm_map, va_heap, vl_ptr>*, modref_parm_map*, bool) > /home/marxin/Programming/gcc/gcc/ipa-modref-tree.h:550 > #1 0x188452c in modref_propagate_in_scc
At 4385 I have: changed |= cur_summary_lto->stores->merge (callee_summary_lto->stores, &parm_map, &chain_map, !first); parm-map is the vector, however there is no read of it. There is bool which is relevant only when parm_index is not unknown, so I suspect it may a full copy with uninitialized bool which would be harmless. We had similar issues with asan before. How do you build ubsan compiler? Honza