lookup_storage
struct storage *in = lookup_storage(entry->bb, arg, STOR_IN);
struct storage *out = lookup_storage(bb, pseudo, STOR_OUT);
struct storage *out = lookup_storage(bb, pseudo, STOR_OUT);
parent_out = lookup_storage(bb, pseudo, STOR_OUT);
child_in = lookup_storage(child, pseudo, STOR_IN);
struct storage *storage = lookup_storage(bb, phi->target, STOR_OUT);
struct storage *lookup_storage(struct basic_block *, pseudo_t, enum inout_enum);