rewrite_branch
changed |= rewrite_branch(source, &br->bb_true, bb, target);
changed |= rewrite_branch(source, &br->bb_false, bb, target);
return rewrite_branch(bb, target_p, target, final);
changed |= rewrite_branch(bb, &insn->bb_false, old, new);
changed |= rewrite_branch(bb, &insn->bb_true, old, new);
changed |= rewrite_branch(bb, &jmp->target, old, new);