Search for the last branching exit, just like
        #   if (t12) { PUT(184) = 0xBADF00D:I64; exit-Boring }
        and then taint the temp variable inside if predicate

def _last_branching_statement(statements):
        """
        Search for the last branching exit, just like
        #   if (t12) { PUT(184) = 0xBADF00D:I64; exit-Boring }
        and then taint the temp variable inside if predicate
        """
        cmp_stmt_id = None
        cmp_tmp_id = None
        total_stmts = len(statements)
        statements = reversed(statements)
        for stmt_rev_idx, stmt in enumerate(statements):
            if isinstance(stmt, pyvex.IRStmt.Exit):
                stmt_idx = total_stmts - stmt_rev_idx - 1
                cmp_stmt_id = stmt_idx
                cmp_tmp_id = stmt.guard.tmp

        return cmp_stmt_id, cmp_tmp_id