code: def _last_branching_statement(statements):
          
          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
docs: 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