Method replace_var

src/jit/impl/executor_opr.cpp:456–465

    }
    VarNode* dest_var() { return m_dest_var; }
    void replace_var(VarNode* src, VarNode* dst) {
        // Note: do not perform var replacing recursively
        // when we extract used placeholders from internal graph, we don't
        // consider placeholder replacement pair (a to b), (b to c) as a
        // var replacing chain (a to b to c) but as a injective function
        // from (a, b) to (b, c)
        // in other cases, each var node would be passed as \p src or
        // \p dst at most once
        m_var_map[src] = dst;
    }
    void auto_replace_outputs(cg::OperatorNodeBase* opr) {
        // in JIT internal graph, output size of opr is always 1
        mgb_assert(opr->usable_output().size() == 1);