本页内容

新增 uvm_sequencer_base::get_arbitration_sequence / start() 重入检测改 mutex

其他行为变化

新增功能：目标库新增的 API 和可选替代接口；已有用法的迁移要求列在用户接口与行为中。

影响范围

重入 start 同一 sequence，或采用仲裁队列观察接口。

具体差异

新增只读仲裁观察 API；start() 重入检测行为等价（重复 start 仍 SEQ_NOT_DONE fatal）。

修改方案

无。

兼容措施与范围：本条是新增能力或实现说明，无需恢复旧接口；按使用条件核对行为。

迁移后验证

并发重复 start 应被诊断；正常重复启动前确认前次结束，仲裁索引限制在当前队列范围。

补充查阅

扫描定位与记录结果

无对应规则。当前脚本没有针对本条的直接检测规则。

本条处理级别为“可选采用”，按修改方案评估；缺少扫描规则本身不增加迁移改造要求。

扫描器下载、输入范围与报告说明

源码与标准依据

核查方式：源码核对。未单独进行 VCS 行为实测。

VCS 内置 UVM-1.2：uvm_sequence_base.svh:282 附近（start 用状态枚举做重入检查）

VCS 内置 uvm-ieee-2020-2.0：uvm_sequencer_base.svh:312/uvm_sequencer_base.svh:1292（get_arbitration_sequence(int index) 返回仲裁队列中第 index 个 sequence）；uvm_sequence_base.svh:149/uvm_sequence_base.svh:290（m_sequence_state_mutex.try_get 做重入检查）

引用代码（高亮为引用行）；上方行号链接可直接定位。

src/vcs-uvm-1.2/seq/uvm_sequence_base.svh
    end
    if (this_priority < 0) begin
       if (parent_sequence == null) this_priority = 100;
       else this_priority = parent_sequence.get_priority();
    end

    // Check that the response queue is empty from earlier runs
    clear_response_queue();

    m_priority           = this_priority;

    if (m_sequencer != null) begin
       integer handle;
       uvm_tr_stream stream;
       if (m_parent_sequence == null) begin
          stream = m_sequencer.get_tr_stream(get_name(), "Transactions");
          handle = m_sequencer.begin_tr(this, get_name());
          m_tr_recorder = uvm_recorder::get_recorder_from_handle(handle);
       end else begin

完整源码 · SHA256：1594d38afd79cb400a689fdbe6c8e33ff60714bb7527cd8d79739d9357b31682

src/vcs-uvm-ieee-2020-2.0/seq/uvm_sequencer_base.svh
  // Added in IEEE. Not in UVM 1.2
  // @uvm-ieee 1800.2-2020 auto 15.3.2.4
  extern virtual function uvm_sequence_base get_arbitration_sequence( int index );

  //----------------------------------------------------------------------------
  // INTERNAL METHODS - DO NOT CALL DIRECTLY, ONLY OVERLOAD IF VIRTUAL
  //----------------------------------------------------------------------------

  extern protected function void grant_queued_locks();


  extern protected task          m_select_sequence(output uvm_sequence_request selected_sequence_request);
  extern protected function int  m_choose_next_request();
  extern           task          m_wait_for_arbitration_completed(int request_id);
  extern           function void m_set_arbitration_completed(int request_id);


  extern local task m_lock_req(uvm_sequence_base sequence_ptr, bit lock);

src/vcs-uvm-ieee-2020-2.0/seq/uvm_sequencer_base.svh
// get_arbitration_sequence
// ---------------
function uvm_sequence_base uvm_sequencer_base::get_arbitration_sequence( int index);
  return arb_sequence_q[index].sequence_ptr;
endfunction


// analysis_write
// --------------

function void uvm_sequencer_base::analysis_write(uvm_sequence_item t);
  return;
endfunction


// wait_for_sequences
// ------------------

完整源码 · SHA256：6d2477484529dad661a38b31619edf9898bfa3375f217f06a27b3a69af32ccf7

src/vcs-uvm-ieee-2020-2.0/seq/uvm_sequence_base.svh
  // This semaphore is provided to ensure that a sequence is only being
  // run from a single thread at a time.
  protected semaphore          m_sequence_state_mutex;
  protected uvm_sequence_state m_sequence_state;
            int                m_next_transaction_id = 1;
  local     int                m_priority = -1;
            uvm_recorder       m_tr_recorder;
            int                m_wait_for_grant_semaphore;

  // Each sequencer will assign a sequence id.  When a sequence is talking to multiple
  // sequencers, each sequence_id is managed separately
  protected int m_sqr_seq_ids[int];

  protected bit children_array[uvm_sequence_base];

  protected uvm_sequence_item response_queue[$];
  protected int               response_queue_depth = 8;
  protected bit               response_queue_error_report_enabled;

src/vcs-uvm-ieee-2020-2.0/seq/uvm_sequence_base.svh
    set_item_context(parent_sequence, sequencer);

    if (m_sequence_state_mutex.try_get(1) == 0) begin
      uvm_report_fatal("SEQ_NOT_DONE",
         {"Sequence ", get_full_name(), " already started"},UVM_NONE);
    end

    if (m_parent_sequence != null) begin
       m_parent_sequence.children_array[this] = 1;
    end

    if (this_priority < -1) begin
      uvm_report_fatal("SEQPRI", $sformatf("Sequence %s start has illegal priority: %0d",
                                           get_full_name(),
                                           this_priority), UVM_NONE);
    end
    if (this_priority < 0) begin
       if (parent_sequence == null) this_priority = 100;

完整源码 · SHA256：aedbad6d9991d5712dd8e5e676a9fb5487ab33af52219ae4786e6adaa7001375

术语解释 · 兼容配置

返回Sequence / Sequencer · 迁移清单

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